chemical thermodynamics of americium

CHEMICAL THERMODYNAMICS

OF AMERICIUM

Rol~ert J. SILVA (Cl~,(rr.~'rrraa) Lawrence Livemlore National Lal~oratory

Livern~ore~ Californial USA

Giovaln~i BIDOGLIO Envirolnnent I l~s t i t i~ te ; JRC, CEC

Ispra, Italy

Malcohn H. RAND Wint,ersHill Consilltallcy

Dry Sall(1fi)r~l~ Al)ing(lon, United Kingdom

Piotr B. ROBOUCH Instit,ute of Reference Materials ancl Measi~relnent,s~ JRC, CEC

Geel; Belgiiln~

Har~s WANNER MBT Environmelltal Engineeril~g Lt,d

Zilricl~; Switzerland

Ignasi PUIGDOMENECH OECD Nilclear Energy Agellcy, Data Bank

Issy-les-Moi~lineai~x, France

With an Appendix on "Chemical Thermodynamics of Uranium" written by:

Irlgrnar GRENTHE Ignasi PUIGDOMENECH Royal Irlstitl~te nf Techr~nlogy OECD Nllclear Energy ,\gency, Data Bank

Sto(:kholrn, Srve(ie11 Issy-les-Rlo~~lir~ea~~x, France

M. C. Arnaia SrllUDINO \lalcolrn H. RAND Kar l s r~~he , Germany WntersHill Cor~sl~ltar~cjr

Dry San(ifor(1, rll)ing(ior~, United Kirlg(1orn

NUCLEAR ENERGY AGENCY ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT

ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT

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NUCLEAR ENERGY AGENCY

The OECD Nuclear Energy Agency (NEA) was established on 1st February 1958 under the name of the OEEC European Nuclear Energy Agency. It received its present designation on 20th April 1972, when Japan became its first non-European full member. NEA membership today consists of 28 OECD member countries: Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Luxembourg, Mexico, the Netherlands, Nomay, P o d g a l , the Republic of Korea, the Slovak Republic, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The Commission of the European Communities also takes p& in the work of the Agency.

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In these and related tasks, the NEA works in close collaboration with the International Atomic Energy Agency in Vienna, with which it has a Co-operation Agreement, as well as with other international orgmisations in the nuclear field.

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11 1 1 , 1 1 - .I L\ I~I 11111.1. .I#. . b . 11 .Ic . I IL ' 'I 1 111. . ]c - il II..I--.\II~II.III.. - 1'111- 1 1 11.. 1 ~ 1 11-1 1 1 - I- - I l i 11- I I 11 c - I, 1 . 1 L \ d \ ..III.II\ L\.1111 11.. l I.III.I >11rc. I,. 11.. 1 , . 1 1 ~ . l \11I~.lICI11.1..1.,. . l 1 1 1 1 1 1 , . 1 1 1 l l l . L . l 1 1 . 1 . 1 1 1 1 . II., ' . 1 1 \ 1 1 J . 1 . . Clearance Center, ~ u i o m e r Service, (508)750-8400, 222Rosewood D&, Danvers, MA 01923, USA, CCC &lie : h t t p : lh . copy igh t . cod . All other applications for permission to reproduce or translate all or p~ of this book should be made to OECD Publications, 2, rue Andre-Pascal, 75775 Paris Cedex 16, France.

Editor's note to the 2004 reprint

The present volume is a reprint of the 1995 edition of Chemical Thermodynamics of

Americium by Robert J. Silva, Giovanni Bidoglio, Malcolm H. Rand, Piotr B.

Robouch, Hans Wanner and Ignasi Puigdomenech, which also contains an Appendix

on the Chemical Thermodynamics of Uranium by Ingmar Grenthe, M. C. Amaia

Sandino, Ignasi Puigdomenech and Malcolm H. Rand. The book was edited at the

NEA Data Bank and published by Elsevier under the North-Holland imprint.

As part of Phase I1 of the NEA Thermochemical Database Project (TDB), a new

publication entitled Update on the Chemical Thermodynamics of Uranium,

Neptunium, Plutonium, Americium and Technetium and authored by Robert

Guillaumont, Thomas Fanghanel, Jean Fuger, Ingmar Grenthe, Volker Neck, Donald

A. Palmer and Malcolm H. Rand, was published by Elsevier in 2003. For americium

(and for the topics dealt with in the 1995 Appendix on uranium), this Update contains

a review of the literature published since the cut-off date for the literature reviewed in

the 1995 edition cited above. As a consequence of this new TDB Review, some of

the values selected in the earlier publication have been superseded while others have

retained their validity. The 2003 Update is self-contained with respect to any new

data selections, but the discussions leading to the retained selections can in most cases

only be found in the 1995 publication. Since the latter is no longer available from its

original publisher, the NEA is making the present reprint available to the scientific

community. Consequently, I? is important to note that the Tables of Selected Values

contained in this reprint ARE OUTDATED AND SHOULD NOT BE USED. The

updated Tables and the rationale behind the new and updated selections can be

consulted in the above-mentioned 2003 Update.

This reprint has been prepared at the NEA Data Bank by Federico Mompean,

Myriam Illemassene and Jane Perrone by reprocessing the files employed in the

production of the 1995 edition. Every effort has been made to preserve the original

layout and page numbering. We are grateful to the many readers who have provided

feedback and pointed out errors in the 1995 book. In an attempt to make this reprint

as close a reproduction of the original publication as possible, we have not

implemented any corrections - major issues having been dealt with in the 2003

Update.

Preface

This is the sccorltl volnrnc in n scrics of critical rcvic\vs of t,llc cllcrrlicnl thcrmotlynamic dat,a of t,llosc clcrrlcnts of part,iciilnr irnport,ancc in the safety asscssmcrlt rrlodcling of high-lcrcl radioactive \~~ast,c storage and tlisposal facilities. The Nllclcar Energy .Igcncy (YE.$) Thcrrnodynnrnic Data Base (TDB) project urns st,art,ctl in 1984 by the Organisnt,ion for Ecorlomic CO-opcmt,ion and Dcvcloprncnt (OECD). Tllc ohjcct,ivc, as ollt,lincd in YE.$-TDB report 0. urns t,o tlcvclop a set of rclial~lc thcrmotlynamic dat,a that conltl i)c iiscd t,o tlcscril)~ t,llc hchavioiir of these clcrrlcnt,~ iindcr co~ltlit,ions rclcxi~,nt for rntlionct,ivc \~~ast,c disposal syst,cms nrltl the gcochcmical cnvironrncnt,~. Tllc init,iat,ion of t,llis pccr review of t,hc t,hcrrnodynamic data of arncricillrn rcsiiltcd from disc~lssiorls hct,\~~ccn Hnrls Wanner, t,llc TDB projcct lcntlcr at t,llat t,irnc, nrltl the cllairmar1 t,llat t,ook place tlllrirlg the JVorkshop on Gcochcrrlical hlodcling at, Fallcn Lcnf Lake; California in Scptcrrlhcr 1986. -4 rrlccting was held at t,hc NE.4 Dat,a Bank, Saclay, France. in Scptcrrlhcr of 1987 \vhcrc the initial rcvic~v comrrlit,t,cc rrlct for the first t,imc and nrhcrc review philosophy. assignmcrlt,~ and corrlrrlitmcrlt,~ ~vhcrc tlisciissctl. Prcscnt at t,his rnccting, in addition to the chairman. nrcrc Dr. B. .Illart1 (Linkiiping, S~vcdcn). Dr. G. Bidoglio (.JRC Ispra, It,nly) nrltl Dr. 11. Rnrltl (-4ERE Har\~rcll. U.K.). Rcprcscnt,ing t,llc NE.4 TDB projcct nrcrc Drs. H. Wanner nrld I. Poirot,. .I sccond mcct,ing as held at the YE.% Data Bank, Saclay, in llny of 1990. .It t,his rnccting, first draft rcvic\vs of sorrlc of t,llc scct,ions of the .%m rcric\v wcrc sllhrrlitt,cd nrltl tlisciissctl. Bccaiisc of his work schcdiilc; Dr. -4llard as 1l11al)lc to rrlakc cont,rih~lt,ions to the r e ~ ~ i c w n11d IITGS rc~~lnccd by Dr. P. Rol)o~~Ch (IRhIlI, Gccl, Bclginrn). Dr. I. Pnigdorncncch hccnrrlc the TDB project dircct,or in 1992 nrltl nssnrncd orcrsight of t,hc final st,ngcs of t,llis rcric\v.

This is n review of cxpcrirncntal dnt,n rcport,ctl in t,llc lit,crat,llrc for arncricillrn. On n fc\v occasions. ~vllcrc no tlat,a cxist,ctl; compnrisorls and cst,irnatcs nrcrc rnadc i)ascd on cxpcrirncntal data on analog lant,llanidc clcmcnt,~. The l~asic philosophy urns t,o develop a rrlinirrlllrrl set of solitl phases arid solllt,ion species of arncricillrn t,hnt \~ronltl fit all cxpcrirncrlt,nl tlat,a hcing rcric\vctl.

Each comrrlit,t,cc part,icipnrlt cont,rihllt,ctl sclcct,cd rcvic~v scct,ions. Giovanni Bidoglio contril)iit,cd t,hc scct,ions on hytlrolysis prodnct,~. llalogcrl cornplcxcs nrltl hydroxitlc solids. Elcrrlcnt,al .Irn. aqua ions. oxitlcs and cornpounds of t,llc hnlogcns, snlph~lr, nit,rogcn, phosphorous. etc. nrcrc tlrnft,ctl by lInlcolm Rnntl. Tllc data on s~llphatc, nit,mt,c; phosphat,c. carl)onnt,c nrltl t,hiocynnat,c corrlplcxcs n7crc rcric\vctl by the chairman, by Piotr Robo~lch and by Ignasi Plligdorrlcncch in close collnhorat,ion. 1l:hcn the scctiorls n7crc cornplct,ctl and nsscrrlhlcd int,o one vol~lrnc, all t,llc rncmbcrs of the

tcam crit,ically rcvic\~rcd t,llc cntirc ~~oli imc. Tllc final st,cp. hcforc snbrnission for publicat,ion, was a t,ccllnical review 1)y t,hrcc intlcpcndcnt rcric\vcrs. Drs. Charles Bacs, Lcst,cr hlorss and .%rt,hnr ilartcll. and as a jiidgcrrlcrlt of the pccr review according to rrlct,llods oiit,linctl in YE.%-TDB report 6.

This rcric\v has bccn a very long t,imc in cornplct,ion. It n~ollld not have hccn possible ~vit,lloiit t,hc constant at,tcntiorl and prodding of Harls Ilknncr and, in the lat,cr stages; Ignasi Plligdorncncch. hIy pcrsonal t,harlks t,o t,llc rncmbcrs of t,llc rcric\v tcam \~rllo remained tlcdicat,cd and diligent t,o t,llc end. On hchalf of t,hc rcric\v t,carn; I \voiild like t,o t,harlk t,hc many collcag~lcs ~vho lla~rc llclpctl arltl supported 11s in the corrlplctiorl of t,llis rcric\v.

Li~~crrnorc. California, Scpt,cmbcr 1994 Ro1)crt J . Silva, Chairman

Acknowledgement S

Tllc contril)iit,ions of Rol~crt J . Silvn nrcrc prepared as a Yucca hIoiint,ain Site Char- nctcrizat,ion Project (YRISCP) part,icipnrlt as part of the Civilinn Radioact,ivc Ilkstc hlarlagcrrlcnt Program. Tllc YlISCP is rnanagcd by t,llc Yucca hlonntain Sit,c Char- nctcrizat,ion Projcct Officc of t,llc U.S. Dcpart,rncnt of Energy. Yucca lIo~lrlt,ain Sit,c Charact,crizatio~l Projcct work is sporlsorctl1)y the DOE Officc of Civilian Radioact,ivc \Vnstc hlanngcrncnt,. A% snbst,a~~t,ial part of t,llc rcric\v ~vork carried out 1)y h'1.H. Rand was fiindcd by the

Corporate Rcscnrcll Progrnrrlmc of .$E.% Tcc;hnology; Har11~11. while llc was employed by t,llc U. K. .%t,ornic Encrgy .%iit,llorit,y.

P.B. Rollouch nro~lld like t,o t,hnrlk t,llc La\vrcncc Livcrrrlorc Xnt,ional Lnborat,ory for finnrlcinl slipport tl~lrirlg his postdoct,ornl stay.

Tllc follo~ving tllrcc intlcpcndcnt cxpcrt,s have rcvic\~~cd t,hc contents of the present book (cxcliiding .%ppcndix D) accortling to the pccr review procctl~lrcs (cf. [90\V.4N]) prepared for this piirposc in t,hc framc~~wrk of the NE.% Thcrrrlochcrrlical Data Base project,. They have vic~vcd nrltl approved t,hc rrlodificnt,ions rnadc by t,hc aiit,llors nccortling to their cornmcnt,~. Tllc pccr rcvic~v comrrlcnt records rnay l)c obt,airlcd on rcq~lcst fiorn t,hc OECD Xnclcnr Encrgy .%gcncy.

Dr. C.F. Bacs. Jr. Oak Ridge Nat,ionnl Lal~oratory, Oak Ritlgc, Tcnncsscc, US.% (Rct,ircd)

Prof. .%.E. hIart,cll Tcxas .l. and h1. Univcrsit,y, Collcgc Station, Tcxas. US.%

Dr. L.R. hlorss -4rgonnc Xnt,ional Laboratory, .%rgonnc; Illinois. US.%

\VC arc grat,cfiil t,o t,llc rncmbcrs of l)oth t,llc NE.% Radioacti~rc \Vast,c hlanagcmcnt, Corrlrrlitt,cc and it,s Pcrforrrlancc .4sscssrncnt .%dvisory Group for their g~lidancc nrltl nssistancc in seeking finnrlcinl slipport for t,his rcvic\v. I\? t,hnrlk the support nrltl crlco~lrngcrrlcnt of t,hc follo~ving persons ~vit,llin t,hc NE.4: Dr. K~lnihiko Ucrnat,sn, Director Gcrlcral; Dr. Philippc Snvclli. Dcpiit,y Dircct,or; Scicncc. Computing nrltl Dcvclopmcnt,; hlr. Jcnn-Picrrc Olivicr; Hcntl of t,llc Division for Radiat,ion Prot,cctiorl nrld Radioacti~rc i\:ast,c hlanngcrncnt,; Dr. Nigcl Tiil)bs and hlr. Clacs Nordl~org, of the Data Bank; Dr. Etl\~rard Pat,cra of the Division for Radiat,ion Prot,cct,ion nrltl Waste lInrlagcrrlcnt; nrltl Mrs. 1sal)cllc Forest and Mrs. Sncha Koo-Oshimn of the

Dat,a Bank. The NE.4 TDB dat,a base systcrn (cf. Forc~~wrd and Scct,ion 11.6) has bccn tlcvclopcd and rnaintaincd ~v i th cnthiisiasm by Dr. Picrrc Nagcl of the NE.4 Dat,a Bank. Thanks arc tl~lc t,o S. Girod and L. hlorcl for their forrnatt,ing arltl ctliting help.

\VC arc grat,cfiil t,o Prof. I. Grcrlt,hc Royal Inst,itiit,c of Technology, Stockholm, Swcdcn, for his cngagcmcnt arltl irlt,crcst in t,hc NE.4 TDB project,, arltl for allo~ving us to reproduce t,llc t,cxt in .4ppcndix B of t,hc i lmni~nn rcvic~v [92GRE/FUG].

In addit,ion. nrc t,llank the follo\~.ing for t,llcir t,cchnical corrlrrlcnts and s~lggcs- tions in the coiirsc of t,llc project: E. Falk. 11's .It,kins Intcrnat. Ltd.. Berlin. Gcr- rnnny; J. Fiigcr, Corrlmissiorl of the European Cornmnnit,ics; JRC; Karlsriihc, Gcr- rnnny; E. Giffant. .4XDR.I; Font,cnay-a~lx-Roscs; Francc; C. Pcscat,orc; NE.4, Issy-lcs- hlo~llincaiix. France; J. Rytlhcrg. Radiochcrnist,ry Consliltant Groiip .$B, l'.. Friilnnda, Swcdcn; K. Spahin, hIBT Tccnologia -4rnhicntal; Ccrdanyola. Spain; P. I7it,orgc, Corn- rnissariat a 1'Encrgic .4torniqiic, Fontcnay-aiix-Roses. Francc; hI. Nli. Power Rcact,or and Xnclcar Fuel Dc~~cloprncnt Corporation, Tokai LInra, Japan.

This hook has hccn prcparctl ~vit,ll the aid of the UTEX corrlp~lt,cr typcsctt,ing sofi~varc [86L.4h'I]. Most of the graphs n7crc produced nrit,h t,llc GNUPLOT plott,ing program, originally n ~ i t t , c n by T . I4:illiarns and C. Kclly (WTEX oiit,p~lt option written by D. Kotz arltl R . Lang). Ilkightcd least,-squares fit,ting was pcrformctl ~vit,ll cit,llcr t,hc Dcrrling program by Rinard and Goldrrlan [88RIN/GOL], t,llc DNLSlE- siibrontinc of t,hc S L - T E C library [80HAIS/\:.4X, 84BUZI; or t,llc XLIN proccdnrc of the S.4S soft,\~~arc package [88SAIS].

Tllc aut,hors also t,harlk t,llc follo\ving for t,llcir pcrrnission t,o rcprotl~lcc copyright, rnntcrial: The .4mcrican Irlstitiit,c of Physics and D.D.\Vagrnan (Nat,ional Irlstitiit,c for Scicrlcc and Tcchnology) for their pcrrrlision t,o reproduce Figure 11.1; t,llc Comrrlit,t,cc on Dat,a for Scicncc and Tcchnology, COD.4T.I; for their permision t,o rcprotl~lcc a scnt,crlcc in Chapt,cr 11,'.

Foreword

This is t,hc sccorltl ~~ol i imc of n scrics of cxpcrt rcvic~vs of t,llc chcmical t,hcrrnodynarnics of key chcmical clcrrlcnt,~ in niiclcar t,cchnology and wast,c rnanngcrncnt,. \~'olnrncs on tcchnctinrn, ncpt,~lniiim and pl~lt,orliiim arc ciirrcnt,ly in progress. Tllc rccomrrlcndcd thcrrnodynarnic data arc t,llc result of a crit,ical asscssrncnt of pnblishcd information.

Tllc tlat,a base syst,cm dcrclopctl at t,llc Dat,a Bank of the OECD Ynclcnr Encrgy .kgcncy (YE.k),(:f. Scct,ion 11.6, cnsiircs consistency not only ~vit,llin t,hc rccomrrlcndcd dat,a set on amcricinrn hut also arnong all t,hc data sct,s to bc piii)lishctl in t,llc scrics. Tllc YE.k's t,hcrrnochcmical dnt,n i~asc (TDB) syst,crn takes ntlvantagc of t,hc fimc- tionalit,y of t,llc UTEX dociimcrlt prcpnrnt,ion soft,~varc [86L.%LI], and is tlcsignctl t,o rctricvc t,hc dnt,n base nrltl const,riict t,nhlcs of sclcctctl tlat,a. nut,hors. rcfcrcnccs etc. in WTEX format. ~vhich t,llcn can i)c inscrt,cd in the compntcr files t,hnt const,it,~lt,c the books in t,llis scrics.

Tllc YE.$ Dat,a Bank provides n nnrnhcr of scrriccs that may bc ~lscfill t,o the rcadcr of t,llis hook.

The rccorrlmcrltlcd data can i)c oht,nincd on clcct,rorlic rrlcdin (PC diskct,tcs. magnetic t,apc, or via corrlp~lt,cr nctn~xks) dircct,ly fiorn t,llc YE.$ Dnt,n Bank. The special forrrlat,t,irlg of the tlat,a allo~vs corlvcrsion t,o any specific formnt,~ corlvcnicrlt t,o t,hc iiscr. The dcsigrl and dcrcloprncnt of a corrlp~lt,cr progrnrrl t,o perform s~lcll forrrlat corlvcrsion is ho\vcvcr left t,o the user.

The NE.$ Dnt,n Bank rnaint,nins a lihmry of cornpiit,cr progrnrrls in vnrioiis areas. This incl~ltlcs gcochcrrlical codes such as PHREEQE, EQ3/6, LIINEQL, LIINTEQ, PHRQPITZ, etc., in ~vhich chcmical t,hcrrnodynarnic tlat,a like those prcscnt,cd in this hook arc rcqiiircd as the i~asic i11l)iit dnt,n. Thcsc cornpiit,cr cotlcs can bc oi)t,ainctl on rcq~lcst fiorn the NE.$ Dnt,n Bank.

For requests of tlat,a. compntcr programs. on-line access; and for fi~rt,llcr inforrna- tion. plcnsc \vrit,c t,o:

OECD N~lclcar Encrgy .$gcncy; Dnt,n Bank Lc Scinc St. Gcrrrlain 12, i)onlcvnrd dcs Ilcs F-92130 Issy-lcs-Llonlincn~lx; FR.$NCE

or scrltl clcctronic mail t,hrongh INTERYET to ,'tdb:cQnea.fr". Sorrlc inform. a t ' ,ion on the NE.$ is also nvailablc on the World-Wide Ilkh at "http://www.nea.fr".

Contents

I Introduction 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Ba<:kgro~mcl 1

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 . 2 Fncns of t . l ~ e review 2 1.3 Isotopes of arr~ericil~rr~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.4 Review proce(il~re ar~rl res111ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

I1 Standards. Conventions. and Contents of the Tables 7 . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Syrnt)ols. t. errninology and nornr?rl<.lat. w e 7

11.1.1 .k 1)t)reviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 11.1.2 Syrnl~ols and terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 11.1.3 Chemical forrr1111ae and nornen<.lat. w e . . . . . . . . . . . . . . . . . . . . . . 7

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.4 Phase designat. ors 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.5 Processes 12

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.6 Eq~~i l i t ) r i~~rn cor~st. ants 13 . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.6.1 Protorlatior~ of a ligarlrl 14

. . . . . . . . . . . . . . . . . . . 11.1.6.2 Forrrlat. ior~ of 111eta1 ior~ <:ornplexes 14 . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.6.3 So111t)ilit. y cor~star~ts 16

. . . . . . . . . 11.1.6.4 Eq~lilil~ri a. irlvolvir~g the acldition of a gaseous ligancl 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.6.5 Reclox eq11i1it)ria 17

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.1 pH 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.8 Order of forrr1111ae 20

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.9 Referer~ce corles 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Unit. s and conversion fact. ors 21

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Stanrlarcl ar~rl refererlee conclit. ions 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3.1 St. anclard state 24

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3.2 St. anclard state pressllre 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3.3 Referer~ce ternperat. w e 28

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4 F~~r~rlarr~er~t . a1 physical cor~star~ts 28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.5 Ur~cert.air~t. y estirr~at. es 29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6 The 1UE.k-TDB systern 29

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.7 Preser~tatior~ oft. l ~ e selecte(i rlat. a 31

I11 Selected americium data 35

IV Selected auxiliary data 45

V Discussion of data selection 69 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l Elerr~er~tal arrlerlclllrrl 69

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l .k rnenc~~nn rr~etal 69 . . . . . . . . . . . . . . . . . . . . . V . l . l . l .k llotro1~y and cryst. a1 st. n ~ c t ~ ~ r e 69

V.1.1.2 Low-ternperat~lre heat capacity arlrl stan(iarr1 entropy . . . . . . . . 70 V.1.1.3 High-ternperat~~re lleat capacit. y ancl trar~sforrr~at. iorl data . . . . . . 70

CONTENTS

2 Arnrricilnn irlral rr~or~oatorr~ic gas . . . . . . . . . . . . . . . . . . . . . . . . . 71 V.1.2.1 Heat <:apacity ar~rl entropy . . . . . . . . . . . . . . . . . . . . . . . 71 V.1.2.2 Enthalpy of rxporizatior~ . . . . . . . . . . . . . . . . . . . . . . . . 72

V.2 Simple arr~rri<:i~~rn aq11 a. ior~s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 V.2.1 .A ri'+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 V.2.2 .Am"+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 V.2.3 .A rn4+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 V.2.4 .ArnO: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 V.2.5 .A rnOZt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

V.3 Oxygen ancl hyrlrogrn cornpol~n(is and cornplrxrs . . . . . . . . . . . . . . . . . . . . 79 V.3.1 .A (ll~eolls arr~rri<:i~~rn hy~lroxi~le cornplrxrs . . . . . . . . . . . . . . . . . . . . 79

V.3.1.1 r lql l ro~~s Arn(II1) hy~lroxi~le cornplrxrs . . . . . . . . . . . . . . . . 79 V.3.1.2 r lql l ro~~s .Am(\') and .A rn(\'I) hy(iroxir1r <:ornplexes . . . . . . . . . . 87

V.3.2 Solid arr~rri<:i~~rn oxicles ar~rl l~yrlroxirlrs . . . . . . . . . . . . . . . . . . . . . . 89 V.3.2.1 T l ~ r arr~rri<:i~~rn-oxygen systrrn . . . . . . . . . . . . . . . . . . . . . 89 . . V.3.2.2 .A rnrri<.illrn s r sq l~~ox~( i r . . . . . . . . . . . . . . . . . . . . . . . . . 90 . . V.3.2.3 .A rnrri<.illrn rl~ox~(ir . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 V.3.2.4 Solid rlrn(II1) l~yrlroxirlrs . . . . . . . . . . . . . . . . . . . . . . . . 92 V.3.2.5 .A rn(1V) ancl .A rn(V) hy~lroxi~les . . . . . . . . . . . . . . . . . . . . 96 V.3.2.6 Ternary and q~laterr~ary arr~erici~~rr~ oxirlrs . . . . . . . . . . . . . . . 97

V.3.3 Arnrrici~nn hy(iri(irs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 V.3.3.1 T l ~ r arr~rri<:i~~rn-hy~lr(>grr~ syst. ern . . . . . . . . . . . . . . . . . . . . 99 V.3.3.2 .A rnrri<.illrn rlihy~lri~le . . . . . . . . . . . . . . . . . . . . . . . . . . 99 V.3.3.3 .A rr~rri<.illrn trihy(iri(ir . . . . . . . . . . . . . . . . . . . . . . . . . . 100

4 Grol111 17 (halogen) cornpol~n(is and cornplrxrs . . . . . . . . . . . . . . . . . . . . . 101 l .A (ll~eolls gro1111 17 ha log er^) cornplrxrs . . . . . . . . . . . . . . . . . . . . . . 101

V.4.1.1 r lql l ro~~s Arn(II1) f l~~nridrs . . . . . . . . . . . . . . . . . . . . . . . 101 V.4.1.2 r lql l ro~~s Arn(II1) cl~lorir~r c ~ r r ~ ~ ~ l e x e s . . . . . . . . . . . . . . . . . . 103 V.4.1.3 r lql l ro~~s Arn(II1) t)rornirlrs ar~rl io(iir1rs . . . . . . . . . . . . . . . . 105 V.4.1.4 Higher oxiclatior~ states of arnrri<:il~rn . . . . . . . . . . . . . . . . . 106

V.4.2 Arnrrici~nn l~alirlr cornpo~~nrls . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 V.4.2.1 Intro(il~<:tior~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 V.4.2.2 .A rnrri<.illrn f l~~nr idr ~ O I I I ~ I O I I I I ~ S . . . . . . . . . . . . . . . . . . . . . l08 V.4.2.3 .A rnrri<.illrn chlori~lrs . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 V.4.2.4 .A rnrri<.illrn t)rornirlrs . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 V.4.2.5 .A rnrri<.illrn io~li~les . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

5 Grol111 16 (<:halcogrn) cornpol~n(is ancl cornplrxrs . . . . . . . . . . . . . . . . . . . . 125 l S I I ~ ~ ~ I I I ~ cornpo~~nrls and <:ornplexes . . . . . . . . . . . . . . . . . . . . . . . . 125

V.5.1.1 .A rnrri<.illrn sl~lphidrs . . . . . . . . . . . . . . . . . . . . . . . . . . 125 V.5.1.2 .A rnrri<.illrn sl~lphatrs . . . . . . . . . . . . . . . . . . . . . . . . . . 127

5 2 S r l r r ~ i ~ ~ r r ~ <:ornpo~m(ls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 V.5.2.1 Srlrni~lrs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

5 3 T e l l ~ ~ r i ~ ~ r r ~ ~ O I I I ~ I O I I I I ~ S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 V.5.3.1 Trlll~rirlrs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 V.5.3.2 .A rnrri<.illrn oxytrlll~rirlr . . . . . . . . . . . . . . . . . . . . . . . . . 134

6 Grol111 l 5 cornpol~n(is and cornplrxrs . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 6 l Nit. roger1 cornpol~n(is ancl cornplrxrs . . . . . . . . . . . . . . . . . . . . . . . 134

V.6.1.1 .A rnrri<.illrn r~itricles . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 V.6.1.2 .A rnrri<.illrn azirlr cornplrxrs . . . . . . . . . . . . . . . . . . . . . . . 135 V.6.1.3 .A rnrri<.illrn r~itrit. r <:ornplexes . . . . . . . . . . . . . . . . . . . . . . 136 V.6.1.4 .A rnrri<.illrn r~itratr cornpol~n(is ancl corr~~~lexes . . . . . . . . . . . . 136

V.6.2 Phosphon~s cornpo~~nrls and <:ornplexes . . . . . . . . . . . . . . . . . . . . . . 139 V.6.2.1 r lql l ro~~s arr~rricil~rr~ phosphor~~s cornplrxrs . . . . . . . . . . . . . . 139 V.6.2.2 Solid arr~erici~~rr~ phosphor~~s cornpol~n(is . . . . . . . . . . . . . . . . 144

... CONTENTS xl11

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.6.3 Arsenic <:ornpo~m<ls 145

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.6.3.1 ..l r$rni<irs 145

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.6.3.2 Arsrr~ates 146 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.6.4 .k ntirnony <:ornpo~mcls 146 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.6.4.1 ..l ntirr~oni~lrs 146

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.6.5 Bisrm~th <:ornpo~mcls 147 P . . . . . . . . . . . . . . . . . . . . . . . . . . . V.7 Grol111 14 cornpol~n(is and corr~plrxrs 141 P . . . . . . . . . . . . . . . . . . . . . . . . 7 l Cart~on <:ornpo~mcls ar~rl cornplrxrs 141

. . . . . . . . . . . . . . . . . . . . . . . . . . . V.7.1.1 .A rnrricillrn carl~iclrs 147 V.7.1.2 .A rnrri<.illrn carl~onatr <:ornpo~mcls ar~rl corr~plrxrs . . . . . . . . . . . 148

. . . . . . . . . . . . . . . . . . . . . V.7.1.3 .A rnrri<.illrn cj~aniclr cornplrxrs 165 . . . . . . . . . . . . . . . . . . . V.7.1.4 ..l rnrri<.illrn thio<:pnate cornplrxrs 166

P . . . . . . . . . . . . . . . . . . . . . . . . V.7.2 Sili<:on <:ornI~o~mcls ar~rl cornplrxrs 110 . . . P . . . . . . . . . . . . . . . . . . . . . . . . . . . V.7.2.1 .A rnrri<.illrn s ~ l ~ c ~ r l r s 110

. . . . . . . . . . . . . . . . . . . . . . V.7.2.2 r l q l ~ r o ~ ~ s arr~rricil~rr~ silicates l71 . . . . . . . . . . . . . . . . . . V.7.2.3 Solid a r r~r r ic i~~rr~ silicat. r cornpol~n<is l71

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.7.3 Gerrr~ar~il~rr~ cornpol~n<is 171 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Grol111 13 cornpol~n(is 171

P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.8.1 .k 111rnini11rn i:ornpo~mcls 111 P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.8.2 T l ~ a l l i ~ ~ r r ~ corr~po~~nrls 111

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Grol111 9 cornpo~~nr l~ 172 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l Cot)alt corn1)ol~n(is 172

P' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.10 Grol111 6 corr~plrxrs 112 P' . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.10.1 Rlolyl)<iates ancl tlmgst. airs 112

. . . . . . . . . . . . . . . . . . . . . . . . . V.10.2 P o l y ~ ~ h o s ~ ~ h o t ~ ~ r ~ g s t a t p cornplrxrs 172 P' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.11 Grol111 5 cornplrxrs 112 P' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.12 Grol111 4 corr~plrxrs 112

. . . . . . . . . . . . . . . . . . . . . . . . . . . \:.l3 rlctirlirle C C ) I ~ I ~ C ) I ~ I L < ~ S a l ~ i I:OIII~~PXPS 172 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.13.1 .k ctini~lr cornpol~n<is 172

P' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.13.1.1 Un .;.km, ,.502(cr) 112 . . . . . . . . . . . . . . . . . V.13.1.2 Ot. l ~ r r ternary and qlat. ernary oxiclrs 173

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V . 13.2 .k ctini~lr cornplrxrs 173 . . . . . . . . . . . . . . . . . . . . . . V.13.2.1 .k<.tir~irlr-act. ini<ir ir~teract. ior~s 173

V.14 Gronp 2 (alk~lirlr-rartt~) arlrl gronp 3 corrq~onr~rls . . . . . . . . . . . . . . . . . . . . 173 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.15 Grol111 1 (alkali) cornpol~n<is 173

P l T r l ~ t r r a r y x i s . . . . . . . . . . . . . . . . . . . . . . . . . . 113 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.15.2 Trrr~ary fll~orirlrs 173

P V.15.3 Trrr~ary ar~rl q~~a t r rna ry <:hlori<irs . . . . . . . . . . . . . . . . . . . . . . . . . 113 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.15.4 .k l h l i sl11ph;~trs 174

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.15.5 .k l h l i phosphat. rs 174 P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.15.6 .k l h l i arsrr~atrs 114 P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V.15.7 .k l h l i carl~onatrs 114

V1 Reference list 175

V11 Authors list 213

V111 Formula list 229

A Discussion of selected references 243

xiv CONTENTS

B Ionic strength corrections 311 B.l Tile sl~ecific iorl irlteract. iorl ecll~at. ions . . . . . . . . . . . . . . . . . . . . . . . . . . . 312

B . l . l Backgrolln(i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312 0.1.2 Iorlic strerlgtll correctiorls a t ternperat. ures otller t. llarl 298.15 K . . . . . . . . 316 0.1.3 Estirrlat. iorl of iorl irlteract. iorl coeffic:ients . . . . . . . . . . . . . . . . . . . . . 318

B.1.3.1 Estirr~atior~ frorrl rrlearl activity c:oefficient rlat. a . . . . . . . . . . . . 318 B.1.3.2 Estirrlatiorls t)ase(i on experirr~ental x~ahles of ecll~ilil~rillrn c:onstants

a t cliffererlt ionic: strerlgtlls . . . . . . . . . . . . . . . . . . . . . . . 318 0.1.4 On t. lle rrlagrlitllrle of iorl irlteractiorl coefficierlt. s . . . . . . . . . . . . . . . . . 322

B.2 Iorl interac:tior~ c:oefficier~ts afmsrrs ecll~ili l~ri~~rn cor~star~t. s for iorl pairs . . . . . . . . . 323 B.3 Tal~les of iorl ir~teractior~ c:oefficier~ts . . . . . . . . . . . . . . . . . . . . . . . . . . . 323

C Assigned uncertainties 333 C. l OIIP sollrc:~ (iat~lrrl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 C.2 Two or rrlore inrle~~er~cler~t sollrce (iat a . . . . . . . . . . . . . . . . . . . . . . . . . . 334

C.2.1 Discrepancies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336 C.3 Several rlat. a a t (iifferent iorlic strerlgt. hs . . . . . . . . . . . . . . . . . . . . . . . . . 338

C.3.1 Discrepancies or irls~~fficierlt I I I I I ~ I ~ ) ~ ~ nf (iatrx pnirlt. S . . . . . . . . . . . . . . . 340 C.4 PIO~:P~IIIPS fnr data han(ili11g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342

C.4.1 Correc:tion to zero iorlic strerlgtll . . . . . . . . . . . . . . . . . . . . . . . . . 342 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C.4.2 Propagat. ion of errors 344

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C.4.3 Ro~~nr l i r~g 345 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C.4.4 Sigr1ific:ant rligits 345

D Corrections to the Uranium NEA-TDB review 347 D.l Intro(il~c.tior~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347 D.2 Urar l i~~rr~ trichloricle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348 D.3 rlcll~eo~ls l~rarli~~rrl l~yrlroxirle c:ornplexes . . . . . . . . . . . . . . . . . . . . . . . . . . 348

D.3.1 UOa(OH)a(a(l) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348 D . 3.2 U(I\') hy(iroxi(ie corr~plexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349

D.4 Urar l i~~rr~ cart)or~at. e corr~plexes arlrl cornpol~n(is . . . . . . . . . . . . . . . . . . . . . 349 D.4.1 U(\'I) c:arl)onate complexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351

D.4.1.1 U02C03(aq) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351 D.4.1.2 U O ~ ( C O : ~ ) ; arlrl U O ~ ( C O : ~ ) $ . . . . . . . . . . . . . . . . . . . . 354 D.4.1.3 ( u O ~ ) : ~ ( C O : ~ ) ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354

D.4.2 RIixerl U(V1) hyclroxicle-c:arl)(>r~at~e corr~plexes . . . . . . . . . . . . . . . . . . 354 D.4.3 RIixerl U(VI), Np(\'I) and PII(VI) cart)or~at. e complexes . . . . . . . . . . . . 355 D.4.4 U(\') c:arl)onate complexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355 D.4.5 U(I\') c:arl)onate complexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355

D.4.5.1 U ( C O : ~ ) ; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355 D.4.5.2 ~ ( C 0 : ~ ) g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356

D.4.6 Solid l~rarli~~rrl carl~onates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357 r- D.4.6.1 U02C03(cr) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33,

D.4.6.2 Na4UO2(CO:3):3(c:r) . . . . . . . . . . . . . . . . . . . . . . . . . . . 357 D.5 Urar l i~~rr~ rrlir~erals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358 D.6 Referer~ces t. o Appen(iix D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368

List of Tables

1.1 Isotopes of arr~ericil~rr~ in r ~ ~ ~ c l e a r waste . . . . . . . . . . . . . . . . . . . . . . . . . . 4

11.1 .A l~l~reviatior~s for experirr~ental rnetho(is . . . . . . . . . . . . . . . . . . . . . . . . . 8 11.2 Syrnt)ols arlrl t. errr~ir~ology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 11.3 .A l~l~reviatior~s for <:herni<:al pro<:esses . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 11.4 Unit <:onversion factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 11.5 Cor~versior~ factors of rnolarity t. o rr~olalit. y . . . . . . . . . . . . . . . . . . . . . . . . 23 11.6 Referer~ce st. ates for t. l ~ e elerr~er~t. s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 11.7 R~r~rlarr~er~t. a1 physical cor~star~ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

111.1 S l t r r e r i c i r r a f f r r r t i r . . . . . . . . . . . . . . . . . . . . . . . . . . 37 111.2 S l t r r e r i c i r r a f r e t i o r . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 111.3 Selecte(i ternperat. w e coeffi<:ients of C r l . , , . . . . . . . . . . . . . . . . . . . . . . . . . 44

IV.l Selecte(i auxiliary (iat a of forrrlat. ior~ . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 IV.2 Selecte(i auxiliary data of reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

V. l .Allotropy of .A rn(1.r) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 V.2 Heat capacity coefficier~ts ar~rl t. rar~sforrr~atior~ rlat. a . . . . . . . . . . . . . . . . . . . 71 V.3 lrHi,(.Arr~. g . 298.15K) rlerive(i frorr~ vaporisatior~ rr~easl~rerner~ts . . . . . . . . . . . . 73 V.4 Literaillre eq~~il i t ) r i l~rr~ cor~st. ants for rlrr~(III) l~yrlrolysis reactior~s . . . . . . . . . . . 81 V.5 Re~:a l~ :~~la te ( i eq l~ i l i l~ r i~~rn cor~st. ants for tlle hy(iro1ysis of arr~eri<:i~~rn(III) . . . . . . . 83 V.6 Cryst. allographic data for ternary and qllaternary oxi(ie phases . . . . . . . . . . . . 98 V.7 Literaillre eq~~ilit)ri l~rn cor~st. ants for tlle forrr~atior~ of .Arn~! :-"' complexes. . . . . . 101 V.8 Literaillre eq~~il i t ) r i l~rr~ cor~st. ants for cl~lorirle <:ornplexation . . . . . . . . . . . . . . . 104 V.9 Data 11ser1 tn estirr~ate ArHil(.Ar~~X.4, (W, 298.15 K) . . . . . . . . . . . . . . . . . . . . 107 V.10 Data 11ser1 tn estirr~ate A~H&(.AIIIF~, er, 298.15 K) . . . . . . . . . . . . . . . . . . . . 108 V.11 Lattice pararnet. ers for arr~erici~~rn ternary cl~lorirles . . . . . . . . . . . . . . . . . . . 120 V.12 Literaillre eq~~il i t ) r i l~rr~ cor~st. ants for tlle arr~eri<:i~~rn(III) s l~lpl~ate syst.err1 . . . . . . . . 128 V.13 Forrrlat. ion cor~st. ants for rlrr~(SOq)? ext. rapolate(i to I = 0 . . . . . . . . . . . . . . . 130 V.14 Literaillre eq~~il i t ) r i l~rr~ cor~st. ants for tlle arr~eri<:i~~rn(III) r~itrate syst. ern . . . . . . . . 137 V.15 Literaillre ec~~~il i t ) r i l~rr~ cor~st. ants for tlle arr~eri<:i~~rn-r)l~osr)l~i~te svsterrl . . . . . . . . . 140 . . V.16 Literaillre eq~~il i t ) r i l~rr~ cor~st. ants for tlle arr~eri~:i~~rn(III)-ci~rl~c~~~i~te-~~~i~t~er syst.err1 . . . 149 V.17 Literaillre eq~~il i t ) r i l~rr~ cor~st. ants for tlle arr~eri<:i~~rn(III)-thio<:pnate systern . . . . . 167 V.18 Literaillre review oft. llr t l~er r r~or l~~r~ar r~ ic fim<:tior~s for t. llr .Arn(III ) - S C N systern . . 169

. . . V.19 S t r~~c t . ural rlat. a for arr~rr ic i~~rn s~hc~( ies . . . . . . . . . . . . . . . . . . . . . . . . . . l70

A. l Experirr~ental rrlat. rix clescrit)ir~g t l ~ e rrleasllrerrler~ts of '41.Arn(III) in Refs . [84BER/KIhI . 84KI\I/BER] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

B . l Det~ye-Hiickel cor~st. ants a t several ternperat. ures . . . . . . . . . . . . . . . . . . . . . 317 B.2 Preparat. ion of experimental rlat. a for tlle ext. rapolation t. o I = 0 . . . . . . . . . . . . 319 B.3 Ior~ interaction <.oefficier~ts. E . for cat. ior~s . . . . . . . . . . . . . . . . . . . . . . . . . 325 B.4 Ior~ interaction <.oefficier~ts. E . for ar~ior~s . . . . . . . . . . . . . . . . . . . . . . . . . 329

xvi LIST OF TABLES

B.5 Ior~ interaction <:orfficients c l ar~rl € 2 for: c = E I + ca loglo I... . . . . . . . . . . . . . 331

D . l Reviser1 E-V~L~IIPS f ~ r I I ~ ~ L I I ~ I I ~ I I carl~onatr <:ornplexes . . . . . . . . . . . . . . . . . . . 351 D.2 Reviser1 forrr~atior~ data for ~ ~ r a r ~ i l ~ r r ~ <:arl)onate complexes ar~rl cornpol~n(is . . . . . . 352 D.3 Reviser1 rractior~ data for l ~ r a r ~ i ~ ~ r r ~ cart)onat. e cornplrxes ancl cornpo~~nrls . . . . . . . 353 D.4 Exprrirnrntal data for the forrr~atior~ of UOaCO:4(aq) . . . . . . . . . . . . . . . . . . 354 D.5 Exprrirnrntal data for the forrr~atior~ of UOaCO:4(<:r) . . . . . . . . . . . . . . . . . . 35'7 D.G Mir~erals of ~ ~ r a r ~ i ~ ~ r r ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361

List of Figures

11.1 Stanrlarcl or(ier of arrarlgerrlerlt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 11.2 Principal schrrn a. of t l ~ e NE.4 Tl~errr~ocl~err~ical Data Base . . . . . . . . . . . . . . . 30

. . l Poterltial Diagrarr~ for Arnenc~~nn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 V.2 Literaillre data. for t l ~ e 1st . hyclrolysis <:onstant of .&rn(III) . . . . . . . . . . . . . . . 84 V.3 Literaillre data for t l ~ e 2nd . hy(iro1ysis cor~st. ant of rlrn(II1) . . . . . . . . . . . . . . 85 V.4 Re-eval~~aterl vah~rs for t l ~ e 1st . hyclrolysis <:onstant of rlrr~(III) . . . . . . . . . . . . 87 V.5 Fraction rliagrarr~ for t. llr hyclrolysis of rlrr~(III) a t I = 0 . . . . . . . . . . . . . . . . 88 V.6 Iorlic strerlgt. h cle~~en~ience of t. llr rlistril)~~tior~ of hy(iro1ysis species of Arn(II1) . . . . 88 V.7 Trrlt. ativr arnerici~nn-oxygrn phase rliagrarr~ . . . . . . . . . . . . . . . . . . . . . . . 90 V.8 So111t)ilit. y r r~eas~~rerr~er~ts of Arn(II1) hy(iroxi(ie in 0.1 RI NaC104 . . . . . . . . . . . . 95 V.9 Ext. rapolation to I = 0 of r ( l~~i l i l ) r i~nn <:onstants for t. l ~ e forrr~atior~ of rlrnSO2 . . . . 129 V.10 Ext. rapolation to I = 0 of r ( l~~i l i l ) r i~nn <:onstants for t. l ~ e forrr~atior~ of rlrr1C0: . . . . 153 V.11 Fraction rliagrarr~s for t l ~ e Arn(II1) l~y(iroxi(ie-cart)or~ate systrrn: a ) at pcoz = l()-"' l) AI, .

ar~rl h ) at [CO:-] ,,, = 0.01 RI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 V.12 Prerlorr~ir~ar~ce area rliagrarr~ of t l ~ e rlrr~(III) hyclroxiclr-cart)or~atr systerrl a t 25°C . . 163 V.13 So111t)ilit. y of rlrr~(III) as a. f i~r~ct ior~ of pH ancl log,, pc.0, at I = 0 ancl 25°C . . . . . 164

A. l Ext. rapolation to I = 0 of soh~l)ility data in [69SHI/GI\'] . . . . . . . . . . . . . . . . 257 A.2 Dist.ril)ut. ion <:orfficier~ts of rlrr~(III) frorr~ [82BID] . . . . . . . . . . . . . . . . . . . . 272 A.3 So111t)ilit. y r r~eas~~rerr~er~ts of Arn(II1) hy(iroxi(ie in 0.1 RI NaC104 frorr~ [82SIL] . . . . 276 A.4 So111t)ilit. y r r~eas~~rerr~er~ts of arnorpho~~s rlrr~(III) hyclroxi(ie . . . . . . . . . . . . . . . 280 A.5 So111t)ilit. y rrleasllrrrrler~ts of rlrr~(III) hy(iroxi(ie in 0.1 RI NaC104 frorr~ [84BER/KI\I,

84KI\I/BER] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282 A.6 So111t)ilit. y rrleasllrerrlerlts of arnericil~rr~(III) frorr~ [84BER/KIhl] in t. llr at~srncr arlrl in

the ~ I P S ~ I I C : ~ of COa (g) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 A.7 rlrr~rri<:illrn corlcerltrat. ions in .'concret. e ecll~ilil)ratr(i \%-ater" frorr~ [86EK4/HOIT] . . 289 4 .8 Dist.ril)ut. ion <:orfficier~ts of rlrr~(III) in carl~onatr rr~erlia frorr~ [88R.40/h1.4 H] . . . . . 292 '4.9 So111t)ilit. y rrleasllrerrlerlts of Arn(II1) hy(iroxi(ie in 0.1 RI NaC104 frorr~ [88STA4/KIhI] 294 A.10 So111t)ilit. y r r~eas~~rerr~er~ts of '4 rr12(CO.3).3(cr) in 3 \I NaClOq frorr~ [RSROU] . . . . . . 297 '4.11 Bat. c11 Arn(II1) so111t)ilit. y r r~eas~~rerr~er~ts in 3 RI 1UaC1O4 frorr~ [89ROB] . . . . . . . . 299 A.12 So111t)ilit. y r r~eas~~rerr~er~ts of '4 1nC0.~OH(cr) frorr~ [SOFEL/RAI] . . . . . . . . . . . . 302 A.13 So111t)ilit. y r r~eas~~rerr~er~ts of .4rr12(CO:3):3(cr) frnrr~ [SlhIEI/KI\I] . . . . . . . . . . . . 304 A.14 So111t)ilit. y r r~eas~~rerr~er~ts of ArnP04 . .rHaO(arr~) frorr~ [92RAI/FEL] . . . . . . . . . . 307

B. l Ext. rapolatiorl to I = 0: -411 example . . . . . . . . . . . . . . . . . . . . . . . . . . . 320

LIST OF FIGURES

Chapter I

Introduction

1.1. Background

Tllc rrlodcllirlg of t,hc hchavioiir of hnzardol~s mat,crials 111lt1cr c~~vironrrlcnt,al COII- dit,ions is arnong the rrlost important npplicat,ions of natiiral and t,ccllnical scicrlccs for t,hc prot,cction of t,hc cnvironrncnt. In ordcr to assess. for cxarnplc, t,llc safct,y of a ~vast,c deposit,, it is csscrlt,ial t,o bc nhlc t,o prctlict t,hc cvcntiial tlispcrsion of it,s hnzardons corrlponcnts in the cnvironrncnt (gcosphcrc, biosphcrc). For haznrdo~ls rrlntcrinls st,orctl in the groiind or in gcological forrnat,ions; t,llc rrlost probnhlc transport mctliiim is t,llc aqncoiis phase. .l11 important fact,or is t,hcrcforc t,llc qiiantitatirc prctlictiorl of t,hc rcactiorls that arc likely to occur i)ct,~vccn hazartloiis waste tlissolvcd or s~lspcrltlcd in groiindn~nt,cr, and t,hc siirro~lrltling rock mnt,crial, in ordcr to cst,i- rrlntc the q~lant,it,ics of ~vast,c that car1 i)c transport,cd in t,hc aqncoiis phase. It is tlms csscnt,ial to know t,hc relative st,nhilit,ics of the corrlpoiinds nrltl complcxcs t,llat, may form llrltlcr t,hc rclcxi~,nt conditions. This irlforrnnt,ion is providctl by spccin- tion calc~llations using chemical t,hcrrnodynnrnic dat,n. Tllc local condit,ions, sllcll as gronnd~vat,cr and rock cornposition or tcrnpcrat,~irc. may not he const,nrlt along the migration paths of haznrdo~ls mnt,crials. nrltl fiindnrncntal t,hcrrnodynarnic dnt,n arc t,hc indispcnsablc basis for a dynnrnic rrlodclling of the chcrrlical hchavioiir of ha~nrdolls ~vast,c cornponcnt,~.

In the ficltl of radioact,ivc waste mnnagcrncnt. t,hc hnzardons rnatcrinl consist,^ t,o n large cxt,crlt of actinitlcs and fission protlllct,~ from rlllclcar rcact,ors. The scicnt,ific lit,cratiirc on thcrmotlynamic tlat,a. mainly on cqlli1il)riiirn const,ant,s and rctlox potcnt,ials in nqllcons soliit,ion, has bccn ~ontradict~ory in a 111lrnl)cr of cases. cspccially in t,llc actinitlc chcrnist,ry. .l crit,ical nrltl cornprchcnsivc rcvic~v of t,llc nvailablc litcratiirc is necessary in ordcr t,o establish a rclial~lc tllcrmochcrrlical dnt,n base that fillfils the rcqnircrncnts of a proper rrlodclling of the i)chnvio~lr of t,llc actinitlc and fission protlllct,~ in the cnvironmcnt,.

Tllc International -4tornic Energy .lgcncy (I.lE.4) in I'icnnn piil)lishctl i)ctn~ccn 1966 nrltl 1983 special issues ~vit,ll compilations of physico-chcrnical properties of cornpoiinds nrltl alloys of clcrrlcnts irnport,ant in reactor t,cchnology: PII; NI). Ta, Be, Th, Zr, hlo. Hf and Ti. In 1976, I.lE.4 also st,nrtcd t,hc pnblicnt,ion of t,hc scrics ,'The Cllcrrlicnl Thcrrnodynnrnics of .lctinitlc Elcmcrlt,~ and Cornpollntls"; oriented to~vartls

nuclear cnginccrs and scicnt,ists. This international effort has rcsnlt,ctl in t,llc publicat,ion of scrcml part,s. each conccrning t,hc thcrmodynarnic propcrt,ics of a given type of cornpounds for t,hc cnt,irc actinitlc scrics. Tllcsc rcvic~vs corer t,hc litcratiirc npproxirnat,cly up t,o 1984. Tllc latest volnrnc in t,his scrics appcarcd in 1992, under Part 12: Tllc .4c,t,inidc .kq~lcons Inorgnrlic Corrlplcxcs [92FUG/KHO]. Unfort,~lnat,cly, dat,a of irnport,ancc for radioactive waste rnanagcmcnt (for cxnrnplc, Part 10: Tllc .kctinitlc Oxides) arc lacking in the I.4E.k scrics.

Tllc Radioact,ivc \Vast,c lInnagcrrlcnt Corrlmit,tcc (RV'RIC) of t,llc OECD N~lclcar Energy -4gcncy rccogniscd t,hc nccd for an int,crnat,ionally ackno\vlctlgcd, high-qualit,y tllcrrrlochcrrlical dnt,n i~asc for t,hc npplicat,ion in t,hc snfct,y asscssmcrlt of radioact,ivc ~vast,c disposal; and ~lntlcrt,ook t,llc tlcvclopmcnt of the NE.% Thcrrrlochcrrlical Dat,a Base (TDB) projcct [85RIUL4. 881\'.4X, 91\V.4N2]. Tllc RV'RIC assignctl a high priorit,! t,o t,hc crit,ical rcvic\v of rc1cxi1,nt chcrrlical t,hcrmotlynamic tlat,a of corrlpoiinds and complcxcs for t,his area containing t,llc actinitlcs ~iraninrn, ncptiininrn, pl~lt,orliiim and amcricinrn; as nrcll as the fission protl~lct tcchnctinrn. .kft,cr t,llc hook on chcrnical t,hcrrnodynnrnics of iiraninrn [92GRE/FUG]; t,llc prcscnt rcport on nrrlcriciiim thcrrnodynarnics is the sccond x~oliimc in t,llc scrics.

Sirniiltancoiisly \vit,ll the NE.4's TDB project,, other rcvic\vs on the physical ant1 cllcrrlicnl propcrt,ics of nct,inidcs have appcarcd. inclnding t,hc book by Cordfimkc et o,l. [9OCOR/KON]. t,hc scrics cditcd by Frccmnn et (11. [84FRE/L.$N; 85FREIL.4N; 85FRE/KEL; 86FREIKEL. 8iFRE/L.%X, 91FRE/KEL]. the t,~vo volnrncs cdit,ctl by Katz et al. [8GK.%T/SE.4], nrhich incl~ltlc n chnpt,cr on amcricinrn [86SCH/PEX], ant1 Part 12 by Fi~gcr et o,l. [92FUG/KHO] \vithin t,hc I.4E.4 rcric\vs rrlcnt,ionctl nhovc. Tllcsc cornpilat,ions arc bot,h an important source of informnt,ion nrhich has bccn iiscd

this vol~lrrlc

1.2. Focus of the review

.Is ontlincd in the ~rexioiis section, t,hc foei~s of the crit,icnl rcvic\v ~rcscntcd in t,llis rcport is on t,hc thcrmotlynamic data of nrrlcriciiim relevant t,o t,hc safct,y nsscssrrlcnt of rntlionct,ivc \~~ast,c rcposit,orics in t,llc gcosphcrc. This inclndcs t,llc rclcasc of \~~ast,c corrlponcnts fiorn t,hc rcposit,ory int,o t,hc gcosphcrc ( i .e . . it,s intcract,ion \vith t,hc \~~ast,c container and t,hc ot,hcr near-ficltl mnt,crials) and t,hcir migration t,llro~lgll the gcological formnt,ions and t,llc vnrioiis compnrtmcrlt,~ of the biosphcrc. -4s groiindn~nt,crs and porc\vnt,crs arc t,hc t,rnnsport rncdia for t,llc \~~ast,c componcnt,~, t,llc kno\~~lcdgc of the thcrmotlynamics of t,hc corrcspontling clcrrlcnts in \vat,crs of vnrioiis cornpositions is of fimdnrncntal irnport,ancc.

Tllc prcscnt rcvic\v put,s rrliich weight on t,llc nsscssmcrlt of t,llc lo~v-t,crnpcratiirc thcrrnodynarnics of arncrici~lrn in aqil,r.eo?rs sol'i~,r.t%orr and rrlakcs intlcpcndcnt analyscs of t,llc nvailablc lit,crat,urc in t,his nrca. Thcrc is litt,lc tlat,a ax7ailal)lc above roorrl tcrnpcratiirc. Tllc st,andard mct,hotl used for the nnalysis of ionic int,cractions i)ctn~ccn corrlponcnts dissolrctl in nrnt,cr (sec -4ppcntlix B) allows t,llc gcncral ant1 consistcnt nsc of t,llc sclcct,cd dnt,n for rrlodclling purposes, rcgnrdlcss of t,llc t,ypc ant1 corrlposit,ion

Isotopes of (i;rrtwr.%riwn 3

of the gronnd~vat,cr; ~vithin the ionic st,rcrlgt,ll limit,s given by t,llc cxpcrirncnt,al dat,a nsctl for t,hc tlat,a analyscs in the present rcric\v.

This hook cont,ains a snrnrnary and a crit,ical rcric~v (cf. Chapter 1') of t,hc t,llcrrnodynarnic tlat,a on cornpounds arltl aqllcons corrlplcxcs cont,ainirlg arncrici~lrn. as rcport,ctl in the available cllcrrlical litcratiirc up t,o 1992; hut a few more rcccnt rcfcrcnccs arc also incliidcd. .l compamt,ivcly large niirrlhcr of primary rcfcrcnccs arc disciissctl scpamt,cly in .lppcndix -4. On~ing t,o t,llc focns of t,his rcric\v, this report, does not incliidc data on t,llc follo~ving it,crns:

Gascons ions. .l rcvic~v on t,llis subject,, piil)lishcd by t,hc 1.lE.l [85HIL/GUR]; will bc ~lscfill for persons irlt,crcstcd in gasco~ls ions of amcricinrn.

-4lloys and int,crrnctallic cornpoiinds. .lgain; a review pnblishcd by t,hc I.lE.4 [81CHI/.lKH] can i)c used as init,ial source of information on this s~lhjcct,.

Data on non-aq~lcons solutions (rnolt,cn salts; organic solvents, etc.)

Cornpounds or aqiicolls corrlplcxcs cont,ainirlg organic ligands. This class of cornpounds is plannctl t,o bc t,llc snbjcct of a later rcvic~v in t,llc NE.4-TDB scrics.

Allt,lloiigh the focns of t,llis review is on arncrici~lrn, it is ncccssary to 11sc dat,a on a nurnl)cr of ot,hcr species diiring the cval~lat,ion process that lcatl t,o the rccomrrlcndcd dat,a. Tllcsc so-called auxiliary tlat,a arc taken hot,ll fiorn t,llc puhlicat,ion of COD.lT.4 Kcy 1~'alncs [89C0?(/1\:.lG] arltl from t,hc cvaliiation of additiorlal aiixiliary data in the nraniiim vol~lrrlc of t,his scrics [92GRE/FUG]; arltl t,hcir iisc is rccomrrlcndcd by t,llis review. Care has hccn taken t,llat all t,llc sclcct,cd thcrrnodynarnic tlat,a at standard condit,ions (cf. Scctiorl 11.3) and 298.15 K arc int,cmally consistent. For t,llis purpose, a special softn~arc has bccn dcvclopcd at t,hc YE.$ Dat,a Bank t,llat is operational in corlj~lrlct,ion ~vi th the NE.4-TDB dat,a hasc syst,crn, cf. Scct,ion 1I.G. In order t,o rrlnirlt,ain consist,cncy in the applicat,ion of t,hc val~lcs sclcct,cd by t,his rcvic~v. it is csscrlt,ial t,o use t,llcsc aiixiliary tlat,a nrhcn calcnlat,ing cq~lilihri~lrn constants i~lvolring arncricinrn corrlpoiinds and cornplcxcs.

1.3. Isotopes of americium

.llthongh tllcrc arc foiirt,ccn kno~vn isotopes of arncriciiim, only t,hrcc have half-lives lorlgcr t,harl a few days and ~voiild bc of any concern in niiclcar ~vast,c. Tllc isotopes, t,hcir half-lives. motlcs of decay and specific act,ivit,ics arc given in Tahlc 1.1 [78LED/SHI]. Tllc isot,opc "'-4rn is ncrcr prcscnt in spent reactor file1 in cxccss of a w r y srrlall fract,ion of t,hc total percent of amcricinrn radioact,ivit,y. ~vhilc "I'.lrn dorn- irlntcs tl~lrirlg the first fcxv thousand years of decay ant1 "'3.4rn dorninatcs tllcrcaft,cr [8OCRO].

O~ving to t,llc fact t,llat amcricinrn is a synt,hct,ic clcmcnt,, all t,hcrrnodynarnic prop- crtics rcvic~vcd in this report have bccn oht,aincd from mcasllrcrrlcnts on cit,llcr "'-4rn or "'3.4rn.

Tahlc 1.1: Isotopes of amcricinrn in rl~lclcar \~~ast,c

Isot,opc Half-life lIotlc of decay Specific act,ivit,y

(GBq/g)

"'-4rn 433 years alpha 128 "'-4rn 16 lloiirs 82.7% hct,a 2 .99~10 '

17.3% clcct,rorl capt,urc "2m.4rn 152 years int,crrlal t,ransition 360

0.5%, alpha 2x3 km 7370 years alpha 7.40

1.4. Review procedure and results

Tllc ol)jcctirc of t,hc prcscrlt review is t,o present an asscssmcrlt of t,llc soiirccs of puhlisllcd t,hcrrnodynarnic tlat,a in ortlcr to tlccitlc on t,llc rrlost rcliahlc ~ ~ a l n c s t,hat can bc rccomrncndcd. Expcrirncntal rncasnrcrncnt,~ piil)lishcd in t,hc scicnt,ific litcratiirc arc t,llc main source for the sclcctiorl of rccomrncndcd tlat,a. Prcvio~ls rcvic~vs arc not, ncglcctcd i)iit form a valiiablc sourcc of crit,ical irlforrnnt,ion on t,llc quality of primary public. a t ' ,ions.

TVhcn ncccssary, cxpcrirncntal sourcc data arc re-cvaliiatcd by nsing chcrrlical rnod- els ~vhich arc cit,hcr fo~lrltl more realistic than those iiscd by t,llc original a~lt~hor, or ~vhich arc consist,crlt ~vi th side-rcact,ions discnsscd in anot,hcr scct,ion of t,hc review (for cxarnplc, tlat,a on carhonatc complex formation might nccd to bc rcint,crprct,ctl t,o t,akc irlt,o accoiint consist,cnt valiics for hydrolysis rcact,ions). Re-cvaliiation of litcratiirc T ~ ~ ~ I I C S might be also ncccssary t,o correct for kno\vn syst,crnatic crrors (for cxarnplc, if the jiinctiorl potcntials arc rlcglcctcd in t,hc origirlal puhlicat,ion) or t,o rnakc cx- trapolations to st,arltlartl st,at,c corltlit,ions (I = 0) by nsing t,llc specific intcract,ion cq~iations (cf. .4ppcndix B).

In ortlcr to ensure t,llat corlsistcnt procctl~lrcs arc nsctl for t,llc c~i~,lnat,ion of primary dat,a. a 111lrnl)cr of giiidclincs have hccn tlcvclopcd, e.g., assignmcrlt of ~lnccrt,aintics. They have l)ccn ~lptlat,cd and improrctl sincc 1987. and t,llcir rrlost rcccrlt ~~crsions arc available at the YE.$ [91TV.4N2. 91TV.4N3. 92GR,E/I\:.4Y, 93PUI/R.%R. 921\:.4Y, 9 941V.$N]. Sorrlc of tllcsc proccdnrcs arc also ontlincd in t,his ~~oli imc; cf. Chapter 11; -4ppcntlix B, and -4ppcntlix C. Tllcsc scct,ions; ~vhich wcrc also piil)lishctl in t,hc ~lrarliiim l~ook [92GRE/FUG], have hccn rcviscd in this rcvic\v. For cxarnplc, in Chapter 11; the Scctiorl on "Rcdox cqiii1il)ria" has l)ccn rcviscd. a ncx~~ Scct,ion on ,'pH" has bccn incl~ltlcd. Tahlc 11.5 has l)ccn cxpandctl, and t,~vo Scct,ions (11.6 arltl 11.7) have been moved fiorn Chapt,cr I. Tllc rrlost promirlcnt charlgcs in .4ppcndix B arc in Tal)lc B.1; Eq. ( B . l l ) and Scct,ion B.1.4. Sorrlc minor crrors have also hccn

rcrnorctl from .4ppcndix C. Orlcc t,hc critical rcvic~v process in t,hc XE.4-TDB project is cornplct,ctl, the rc-

siilt,irlg rnannscript is rcvic~vcd indcpcntlcnt,ly by qualified experts norninatcd by the NE.4.t Tllc intlcpcndcnt pccr rcvic\v is pcrforrrlcd according t,o t,llc proccdnrcs oiit,. linctl in the TDB-6 gnitlclinc [9011:.4N]. Tllc purpose of t,llc additiorlal pccr rcvic\v is to rcccivc an intlcpcndcnt vic\v of t,llc jiidgcrrlcnts ant1 asscssmcrlt,s rnadc by t,llc 1)ri- rnnry rcric\vcrs. t,o verify assiimptions, rcs~llt,s arltl concliisions. and t,o cllcck \vllcthcr the rclcvarlt lit,cmt,urc has bccn cxhanst,ivcly considered. The indcpcrltlcnt pccr rc- view is pcrforrrlcd by pcrsorlrlcl having t,ccllnical cxpcrtisc in t,llc snbjcct rrlat,t,cr t,o bc rcvic\~rcd, t,o a tlcgrcc at least cq~livalcnt t,o t,hat rlccdcd for t,hc original rcvic\v.

Tllc t,hcrrnodynarnic data sclcct,cd in t,llc prcscrlt rcvic\v (sec Cllapt,crs I11 arltl 11,') rcfcr t,o the rcfcrcncc t,crnpcratiirc of 298.10 K and t,o st,arltlartl contlit,ions. cf. ScctiorlII.3. For t,llc rrlodclling of real syst,crns it is, in gcncml. ncccssary t,o rccalciilat,c the st,andard thcrmotlynamic data t,o non-st,andard statc contlit,ions. For aqllcons species a procedure for t,llc calcnlat,ion of t,hc act,ivity fact,ors is t,hns rcqnirctl. This rcvic~v 11scs t,hc approxirnat,c specific ion irlt,cract,ion rrlct,llod for t,llc cxtrapolat,ion of cxpcrirncnt,al tlat,a t,o the st,arltlartl statc in t,hc tlat,a cxi~,lnat,ion process. and in some cases this requires the re-cval~lat,ion of original cxpcrirrlcnt,al val~lcs (solnbilitics, crrlf dat,a. etc.). For rrlaxirrl~lrrl consist,cncy, t,llis rncthod, as t1cscril)cd in -4ppcntlix B; sllo~lld al~vays bc used in corlj~lrlct,ion \vith t,hc sclcctctl dat,a prcscntcd in this rcric\v.

Tllc t,hcrrnodynarnic dat,a sclcctcd in t,his rcric\v arc providctl \vith ~lrlccrt,aintics rcprcscrlt,irlg the 90% confidcncc l c ~ ~ l . .Is tlisciissctl in .4ppcndix C, t,llcrc is no ~lniqiic ~vay t,o assign nnccrt,aint,ics. and t,llc assignrncnt,~ made in t,llis rcric\v arc to a large cxt,cnt based on the snbjcct,ivc choice by t,hc rcric\vcrs, siipport,cd by their scicnt,ific and t,cchnical cxpcricncc in the corrcsporltling area.

Tllc qiialit,y of t,hcrrnodynarnic rrlodcls carlrlot be bct,tcr t,llan t,llc qiialit,y of the dat,a they arc i)ascd on. The quality aspect inclndcs bot,h t,hc nnrncrical valiics of the t,hcrrnodynarnic tlat,a iiscd in the rrlodcl and the "cornplctcncss" of the cllcrrlical rrlodcl used, e.g.. t,hc incl~lsion of all t,hc rclcxi~,nt tlissolrctl chemical species and solid phases. For t,hc user it is irnport,ant t,o corlsitlcr that the sclcctcd data set prcscntcd in this r e ~ ~ i c w (Chapt,cr 111) 111ay not I)e .'corrlplctci' ~vitll respect to all t,hc con~ci~~aI) lc syst,cms and corltlit,ions; tllcrc arc gaps in t,hc informat,ion. part,icnlarly conccrrling aqiicolls species t,llat cont,ain rrlorc t,llan one kind of ligands. Tllc gaps arc point,ctl out in the various scct,ions of Chapt,cr l'.. and t,his irlformat,ion rnay bc iiscd as a basis for the assigrlrrlcnt of research priorit,ics.

t It, s110111d t)e rlnt,e11 t,ll&t, .ipper~~lix D has riot, beer1 i11c11111e11 i11 t, l~e peer-~evie\%- <lescrit)e(l here.

Chapter I1

Standards, Conventions, and Contents of the Tables

This chapt,cr o~lt,lincs and list,s t,llc symbols. terminology and norncnclatiirc. t,hc iinits and conversion fact,ors. t,hc order of formulae, the starltlartl conditions, arltl the filn- damcrlt,al physical const,arlt,s iiscd in t,llis vol~lrnc. They arc derived fiorn international st,andards arltl have bccn specially acl,j~lstcd for t,llc TDB p~lhlicat,ions.

11.1. Symbols, terminology and nomenclature

.khl)rcviat,ions arc rnainly ~lsctl in t,al)lcs \vhcrc spacc is lirnitcd. .khhrcviations for rrlctllods of rncasiircmcnt arc kept t,o a maximurn of tllrcc charact,crs (except for corrlposcd syrnl)ols) and arc listed in Tal)lc 11.1.

Ot,hcr ahhrcviations rnay also bc ~lsctl in t,al)lcs, such as SHE for t,hc standard hytlrogcn clcctrodc or SCE for t,llc sat,~lrat,ctl calorrlcl clcctrodc. Tllc al)l)rcviat,ion NHE has bccn widely used for the "norrnal hytlrogcn clcctrodc"; nrhich is by dcfinit,ion itlcntical t,o t,llc SHE. It shonltl ncvcrt,hclcss bc not,ctl t,llat NHE ciist,ornarily rcfcrs t,o a standard st,at,c pressure of 1 at,rn; \vhcrcas SHE al~vays rcfcrs t,o a st,andard state prcssiirc of 0.1 hIPa (1 bar) in this review.

Tllc syrnl)ols for physical and chemical q~lant,it,ics nsctl in t,hc TDB review follow the rccorrlrrlcndnt,iorls of the International Union of Pure and .kpplictl Chcrnist,ry, IUP.kC [iS\VHI2. 8811IL/C\.'I]. They arc siimrrlariscd in Table 11.2.

11.1.3. Claenrical fofol.rnulac. arad nonrc.raclo,tufol.c?

This rcric\v follo\~rs t,hc rccorrlmcrltlat,ions rnadc by IUP.kC [ i l JEN; 7iFER. 9OLEII on the nomcnclat,nrc of inorgarlic cornpounds and cornplcxcs, cxccpt for t,hc follo~ving it,cms:

CHAPTER II. STANDARDS AND CONVENTIONS

Tahlc 11.1: .~hhrcviations for cxpcrirncntal rnct,hods.

aix cal cllr cix col con cor Col? cry tlis cm cmf

g1 isc-X ix kin rrlvd 111111

pot, prx q11 rctl rev sp sol t, c t,ls vlt, ')

anion cxcharlgc calorirnctry chrornatogmphy cat,ion cxcharlgc colorirnctry condiictirit,y corrcct,cd coiilornctry cryoscopy distril)iit,ion bct,~vccn t,~vo phases clcct,rornigration clcct,rorrlot,ivc force, not spccifictl glass clcct,rodc ion sclcctirc clcctrodc nrit,h ion X st,at,ctl ion cxchangc rate of rcact,ion rrlolc vol~lrrlc dctcrmi11. a t ' ,ion nuclear magnetic resonance polarogmphy pot,cnt,iomct,ry proton rclaxat,ion qninhytlronc clcct,rodc crrlf ~vi th rctlox clcctrodc r c ~ i c w sl)cct,rophot,ornctry sol~lhilit,y transient condnct,ivit,y thermal lcnsing spcctrophot,ornctry ~rolt,amrnct,ry rrlct,llod ~lnkno\vn t,o the rcvic~vcrs

Table 11.2: Svmbols nrltl terminology.

volnrnc Illass tlcnsitv (rnass tlividctl by ~~oli imc)

disrcgnrdirlg bo~lntlary or container infl~lcncc) int,crrlal t,rnrlsrrlission dcnsit,y, (tlccntlic absorl)ancc): log,, (l/T) rrlolar (tlccntlic) absorpt,ion cocficicnt,: .4/f:B/ rclaxnt,ion tirrlc .%vogadro constant relative rrlolcciilnr mass of n snbst,a~lcc ("1

t,hcrrnodynarnic t,cmpcmt,urc, absol~lt,c t,crnpcrnt,urc Cclsills tcrrlpcrat,llrc (molar) gas const,nrlt, Boltzrnann const,ant, Fnmtlay constant (molar) cnt,ropy (molar) heat capacity at const,ant prcssiirc (rnolnr) cnt,hnlpy (molar) Gibbs cncrgy cllcrrlicnl pot,cnt,ial of sllbstancc B prcssiirc part,ial prcssiirc of siil)st,ancc B: .xBp f~lgacit~y of snbst,ancc B f~lgacit~y cocficicnt,: ,fB/pB amollrlt of siil)st,ancc (h)

rrlolc finct,ion of snbst~ancc B: nB/Ci rri

rnolarit,y or conccnt,rnt,ion of a solute sllbstancc B (nrnonnt of B diritlcd by t,hc volnrnc of t,llc solution) ('1

rnolalit,y of n solllt,c snbst,ancc B (amollnt of B diritlcd by tllc rrlass of t,llc solrcnt,) ("1

rrlcnrl ionic rnolnlity ('1; rnp+"-) - - iij,yrr~r-

10 CHAPTER II. STANDARDS AND CONVENTIONS

act,ivit,y of siil)st,ancc B act,ivit,y coefficient. molalit,y basis: (~g/rng act,ivit,y coefficient. corlccntrat,ion basis: ( ~ g / ~ g

mean ionic nct,ivity ('1. n("++"-) - V+ V- + - (Ig = n + 0-

( + + ) v+ U- mean ionic nct,ivity cocficicrlt ("); ?+ - "+ ;!-

osmot,ic coefficient. rnolnlity basis I ionic strength: I,,, = 7 xi r n i t f or I, = h L xi (:iz?

ion irlt,crnct,ion cocficicrlt bct,~vccn sllbstancc Bl and siil)st,ancc B2

st,oichiomct,ric cocfficicnt of snbst,ancc B (ncgnt,ivc for rcnct,ant,s, positjive for prodnct,~)

gcrlcral cqnnt,ion for n cllcrrlicnl rcnct,ion cqnilibrinrn const,ant (f)

rat,c constant Faraday constant chnrgc niimbcr of an ion B (positjive for cat,ions. ncgat,ivc for

anions) chnrgc niimbcr of n cell rcnct,ion clcctromot,ivc forcc pH = - loglo[rrH+/(mol . kg-')], cf. Scct,ion 11.1.7 clcctrolytic contlllct,ivity

sllpcrscript for st,arltlartl state ( g ) 0

(a) Tlle ratio of the average rrlass per forrmlla. llrlit of a s l~l~stance to of the rrlass of an at,orr~ of mlclicle 'T.

(I)) f : j Se<:tions 1.2 ancl 3.6 of t l ~ e IUPAC rrlarl~lal [79IYHI"].

(c) This qllantity is called .'arnol~~~t-of-s~~t)st,ar~<:e <:oncentrat,ion'; in t,lle IUPAC rrlarl~lal [79\YHI2]. '4 soll~tior~ wit,h a. con<:entrat,ion ecplal to (1.1 rrlol. clrn-"S caller1 a. 0.1 rrlolar solllt,ior~ or a 0.1 M sohlt,ion.

((i) .4 solllt,ior~ l~av i r~g a rrlolalit,y eqllal t,o 0.1 rrlol . kg-' is 1:allecl a. 0.1 rrlolal soll~tior~ or a. 0.1 rn sohlt,ion.

(P) For an electrolyte N , ,+S , , r r l~ ic l~ (iisso<:iat,es into v+(= v+ + v-) inons, in an acllleolls solllt,ior~ wit,h <:oncentration rrr . the in(iivir111al cationic rnolality ancl a<:tivit,y coefficier~t, are rrr+(= ~/+rrr) arlrl y+(= a+/rr~,+). -4 sirrlilar (iefinition is ilse(i for the ~ I I ~ O I I ~ ( : sj~rnl~ols. Elect,rical rlel~t,ralit,y recp~ires illat v+z+ = v-z-.

(f) Special rlotat,ior~s for eqllilit)rillrr~ corlstarlts are o~~t l ine( i in Sectior~ 1.2. In sorrle cases, I<, is 11secl to irlrlicat,e a cor~cer~tratior~ corlstar~t in rrlolar lmits, and K,,, a corlstar~t in rrlolal lmits.

(g) See Sectior~ '.Stanrlarcl <:onrlitions".

i) The formnlac of coortlination cornpounds and corrlplcxcs arc not cncloscd in sqllarc i)rackct,s [il.JEN. Rule 7.211. Xo brackets or parcrlt,hcscs arc ~lsctl at all t,o tlcnotc coordirlat,ion compo~lntls.

ii) The prefixes "oxy-" arltl .'hytlroxy-" arc rct,ainctl if iiscd in a gcncral way, e.g.; "gascons ~lrarliiim oxyflnoritlcs" . For specific formula names, ho~vcvcr. t,llc IU- P.kC rccorrlrrlcndctl citation [il.JEN. Rnlc 6.421 is used, e.g., "iiraninrn(I\~) diflnoritlc oxide" for UF20(cr).

A k ~ l IUP.4C rule that is often not f o l l o \ ~ ~ d by rnany a~lt~hors [71JEN> R~llcs 2.163 arltl 7.211 is rccallcd hcrc: t,llc ortlcr of arranging ligarltls in coordirlat,ion compo~lrltls arltl corrlplcxcs is t,hc follo~ving: central at,om first. follo\~~cd by ionic ligarltls arltl t,hcrl by the rlciit,ral ligands. If t,llcrc is morc than orlc ionic or rlciit,ral ligand, t,llc a1phal)ctical order of the symbols of the ligat,ing at,orrls tlct,crrrlincs t,llc scqncncc of t,hc ligands. For cxarnplc, (U02)aCO:3(OH): is standard, (U02)2(0H):jC0, is non-standard arltl is not used.

Akhhrcviatio~ls of narncs for organic ligarltls appear sorrlct,imcs in formnlac. Follo\~r- irlg t,llc rccorrlrrlcndnt,iorls by IUP.kC, lower casc lct,t,crs arc used, arltl if ncccssary, the ligarltl ahhrcviation is crlclosctl ~vit,llin parcnthcscs. Hydrogen at,orrls t,llat car1 i)c rcplaccd by t,hc rrlct,al at,orrl arc sho\vn in t,llc al)l)rcviat,ion \\,it11 an upper casc "H"; for example: H3ctlt,n, .km(Hctlt,a)(s) (\~,hcrc ctlt,a stands for ct,l~ylcnctliarni~~ctctri~~- acct,at,c).

Cllcrrlical forrn~llac rnay rcfcr t,o diffcrcrlt chcrrlical spccics and arc oft,cn rcq~lircd t,o bc specified morc clearly in ortlcr t,o avoid ambigiiitics. For cxarnplc, UF4 occiirs as a gas. a solid. arltl an aqncoiis complex. The distinct,ion bct,~vccn the diffcrcrlt phases is rrlndc by phase dcsigrlat,ors t,llat irnrncdiat,cly follow t,llc cllcrrlical formula and appear in parcnt,hcscs. The only forrn~llac that arc not provided ~vit,ll a phase tlcsignat,or arc aqlicolls ions. They arc t,hc only charged spccics in t,his review sincc cllargcd gascs arc not considcrctl. Tllc nsc of t,hc phase dcsigrlat,ors is dcscrihcd i)clo\~r.

The dcsigrlat,or (1) is iiscd for piire liquid siil)st,anccs, e.g.. H20(1).

The tlcsignat,or (aq) is used for ~lntlissociat,ctl, nnchargcd aqllcons spccics, e.g.; U(OH)4(aq). C02(aq). Sincc ionic gascs arc rlot corlsitlcrcd in this review; all ions rnay bc ass~lrncd t,o i)c aqncoiis arltl arc not dcsigrlcd \\,it11 (aq). If a cllcrrlical rcact,ion refers to a mctliiim ot,llcr t,harl H 2 0 (e.g.. D20 , 90%' ct,hanol/lO% H,()); t,llcn (aq) is rcplaccd by a rrlorc explicit designator. e.g.. "(in D20)" or "(sln)". In t,hc casc of (sln); t,hc corrlposit,ion of the sol~it,ion is dcscrihcd in t,llc t,cxt,.

The designator (sln) is used for snbst,anccs in sol~lt,ion nrit,ho~lt spccifyirlg the act,nal cq~lilihri~lrn composit,ion of t,hc siil)st,ancc in the solution. Note t,llc tliffcrcncc in the designation of H 2 0 in Eqs. (11.2) and (11.3). H20(1) in Rcac- t,ion (11.2) irltlicat,cs that H 2 0 is present as a piire liquid, i.e.; no solntcs arc


present,, \vhcrcas Rcact,ion (11.3) involvcs a HC1 solution, in ~vhich the t,llcr- motlynamic propcrt,ics of H20(sln) rnay not i)c t,llc sarrlc as t,hosc of t,llc pure liquid H20(1). In tlilntc solutions, ho\vcvcr, this diffcrcncc in the thcrmotlynarnic properties of H 2 0 can i)c ncglcctcd, and H20(sln) rnay bc rcgartlcd as piire HZO(l).

The dcsignators (cr), (am); (\,it,). arltl (S) arc iiscd for solid snbst,anccs. (cr) is iiscd nrhcn it is kno\vn t,llat t,llc cornpound is cryst,allinc, (am) nrhcn it is kno\vn t,llat it is amorphous, and (vit) for glassy s~lhstanccs. Ot,hcr~visc. (S) is iiscd.

In sorrlc cases. rrlorc than one cryst,allinc for111 of the same chcrrlical corrlposit,ion may exist,. In such a casc. the tliffcrcnt forms arc dist,ingnishctl by separate dcsigrlat,ors that dcscrihc the forrrls rrlorc precisely. If t,llc cryst,al has a mirlcral narnc. the designator (cr) is rcplaccd by t,hc first four cllaractcrs of t,hc mirlcral narnc in parcnt,hcscs, e.g., Si02(qiiar) for q~lart,z and Si02(cllal) for chalcedony. If tllcrc is no mirlcral narnc, the designator (cr) is rcplaccd by a Grcck lctt,cr prccctling t,hc formula arltl indicating t,llc st,rnct,~lml phase, e.g.. o.-UF5, L/-UF5.

Phase dcsigrlat,ors arc also ~lsctl in conjnnct,ion nrit,ll thcrmotlynamic symbols t,o define t,llc st,at,c of aggregation of a corrlpoiind a t,hcrrnodynarnic qnnnt,it,y refers t,o. Tllc not,at,ion is in this casc t,llc sarrlc as oiit,linctl above. In an cxt,crltlcd not,at,ion (cf. [82L.$F]) t,hc rcfcrcncc t,cmpcmt,urc is nsiially given in atltlit,ion to t,llc st,at,c of aggregation of t,llc cornposition of a mixt,urc.

Examples:

AfG;(Na+> atl, 298.15 K) stan(lar(1 rnolar G i l~ l~s energy of format,io11 of aqileous Na+ at 298.15 K

S;(UOzS04. 2.5H201cr; 298.15 K) stan(lar(1 rnolar elltropy of U O ~ S O I . 2.5HaO(cr) at 298.15 K

C,O,,(UO:3; ru, 298.15 K) stan(lar(1 rnolar heat capacity of (v-UO.3 at 298.15 K

AfHm(HF1 slrll HF . 7.8HZO) er~tl~alpy of forn~ation of HF (lili~te(l 1:7.8 wit11 water

Cllcrrlical processes arc tlcnotcd by t,llc opcrat,or 1; ~vrit,tcn before t,llc symbol for a propcrt,y. as rccorrlrrlcndctl by IUP.$C [82L.$F]. .l\n cxccpt,ion to this rule is the cq~iilil)riiim const,ant,, cf. Scct,ion 11.1.6. The natiirc of t,hc process is dcrlot,cd by

Tahlc 11.3: .%hhrcviations iiscd as sllhscript,~ of l to dcrlot,~ the type of chemical proccsscs.

at,

tlchyd tlil f f11s hytl rrlix r sol sub t, r t,rs vap

separation of a siil)st,ancc into it,s const,it,llcrlt gasco~ls at,orrls (at,omisat,ion) climirlat,ion of \vater of hydration (dchytlmt,ion) dilllt,ion of a solution format,ion of a cornpound from it,s const,it,llcnt clcrrlcnts mclt,ing (fusion) of a solid addit,ion of ~vat,cr of hytlmt,ion t,o an iinhydrat,cd corrlpoiind mixing of flnitls chcrrlical rcactiorl (general) process of dissolllt,ion s~lhlirrlat,ion (evaporation) of a solitl t,rarlsfcr from one soliit,ion or liqnitl phase to arlot,llcr t,rarlsit,ion of orlc solitl phase to another vaporisat,ion (evaporation) of a liquid

annotation of t,hc 4; e.g., t,hc Gihhs cncrgy of forrnat,ion, l f G , , t,llc cnt,halpy of siiblimat,ion. l s n h H m . etc. Tllc ahhrcviations of cllcrrlical proccsscs arc siimrrlariscd in Tahlc 11.3.

Tllc rrlost frcqiicntly used syrnl)ols for proccsscs arc l f G and &H. the Gil)l)s cncrgy arltl the cnthalpy of forrrlat,ion of a corrlpoiind or cornplcx from t,hc clcrrlcnt,~ in t,hcir rcfcrcrlcc states (cf. Tal)lc 1I.G).

Tllc IUP.4C has not cxplicit,ly dcfinctl the symbols and terminology for cqnilibrinrn const,ant,s of rcact,ions in aqiicolls sol~lt,ion. The NE.4 has t,llcrcforc adopt,ctl the convcnt,ions t,hat have l)ccn iiscd in the \vork Sto,bilitg corrstcxrrts of nrc.to,l i o n conl,ple:cc.s by Sillkn and IIartcll [64SIL/II.%R; 71SIL/II.%R]. .4n ollt,linc is given in the pam- graphs bclo~v. Not,c t,hat,, for sorrlc simple rcact,ions. t,llcrc may l)c diffcrcrlt correct, ~vays tto index an cqnilibrinrn constant. It may sorrlct,irrlcs i)c prcfcrahlc t,o indicat,c the 111lrnl)cr of the rcact,ion t,hc dat,a rcfcr t,o. cspccially in cases \vhcrc scrcml ligands arc discnsscd that rrligllt i)c confilsctl. For cxarnplc, for the cqllilihrillrn

bot,ll ,,,, and fi(II.4) \~ronltl l)c appropriate, and i/ ,,,, (11.4) is acccpt,cd. t,oo. Xot,c t,llat,, in gcncral; K is iiscd for t,llc conscc~lt,ivc or st,cp\visc formation const,ant,, and 9 is iiscd


for the ciimnlat,ivc or ovcrall formation const,ant,. In t,llc follo~ving o~lt,linc, cllargcs arc only given for act,ual chcrrlical spccics, but arc omit,tctl for spccics corlt,aining gcncral symbols (M. L).

II.1.6.1. Protoraation of a ligcxrrci

This not,at,ion has bccn proposed arltl iiscd by Sill611 and hlart,cll [64SIL/hI.$R], but, it has i)ccn simplified lat,cr by the sarnc aiit,llors [71SIL/II.%R] from lil,, t,o K,. This review retains, for t,llc sake of consist,cncy, cf. Eqs. (11.7) arltl (II.8), the ol~lcr. forrrliilnt,ion of lil,,.

For the atltlit,ion of a ligand, the not,at,ion sho117n in Eq.(II.i) is used.

HL,-I + L + HL, l< [m] " [HL~-I][LI

Eq. (11.8) refers to the ovcrall format,ion constant of t,hc spccics H,L,

In Eqs. (II.5), (11.6) arltl (11.8); t,llc sccorltl s~lbscript r car1 be ornit-tctl if r = 1, as sho11~11 in Eq. (11.7).

Example:

II.1.6.2. Fornrcxtion of rraetcxl ion corn,plexes

hIL,-I + L + IIL, l< - - [IILq-I][L]

For the atltlit,ion of a rnctal ion, i.e., t,llc format,ion of polynilclcas cornplcxcs, the follo\~.ing notation is ilsctl; analogoils t,o Eq.(II.5):

Eq. (11.12) refers to t,llc orcmll formnt,ion constant of n complex h I ,L ,

Tllc second index can i)c orrlitt,cd if it is cqiial to 1; i.e.. p,,,, bccorncs il, if r r , = 1. Tllc formnt,ion const,nnt,s of rrlixcd lignntl complcxcs arc not indcxctl. In t,his casc, it is ncccssnry t,o list t,llc chcrrlical reactions considcrctl and t,o rcfcr t,hc const,ant,s t,o the corresponding rcactiorl nnrnbcrs.

It has somct,irrlcs bccn ciist,ornary t,o iisc ncgat,i~-c .c:ralncs for the indices of the prot,ons t,o indicate complcxation \vit,ll hydroxide ions. OH-. This practice is not, ntloptcd in t,his rcric\v. If O H occiirs as a rcact,nnt in t,llc not,at,ion of t,hc cqnilibrinrn, it is t,rcnt,ctl like n norrnal lignntl L; i)iit in gcncral formulae the index varinblc rr is nsctl irlstcntl of q. If H 2 0 occurs as n rcact,nnt t,o form hydroxitlc cornplcxcs, H 2 0 is considcrctl as n protonnt,ctl ligand, HL, so t,llat the rcnct,ion is t,rcat,cd as t1cscril)cd l>clo\~r in Eqs. (11.13) t,o (11.15) iising r , as t,llc intlcx variable. For convcnicncc, no gcncrnl forrrl is llsctl for the st,cp\visc constants for t,llc formation of t,hc cornplcx hI,,L,H,. In many cxpcrirncnts, t,llc formnt,ion corlstnrlt,~ of rnctal ion complcxcs arc dct,crrrlinctl by ntltling t,o a rrlct,al ion solllt,ion a ligantl in it,s prot,onatcd form. Tllc corrlplcx forrrlat,ion rcnct,ions t,lllls involve a dcprot,onation rcnct,ion of the lignntl. If this is the casc. t,llc cqllilibrillrn constant is siipplicd \vit,ll an ast,crisk; as sho\~rn in Eqs. (11.13) and (11.14) for mononiiclcar and in Eq. (11.15) for polyniiclcar cornplcxcs.

Examples:

3 U@+ + 5 H20(1) + (U02) :3 (0H)~ + 5 H+ '715.:3 = [(U02):3 (OH):] [H']"

[L 0 y ] :3 Not,c t,hnt an asterisk is only nssigncd t,o t,hc forrrlat,ion constant if the protonnt,ctl

ligand t,llat is added is tlcprot,onatcd diiring t,hc rcact,ion. If a protonnt,ctl lignntl is ntldcd ant1 coordinat,cd as such t,o the rrlct,al ion. the ast,crisk is t,o be omit,tcd, as sllo\~~n in Eq. (11.16).

Example:


11.1. G. 3. Sol?rhil%ty corastarats

Con~~cnt,ionally, cqnilibrinrn constants involving a solid compollrltl arc dcnot,ctl as "solnl>ility const,a~~t,s" rat,hcr t,harl as format,ion const,ant,s of t,llc solid. .l11 intlcx "S"

to t,llc cqiii1il)riiim constant indicat,cs t,llat t,llc const,ant rcfcrs to a sol~lbilit,y process. as sho\17n in Eqs. (11.17) to (11.19).

I%'s,O is the convcntional solubility prodiict. and t,llc sllbscript "W' indicat,cs t,llat the cqlii1il)riiim rcact,ion involrcs only iincornplcxcd aqueous species. If t,llc sol~lbilit,y const,ant incliidcs the formation of aqllcons complcxcs, a notation analogo~ls t,o t,llat, of Eg. (11.12) is ~lsctl:

rrr -Ll,Lb(s) + Ll,,,Lq+ L I' = [ L I ~ , L , ] [ L ] ( - - ~ (11.18) II

Example:

Similarly, an asterisk is added to t,llc solubility corlst,arlt if it sirniiltancoiisly involrcs a prot,onat,ion cqnilibrinrn:

Example:

11.1.6.4. Eq11,ilihria in?iol?iirr,y t h e acirlitiorr o f a go,,seo~i~,,s ligarad

.l special not,at,ion is llsctl for constants describing cqlii1il)ria t,llat involrc the addit,ion of a gascoils ligand. as ontlincd in Eq. (11.20).

Tllc subscript "p" can i)c combincd \vith any ot,hcr not,at,ions given above

Examples:

C02(g) + C02(aq) h',, = [COL (41

Pro2

In cases ~vhcrc t,llc subscripts hccorrlc cornplicatcd, it is rccorrlrrlcndctl that K or 9 bc iiscd ~vit,ll or nrit,ho~lt s~lhscript,~. hut aln~ays follo\~~ctl by the cquat,ion niimbcr of the cqiii1il)riiim to nrhich it refers.

Rcdox rcactiorls arc nsiially q~lant,ificd in t,crrrls of their clcct,rodc (half ccll) potential. E, nrhich is itlcnt,ical t,o t,hc clcctromot,ivc forcc (crnf) of a galvarlic ccll in nrhich the clcct,rotlc on t,llc left is the st,andard hytlrogcn clcct,rodc, SHE t ; in accordarlcc ~vit,ll the '.l953 St,ockholrrl Convcnt,ion" [88hIIL/C\'I]. Thcrcforc, clcctrodc pot,cnt,ials arc give11 as rcdiictiorl pot,cnt,ials rclat,ivc t,o t,llc st,arltlartl hydrogen clcct,rotlc. nrhich act,s as an clcct,ron donor. In t,hc standard hytlrogcn clcctrodc, H2(g) is at urlit f~lgacit~y (an ideal gas at iinit pressure, 0.1 hlPa). arltl H+ is a t unit act,ivit,y. The sign of the clcct,rotlc potential. E, is that of t,hc ol)scrvcd sign of its polarity ~vhcn coiiplctl with t,hc st,andard hydrogcn clcct,rotlc. Tllc clcct,rodc pot,cnt,ial is rclat,cd t,o the Gil)l)s cncrgy change &G, arltl the cq~lilihri~lrn constant Ii as o~lt,lincd in Eq. (11.21).

Tllc syrnl~ol E" is used for the cmf of a st,andard galxi~,nic ccll rclat,ivc t,o the st,andard hytlrogcn clcctrodc (all cornponcnt,~ in t,hcir st,andard st,at,c. cf. Scct,ion 11.3.1, and ~vit,ll no liqnitl jnnct,ion pot,cnt,ial). Eq. (11.21) car1 then he \vrit,t,cn in terms of E". !l&': and Ii".

For example. for t,hc hypot,hct,icnl galvanic ccll:

; Fc(C104)2(aq, 0;) P t H2(g.p = lbar) 1 HCl(aq o,+ = l) 1

I Fc(C104):3 (aq, 0;) 1 Pt . (11.22)

~vhcrc ''i" dcnot,cs a liquid jiinctiorl arltl " 1 " a phase bo~lntlary. t,hc ccll rcactiorl is:

t Tlle rlefir~itior~s of SHE arlrl NHE are given in Section 11.1.1


For convcnicncc Rcact,ion (11.23) can l)c rcprcscrlt,cd by half ccll reactions, each irlvolving an equal 111lrnl)cr of '.clcct,rons", as sho~vn in the follo\ving cqllat,ions

~vhcrc .'c-" is a syrnl~ol devoid of any physical or cllcrrlical significance. and t,llcrcforc it,s narnc, "clcct,ron". might i)c rrlislcading hut t,his irlcorlvcnicrlcc is corrlpcnsat,cd by it,s iiscfiilncss.

Eqnilibrinrn const,arlt,s may bc ~vrit,tcn for tllcsc half ccll rcact,ions in the follo~ving Ivay:

In addition, 1,Gm(II.25) = 1,H;(II.25) = A,Sk(II.25) = 0 by dcfinit,ion. at all tcrnpcratiircs; and t,llcrcforc 1,Gm(II.24) = A,Gk(II.23).

Tllc follo~ving cqiiations dcscrihc t,llc charlgc in t,hc Gil)l)s cncrgy arltl rctlox pot,cn- tial of Rcact,ion (11.23); if pH2 and (IH+ arc cqllal t,o imit,y (cf. Eq. (11.21)):

Tllc .'activit,y of clcct,rons" in Eqs. (11.26) and (11.27) rnay he intcrprct,cd to rcprc- sent t,llc relative t,cntlcncy for clcct,rons to lcavc an aqueous soliit,ion. For the standard hydrogen clcctrodc (I,,- = 1 (by t,llc convcntiorl cxprcssctl in Eq. (II.27)), \vhilc rcar- rangcrncnt of Eq. (11.26) for t,hc half-cell corlt,aining t,llc iron pcrclllorat,cs in ccll 11.22 gives:

and by t,llc corlvcnt,ion in Eq. (11.27):

1 I = log,, h'"(II.23) - log,,

cornparison of Eqs. (11.28) arltl (11.29) taking into accoiint Eq. (11.21) sllo\~rs t,llat, for the right half-cell in 11.22:

log,, 0,- = F E(II.23) RT ln(10)

Tllc split,ting of rcdox rcact,ions into t , ~ ~ ~ o half ccll rcact,ions by introdiicirlg t,hc syrn- bol "e-". ~vhich accortling t,o Eq. 11.30 is rclat,cd t,o t,hc st,arltlartl clcct,rotlc pot,cnt,ial, is

nrbit,mry hut jiist,ificd by t,llc ~lscfillncss of t,hc rcsnlt,ing cqiiations. TVhcn cnlcnlat,ing the cqiii1il)riiim composit,ion of n cllcrrlicnl syst,crn. both "e-" and H+ can i)c clloscn as comporlcnt,~ ant1 they can i)c t,rcat,cd niimcrically in a similar ay: cqnilibrinrn const,ant,s, mass halnncc, etc. rnay he dcfinctl for bot,h. Ho~vcvcr. while H+ represents the hydrat,cd proton in nqllcons sol~lt,ion. "c-" is void of chemical ant1 physical sig- nificnncc, and it,s conccnt,ration must i)c set t,o zero during t,hc cnlcnlat,ions (nrbit,rary T ~ ~ ~ I I C S ; ho~vcvcr. 111ay lbc assignctl t,o ( I , , ~vhich arc the11 rclat,cd t,o E by Eq. (11.30)).

In the litcratiirc on gcocllcrrlicnl rrlodclling of rlat,ural ~vat,crs, it is ciist,ornary to rcprcscnt t,llc "clcctron act,ivit,y" of an aqncoiis sol~lt,ion nrit,h the syrnhol "pc" or " p ~ " (= - log,, (L,-) by analogy ~vit,ll pH (= - log,, aH+). and t,hc redox potential of an nqiicolls soliit,ion relative to t,llc st,nrltlartl hytlrogcn clcctrodc is iis~lally dcnot,cd by ci- thcr '.Eh'' or "EH3' (sec for example [81STU/hIOR. 82DRE; 84HOS, 86NOR/IIUN]).

Bccn~lsc of t,llc irrlport,nncc t,hnt potcntiornctric rrlcthotls lla~rc in t,llc dctcrmin a t ' ,ion of cqiii1il)riiim const,nnt,s in nqllcons sol~lt,ions; n short disc~lssiorl on t,hc tlcfinitiorl of "pH" ant1 n simplified dcscript,ion of the cxpcrirrlcnt,al tcchniqiics used to rncnsnrc pH will bc given hcrc.

Tllc acitlit,y of aqncoiis sol~lt,ions is oft,crl cxprcssctl in a logarit,llrrlic scale of the hytlrogcn ion actirit,y. The dcfinit,ion of pH as

pH = - log,, OH+ = - 10910(771H+;!H+)

can only he st,rict,ly used in t,hc lirrliting range of t,hc Dcbyc-Hiickcl cqiiation (that is, in cxt,rcrncly tlilntc sol~lt,ions). In prnct,icc t,llc use of pH vnliics requires extra assnrnp- tions on t,llc ~ ~ a l n c s for single ion nct,ivitics. In t,his review vnliics of pH arc used t,o dcscril~c qiialit,at,ivcly ranges of acitlit,y of cxpcrirrlcntnl st,udics, ant1 t,llc assnrnpt,ions dcscril~cd in .%ppcndix B arc ~lsctl t,o calciilnt,c single ion act,ivit,y cocfficicnts

Tllc dctcrminat,ion of pH is often pcrforrrlcd by crrlf rncnsnrcrncnt,~ of galvanic cells involving liquid j~lrlct,ions [69ROS. 73B.%T]. -4 corrlrrlon sct,~lp is n ccll rnadc up of a rcfcrcncc half-cell (e.g. .%g(s)/.%gCl(s) in n sol~lt,ion of const,ant cllloridc conccnt,mt,ion); n salt hritlgc, t,llc t,cst solution; and a glass clcct,rotlc (~vhich cncloscs n soliit,ion of constant acidity and an internal rcfcrcncc half-cell):

j salt j test Pt(s) Ag(s) AgCl(s) HCl(aq) :

, txiclge I soli~t,iol~ l l I (I S b (11.31)

~vhcrc " / / " stands for a glass rrlcrrlhrnrlc (pcrrncablc to hydrogcn ions). The crrlf of slid1 a ccll is given by

RT E = E"' - - l11OH+ + Ej

rap

~vhcrc E"' is a constant. and Ej is t,llc jnnct,ion potcnt,ial. The piirposc of t,hc salt, britlgc is t,o rrlinirrlisc t,hc jnnct,ion pot,cnt,ial in jiinction " h" . \vhilc keeping const,nrlt,


the jnnct,ion pot,cnt,ial for ,j~lrlct,ion '.o,". Two rncthods arc rrlost often iiscd t,o rcdncc and control t,hc ~ralnc of E,. -4n clcctrolytc soliit,ion of high conccnt,ration (t,hc "salt britlgc") is a rcqiiircrncnt of hot,ll rncthods. In t,llc first mct,hotl, the salt i~ridgc is a sat,uratcd (or nearly satiirat,cd) soliit,ion of pot,assiiim chloride. .4 prohlcrrl \vit,ll a britlgc of high potassiiim conccntrat,ion, is t,hat pot,assi~lrrl pcrclllorat,c rrligllt prccipitat,c t inside t,hc liqiiid jiinction \vhcn t,llc tcst solut,ion corlt,ains a high conccnt,ration of pcrclllorat,c ions

In t,llc other mct,hotl the salt i~ridgc cont,ains t,llc sarnc lrigh conccntrat,ion of the sarnc inert clcct,rolyt,c as t,hc tcst solution (for cxamplc, 3 11 NaC1(I4). Ho~vcvcr. if the conccnt,ration of the i)ackgroiind clcctrolytc in the salt i~ridgc and t,cst solutions is reduced, t,llc ~ ~ a l n c s of E, arc drarnat,ically incrcascd. For cxamplc. if imth t,llc i~ridgc and t,llc tcst solution have [ClOT] = 0.1 hI as backgro~lntl clcct,rolyt,c, t,llc dcpcrltlcncc of t,llc liqiiid jiinction at "b" on acitlit,y is E, zz 4 4 0 X [H+] rn\' . dm" . rrlol-l at 25°C [GSROS; p.1101, \vhich corresponds t,o an error at pH= 2 of 2 0.07 pH ilnit,s.

Bccansc of t,llc prohlcrrls in clirninating t,llc liqnitl,j~lrlctiorl potcntials and in tlcfining intliritl~lal ionic actirit,y cocficicnt,~. an "opcrat,ional" dcfinit,ion of pH is given by IUP.4C [88hIIL/C\'I]. This dcfinit,ion involrcs t,llc mcasllrcrrlcnt of pH diffcrcrlccs bct,\~~ccn the t,cst sol~lt,ion and st,antlartl solutions of kno\vn pH ant1 sirrlilar ionic st,rcngtll (in t,llis \!,ay sirrlilar val~lcs of :H+ and Ej canccl each other nrhcn crrlf val~lcs arc s~lhstractcd').

To he consistcnt \vit,ll COD.4T.I; t,llc data tables arc given in ',Standard Order of .Irmngcrncnt," [8211:.IG/E\'.I]. This scllcrrlc is presented in Figiirc 11.1 bclo~v ~vhich sho \~~s t,hc scqiicncc of t,llc ranks of the clcmcrlt,~ in t,llis convcnt,ion. The ordcr follo\~rs the ranks of t,hc clcmcnt,~. For nraniurn. this means t,hat. aft,cr clcmcnt,al ~lrarliiim ant1 it,s rrlonoat,orrlic ions (e.g., U'+), t,hc iiraninrn compo~inds and cornplcxcs nrit,h oxygen arc listed, t,llcn those \vit,ll hydrogen. t,hcrl t,hosc nrit,ll oxygen and hydrogcn, ant1 so on. \vith decreasing rank of the clcrrlcnt ant1 combinations of t,hc clcrncnt,~. 1l:ithin a class. incrcasing cocfficicnts of t,hc higher rank clcrrlcrlt,~ go i~cforc increasing cocficicrlt,s of t,hc lo\vcr rank clcrncnt,~. For cxarnplc, in t,llc U-(1-F class of cornpounds ant1 cornplcxcs, a t,ypical scq~lcncc nro~lld bc UOF2(cr), UOF4(cr); UOF4(g), U02F(aq) , U02F+, U02F2(aq), U02F2(cr), UOaF2(g), UOaF,, U02F:-; U20:jF6(cr), etc. For- rrl~ilac \vith identical stoichiornctry arc in alphabct,ical ordcr of t,llcir tlcsignat,ors.

Tllc rcfcrcnccs cit,cd in the rcvic~v arc ordcrctl chronologically and al~)hal>ct,ically by the first t , \~~o authors ~vit,llin each year, as t1cscril)cd by COD.4T.I [87G.%R/P.%R]. .I rcfcrcncc code is matlc up of t,hc final t,~vo tligit,~ of t,llc year of appcamncc (if the puhlicat,ion is not fiorn t,hc %Oth ccnt,l~ry, t,hc year will he piit in full). The year is follo\~~ctl by t,llc first tllrcc lctt,crs of t,hc first t , \~~o anthors, scparat,ctl by a slash. If

Figure 11.1: Standard ortlcr of arrarlgcrrlcnt of t,hc clcrrlcnt,~ and corrlpoiinds basctl on the periodic classificat,ion of the clcrrlcnt,~ (from Ref. [821\~.$G/E\~.$]).

Li - Be

I I Ns hlg

I I

Rh Sr Y- Rn-Rh-Pd

I I L

Fr - Ra -.Ac I (:e-Pr-Sd-Pm-S~-E~-(:~-T~-D~-H~I-E~-T~-Y~-LI~

l Th- Pa- T T -NP-Pn-Am-(!m-Bk- (:f - Es -Fm-\ld-No- Lr

tllcrc arc mnlt,iplc rcfcrcncc codcs, a '2'' will i)c addctl to t,hc sccorltl one. a "3" t,o the t,hird one; and so fort,h. Rcfcrcrlcc codcs arc alnra,ys cncloscd in sqiiarc brackets.

Tllc assignrncnt of t,llc rcfcrcncc cotlcs is done aiit,ornat,ically by t,llc NE.$ npdat,ing programs for the TDB dat,a base (cf. Scct,ion 11.6). It is tllcrcforc possible t,llat, rrl~iltiplc rcfcrcrlcc codcs in t,hc TDB tlat,a I~asc do not occiir in rn~llt,iplc form in the prcscrlt volnrnc. Tllc dcsigrlat,ors "2", "3''; etc.. arc rlcvcrt,hclcss rctaincd for reasons of cornpat,il)ilit,y ~vit,ll t,hc TDB tlat,a base.

11.2. Units and conversion factors

Thcrmotlynamic tlat,a arc givcn accordirlg t,o t,hc Systi.rnc Iritcnintional d'unitb (S1 nnit ,~) . Tllc iinit of cncrgy is the joule. Sorrlc basic conversion fact,ors, also for non- thcrrnodynarnic ilnit,s, arc givcn in Table 11.4.

Sirlcc a large part of t,hc YE.$-TDB project deals nrit,h the thcrmotlynamics of aqiicolls sol~lt,ions; t,hc nnit,s t1cscril)ing the arnoiint of dissolved s~lbstancc arc iiscd w r y frcqiicntly. For convcnicncc. t,his rcvic~v 11scs "II" as an abbreviation of "m01 . drn-"" for molarity, c; and '.rn" as an al)l)rcviat,ion of '.rnol . kg-'" for ~nolalit~y, rn. It, is oft,cn ncccssary t,o corlvcrt conccnt,rat,ion data frorn rnolarit,y t,o rnolalit,y and vice versa. This corlvcrsion is iiscd for t,llc corrcct,ion and cxt,rapolation of cqiii1il)riiim dat,a to zero ionic strength by t,hc specific ion int,cractiorl t,llcory ~vhich works in molalit,y


Tahlc 11.4: Unit corlvcrsion factors.

nnit,s (cf. .4ppcntlix B). This corlvcrsion is rrladc in t,hc follo~ving ay. hlolalit,y is defined as rnB rrlolcs of slll)st,ancc B tlissolvcd in 1000 grams of piire ay at cr. LIolarity is dcfirlcd as (:B moles of slll)st,ancc B dissolved in (1000p-cB1\I) grarrls of ~ I I I C nrat,cr, ~vhcrc p is t,hc density of t,hc solution arltl .\I t,hc molar \~,cight of the solllt,c. Frorn this it follo~~rs that

Bacs and LIcsrrlcr [i6B.AE/LIES, p.4391 give a t,ahlc ~vi th conversion fact,ors (fiorn rnolarit,y t,o molalit,y) for nine clcct,rolyt,cs arltl various ionic st,rcngt,hs. Corlvcrsion factors at 298.15 K for t~~.cnt,y one clcct,rolyt,cs, calciilat,cd usirlg t,hc tlcnsit,y cqiiations rcport,ctl by Sijhncl and Xovot,~lf [85SOH/NO\:], arc rcport,cd in Tahlc 11.5.

rr1111t,iply 11~7

l X l()-'" (exact,ly) 1.01325 X 101 (exactly) 1 X 10'' (exactly) 4.184 (exact,ly) 4.184 (exact,ly)

To convert frorr~ (norl-S1 ur~it syrr~l~ol)

;ingst,riirn (.k) stanrlarcl atrr~ospherr (atrn) t)&r ( t ) ~ ) tl~errr~ocl~err~ical calorie (i:al)

A entropy urlit, (e.11. = <:a1 . K-' . 11101-')

Examples: A 1.00 hl NaC104 = 1.05 rn N a C 1 0 ~ A 1.00 hl NaC1 = 1.02 In NaC1 A 4.00 hl NaCl(I4 = 4.95 N a C 1 0 ~ A 6.00 hl NaN0:j = 7.55 1n NaN0:j

t,o (S1 ur~i t s~irnl~ol)

rr~rtrr (rn) paxcal (Pa) paxcal (Pa) jo~lle (J) J . K-' . rnol-'

It slloiild bc noted t,hnt cql1ilil)rillrn const,ant,s, llnlcss t,llcy arc dirncnsionlcss, rlccd also t,o he corlvcrt,ctl if t,llc corlccntrat,ion scale is changed from rnolarit,y to rnolality or vice versa. For a gcrlcral cql1ilil)rillrn reaction, 0 = CB uBB; t,hc cq~lilihri~l~rl C O I I S ~ , ~ I ~ ~ , S

can bc cxprcssctl cit,llcr in rnolarit,y or rnolality ~lnit,s, h', or K,,,, rcspcctircly:

logln IG = X VB logln B

log,, K,, = X VB log,, r n ~ B

Wit11 ( i i ~ ~ / ( : ~ ) = p. or (log,, r i b B - log,, cB) = log,, p. t,hc relationship hc t ,~~~ccn IT'? and l < , hccorrlcs very sirnplc, as sho117n in Eq. (11.32).

log,, K,,, = log,, IT'? + X I/B log,, p (11.32) B

Tahlc 11.5: Factors Q for t,hc corlvcrsion of molarit!.. CB, to nlolnlity, r n ~ , of n sub- st,ancc B, in various rncdia a t 298.15 K (calc~llatcd from densities in [85SOH/X0\']).

c (hl)

0.10 0.25 0.50 0.75 1.00 1.50 2.00 3.00 1.00 5.00 6.00

c (hl)

0.10 0.25 0.50 0.75 1.00 1.50 2.00 3.00 1.00 5.00 6.00

c (hl)

0.10 0.25 0.50 0.75 1.00 1.50 2.00 3.00 1.00 5.00 6.00

p = rnulcu (d rnq~f w ~ l n t i < ~ n per kg of H 2 0 )

H(:lOa Ns(!lO1 Li(:1O4 SH4(:10a Ba((:10a)2 H(!l sa(:l LiCl

1.0077 1.0075 1.0074 1.0091 1.0108 1.0018 1.001(i 1.0049 1.0117 1.0145 1.0111 1.018Ii 1.02:31 1.0076 1.0072 1.0078 1.026fi I.OZ(i5 1.025fi 1.0331 1.0450 1.0123 1.0118 1.0127 1.0:38(i 1.0388 1.0374 1.052:3 I.O(i85 1.017'2 1.0163 1.0177 1.0508 1.0515 1.019(i 1.0703 1.09:3Ii 1.0222 1.0213 1.0228 1.0759 1.0780 1.0750 1.108li 1.1491 1.0321 1.0:319 1.033:3 1.1019 1.10(?2 1.1019 1.2125 1.04:30 1.0129 1.0141 1.1571 1.1678 l . l l i03 1.3(iX9 I.O(i51 1.0li68 1.06(ili 1.2171 1.2371 1.2264 1.0893 1.0930 1.0901 1.282fi l..'3l(i7 1.1117 1.1218 1.113li 1.3517 1.1077 1.1418 1.112:3

K(:l NH4(:I hlg(:12 (!a(:12 NaBr H S 0 3 S a N O s LiSO?

1.0057 I.OO(iIi 1.0019 1.0041 1.0051 1.0056 1.0058 1.0039 1.0099 1.012:3 1.0080 I.OO(i9 1.0090 1.0097 1.0102 1.010:3 1.0172 1.0219 1.0133 1.0119 1.0151 1.0lli9 1.0177 1.0178 1.0218 1.0318 1.0193 1.017li 1.0220 1.0212 1.025fi 1.023li 1.0:32(i 1.0120 1.0258 1.0239 1.0287 1.0319 1.0:338 1.0335 1.0489 1.0632 1.0:393 1.03X2 1.0$28 1.0478 1.0510 1.0197 1.0li62 1.0835 1.0510 1.054li 1.037li I.O(i17 1.0li92 1.06fi7 1.1037 1.1339 1.0867 1.0931 1.089:3 1.1012 1.1090 1.1028 1.1153 1.1877 1.1211 1.110li 1.1210 1.1417 1.1534 1.1120

1.2177 1.1971 I.l(il9 l.lXIi5 1.2030 1.184li 1.20:3:3 1.23lil 1.2583 1.2309

NHaS03 HnS04 NszSOa (NHa)2S04 H3PO4 Sa2(:03 K2(:03 NaS(:N

1.0077 1.00(i1 1.0014 1.00X2 1.0071 1.0027 1.0012 I.OO(i9 1.0151 1.0llli 1.0071 I.Ol(iIi 1.011:3 1.00:30 1.0068 1.0130 1.027fi 1.0209 1.0127 1.0319 1.02lil 1.0013 1.0121 1.0231 1.0103 1.0305 1.0194 1.018li 1.038:3 1.00li5 1.0183 1.03$2 1.0539 1.010li 1.0268 1.06fi5 1.0309 1.0091 1.0259 1.013:3 1.0818 1.0619 1.0111 1.10(?2 1.077:3 1.0170 1.0130 1.068li I . l l l ( i 1.0848 1.1511 1.1055 1.02li8 1.0li32 1.0931 1.1769 1.1335 1.2610 l.l(i75 1.1130 1.1171 1.2512 1.1935 1.1037 1.238:3 1.1764 1.208:3 1.3:363 1.2600 1.3191 1.2560 1.2773 1.4:351 1..'33(i5 1.11:31 1..'3537


CB V B is t,llc snrn of t,hc st,oichiomct,ric cocfficicnts of the rcact,ion. cf. Eq. (11.48); arltl the val~lcs of p arc the fact,ors for t,hc conversion of rnolarity t,o molalit,y as tabnlat,cd in Tahlc 11.5 for scrcml clcct,rolyt,c rrlcdia at 298.15 K. The tliffcrcnccs hct,\~~ccn t,llc val~lcs in Tal)lc 11.5 and t,hc valiics list,ctl in t,llc nraniurn YE.$-TDB rcvic~v [92GRE/FUG. p.231 arc foiind at the highest conccntrat,ions. and arc 5 *0.003drn"/kg; rcflcct,ing the acciiracy cxpcct,cd in this t,ypc of conversions. Tllc iinccrtaint,y introdiicctl by the nsc of Eq. (11.32) in t,llc valiics of log,, K,,, will then i)c 5 *0.001 CB [/B.

11.3. Standard and reference conditions

11.3.1. Staradarrl sto,tr

.$ precise tlcfinitiorl of the t,crrrl "st,antlartl state'' has i)ccn given by IUP.$C [82L.$F]. Tllc fact t,llat only cllangcs in t,llcrrnodynarnic pamrnct,crs, hut not t,hcir absol~lt,c T ~ ~ ~ I I C S ; can he tlct,crrrlinctl cxpcrirncntally, rrlakcs it irnport,ant t,o lla~rc a ~vcll-tlcfincd st,andard statc t,llat forrrls a base line t,o n~hicll t,hc cffcct of variat,ions can he referred. Tllc IUP.$C [82L.$F] dcfirlit,ion of t,hc standard st,at,c has bccn atlopt,cd in t,llc YE.$- TDB project,. The st,arltlartl st,at,c prcssnrc, p" = 0.1 hIPa (1 bar). has tllcrcforc also bccn adopt,ctl, cf. Scct,ion 11.3.2. Tllc applicat,ion of the st,arltlartl st,at,c principle t,o pure s~lhstanccs arltl rrlixtiircs is s~lrrlmarisctl below. It slloiild bc not,ctl t,llat the st,andard st,at,c is al~vays linkctl t,o a rcfcrcrlcc t,crnpcrnt,urc, cf. Scct,ion 11.3.3.

The st,andard statc for a gasco~ls siil)st,ancc, ~vllcthcr piire or in a gascoils rnix- t,urc, is the piire s~lhstancc at t,hc st,andard statc pressure and in a (hypot,l~ct,ical) st,at,c in \vhich it cxhihit,~ itlcal gas i)chavionr.

The standard st,at,c for a piire liqnitl snbst,ancc is (ortlinarily) t,llc pure liqnitl at, t,llc st,arltlartl statc pressure.

The st,arltlartl statc for a pure solid s~lhstancc is (ordinarily) t,llc pure solid at, t,llc st,arltlartl statc pressure.

The st,arltlartl st,at,c for a solute B in a solution is a llypot,llct,ical solution; at, t,llc st,arltlartl st,at,c prcssnrc, in ~vllich r r k ~ = rra" = 1 mol . kg-'. arltl in ~vllich t,llc act,ivit,y coefficient ;!B is ilnit,y.

It sho~lld i)c crnphasiscd that t,llc iisc of "; e.g., in $H:, irrlplics t,hat the compo~lrltl in qncstion is in t,hc standard st,at,c arltl that t,hc clcrrlcnts arc in their rcfcrcncc st,at,cs. Tllc rcfcrcrlcc states of t,hc clcrrlcnts at t,hc rcfcrcncc t,cmpcmt,urc (cf. Scct,ion 11.3.3) arc listed in Tahlc 11.6.

11.3.2. Staradarrl sto,tc. p ~ r . ' Y . E%I.~'(?

Tllc st,andard st,at,c prcssiirc clloscn for all sclcct,ctl dat,a is 0.1 hIPa (1 bar) as rccorn- rrlcndctl by t,llc International Union of Piirc and .$pplicd Chemistry IUP.$C [82L.$F]. Ho~vcvcr. the majority of t,hc t,llcrrnodynarnic dat,a p~lhlisllcd in t,hc scientific lit,crat,urc and ~lsctl for t,hc cvaliiations in t,his rcvic\v. rcfcr to t,llc oltl st,arltlartl statc

Tahlc 11.6: Rcfcrcrlcc states for t,hc clcrrlcnt,~ a t t,llc rcfcrcncc tcrrlpcrat,~lrc of 298.15 K [82\V.4G/E\Y4, 89COX/\V.4G].

gascons liqiiid

cryst,allinc, ort,horhornl)ic cryst,allinc, hcxagonal (',black') cryst,allinc, hcxagonal gascons cryst,allinc, ciil~ic ("11~11itc") cryst,allinc, rho1nl)ohctlml (,'grey3') cryst,allinc, rho1nl)ohctlml cryst,allinc, rho1nl)ohctlml cryst,allinc, hcxagonal graph it,^) cryst,allinc, ciil~ic cryst,allinc, ciil~ic cryst,allinc, t,ct,ragonal ("~vhi t ,~")

cryst,allinc, cubic 9; crystalline; rhombohcdral cryst,allinc, cubic cryst,allinc, llcxagonal cryst,allinc, llcxagonal liqiiid cryst,allinc, cubic cryst,allinc, cubic cryst,allinc, cubic cryst,allinc, cubic cryst,allinc, llcxagonal cryst,allinc, ort,horhombic cryst,allinc, cubic cryst,allinc, llcxagonal cryst,allinc, llcxagonal cryst,allinc, cubic cryst,allinc, cubic cryst,allinc, cubic cryst,allinc, cubic cryst,allinc, cubic cryst,allinc, cubic cryst,allinc, cubic cryst,allinc, cubic

prcssiirc of 1 '.st,andard atmosphcrc" (= 0.101320 LIPa). Tllc diffcrcncc hc t ,~~~ccn tllc thcrrnodynarnic tlat,a for t,llc t,~vo st,andard statc prcssiircs is not largc and lies in rrlost, cases ~vit,llin tllc iinccrtaint,y lirnit,~. It is ncrcrthclcss csscnt,ial t,o rrlakc t,llc corrcctions for t,llc change in t,llc st,arltlartl st,at,c pressure in order t,o avoid inconsist,crlcics and propagation of errors. In pract,icc t,llc paramct,crs affcct,ctl by t,hc cllangc be- tween tllcsc t,~vo standard statc prcssiircs arc tllc Gibl~s cncrgy and cnt,ropy charlgcs of all processes t,llat involve gasco~ls species. Conscqiicntly, changcs occur also in tllc Gihhs cncrgics of formation of species t,llat consist of clcrrlcnt,~ ~vhosc rcfcrcncc st,atc is gasco~ls (H, (1, F, Cl; N; arltl t,hc nohlc gases). No ot,llcr pararrlctcrs arc affected significant,ly. -4 largc part of tllc follo~ving disc~lssiorl has l)ccn t,akcn from tllc NBS t,ahlcs of chemical t,hcrrnodynarnic propcrt,ics [821\:.4G/E\:.4], sec also Frccman [84FRE].

Tllc follo\ving cxprcssions dcfinc tllc effect of prcssiirc on tllc propcrt,ics of all


RT R I For itlcal gascs, 1'' = - arltl (I = - = ,. Tllc corlvcrsion cq~lat,ions listed bclo~v P P I

(Eqs. (11.38) t,o (11.45)) apply t,o t,llc small pressure cllangc frorn 1 atm t,o 1 bar (0.1 LIPa). Tllc qnant,it,ics t,hat rcfcr t,o t,hc oltl starltlartl statc prcssiirc of 1 at,rrl arc assigned tllc s~lpcrscript here; t,hc orlcs t,hat rcfcr t,o t,hc ncnr st,andard statc prcssiirc of 1 bar the siipcrscript (h"r).

For all s~lbstanccs t,hc cllangc in t,llc cnt,lialpy of format,ion and the heat capacit,y is rrl~ich smaller t,lian t,hc cxpcrimcrlt,al accuracy and can bc disrcgartlcd. This is exactly true for idcal gascs.

A ~ H ( ~ ~ ~ ) ( T ) - A ~ H ( ~ ~ ~ ) ( T ) = 0 (11.38)

c p ) ( T ) - ~ ( a t m ) ( T ) = 0 P (11.39)

For gascons siil)st,anccs. t,hc cnt,ropy diffcrcrlcc is (a tm)

( T ) s ( ~ ~ ~ ) ( T ) = h! 111 (C) ],(b"')

= R 111 1.01325

= 0.1094 .J . K-' . rnol-l. (11.40) R This is cxact,ly t,rnc for idcal gases; as follo~vs frorn Eq. (11.35) nrit,h 0 = -. Tllc

P I cnt,ropy change of a rcact,ion or proccss is tlliis tlcpcntlcnt on the niimbcr of rrlolcs of gascs involrctl:

~vhcrc n' is t,hc r~ct incrcasc in rrlolcs of gas in the process. Similarly, the change in t,hc Gil)l)s cncrgy of a process bc t ,~~~ccn t,hc t , ~ ~ , o standard

st,atc pressures is

Eq. (11.42) applies also to - _I~G( '~") ; since t,hc Gibbs cncrgy of forrrlat,ion dcscril)cs t,llc format,ion process of a cornpound or cornplcx from t,hc rcfcrcncc st,at,cs of t,hc clcrrlcnts involved:

Tllc change in t,llc cqiii1il)riiim const,ant,s ant1 ccll pot,cnt,ials ~vit,ll t,llc cllangc in the st,antlartl state prcssiirc follo\~rs from the cxprcssion for Gihhs cncrgy changcs. Eq. (11.42):

It shonltl he noted t,hat the standard pot,cnt,ial of the hydrogcn clcct,rodc is cqiial t,o 0.00 1' cxact,ly. by dcfinit,ion.

d r f H+ + c + $HL(g) E = 0.0017 (11.46)

This dcfinit,ion will not i)c changed. although a gaseous snbst,ancc, H2(g); is inx~olvcd in the process. Tllc cllangc in t,llc pot,cnt,ial ~vi th prcssiirc for an clcct,rodc potential conx~cnt,ionally \vrit,t,cn as

sllo~lld tlliis bc calcnlat,cd from t,llc halarlccd reaction t,llat incllltlcs t,llc hydrogen clcct,rotlc.

.kg+ + :H2(g) + .kg(cr) + H+.

Hcrc 0' = -0.0. Hcncc; t,hc cont,rihllt,iorl t,o 0' from an clcct,ron in a half ccll rcactiorl is the same as t,llc contril)iit,ion of a gas rnolccnlc nrit,ll the st,oichiomct,ric cocficicnt, of 0.5. This leads t,o the sarrlc valllc of 0' as t,hc cornbinat,ion nrit,h t,hc hydrogcn half ccll.

Examples:

Fe(f:r) + 2 H+ + Fe2+ + H2(g) 6 = 1 ~ ( l ' a r ) - E ( ~ " ~ ~ ~ ) = ().()()()liT CO2(g) + COn(a(1) 6 = - l log,, - loglr1 = -0.005'7 KH,(g) + $Oa(g) + KO(g) + $H20(g) 6 = 0.25 - 4,G(a1rrr' = -0.008k.l. rr~ol-l $la(g) + 2 Oa(g) + e + C10, 6 = -3 lrG(IJar) - 4rG(a'"'1) = 0.098 kJ . rr~ol-l


Tllc dcfirlit,ions of st,arltlartl st,at,cs given in Scctiorl 11.3 make no rcfcrcrlcc to fixed tcrnpcratiirc. Hcncc. it is thcorct,ically possiblc t,o have an in fin it,^ nnrnhcr of standard st,atcs of a siil,st,ancc as the tcrrlpcrat,llrc varies. It is, ho\~~crcr, corlvcnicrlt t,o cornplct,c the tlcfinitiorl of the st,andard st,at,c in a part,iciilar corlt,cxt by clloosirlg a rcfcrcncc tcrnpcratiirc. .%S rccorrlmcrltlcd by IUP.%C [82L.%F], the rcfcrcncc t,crnpcratiirc clloscn in t,llc NE.%-TDB project is T = 298.15 K or t = 25.00°C. TVhcrc necessary for the discussion, ~ ~ a l n c s of cxpcrirncnt,ally rncasiircd tcrnpcratiircs arc reported aft,cr conversion to the IPTS-68 [69COII]. Tllc rclation l,ct,~vccn the al,solntc tcrrlpcrat,llrc T (K; kelvin) and the Cclsills tcrrlpcrat,llrc t ("C) is tlcfincd 1,y t = (T - TO) ~vhcrc To = 273.10 K.

11.4. Fundamental physical constants

Tllc fimdarncntal physical const,arlt,s arc t,akcn from a recent p~lhlicat,ion by COD.4T.4 [86COD]. Those rc1c~i1,nt t,o this rcvic~v arc listed in Tal,lc 11.7.

Tahlc 11.7: Fnndarncntal physical const,ant,s. Tllcsc val~lcs lla~rc been t,akcn fiorn COD.%T.% [86COD]. Tllc digit,s in parcnthcscs arc the one-st,nntlartl-tlcvint,io~l iinccrtaint,y in the last digit,s of t,hc given valllc.

Ql~ar~tit,y

sprerl of light in V ~ < : I I ~ I I ~ I prrrnrat)ilit,y of r~t~cll~lrn

prrrnit,tivity of V ~ < : I I ~ I I ~ I

Plan1:k cor~st,ar~t r l r r r~er~ ta r j~ cllarge .ivogarlro cor~star~t, F. a~arlay .. constant, NA X e

rr~olar gas cor~st,ar~t Boltzrr~ar~r~ const,ant, R/NA

Non-S1 llrlits 11srcl wit,h SI:

rlrctror~ volt, (f'/C) J ,Itornic rrlass i~nit,. 111 = m,, = &rn(12C)

Syrnl~ol

f:

to

h 6'

V F R k

PT 11

17t~111e

299 792 458 4~ X 1 0 ~ = 12.566 370 614. . .

= 8.854 187817.. . 6.626 0755(40) 1.602 17733(49) 6.022 1367(36) 96485.309(29) 8.314510(70) 1.380658(12)

1.602 17733(49) 1.660 5402(10)

Ur~its

111 . S-'

10-7 N . ..I-'

10-'"' . J-' . 111-l

10-:44 J . 10-'g C 10'%11ol-l C . rnol-' J . K-' . 11101-' 10-"8 J . K-'

lO-I9 J 10-" kg

11.5. Uncertainty estimates

Orlc of t,hc principal ol),jcctircs of the NE.%-TDB tlcrcloprncnt effort is t,o provide an itlca of the ilrlccrt,aintics associat,ctl \\,it11 the dat,a sclcctcd in t,llc rcric\vs. In general the ilrlccrt,aintics shoilld dcfirlc t,llc range ~irithin \vhich t,llc corresponding dat,a car1 he rcprodnccd ~vit,ll a prol)ability of 95%. In Inany cases; a fill1 st,at,istical trcat,rrlcnt is limit,ctl or impossible tlilc t,o t,llc availal)ilit,y of only orlc or few dat,a points. .%ppcndix C dcscribcs in tlct,ail t,llc proccdiircs used for the assignmcrlt arltl trcat,rrlcnt of nnccrt,aint,ics. as nrcll as the propagation of errors and the st,arltlartl rules for rounding.

11.6. The NEA-TDB system

.% tlat,a base syst,crn has bccn tlcvclopcd at the YE.% Dat,a Bank t,llat allo~vs the st,oragc of t,hcrrnodynarnic pararnct,crs for indiritlilal spccics as ~vcll as for rcact,ions. .% sirnplificd schcrna of t,llc NE.%-TDB syst,cm is sho\vn in Figure 11.2. Tllc st,riictiirc of t,hc tlat,a l)asc syst,cm allo\vs consist,cnt derivation of t,hcrrnodynarnic dat,a for indiritlilal species fiorn rcact,ion dat,a at standard condit,ions, as nrcll as irlt,crnal rccalciilat,ions of data at standard contlit,ions. If a sclcct,cd valiic is changed. all the dcpcndcnt ~ ~ a l n c s will bc rccalciilat,ctl consistently. Tllc rnaint,cnancc of consist,cncy of all t,hc sclcctcd data, incliltling t,llcir iinccrtaint,ics (cf. .%ppcndix C); is cnsnrcd by the soft,~varc dcvclopcd for t,his purpose at t,llc YE.% Data Bank.

Tllc litcratiirc sources of t,llc tlat,a arc st,orcd in the REFERENCES rccortl, arltl cad1 aiit,llor narrlc has a link t,o t,hc .%UTHORS record for direct rctricxi~,l of aiit,llor names.

Tllc t,hcrrnodynarnic data and t,llcir ilrlccrt,aintics sclcctcd for individiial spccics arc stored in t,llc D.4T.I rccortl. The follo\~.ing pararnct,crs, valid at t,llc rcfcrcncc tcrnpcratiirc of 298.15 K arltl at t,llc st,arltlartl prcssiirc of 1 bar. arc consitlcrcd:

AfGk the st,andard molar Gil)l)s cncrgy of formation (kJ . rnol-') from t,llc clcmcrlt,~ in t,llcir rcfcrcncc st,at,c

AfH; the st,andard molar cnt,halpy of forrrlat,iorl from (kJ . rnol-') the clcrrlcnt,~ in t,llcir rcfcrcncc st,at,c

S; the st,andard molar entropy ( J . K-' . mol-l)

C,",, the st,andard molar heat capacit,y ( J . K-' . mol-l)

For aqiicoils neutral species arltl ions, t,llc ~ ~ a l n c s of AfG$. AfHkr S: a11d C;,, correspond to the standard part,ial rrlolar qiiantitics, arltl for indiritlilal aqilcons ions t,llcy arc rclat,ivc qiiantitics, tlcfincd nrit,h respect to the aqiicoils hydrogcn ion. accortling t,o t,llc con~~cnt,ion [89COX/II:.%G] t,llat LfHg(H+; aq,T) = 0; and t,llat, Sk(H+, aq,T) = 0. Filrthcrrnorc; for an ioraiseci ,sol~r.tc. B cont,ainirlg any nnrnhcr of different cat,ions arltl anions:

LfH;(B+. aq) = E l/+Af H: (cation. aq) + E 11- &H: (anion. aq)

S:(B+. aq) = E ~/+S:(ration, aq) + E a-S:(anion. aq).


Figiirc 11.2: Prirlcipnl schcrna of the NE.% Thcrrnochcmical Data Base,

ELEhIEhTS RE 1CTIONS RECOEFS

v

FORIIUL &E REFEREhCES A

1UTHORS

A%s the paramct,crs in t,llc D.4T.I record vary as a fimct,ion of t,cmpcmt,urc, prori- sion is mntlc t,o incl~ltlc t,llc cornpilat,ion of t,hc cocficicnt,~ of crrlpiricnl tcrrlpcrat,~lrc fi~nct,ions for t,llcsc t,hcrrnodynarnic data in the records G-COEF. H-COEF, S-COEF nrld C-COEF. as 117~11 as the tcrrlpcrat,~lrc ranges over ~vhich t,llcy arc ~ralitl. In many cascs t,hc thcrmotlynamic tlat,a mcas~lrctl or calc~llatctl at several t,cmpcmt,urcs Ivcrc pilhlisllcd for n part,iciilnr spccics, rather t,llan t,llc dcdiicctl tcrrlpcrat,~lrc filnct,ions. In tllcsc cascs. n non-linear rcgrcssiorl rrlct,llod is ~lsctl in t,his rcvic~v t,o obtain t,llc rrlost, significant cocfficicnts of t,llc follo~ving crnpirical fiinct,ion:

hlost t,cmpcmt,urc varint,ions can bc dcscrihcd ~vit,ll tllrcc or four pnmrnctcrs, (I,, 11

nrld e hcing t,hc orlcs most frcqncnt,ly used. In t,llc prcscrlt rcric\v, only C,":,(T), i .e.; the t,hcrrnal fimct,ions of the heat capacit,ics of irltlivitl~lal spccics, arc cons~dcrctl nrltl st,orcd in the rccortl C-COEF. They rcfcr t,o t,hc rclat,ion

nrld arc listed in Tal)lcs 111.3 . Tllc prcssiirc dcpcrltlcncc of t,hcrrnodynarnic dnt,n has not hccn t,llc snbjcct of criti-

cal analysis in the prcscnt cornpilat,ion. The rcadcr irltcrcst,cd in higher tcrrlpcrat,~lrcs

Prrsratat%oa of the srlertrtl dnta 31

and pressures. or t,llc pressure dcpcndcncy of t,hcrrnotlynamic fimct,ions for gcochcrn- ical appli~at~ions. is rcfcrrctl t,o t,llc spccialisctl lit,cratiirc in t,his area. e.g., [82H.%II, 84hI.4R/IIES, 88SHO/HEL. 88T.%N/HEL. 89SHO/HEL, 89SHO/HEL2, 90hION; 91A%ND/C.%S].

Sclcct,ctl st,arltlartl thcrmotlynarnic tlat,a referring t,o chcrrlical rcact,ions (~vhich arc st,orcd in t,llc RE.%CTIONS rccord in alphaniimcric not,at,ion) arc corrlpilctl in the RED.%T record (cf. Figure 11.2). -4 chemical rcact,iorl ''7'' ; involving reactants arltl protl~lct,~ "B". car1 be al)l)rcviat,ctl as

~vhcrc the stoiclliorrlctric cocfficicnts a;; arc positjive for prodiicts, and ncgat,ivc for reactants. Tllc rcact,ion pararnct,crs considcrcd in the NE.4-TDB syst,cm inclndc:

log,, li," the cq~lilibri~lrn const,ant of t,llc rcact,ion, logarithmic &G$ the rrlolar Gibbs cncrgy of reaction (k.J . rnol-') H the rrlolar cnt,halpy of rcact,ion (k.J . rnol-') 1.5': the rrlolar cnt,ropy of rcactiorl (.J . K-' . rnol-l)

&C,",, the rrlolar heat capacity of rcact,ion (.J . K-' . rnol-l)

Tllc tcrrlpcrat,~lrc fimct,ions of tllcsc tlat,a. if available; arc st,orctl in t,hc rccortl RE- COEFS; accortling t,o Eq. (11.47).

Tllc cq~lilibri~lrn constant. K,", is rclat,cd t,o &G$ accordirlg t,o t,hc follo~ving rclation.

log,, K," = - RT 111(1n)

and car1 i)c calc~llatcd from the intlividnal valncs of AfG$(B) (for cxarnplc, those give11 in Tables 111.1 and I\'..l) according to,

1 log,, h'," = X 1 4 &Gk(B)

RTln( l0) B

11.7. Presentation of the selected data

Tllc sclcct,ctl tlat,a arc prcscnt,cd in Chapt,crs I11 arltl I\'.. Urllcss ot,hcr\visc intlicnt,ctl, they rcfcr t,o standard corltlit,ions (cf. Scctiorl 11.3) and 298.15 K (25.00°C) and arc provided ~vit,ll an ~lnccrt,ainty nrhich slloiild correspond t,o t,hc 95% confidcncc lcvcl (scc -4ppcntlix C).

Chapt,cr I11 contains a t,al)lc of sclcctcd thcrmotlynarnic data for indiritl~lal cornpoiinds arltl corrlplcxcs of arrlcriciiim (Table 111.1). a t,ablc of sclcct,ctl rcact,ion dat,a (Table 111.2) for rcact,ions conccrrling amcricinrn spccics. and a t,ablc corlt,aining sclcct,ctl t,hcrrrlal filrlct,ions of t,llc heat capacit,ics of individiial spccics of arrlcriciiim (Table 111.3). Tllc sclcct,ion of t,llcsc dat,a is discnsscd in Chapt,cr 1'.

Chapt,cr I \ ' cont,ains; for aiixiliary compo~lrltls arltl cornplcxcs t,hat do not contain arncricinrn; a t,al)lc of the t,hcrrnodynarnic dat,a for individiial spccics (Tal)lc I\'.l) arltl


a t,al)lc of rcactiorl dat,a (Table I\'.%). hIost of t,hcsc val~lcs arc t,llc COD.4T.4 Key I'aliics [89C0?(/1\:.4G]. Tllc sclcctiorl of t,hc rcrnaining aiixiliary dat,a is discnsscd in Chapter \"I of t,llc iiraninrn rcric\v [92GRE/FUG].

A411 the sclcct,cd data prcscnt,cd in Tables 111.1, 111.2. I\'..1 and I\'..% arc intcrnally consist,cnt,. This consist,cncy is rnai~lt,aincd by the int,crnal consistency ~~crification and rccalciilat,ion soft,\~~arc dcvclopcd at the NE.% Data Bank in conjnnct,ion ~vi th the NE.4-TDB data base system; cf. Scct,ion 11.6. Thcrcforc. ~vhcn using t,llc sclcctcd dat,a for arncrici~lrn species. the aiixiliary dat,a of Chapt,cr I \ ' rrlllst i)c ~lsctl t,ogct,hcr with t,hc tlat,a in Chapter I11 t,o ensure internal consist,cncy of t,hc tlat,a set,.

It is irrlport,arlt to rlot,c t,llat Tables 111.2 ant1 I\".2 incl~ltlc only t,llosc spccics of ~vhich the primary sclcctcd tlat,a arc rcact,ion tlat,a. Tllc forrrlat,ion dat,a tlcrivcd thcrcfrorn and list,cd in Table 111.1 is obtaincd using aiixiliary dat,a, ant1 their ~lnccrt,aintics arc propagat,ctl accordingly. In order t,o maintain t,hc ~inccrtaint,ics originally assigned to the sclcctcd dat,a in t,llis rcric\v, t,llc iiscr is atlviscd t,o rnakc direct nsc of the reaction dat,a presented in Tables 111.2 and I\".2; rat,llcr t,harl taking t,hc tlcrivcd T ~ ~ ~ I I C S in Tables 111.1 and I\'..1 to calcnlat,c t,hc rcact,ion tlat,a ~vi th Eq. (11.49). Tllc lat,cr approach ~voiild imply a t,~vofoltl propagat,ion of t,hc iinccrtaint,ics and result in reaction data \~rllosc nnccrt,aint,ics ~voiild i)c considcral)ly larger t,harl t,llosc originally assigned.

Tllc t,hcrrnodynarnic data in t,llc sclcct,ctl set rcfcr t,o a tcrrlpcrat,~lrc of 298.10 K (%5.00°C), l)iit t,llcy can be rccalc~llatcd t,o ot,llcr t,cmpcrat,~lrcs if t,llc corresponding dat,a (cnt,halpics, cnt,ropics. heat capacities) arc available [93PUI/R.%R]. For cxarnplc, the tcrrlpcrat,~lrc dcpcndcncc of t,llc standard rcact,ion Gibbs cncrgy as a fimct,ion of the st,andard rcact,ion cnt,ropy at the rcfcrcncc t,crnpcrnt,urc (TO = 298.10 K), and of the heat capacit,y fimct,ion is:

T

A T ) = ArH;(T,) + ArC;,mcIT

and t,llc t,cmpcmt,urc dcpcndcncc of t,llc st,antlartl cqnilibrinrn const,ant as a fiinctiorl of t,hc standard rcact,ion cnthalpy and heat capacit,y is:

log,, K"(T) = log,, K"(TO) - P

R ln(10) 1 T

RTln( l0) R ln(10)

~vhcrc R is the gas const,arlt (cf. Tal~lc 11.7). In t,hc case of aqllcons spccics, for ~vhich cnt,halpics of rcact,ion arc sclcct,cd or can

bc calciilat,ctl fiorn the sclcct,cd cnt,llalpics of format,ion, but for nrhich t,hcrc arc no sclcct,ctl heat capacit,ics; it is in rrlost cases possible to rccalcnlat,c cqiii1il)riiim const,ants to tcrrlpcrat,~lrcs up t,o 100 t,o 100°C. ~vit,ll an atltlit,ional nnccrt,aint,y of perhaps about 1 to 2 logarit,llrrlic nnit,s. diic to t,hc disrcgartl of t,hc heat capacit,y cont,rib~l- tions t,o t,hc tcrrlpcrat,~lrc corrcct,ion. Ho~vcvcr. it is irnport,ant t,o obscrrc t,llat "nc\v3'

Prrsratat%oa of the srlertrtl dnta 33

nqiicolls spccics, i . e . , spccics rlot prcscrlt in significant arnoiint,~ at 25°C and t,llcrcforc not dct,cct,cd. may bc sigrlificnrlt at higher tcrnpcrat,~lrcs, sec for example the work by Ciavatt,a. Inliano and Port,o [87CI.%/IUL]. .%tltlit,ional high-t,cmpcmt,urc cxpcrirncnt,~ rrlay tllcrcforc he nccdcd in ortlcr t,o asccrt,ain that proper chemical rrlodcls arc iiscd in t,llc rrlodclling of hydrot,hcrrnal syst,cms. For rnany spccics, cxpcrimcrlt,nl t,llcrrnodynnrnic data arc rlot available to nllo\v n sclcct,ion of pnrnrrlctcrs t1cscril)ing the tcrnpcratiirc tlcpcndcncc of cq~lilihri~lrn const,ant,s and Gihhs cncrgics of forrnat,ion. .% guideline has t,hcrcforc l)ccn tlcvclopcd at t,llc YE.% [93PUI/R.%R] t,hnt gives t,hc user sorrlc informnt,ion on various proccdiircs to cst,imnt,c t,llc t,crnpcratiirc dcpcndcncc of tllcsc t,llcrrnodynnrnic pararnct,crs.

Chapter III

Selected americium data

'l'liis c:iriipror prc:sr:rits ttro c.trc:rrrii:;rl ri~c~i'rriotiyri;ris~i(: tliita M:T fin a,rii(:ri(.i~lir~ sj)e:(:ic:s wliic:ii kitis i)or:ri sc:li:c:t,c~rl irr rliis r ~ ~ i r i ~ w . .I';ri)lc% 111.1 (~orit,:iirlb t,trc: i~(~co~sirii(:i~(I(!il t,li(:r- rrrodyri;irllic~, il:it,;i of t,li(: ;irrrc!~i(~i~irrl e~,orrrpo~lri~ls arid (~or~~plc:x(:s. 'l~';rbli: 111.2 t,li(: i'(:c,,- orrlrrrc!rlil(~il t,trc:~~ri~o(lj~rl;irrri(: <l;rt,:i of (:l~i:rrii(,:il (!il~~ilit)ri~~iri r(:i>.(:t,ioris t)y wtri 11 t,lic> a111- 3". . e~ri(:i11111 e~,orrrpo~lri~ls arrd (:oirlpIr:x(:b ;rr(: f o ~ r l l ( ~ l > ;riiti 'i';iI)lc! 111.3 t,li(: t,(:rr$D c i t ,~~i ( : (:o- c4fic:ic:ilt,s of t,iic: 1icil.r c:ap;ac,it,y data of 'l'ilt)lr: I l

,~ 1 ilic: ~~~~~~ic.s arid l.i:acrio~is i i ~ 'i':ii-jiivi 1ii . l : ii1.2 thrl stwiitl;il.tl <)r(l(xr i>f ;r,rrarig(:iriei~t, (c$ Fig~~rc: i1.1. 1~.21).

.TiiIile: 111.2 cont,aiirs infi)riri;irion oi1ly iiii

v~irlr cla,tii for l i c y arrie:rici~irrr spi~ie:s (fix Tiiblii I\..l, to ticrivc t,lic t ies associated v-ii,ll examplc arlti for tlic ailxiliar\; data arc in most rases 1%. in the foirilii;ios

.2rrrHI'():, c ; i i : . ) . 'l'i~c~i'c:fo~~r:. ttro 1.r:;rtli:i. stroiilti ho a\vil.ro of rile' f;tc.t t,li;rr i:cjniliI)riiirii coirst,;rirt,s i~,;rIi~,irl;it(:(i frorrr Af<i;n ~;rliii:s ill '1~';rbIr: 111.1 irliglit, ri:slllt, ill i~,or~fidi:rrc~,(: liir~its wliii:ii 1)r:rlr;aj)s tic> riot i:orl.r:sporirl triily t,o the% 95% c:orifiilc~irc:c: lirrrit. ' l ' k i c x ir~(:I~~sioir of w t,wl)lc: for ic:;rc:t,ion tl;rt,:i (I';ri)lcx 111.2) i r ~ tkiis i.c'j)ort ;iiIo\~rs ttro uso of i:cjnilil)- i'inrrr c:oilst,;riit,s wit,lr totill nilc~cxrr;iirrt,ics wl~iclr w ~ r : tliri:c:t,ly 1);rsoti or1 tirc: c:xporinrc:rrt~;rI :ic:c:~~r:ic:ic~s. 'i'liis is t,hr: rrla,iii rc:wsoir for ini:lniliiig hot,li tirc: ta,t)lc: for r.r:iic:t,iorr tl;rt,:i ('I3>t,t)l(: 111.2) ;rr1(1 t,kir: t,:ik)l(! of A:(.::.,. A:HI:,, S:, i>,ii<l (,'~,rn\~:il~~c~s ['l~';rbli: 111.1~).

,~ 1 i lie: sc,lc~ctctl t,kii:ririal filiictioris of t,lic: ilcwt (:w~);l(~~i~ies: lii-t,(~il iri 7'alilt: 111.3, i,i.fi:r t,<)

35

X0 rc.fcrrnccs arc g i \ w in t.licsc t.;ihlcs siricc i,hc sclcci,rd d;i!,a arc. gcncr;illy not. dirc.ct.ly at.t,rih~st.;ihlc 1.0 a specific piihlishcd iiJiircc. -4 rlct.ailcd discisision OS t.lic iclcct.ioii pri)ccdisrc is prcsciit.cd in Chapt.c.r 1..

4 r ~ i : Tllc arlclit,ion of itriy i~,qi~coiis sl)cc,ics itritl tllcir dat.;i 1.o !,his int.crslally coslsist.cslt, tii~,t,a I>asc c21,n r~sislt, in it mi)tliIicd ilat.it sci, which is rio loiigcr rigoroiss ;iriti c.;rir loa,rl t,o r:ri~ciricxoiis rc:snlts. 'l'li(: sir~swt,ion is siis~iliii~. ro ;i 1c:ssc:i. tl(:grcxr:. wit,l~ T/I ( \

titlrlitior~ of gasc:s arrti solitis. it slionltl ;rlso ho iiotr:tl t11il.r tlro tiwt,;r hc:r prcxsc:rrt,c:ti iii this C:lra,ptc:r rrray riot i)('

"c:oirrpIr:t,c" fol. a,ll t,l~r: c:oiic:oiv;ri)Ir: hj~st,c:rrrs a,ritl c,or~rlit,ions. C:;rps a1.r: poirrtc:tl oiit i r i t11c: v;ii.io!~s h~(:tioiis of (.llribj)t,(:~ \'.

l 111.1: Selectet1 t1iermotiyn;iniic riatti for ai~ierit:iinn co:nporil~tis anti !.oliiplt:xes. -411 iciliii: sl)ei.irs list,c~tl in tliis ta1)le a1.r atllii.oiis spc.i:irs. Unless ~lorc~tl o t l i e r~ i i e . all i i i~ta refi'r TO

tlie i.efei.ence t,eri~per.;it,irr.e oi'?il8.:15 K and to ilre stw.rr~lar~1 st,ate. i . r.. a. p~.essirre of O.:l M1"a a.11!1. SC~Y ;~,tl~leoir. s11ec:ies. i!~liliile (li111lio11 (1 ~~~~~ 0). The 1111cer.tai111ies list,etl t)elrw em11 v;~,I,ie re!prese!l~t total ~~~ire!rt>~i:itie*s ;%II(~ <:tjrrt~!s~~o~id i ~ i prii~ripic* to t1~ : statisti<:>kily ilefi~retl 95% <:o~~fitit:~~t:t: i~~t(:rval. \'all~!!s tok)t,;~i:ied fro:^^ i11t(:rr1;~1 ~ : > ~ l r i i l ; ~ t i o ~ ~ ~ <;f. foot,~lotes (;L) ; I I I ~ (1))- are rol~ntlexi ;it the third digit, i~fier the ricli:irn;rl poirit ~ L I I ~ Intry t,hclrt:fi)re 110t 118 ex&(:tly r t i c l l 1 1 1 s e r 1 1 C . 1. S.vste!r~atically, all ilie va111rs are [~~.esenl~e(l wit,lr t,lii.c.e tligits i~ft.e~. t,lie (I~ciiiiiil j)ciiiit.. rega~~tllrss or i.lie sigiiiiirw~ice of t,k~ese i1igiI;s. The <la,l.a, pr.esentei1 iii t,k~is t.n,lile are ava.ilwl)le or1 PC tlisket,t,ei or. o t l~er co!~ij)iit,er. uie(iia koni i11e OE'CD Xiicleal. E'ne~gy ilge:ic\-

~0111~)0l11li~ arc. ,,, ArIC, C;,,,, l ~ 1 ' ) [kJ . 11101') [.J . I ; ' . 111ol'i , (*I . . K ~ ~ ~ ' . 111(,1~~~' j

(:L) J~>ISI~E: c;;~lr~il:~t,c,il ii!t,c,rri:~lly with the G i ~ ~ ~ ~ s - H ~ ~ I i r ~ ~ i o l t ~ z cq~i;~,tioii, ArG;, = &HE;, - TliSE,.

( 1 1 ) \';~,l~ic: r:~lc:~~l;~,rc:ci iIl~<:!.ri:liiy f1:oiri ~x:ac:tiori il:l,t:~ {X:P 'II::L~IP IIlI.2).

( c ) 'Teni~~erariire roeifii:ierlts of illis Eii~ictio~i are listr(1 in Table 111.3. ((l) For tliis i:orripniiiiil ~iitlialpii:.: of ptiasi: tiaiisfoi~riinrioii :i.ie givf*ii iii Sect,ioii \ ' . l , arid

;l, t r iript?i~>t,~~rf~ f ~ ~ i ~ c t i o i ~ the, Iif:;lt, c;:ilm:ity is gi\:t?ii iii 'l';l,t~It? 111.3.

(r) 0111s re;~ci in11 d;~l a ai~e srlri:t ed fc~r Illid i:i~irlpn~~11(1. (,l. Table 111.2.

l l . : Srlect,e(l t.lrer~rrnilyiinir,ic (in,t,a f i ~ react,in~rs iiivolvirig ar11el:iciinrr couij~nini(ls i u ~ l (.oiiiplt:xes. All iciriit: si~ecies list,eil ill tliis t;thle itre a(1iw:orls species. Ilnless riott:{i Ot,ll- erwisi., all ilat,;i r r k r to thi. rc,ff:rc,nce aemperiitiirr of 298.1.5 I i i~n(1 to tlif: stariiiiwii state, i . i:,> a prcss1~1': of 0.1 MP;L ;lll(ll fir ailiii:oim spet:ies, ilifiriitc (liliit,iori (I = 0 ) . 'The iniccr- I,ail~t,ies lkl,e(l l)el!;iv each v;~,llie rrpreseiil, t,<il,al ~ i i~cer I , a i~~~ , ies ;I,II!! corrrspoii(1 ill 1)rirlc:iple l,()

t,11e st;~~:i~l:ically ilefilled 95%, c,o~~Ii~leiice i111,erval. Valties nhtaixecl f'rciiri i i~te~,nal calc~~la,t,ior~. r:f. footnoro !;L); arc roiinilc{i a t rile third {iigir nftcr tlio ilccirnnl poilit ancl niny rlit:rcforo not i)e t,xi~i:aly itlt:litir:;ri to tliost, given iri Chi~1)at.r V. Syst,en~;itit.i~lly~ all rile: viili~es are i~rewntc:(l with tliree (ligits after tlie riet:imal poinit, i.egar(lless of tlit: sig~lifi(:ancr: cif these <iigi(:s. Tile (i;%,t,a, pwseiite(1 i r k (:t~is l~a1)le me ;~,v;~,il;%l)le I'C (iiskettes or i ) ( : t~e~, c,o1111>1it,er rnrilin f h i i t,k~e OE('i3 N1ic1ea.r 121rer.gy .?igeiicy.

:\iri:fi~+ - 2 F ~~ + .AiiiF~ 8 5,500 -33,107

10.200 11.142

,\iriF, ((:l:) + :imF, (g ) h 2 . 9 8 2 ~ ~ 1 1.333

-3oar e 1 W i O 13.906 A'

.&1Si(CO:,).~

AISI(CO,);-

A m O 2 ( 6 O : , ) ~ ~

.!l!~(c(:)~);~~~

Arn,(CO, j, (crj

ArsiC0,O~I jcr)

:i11iSCK21+

(aj l r ; i l ~ ~ e <:ali:iil;i~,e~l i~~leriially ~ i t , l i !lie C ~ i ~ ~ ~ ~ ~ - E I e l i ~ ~ l i n l ~ z eqi~; i~ , in~i , Ar<Ti, = ArIfi, - TA?S;, ( t \:;iliir. c;iIcrrl;it~r~~i fiiiiii ;! sr4r~i.at:il st,;!rril;rrtl pot,r.irt,i;~l.

) \;iliii, of loglo ii" r:;ri<:irl;~.tcil iiit,i,riinlly f1.orr1 Arc;:,.

Tal>lc 111.3: Sclcc~,cii tcriipcra1,tirc cocfiiric~its for h a t , rapacitics fiiiict~ioils for tlic -ialiics markcd n-iLli i'.) in T a i h 111.1. accorriirlg t,o t,lic fc>i,rm

C:'' (7'j = (, h 7' 1 (; 7 7 2 1 2 , P,,"

Tllc filiictioxis arc -i;rliti iic:t~ici'rl tirc rcrnpcrwtilriis 7;,i, axiil '7;,,x (iii I<). 7111: valncs ill p;rrciirIic~scs rcpicscnr tlii. poncr of 10. L-liirs fol. C,,I,.,wrc .J . K-' . moi-'.

irrl jcrj ,!i-:i111 ?-A111 ,4111(1) .i111(g) : \ r r 1 0 ~ {rrj ,1111~0:~ ( u j ,411iE1~ (rrj x i l l loc l ( l : r~~

Chapter IV

Selected auxiliary data

This clraptcr jircisc'rits tho ciicrsiical rlrc~i.motiyii;rrs~ic: data for ailxiliary cornpoiiirtls niicl comp1cxc:s whicir a,r(i ~ I S C ~ n.it,hiii t,lic NE:,:l's TIIH jirojcct. \lost cif t,lit:so a,iisiliary spc.cics arc. iisctl in t,lic c:\-;rliiat,ioir of t,lic: rc:corriiircintic:ti ;rrsioriciiiin cla,tii in i';ri,lcs 111.1~ niitl 111.2. It is tircrcforc cssc:nt,ial to wl\vwys iisci thcsc: a,iisiliary data i i r coirjiiiictioii v~irlr tiii: sclcctcti arric:~.iciiirn data. 'l.11~ iisc cif citircr a,iisilial.y diira cair lo;&tci incciii- sistciicics aiid rrrcjnCoiis rcs~l l t ,~ .

Tlic valilcs in i.lic: froril Rcf'. [89COX/\I drscril~cci iri Clial~tcr

spci:ir.s. 7fli~- rc~ison iiir li cricrgics OS Li~rma~.inn is, a3 dcscrilcccl d . ~ ~ I , A . arc oSt.cn smallcr 1.1 ;icc~imirlnt.ioii during t.lic

-411 cl;i!,a in Tai~lcs I\'7.1 a cr;i!,iirc OS 298.1.5 I<> !.lit st.anilnrd it,atc prcssiirc OS 0.1 AIPa ics and react.ii!ns, !,cc !,h(: irifirii1,c tlililriorr ~.r:fi:r.c:irc.c~ st,;rt,cx (1

'ill(: uilc:ort~;rir~t,ios 1istc:tl ! ill rI.i,,l>lc' l v.2 ;i,r(r t,ot,;rl iirrc~r:rti,,iir- tics; iir~ti c:cirrospc>rrtl rrr;iirrl lly tIr:firictl 95% c.or~titIr:r~c:c: iirt,c:i.v;il. 'l'lrc' i~nc:c:i.t,;rintics libt,cd 1icIo1-v io ,Ir. l i~i>rrr: t,ilc: foiio\~irlg sigirific:;airc.c~:

6'. r for C101):i':IL:\ li$$% from :YSC'OY/\\:A(I:]. t,i-rc: - t,c:rrns h : n ~ t,iic 111c;rning: "it

is pri,b;ri)lt:. l>& ncit a t ;ill ccrt,;iii~. that tlic- trilc: raliitrs of tiro tirtrrrnotiynii,iriii: qiiantitir7s tliifr7r fiorii t,i-rc: rocciriilrrtrlitld xaliioi- gi~~trli i ~ r this rr7poi't, 1)y no morr7 t,ii;ri~ t,wic.c t,iic t- t,c:rriis att,achccl t,o t,ht: rr~c:o~r~rnc~nrit.il v;iliics".

r h r virliio~ froin j92GKEiFL-Ci, rho -i- rcrrsis arc ticrivc~cl from tcitiil iiiiccii,t,;riritic:s in tho corrc~spoirtlin:: cijiii1il)riiliri coirstaiit of rciacticin (4 7'al)lc 1\:.2j, airtl fioirr tiii: -i- t,crrns list,c:ti hi. tho iic~ci3ssa,ry i:Otl.!Y17?, kc'y valilcs.

i.oirscijiiciit,ly. all t,lic ~.olc~-\;iirt cc~iiilibriiirri coxisrants ;rird i:irt,iialp;v cliwiigc'.; cwii l,(: i.ali:iilat,cti. 7'lic~ projingiirion of crror.; iliiring riris procceliiri:, irci~icvc~i.. lc.atls to ilirccr- tiiiirt,ics in tiii: rcisilitiag i:c(ililii)riiirn coirst,wiit,s that, arc. sigaiticaiit,ly liigirc'i. t,hair tiros(: oht,aincrl ii.oril cxperiiricnt~-il tlc~,crrninnt.ioii oS t llc cnnst ail's. ThcreSorc, rcnct ion i1nt.a for C02(g) ; IICO:i , CO; anci II2PO., , $2-hicli wcrc a1)scilt l i~rm tlic cnrrcspoildiiig Tahlc IT\-,L' ill [92GRE/FUG], are iiicl~irled iil t,his vtoliiinc! tcj proviil~ the ilscr of SC- lcct,crl d:it,n for a~nerici~im spccies (i:J Chaptcr 111) v-il,ll thc dam iiccdcil r,o ohr,nirl t llc lowest, p~si ih le i i i l c~r ta i~ i t i~s 011 r ~ a c t ion propert ici.

Yoke that tlic ~.alircs iil Tai)lcs I\- , l arlrl 1\'-.2 rimy corlt,nin iriorc tligiti ilia11 tllnsc list.cd in citlicr ij!)COXTi/iV.%."i(;] or in Chapter 1.1 oS [!12GRI?/FTIG], bcc;-iiisc ihc i1nt.a i ~ r tiro prcscnt ci-r;ipt,r'r ;ire: i't:ri'it~ve:il ilirccr1;v froin rht. c-o~nl~iitt:rist~cl tla,tw J ~ I S O iiiiil i'oiiiiticcl to tlirr7c cligiti- aft,(-i' rlrt7 elocimal poi~it throi~glr oiit,.

Tal~lc I\'.l: Selei:t,cvl t l i i '~~rr~o~lyri i~rr i i~: (liitii for aiixilii~ry co~n~~)oiin(ls and cornplexc.~, inr.li~(i- irig tlio C:ODii'l'~i Eicy \ii~liu:s [8!)C:OX/'iv~1G] of s1x:cii:s licit (:orit;iini~~g iiraliium, as xvcll as 01.11er 11ai.a l.lri>(. were evi>l~ial.e~l i r r Ci~al,l.ev V1 or !.Ire l i rari i~~~rr review [!JZGHI2/II'UG]. All ior~ic s l~rc i rs liit,eti iii i.lris taiilr itre it(l11~01is sjiecies. Uiile'is ~rnt,eri otl~erwise: all (liti.a, ~ e l i e ~ t,o l~lie refere~rce l,c.rrlpera,(:~~re of 298.15 I< a,riti to sta,~i(ia,r(i st,a,l:e. i .e.> a pressllre of 0.1 h4Pa ;rnrl, f i ~ aqiir:oiis spt,c:icls. infillitcl riiluaion (I = 0). Tl~t~: u~rr:t>rtain~tit:s listed i)cl- low eac.11 v>tliir: re1)rcsr:lit tottil 1int:ertaiiities aiiil ( :o r respo~~l in print:iple to tlir: statisti(.ally f i 5 : i f i i t e : r . \,Tali~e:~ ili bold t,y~)cif>ic.e a1.r CODiYI'ii I i ry Vi~1iir.s anti axe t,itkeii ilirecIIy ko~rr Rrf'. [81)(.:0X jM:?IG: wit,l~o~rt, fiirt.lrer eval~iat,ion. \'a,111e~ ol~t,:+ir~e(l frtoir~ i~rI,err~al cal~:~ila,l ,ic~~r~ cf. r~i~il,~rc~l,es (a.) a11(1 01). are rcn111(1ed &l 1,lre ILtrivd digit, a,f!,er 1,lre iic~ciririil point i~li(1 ririiy tl~errfi~rc. not l ~ i . exiictly i(ielraii.ii1 a 0 tlii~sc. give11 in Chq) te r V1 of R.d. [!)2GRE/FIJGj. Svstomat,i<:ally, all tha valiios al.(: p1.t:scntod with t,l~rec digits i~fior tlio <ic~c:irn;il poiilrl 1.r:garcllrss of alir: signifii:iinct: of thclst: digit,s, 'Tlicl da ta ~)rest:nt,c~(i in t,k~is table are a~railal~lr nlr I'C (iiskpttes tor o the~ . C O I I I J ) I I ~ , ~ I . iiredia. koiii ilre OI?,Cl) N~icleai- 13rlei.g~ Ageiic,~.

O(gj

Or (g!

H(g)

H :~

H,!")

OII-

H,O(g)

Ii?O(l)

ClO,

cio,

cloy

IIClig)

HC1O:aqi

IIC102 (?L(c)

Ilr(g)

Ij,.~~~

13r2 (;><l)

Dr., (g)

I3r, (l)

IlrO

BrO;

HRi(g)

IIBrO(aiij

G C b i L 5 9 N C - L ? t - G c i a m t - C = G ~ $ 9 m = N O e 3 N 3 03C X i N i m + m +

,-. m

E - .. - .. . . ,., ..

X '7 ,-

F. - - ,- .a * ::

0 5 . '3: - k '"

- - , o r-

b ':

?2 1 4 r,

3 ..~,

,-. m

o - - E ..

4; ..-,

- * * - S - - .. .. S 0

Corn~)o~inil Ar G:, 4r1Ct C;,,,, (kJ . rrlol '1 [kJ . i i l o l ' ) '.J ! . 1; ' . r n o l ' 1 (.J . K ~ ~ ~ ' . i r l ( , l~~~' j

X;

NO,

H K;< (?l(fi

VII, (aqj

-UH,(gj

VII:~

p(arn)(":

p((;T)(<,;

P(g!

r , (g j

P4(!41

ro:

P, ()"G

2 ~ 7

11ro;-

H,P(:),

H4P20,( ;~q)

:is(<;,.,)

.&so.:

1 5 0 1 ~ ~ ~

.As, 0, (ci)

, , l ~ ~ 4 0 6 ( ~ : ~ ~ l ~ i ' ) ~ c ~

. A d 4 o ~ ( 1 I l < , l l n ~ ' ~ ~

H.\sO, (aq!

c:c>r11~~c~l111<1 4c<:;, &IJ:, "'//t $0 c;;.,,, (kJ . 111nl- l ) J ~ 1 ~ ' ) (J . K - ' . (,l . ~~~~1 . I I1nl~~ 1 )

C (m)

C(g)

CO ( g )

CO; ("'l)

CO, (g)

co; ~~

IItro;

. . SC'Y ~~~

c, ,c

.- ,.<

c. - - -,

.c + W 3 N W 'C -S -S, 1 9 a d 'i: 3, 110 P- P- - "! L + I.: - -< -* LT- - 4 P - a m 1 - + + q ii 2 ~ t I g -4 + - - ?i l l l l

Z I ~ jcr)

'AllO

Z1i2+

z,llo(c:r)

cklj(:r)

C(l(gj

c;(,2~.-

G(iO (cr)

,-. m

E - .. - .. . . ,., ..

X -" L.

*-. , ~ , -

,- .a * ::

0 5 . '3: - k '"

- - , o r-

b ':

?2 1 4 r, S.

,-. m

0 5 - E .. L. .. 4, 5

- * * - S - - .. .. S 0

& $ $ E s s m s ~i m s i c m s 9 6 "i

9 2 % 2 2 " ? c - ? N " S

3 3 m c c 3 N + m + m + m + M + so k0

%@ "3 .G . @ Y + ? /

3 n c c + g)-$@a'@9 * m 3 0 C C - m - C ~ L I : m o c c &"*@"C 2: 'I q ?

" a G C c @ m & S m e m i l 2 1 ~ 9 2 1 m b. 1 1

/ @% C@

Q %D Go C& 9 9

c c s s r.b .Q-.. $543 %$L: c s

c c "10 c s S ? n c " ? ? " S 3 - C N O 3 G F- " + " +

N l

%k:-;t. ..9 -9 ?D@ 4-22 5 .-

4 U - 6". .'c 7

3 - N 3 " 3 @m 3 0;t- C m m

3 t - c F -? - 3 3 3 3

2 2 % " " 8 o r ! S - ,, ,, 2 W + - 244 L . + g +

l l

(t:) k'(<:i) rc:fcxr.: t,o ~%-Iiiti., crystalliirc~ jriilii(:j jiliiisj,iionis ;rriii is t,lic: rt:ft?i't:ii(:t: state: fin tlie rlrrrierit pl~c~spl~ori~d. Pjai11) ~ r r e ~ d l,<) recl, ~ ~ ~ ~ ~ ( ~ r p l ~ o i i s ~ ) l ~ o s p l ~ i ~ s i ~ s .

(r) Ci~t)ic.

j Lloni>rliiiic.

(h) iu-Qiinit~.

(i) 'I~kti;~,p,i~~i;i l.

jjj C;~ssitr:iite. tf?tiap,iin;iI

jkj C:iiriiii~linn.

jlj PIo~~tro?.(lit,e, red.

(111) Riiiilr.

( I I ~ B~ornrllil r .

Ti~,ljl(~ 1i7.2: Sr:li~!(:trxi ttie:rrr~o!iy~~;~~~iit. ( i k r for rc>;it.t,ioris i~ivolvilig a11xili;iry ( ;OII I~OII I I (~S ;LXI!I t:onq)lexes risrd in t l ~ c r:valiiittio~~ of tlie si:le(:tt:{i ;tmericiiini (l>?ra. All ioriic specir:s 1istt.d ill this t,>~1)16: ;ire> ;1<111r?oiis spe<:ies. 'rl16: sr?le(.tior~ of tliese! (1;1ta is ties(.rikie(i in Cll;~ptel: 171. Rra.ctioiis are lisCe(i oiily if they u7e1.e trserl fi1r primary ilat,;t seieciin~r. Tire t,l~ei.moiiy~r;i~rric 11aI,a. of fi>r~~ral i i ) ~ ~ !see Ta1)le lV. l ) are (lerive(1 I,t~erel'ro~!~. LY111ess 11!>I,etj !>t,lier~vise. all d:>,f,a rerer l:o [:lie refereltw t,er~iperatiire of 298.15 l< artcl l~o I~11e sl:al~(l;tr(l st,ate; i .e.. a pressilre of 0.1 MPa i~ri(l; for arliicoiis spocios, irifiliito (lillit,io~i [l = 0 ) . 'Ilic iiiicol:t;~int,i!:s listcd 1)i:lou- t:;rc:l~ v;iliis rt:prt:sr:n~t tot,;il inic:t:rt,iiiritic's ali(i (:orrc~spo11!3 in prin(:iple to the stat,isti(:ally !iefilierl 95% t.i)~ifitlt:lic:i: iritr:rval. Vitliir:~ ol)taiiird froni iritr:rlial calculatiol~. cf. foot~iotc (id, me roiirrtie(1 at, ?,lie t,lii~d (ligit, a,l't,er ?,lie (l~ci11t;al 1)oiltt a,:r!i 11t;ay t,l~erefi)re 1101: be exa,ct,Iy iilent.ic:al t,o t,itose give11 i r ~ (litapt,er Vl. Systrin:atically, :all ilre v;dires are preseiitr(1 wit11 tliret: digits aftr:r tlir: {iecim;il point. rt:garrilrss of the signifit.alic:i: of these digits. '1'11i: tlat,;t prc~ierite(1 ill r l~is tal)le arc, av;~il;ii)le on PC tlislic:rtes or o t h ~ r i:ompiirer niedia. iiom tile OECD Sii~:lr i~x Ent'1.g~~ Agt~ri(.y.

I j 1 ) ~ i . i ~ ~ Ri'nctioii log, ,, l<" A&<, l,.IIi: A,&,

(kJ . 1r101~~~'j (Id . r ~ i c ) I ~ ~ ~ ' ) (.l . K ~% ! i t!~l~~~') A\G

1IFji~i1)

H F',

Cl 0 ~~~

eio,;

Spei:iei. Reaa.ioii log,, W' A&':, A,,Sg,

(1,J . rnol-l) [kJ . ~i~cjl-') (.J . I<-' . III~I~- ')

II' t IISr- + I~12Se(+~q) 3.800 -21.691

20.:300 11.712

H , P , ~ ; + H + + H P . L 0:' 7

-6.650 37.958 f O.100 iO.571

Chapter V

Discussion of data selection

V.1. Elemental americiumt

V.1.1.1. Allotropy o,nrl crystixl strfrctfrri:

.41ncricinrn is the first 5f clcmcrlt t,o rcscmblc the carly larlt,harlidc clcrncnt,~. hlcIl:han, Cnnningharn arltl \Vallmann [62hICIl'/CUN] sho\~~ctl t,llat at room t,crnpcrat,~lrc amcricinrn has a double l~cxagonal close-(dhcp) st,riictiirc. confirming the carly ~vork of Graf et al. [56GR.4/CUN]; nrhosc lat,t,icc paramct,crs n7crc appreciably larger. IIcIl:han, C~lrlrlingharrl arltl \Vallmann also observed an fc,c phase formctl by condensing arrlcriciiim on t,o t,arlt,aliirn or q~lart,z fibres, arltl s~lggcstcd a mclt,ing point of 1267 K for .4rn(cr). Il'adc arltl Ilblf [67I1:.4D/\l'OL] (csscnt,ially tliffcrcnt,ial thermal analysis. DT.4; rncasnrcrncnt,~) and St,cphcns; St,rornl,crg arltl Lillcy [68STE/STR] (also DT.4 st,lltlics) I~o th found solid-solid transformations at 1350 K and rrlclt,irlg at 1448 K; lat,cr confirmctl by Sari, IIiillcr and Bcrlcdict [72S.4R/hIUE] and Sclczrlcv et o,l. [77SEL/KOS]. Sari; Iliillcr and Bcncdict wcrc llnal,lc t,o ol,scrvc any indications, in qncnchcd sarnplcs, of a t,ransition bclo~v 1273 K. H o \ ~ ~ c ~ ~ c r , rcccnt work by Sclczrlcv arltl his collcag~lcs by DT.4 and high t,cmpcmt,urc X-ray difiac- tion [77SEL/KOS. 78SEL/SHU. 83SHU/SEL] has clarifictl the allot,ropy of .%m by nnambigiionsly idcntifyirlg a tlhcp t,o fcc tra~lsit~ion at (1042 * 30) K. This t,rarlsit,ion is easily rnissctl, sirlcc it is very sliiggish; has a srrlall associat,cd cnt,halpy, and the principal X-my tliffraction lirlcs of the dhcp and fc,c st,rnct,urcs csscnt,ially overlap. Tllc allotropy is sllrrlmarisctl in Tal,lc \'..l. Tllc st,rllct,llrc of t,llc s.-phasc formctl at, 1347 K has not bccn cst,ablishcd, but is alrnost ccrt,ainly bcc. t,llc phase from ~vhich many rnct,als. partic~llarly t,hc lanthanitlc rnct,als. rnclt,.

t .in earlier vrrsior~ of illis Sect,ior~ \%-as p~~t,lishecl in t,hr volllrr~e erliterl l)$ C ~ r c l f i ~ ~ ~ k e K O I I ~ I I ~ S [9OCOR/KON]. This, horvrver. <:ontainecl a r11nnl)rr of misprints r r l ~ i c l ~ l ~ a v r l ~ r e r ~ <:orrect,ecl in t,hr cllrrer~t versinr~.

Tllc first rncasiircmcnt,s of t,llc lo\~r-tcrnpcrat,~lrc hcat capacit,y of two sarnplcs of "l-4rn by Hall et al. [76H.4L/IIOR] wcrc siipplcrncntcd by fiirt,hcr rncasiircmcnt,s on a sarnplc of "'3.k~n by Hall et al. [80H.4L/LEE]. Tllc high self-heat of tllcsc sarnplcs, t,o- gctllcr \\,it11 t,llc rclatircly srrlall rrlasscs of pure -4rn mct,al available, leads to scrcrc problcrrls in low-t,crnpcratiirc t,hcrrnal rncasnrcrncnt,~. Tllc heat capacity ~ ~ a l n c s for "'3Ak~n(cr) arc appreciably diffcrcrlt from t,hosc of "lAkrn(cr). Given t,llcsc prol)lcrns, tllc corrlposit,~ val~lcs givcn by Hall et n,l. [80H.4L/LEE] arc accepted, lentling t,o

Pllasc

N

i/ Y

V. 1.1.3. High-tern,pern,bi~,~i? heat cn,pixcity arad t~nrasfornrixtion (lain,

Tllcrc arc no cxpcrirncnt,al mcasllrcrrlcnts on tllc high-t,crnl)cratiirc hcat capacit,y of .km(cr); but bot,h Octt,ing, Rand and .kckcrmann [760ET/R.4X] and Ward. Klcin- schrrlidt and Pct,crsorl [8611:.kR/I<LE] lla~rc given very similar cst,imat,ctl val~lcs. Sirlcc tllc lat,t,cr3s t,rarlsit,ion t,crnpcratiircs (sec l)clo\v) arc probably more acciirat,c. t,llcir valncs for C,",,(.4rn; cr) allore 400 K. based on t,hosc of prascotlyrninrq ~vit,ll a corrcctiorl for tllc mass tliffcrcncc. arc llsctl; in order t,o avoid too many csscntially cqnivalcnt, tables of t,llcrrnal fiinctions.

Ho\vcvcr, t,hc tabnlat,cd val~lcs of Ward. Klcinschrnitlt arltl Pct,crsorl [8611:.kR/I<LE] do not rrlcrgc srnoot,hly at 298.15 K. and t,llcir ~ralnc of C,";,(298.15 K) is sornc\vhat, smaller t,harl t,llc cxpcrirncnt,al valllc givcn by Hall et al. [80H.%L/LEE]. Tllc cstirrlat,cs of i1:artl; Klcinschrnidt and Pctcrson [86\V.$R/KLE] from 298.15 K t,o 400 I< arc t,lllls arrlcrltlcd slight,ly t,o provide a smoot,ll join at 298.15 K.

Tllcsc cxprcssiorls arc closcly fit,t,ctl by cqnat,ions of t,llc form

St,riictiirc

dhcp

fc c I~cc?

C," ,(T) = ( n + bT + + ('T-~) J . I<-' .11101-' (\-.l)

Lat,ticc pararnct,crs

n = 0.347. c: = 1.125 nrrl

n = 0.4894 rlrrl c?

T,,, (K)

1042

1350 1449

Rcfcrcncc

[62hlC\V/CUN] [7%SAkR/h1UE] [83SHU/SEL] [83SHU/SEL]

Tal)lc 17.2: Hcnt cnpacit,y cocfficicnts and t,ransformnt,ion data

Phase Heat capacit,y coefficients Tmin Tmax TT,,, AtrsHm (I h X lO" c X 10" r X lO-"K) (K) (K) ( J . mol-l)

21.1868 11.199 3.2462 0.6085 298.15 1042 1042 + 30 870 19.44116 10.836 2.2514 5.2087 1042 1350 1350 + 5 5862

y 39.748 l1 0 0 1350 1449 1449 + 5 14393 liq 41.840 l1 0 0 1449 3000 gas 20.7861 l1 0 0 298.15 1100

25.2809 -4.96394 1.54658 -10.9495 1100 1700 62.3915 -33.5329 7.764011 -199.137 1700 3000

with t,hc cocficicrlt,~ given in Table I,..%. Tllc cnthalpics of tra~lsit~ion arc dcdnccd frorn DT.4 traces by Il:aclc nrltl Ilblf

[67\V.4D/Il:OL] (L/ + ;!; 7 + liquid) and by Sclcznc~r et 111. [77SEL/KOS]. Tllc earlier ~ ~ a l n c s , ~vhich arc 50% largcr t,llan those by Sclczrlcv et al. [77SEL/KOS]. arc prcfcrrctl, sincc t,llcy \17crc oht,aincd on a rnassivc sarrlplc of qiiitc pure .41n(cr). -4n npproxirnat,c val~lc for AtrsSm(o + ,/) can l)e ~ a l ~ ~ l l n t , c d from t,llc ~ ~ C S S I I ~ C rcqiiircd to st,al)ilisc the fc,c phase a t room t,cmpcmt,urc, which is t,akcn to l)c (6 * 1) GPn [79.4KE/.JOH; 8 1 R 0 0 ] . \Vit,h A,,,\ -((Y + L/) = ( 1 . 0 8 * 0.24) X 10-' rrl" . 11101-' [83SHU/SEL], orlc firltls A,,,S = (0.87 * 0.24) J . K-' . mol-l; ass~lrning (tlT/tlp) is constant fiorn 298.15 K to 1042 K. I lk tllcrcforc rct,nin t,llc cnt,ropy of t,rnrlsit,ion cstirnatcd by Octt,ing, Rand and .4ckcrrnann [760ET/R.4N] (and iiscd by Il:artl; Klcinscl~mitlt nrltl Pct,crson [861\:.4R/KLE]), &,,S = 0.837 J . K-' . rnol-l. This is largcr t,llan t,llc vnliic A,,,S = 0.32 .J . K-' . mol-l cst,imnt,ctl frorn DT.4 t,rnccs by Sclcznc~r et al. [77SEL/KOS], nrhich is not surprising in view of t,llc slnggishncss of this t,mnsit,ion.

V.1.2. Arraelici'i~,vr irleo,l rnonoo,torraic gas

V.1.2.1. Heat capacity cxrrci eratropy

Fchcr nrltl Hcrrick [65FEB/HER], Oct,ting, Rand nrltl .4ckcrrnann [760ET/R.4X] nrltl Ward, Klcinschmitlt and Pctcrson [861\:.4R/KLE] cnlc~llatcd t,llc t,hcrrnal fiinctiorls of .41n(g) bnsctl on ohscrrctl and cst,imnt,ctl spcctroscopic cncrgy lcvcls. Tllc rrlost rcccnt T ~ ~ ~ I I C S of Il:artl; Klci~lsCh~rlidt and Pctcrson [861VA4R/KLE]. ho\~~crcr , arc cnlcnlat,cd for t,hc 2'".4m isot,opc. using t,hc 33 spcctroscopic lcrcls 111) to 18000 cm-' given by Brc~vcr [84BRE]. This isot,opc is not t,hc one of rnajor irrlport,nrlcc for rrlost stiidics, so nrc rccnlcnlat,c t,llc thermal filrlct,ions for t,llc "l-4rn isotope, adding as ~vcll 18 more spcct,roscopic lcvcls bct,~vccn 18000 nrltl 30000 crn-l, ~ r c ~ i o i i s l y ~omrrl~l~licnt,ctl by

Frcd [75FRE] to Oct,ting, Rarltl arltl .%r,kcrrnann [760ET/R.%X]. The Gibbs cncrgy fi~nct~ion ( G - H(298.15 K) ) /T at 3000 K is 0.003 ant1 0.0150 J . K-' . rnol-' grcat,cr than those givcn 1)y Il:artl; Klcinschrnidt arltl Pct,crsorl [86\V.%R/KLE] and Oct,ting, Rand and .%r,kcrrnann [760ET/RAkN]. rcspcctircly.

Tllc rccorrlmcrltlcd st,arltlartl heat capacit,y arltl cnt,ropy arc

Tllc heat capacit,y as a fiinctiorl of t,crnpcratiirc is closely fit,tcd 1)y Eq. (\:.l) \\,it11 the cocficicrlt,~ givcn in Ta1)lc l'..%.

Prccisc vapour pressure mcasllrcrrlcnts n7crc rrladc in t,wo scparat,c st,~ltlics 1)y Il:artl; hliillcr arltl Kramcr [76\V.%R/lIUE] ("'3.%rn; 990 t,o 1358 K) arltl by Ward and Klcin- schrrlidt [iSIl:.%R/KLE] (2'".%m, 1200 t,o 1595 K). Tllcsc arc prcfcrrctl t,o t,hc carlicr work by Er~vay a11d S ~ I ~ ~ ~ S O I I [50ER\V/SIlI] ant1 Carniglia and Cnnningharn [55C.%R/CUX], usirlg rrliich less pure rnatcrials. Tllc vapour pressure cqnat,ions fiorn the t,hrcc stiidics arc:

An~(s) : logln(p/atln) = 6.578 - 143.151T ( v 4 990 t,o 1358 K [76WAR/MUE]

An~(s) : logln(p/atln) = 6.296 - 13983/T (V.3) 1200 t,o 1415 K [79WAR/KLE]

Am(1) : logln(p/atln) = 6.279 - 13935/T (v.4) 1469 t,o 1595 K [79WAR/KLE].

The nnccrt,aint,y in t,hc ~ ~ a l n c s of log,, p obtaincd from Eqs. (\:.2) and (\:.3) is proh- ably f O . l O , incrcasirlg to +0.15 for Eq. (17.4).

Tllc cnthalpy of s~lhlirrlat,ion at 298.15 K is calc~ilat,ctl by bot,h the second- arltl third-la\v rrlct,llods usirlg the t,hcrrrlal fimct,ions asscsscd in t,hc prcscnt nrork. nrit,h the rcsult,s sho\vn in Tahlc \".3.

Tllc sclcct,cd ~ralnc is

AfH:(.%m, g, 298.15 K) = (283.8 + 1.5) k.J . mol-l

based on t,hc t,hirtl-law heat fiorn all t,llc st,~ltlics (t,llis is antornat,ically nrcightcd t,o- wards the rrlorc cornplct,c stiidy of Ilkrd, lIiillcr and Kramcr [76Il:.kR/hIUE] ~vhich has c ~ c c l l e ~ ~ t agrccrr~cnt h e t , \ ~ ~ c e ~ ~ the second- and tllird-la\v cnt,llalpics).

It may 1)c rlot,cd t,hat t,hc ~ ~ a l n c s for AfHk(.%m, g; 298.15 K) given 1)y Ilkrd, Klcin- schrrlidt arltl Pctcrson [86\V.%R/KLE] arc itlcnt,ical ~vit,ll t,hosc givcn by Ward arltl Klcinschmitlt [79Il:.kR/I<LE]; ol)t,ainctl using tliflcrcnt tllcrmal fimct,ions for hot,ll .k~n(s; 1) and .%m(g) arltl arc t,hns not qiiitc corlsistcrlt ~vit,ll the tllcrmal fimct,ions give11 in Ilkrd, Klcinschrnitlt and Pctcrson [86\V.%R/I<LE]. Ncvcrt,hclcss. the sclcct,ctl ~ralnc is very close t,o that sclcctcd by bot,h Ward. Klcinschrnidt and Pc- tcrson [86Il:.kR/I<LE] and Oct,t,ing. Rand arltl .%r,kcrmann [i6OET/R.%N]; &H;= (284.1 + 2.1) kJ . mol-l.

S%rrr,~~le nrnevi:%ri;rrt, (ayrn ions 73

Table \'..3: AfHk(.%rn; g. 298.10 K) tlcrivcd from vaporisat,ion mcasllrcrncnts.

Tllc Gil)l)s cncrgy of forrrlat,ion is calcnlat,cd from t,llc sclcctcd cnt,halpy of forrrlat,ion and entropy:

V.2. Simple americium aqua ions

In aqncoiis rncdia. arncrici~lrn cxist,s as t,llc t,rixi~,lcnt ion except ~lrltlcr strongly ox- idising conditions, \vhcrc t,llc five- and six-valcnt dioxoarrlcriciiim ions .%rnO; arltl .%I~o;+ arc forrncd. In acid soliit,ions. the forrrlcr slo~~rly disproportiorlat,cs to .%rnO$+ and .%m3+. Tllc frcc ratlicals protl~lccd from o.-part,iclcs in ~ ~ ~ a t c r readily rcdncc t,llcsc dioxoamcricinrn ions hack to .%m3+. Tct,rax~alcnt, arrlcriciiim is only st,ahlc in the prcscrlcc of strongly corrlplcxirlg agcrlt,s siich as carbonate, fliioridc, phosphat,~ arltl phospllot,~lrlgst,nt,c ions.

Tllcrc arc no soliil)ilit,y or ot,hcr tlat,a from ~vhich t,llc Gihhs crlcrgics of any of the arncricinrn ions can bc related t,o any of the condcnsctl phase cornpoiinds; alt,ho~lgh tllcrc arc cmf tlat,a relating one ion t,o anothcr. Tllc Gil)l)s cncrgics and rclat,ctl propcrt,ics of the ions t,llcrcforc tlcpcnd on cstirrlat,cs of t,hc entropies of t,llc aqua. ions; based on comparisorls nrit,h other act,inidc and lant,hanidc ions.

Fiigcr arltl Oct,ting [7GFUG/OET] rcvic~vcd t,hc t,hcrmotlynamic propcrt,ics of the aqua ions, and except for t,llc t,ct,mvalcnt ion, no fi~rt,llcr rclcvarlt data 11ax.c hccn puhlishcd, so t,hcir carcfi~l cvaliiation is acccpt,cd \vit,h rrlinor charlgcs for t,hc more st,ablc ions. .% later review of the t,hcrrnochcrnist,ry of t,hc simple aqua. ions has bccn given by hlart,inot arltl Fngcr [85hI.%R/FUG]. Tllc discussion in the follo~ving scct,ions siimrnarizcs the original works fiorn nrhich the sclcct,ctl dat,a arc dcrirctl arltl the pot,crlt,ial diagram in Figure \'..l oiit,lincs t,hc sclcctcd x~alncs ~vhich arc given in Tahlc 111.1. Tllc current valiics of t,hc thcrmotlynamic tlat,a for t,llc aqua ions will l)c re-cxarnincd for orcmll consist,cncy ~vit,llin the act,inidc scrics by the rcvic\~rcrs of the Np and P11 x~oliimcs \vhcn their sclcct,ions for the aqueous data for t,llc ions of t,llcsc clcrrlcnts have hccn finalised.

F l : Elcct,rotlc pot,crlt,ials (in nnit,s of 1') for sorrlc arrlcriciiim rctlox coiiplcs. Tllc spccics .%mw is it,alicizctl t,o stress t,llc fact that it is only a t,ransicnt species. cf. Scctiorl \'..%.l.

Fiigcr and Oct,t,irlg [iGFUG/OET] and 1Iartinot and Fngcr [8511.%R/FUG] have disciissctl t,hc critlcncc for the forrnation of the l ~ c ~ ) t , ~ ~ , ~ ~ ~ ~ l c ~ ~ t , aqiiaion in 3 t,o 5 hI N d I H by oxitlising .%m(\:I) sol~lt,ions iising 7-irradiat,ion in t,hc prcscrlcc of xZ(I or K2S2(IR. It is also clairncd (Nikolacvskii et o,l. [75NIK/SHI]) that .%rnOz+ tlisproport,ionatcs to A%~n(I'II) and .%m(\:) in alkaline soliit,ions ~vit,ll conccnt,rnt,ions ahovc 10 11 NdIH. Tllcrc arc no qnant,it,at,ivc t,hcrrnodynarnic dat,a for t,llc .%m(\:II) aqnaion, arltl the species ~vill not he corlsitlcrcd fi~rt,llcr.

.%S tlisciissctl by 1Iartinot and Fuger [85hI.%R/FUG]. t,hcrc is critlcncc for the t,mn- sicnt forrrlat,ion of .%ri" iin aqueous pcrchlorat,c rncdia in piilsc radiolysis cxpcrirncnt,~ [iGSUL/GOR, 78GOR/hIUL] t,hc half life urns rcport,cd t,o he approxirnat,cly 5ps. Radiopolarography (cf. ttllc review by David et (11. [90D.%I'/hI.%S]) sho\~rs fairly 1111-

arnbigiiosly t,llat .%mw is raot an intcrmctliatc spccics in t,llc rcdiictiorl of .%rn"+ to the rnctal in non-cornplcxing mctlia, alt,lloiigh its forrnation has hccn snggcst,cd in molt,cn salt,s [8311IK] arltl organic solvcnt,~ [69hIUS/II.J.%, iGFRI/STO, 92KUL/K.%hI]. NII- gent et o,t. [i3xUG/B.%l-] cst,irnatcd t,hc .%rn"+/.%rn2+ pot,cnt,ial t,o i)c -2.3 1' from a syst,cmat,ic stiidy of the propcrt,ics of t,hc lathanitlc ant1 actinitlc clllorocomplcxcs in rclation t,o their 1I(II)/hI(III) potcntials. -4 similar valiic of -2.4 1' has bccn cst,i- rrlntcd by Bratsch and Lago~vski [86BR.%/L.%G]. Tllc valiic of E" = -(2.3 * 0.15) l:, and t,llc st,arltlartl Gihhs cncrgy of format,ion of .%rn3+ sclcct,cd bclo~v gives

AfGk(.%m"+, aq, 298.15 K) = ( 3 7 7 * 15) kJ . rnol-'.

hlorss and hIorss arltl hlcC11c [iGhIOR. 76110R/hICC] and David [86D.%I7] have siiggcst,cd t,wo similar cq~lat,ions expressing S:(hIwf; acl; 298.15 K) in t,crrrls of the relative at,orrlic mass. charge. ionic ratliiis and t,ot,al angular rnomcnt,nrn qiiantiim nilrnl)cr. Tllcsc cqiiations give the sarnc cst,irnatcd value,

~vhcrc t,hc iinccrtaint,y is cst,irnatcd in this review (t,hc slight,ly earlier cst,imat,c of -9.3 .J . K-' . rrlol-l [85D.%I'/FOU] was prcs~lrnably s~lpcrsctlcd by that of [86D.%I']).

S%rrr,~~le nrnevic%ri;rrt, ~ayrn ions 75

Cornhination ~vi th the st,arltlartl Gibbs cncrgy of formnt,ion gives t,llc follo\~.ing cst,i- rrlntcd st,arltlartl cnt,halpy of forrnation:

AfH;(.Irn2+. aq. 298.10 K) = ( 3 5 0 f 16) k J . rrlol-l

V . . Ayr?+

Tllc first val~lcs of the cnt,hnlpy of solution of arncrici~lm in hydrochloric acid, reported by Lohr and Ciinningllam [51LOH/CUX] and \Vcst,r~lrn nrltl Eyring [51\VES/EYR], wcrc carried out hcforc t,hc dct,nils of t,hc nllot,ropy nrcrc nrcll defined. nrltl t,llc crystalline st,riictiirc of t,hc rrlct,al used in t,llcsc invcstigat,ions is not kno\vn. Both t,hcsc val~lcs correspond to a ~ralnc of AfHg(.Irn"+, aq, 298.15K) = 6 7 0 to 6 8 0 kJ.rnol-' for the st,andnrd cnthalpy of formnt,ion of .Irn"+ ~vi th an iinccrt,nint,y of nhoiit 15 kJ . rnol-'. Later. lIorss [69hIOR] rnadc some prclirninnry rrlcnsllrcrrlcnts ~vhich indicated an np- prccinhly more positjive vnliic of allout 6 2 5 kJ . rnol-'. S~lhscq~lcnt,ly, Fiigcr, Spirlct nrld lIiillcr [72FUG/SPI] rncasiircd t,hc cnt,hnlpy of soliit,ion of t,wo samples of .%m((>. dhcp) in hydrogen-sat,~lmt,ctl 1 hI. 1.5 h1 nrltl 6 hI HC1 sol~lt,ions. Their nrrlcriciiim sarnplcs, ~vhich corlt,nincd rnainly "'.Irn. nrcrc charact,criscd for non-mct,nllic (H, X, 0) nrld rrlct,allic clcrncnts. Their val~lcs for AfHk(.%rn"+. aq, 298.15K) in 1 hI. 1.5 h1 nrltl 6 h1 HC1 n7crc ( 6 1 6 . 1 f 0.8). (610.4*0.8) and ( 6 1 3 . 1 f 1.4) k.J.mol-l; rcspcctircly. hlorc rcccnt,ly. lIorltla1 et al. [8il1ON/RAIS] have fo~lrltl t,hc cnthalpy of dissol~lt,ion of csscnt,ially isotopically pure "".Irn(c~; dhcp), containing < 50 pprrl by weight of rnctallic irnpiirit,ics. in hydrogcn snt,uratcd 1 hI HC1 t,o bc ( 6 2 0 . 6 f 1.3) kJ . rnol-'. Sirlcc t,llc snrnplcs used by Fuger et 1x1. [7%FUG/SPI] wcrc charact,crisctl for hot,ll rnctallic and non-mct,nllic irnpurit,ics, nrltl sirlcc Fuger et al. cnrrictl out consist,crlt, rncnsnrcrncnt,~ in 1; 1.5 and 6 h1 HC1, their val~lcs arc preferred in t,llc prcscrlt asscssrncnt. Extrapolat,ion of t,hcsc vnliics t,o zero ionic strcngt,h leads t,o t,llc sclcct,cd ~ralnc of

AfHk(.%rn3+. aq. 298.10 K) = ( 6 1 6 . 7 f 1.5) kJ . rrlol-l

Tllc reason for the large discrcpnncy ~vit,ll the early rncasiircrncnt,s is not clear. It is too lnrgc t,o he nt,tril)iit,al)lc to the prcscrlcc of L/- or 7-phases of amcricinrn in t,llc carlicr rnatcrinl. Lrltlct,cctcd impurities in t,llc rat,llcr small snrnplcs iiscd coiild of course bc n cont,ribnting factor. The close agrccrrlcnt of t,llc val~lc by [8il1ON/RAIS] l)ascd on dissol~lt,ion of "".Irn siiggcst,~ t,llat t,llc effect of t,llc mtlionct,ivity of nrrlcriciiim (such as radint,ion dnrnagc of t,llc mct,nl) is prol)ably 11cgligil)lc. It rnay l)c not,ctl t,llat, sirrlilar discrcpancics have been found in t,hc cnt,llalpics of sol~lt,ion of iiraninrn and (t,o n lcsscr extent) plntoni~lrn mct,nls; for tllcsc clcrncnt,~; ho~vcvcr. t,hcrc arc prol)lcrns of the forrnation of ~ln\~,antcd oxitlat,ion states (U3+ and Pn4+. rcspcct,ivcly). ~vhich is not t,hc case nrit,h nrncriciiim. Some .%m(\:) is slowly forrrlcd by radiolysis in .%m3+ soliit,ions in t,hc prcscrlcc of Cl-, cf. Scct,ions \".3.1.2 nrltl \'..3.2.5. l)iit t,his cffcct will not he significant in t,hc short t,imc (W 1 h) t,akcn for t,hc calorimct,ric dissol~lt,ion. in the prcscrlcc of l)oth tlissolvcd nrltl evolving hydrogcn.

Ho\vcvcr, t,llc carcfi~l rncasiircrncnt,s of Fngcr, Spirlct and hIiillcr [7%FUG/SPI] arc confirmctl by the stiidy in Ref. [87hIOX/R.%S]. as \ ~ ~ l l as t,llc earlier prclirninnry

work of hIorss [69hIOR] already rncnt,ionctl. Tllc syst,cmnt,ic rclat,ionsllips l)ctn~ccn the cnt,llalpics of forrrlat,ion of the aqua. ions and the cnt,hnlpy of siil)lirnation of the rrlonoat,omic gas in nct,inidc nrltl lanthanitlc rnctals not,ctl by Xngcnt,; B~lrnct~t nrltl hlorss [73NUG/BUR] also suggest t,hc cnt,hnlpy of formnt,ion of .Irn"+ is close t,o the T'>I,lll~ S C ~ C C ~ , C ~ 11~1.~ .

AIs not,ctl prcvio~lsly. t,llc entropy of .4rn"+ as cst,imnt,ctl by Fngcr and Oct,t,irlg [76FUG/OET] from t,hc irlt,crrclat,ionsllip of t,llc ionic rntlii and t,llc kno~vn t,hcrrnodynamic propcrt,ics of lanthanitlc nrltl actinitlc ions. Their vnliic of

is accepted. David [85D.4I'/FOU, 86D.II.'] has cst,irrlat,cd the very sirrlilar vnliic of 1 9 9 J . I<-' . rnol-'.

Tllc Gil)l)s cncrgy of forrrlat,ion is cnlcnlat,cd from t,hc sclcct,ctl val~lcs for the cnthalpy of formnt,ion and the cnt,ropy.

.Is not,ctl in Scct,ion 17.2. this species is ncrcr fo~lrld in any npprccinblc amo~lrlt in tctraxi~,lcnt americium sol~lt,ions; ~vhich arc only stable in t,llc prcscncc of strongly corrlplcxirlg anions. Xcvcrt,hclcss; good cstirrlat,cs of it,s thcrmotlynamic propcrt,ics arc of interest,.

AI fairly precise cstirrlat,c of its cnt,hnlpy of formation urns given by hIorss nrltl Fngcr [81hIOR/FUG]. They point,ctl out t,llat the cntllalpy of t,hc llypot,llct,icnl sol~lt,ion process;

is an cxccllcnt linear fimct,ion of t,llc latt,icc paramct,cr of t,hc dioxide nrhcrc 111 is n lanthanitlc (Cc and Pr) or actinitlc (Th. U, Xp, PII) clcrncnt. Only t,llc ~ ~ a l n c s for tcrbi~lrn arc discrcpnnt,. In t,hc same papcr. hlorss and Fiigcr [8lhIOR/FUG] present n carcfiil calorirrlctric dct,crrnination of t,hc cnthalpy of formnt,ion of t,~vo snrnplcs of .Im02(cr). one cont,ainirlg "'-4rn; the ot,hcr "'3.4m. \Vit,ll n lat,t,icc paramct,cr of a =

0.53743 nm for .Im02(cr). t,llc corrclat,ion rlot,cd above irltlicnt,cs t,llat t,hc cnt,halpy of the above llypot,llct,icnl rcactiorl for 111 = .Irn is ( 4 5 * 5) kJ . rnol-l. ~vhich co1nl)inctl with AfHk(.Im02; cr, 298.15 K) (cf. Scctiorl \'.3.2.3) finally gives

AIlt,lloiigh tllcrc have l)ccn n niimbcr of cst,irnatcs for the clcctrodc pot,cnt,ial of the .I1n"+/.4rn4+ couple. t,hc rrlost rclial~lc val~lc for t,llis is probably fiorn an cstirrlat,c of S;(.Irn4+, nq). Follo\~.ing Fuger and Oct,ting [76FUG/OET], \IT take t,llc diffcrcrlcc in cnt,ropy of .$m4+ nrltl .Irn"+ t,o l)c t,llc snrrlc as that for t,llc pliit,oninrn ions. nnrncly ( 2 0 5 * 21) J . K-' . rnol-l. giving for .Irn4+

~ ; ( . I r n ~ + , aq, 298.15 K) = ( 4 0 6 * 21) J . I<-' . rnol-'

S%rrr,~~le nrnevi:%r~;rrt, (ayrn ions 77

in ngrccrrlcnt ~vi th the cstirrlat,c of Davit1 [85D.41L/FOU; 86D.4I7] of 4 0 2 J . K-' . rnol-'. I\'hcn co1nl)inctl ~vi th t,llc cnt,hnlpy of forrnnt,ion. t,llc sclcctcd valllc of the cnt,ropy gives

Tllc asscsscd vnliics for t,llc Gihhs cncrgics of formation of .Irn"+ and .h4+ cor- rcspontl t,o a rcdiictiorl pot,crlt,ial of E" = (2.62 + 0.11) 1:. This is in rcnso11al)lc ngrccrrlcnt ~vi th the follo~ving vnliics cxt,rnpolnt,ctl fi'orn rncnsnrcrncnt,~ in phosphate nrld cnrbonat,c soliit,ions:

E" = (2.50 + 0.06) 1: cnlcnlat,cd by hIarciis et o,l. [721IAIR/Y.4Y] from the mcasllrctl ~ralnc of E" = (1.75 + 0.03) 1' in 11.5 h1 phosphoric acid [70\i.4N/GII7]. H o \ ~ ~ c ~ ~ c r , given t,llc nnccrt,nint,ics in the spcciat,ion in siich corlccntrat,cd solii- t,ions. t,hc nnccrt,nint,y of f 0.06 1" in the infcrrctl E" ~ralnc is almost ccrt,ainly t,oo 1o\v.

Tllcsc rncasiircmcnt,s arc discllsscd in rrlorc tlct,ail in Scct,ions 17.6.2.1.2. p.142, nrltl IT.7.1.2.l.d, p.157. Tllc correlation ~vit,ll spcct,roscopic val~lcs proposed by Niigcrlt et o,l. [73YUG/B.41-] lcntls t,o t,hc apprccial)ly lo\~rcr vnh~c of E" = (2.2 + 0.2) 1:.

V. 2.4. Am 0;

Tllc cnt,halpy of rcdnct,ion of -4rnO; to .4rn"+ by t,llc Fe" iio1

was rncasiircd by Gnnn and Cnnningharn [57GUN/CUY] in 1 h1 HC104 t,o i)c _1,Hk(1:.6.298.15K; 1 11HC104) = ( 3 0 2 . 1 f 4.0) k.J.rrloll. If t,llis ~ralnc is ass~lrncd to hold at infinite tlilntion (since t,llc corrcct,ion will he i)otll srnall and nnccrt,nin); cornhination nrit,h t,llc cnrrcnt i)cst COD.IT.4 cornpatihlc valllc for the cnt,halpy of the Fc"+/FcW rctlllct,ion [95P.4R/KHO]; (41.0 + 1.5) k J . mol-l; gives n ~ralnc of

for the rcnct,ion

Frorn t,his nrltl the prcvionsly assigned cnthalpy of formnt,ion of .%rn"+. t,hc sclcctcd cnt,halpy of forrnation is oht,nincd:

lfH;(.krnO;. nq. 298.15 K) = ( 8 0 4 . 3 * 5.4) kJ . mol-l

Follo\ving Fngcr nrltl Octt,ing [7GFUG/OET] this rcric\v ncccpt,~

Sg(.%mO:. aq. 298.15 K) = ( 2 1 * 10) .J . K-' . rnol-l,

based on the same valllc for NpO: fiorn the (corrcct,cd) ~vork of Brand and Coi)i)lc [iOBR.k/COB]. Corrcct,ions coiild bc rrladc in an att,cmpt t,o take nccollrlt of the differing magnetic cont,rih~lt,ions t,o t,llc entropies of t,hcsc ions, but sincc t,hc ovcrall sign of t,llcsc (small) corrcctiorls is not kno~vn nrit,h ccrt,ainty, t,llcy arc ignored nrltl dccrrlcd t,o i)c incliidcd in t,llc (incrcnsctl) ovcrall nnccrt,ainty.

Hcncc; t,llc follo~ving Gibbs cncrgy ~ralnc is obtaincd:

A,G';(.%mO:. aq. 298.15 K) = ( 7 3 9 . 8 f 6.2) k J . rrlol-l

Tllc cnt,hnlpy of rcdiictiorl of .krnO$+ to .%rn"+ by t,llc Fe2+ ion i11 1 hI HC104 urns nlso mcasllrctl by Gnnn nrltl Ciinningllam [57GUN/CUN]. For t,hc rcactiorl

they obtaincd A,H;(I:.8.298.15 K; 1 I1 HC104) = ( 4 1 4 . 6 * 1.0) k J . rnol-'. If t,llis T ~ ~ ~ I I C is BSSIIIIIC~ t,o lloltl at irlfirlit,c dilllt,ion (since t,llc corrcctiorl will i)c imth small nrld llnccrt,ain). combinat,ion ~vit,ll the cnrrcnt ixst COD.kT.4 cornpatiblc vnliic for the cnt,hnlpy of the Fc"+/Fi" rcdnct,ion [95PAkR/KHO], (41.0 * 1.5) k.J . rnol-'. gives n valllc of

for the rcnct,ion

Frorn t,llis, t,hc sclcct,ctl cnt,halpy of forrnation is oht,ainctl:

lfH;(.krnO:+. nq. 298.15 K) = ( 6 5 0 . 8 * 4.8) k.J . mol-l

Pcrlrlcmnrl and .%sprcy [50PEX/.%SP] rrlcns~lrctl t,llc pot,crlt,ials of the .km~S+/.krn(l: conplc t,o i)c E(1hl HCl(14) = (1.600+0.0005) 1' nrltl E(0.3hI HC104) = (1.614*0.001) IT. Brnrltl nrltl Coi)i)lc [iOBR.%/COB] siiggcst,ctl t,llat the diffcrcrlcc of 0.100 I' they follrltl bct,~vccn t,hc pot,cnt,ial of t,hc N p ~ l ~ / N p O ~ + coilplc in 1 I1 HCIOl nrld t,llc vnliic cxtrapolat,cd t,o infinite tlilntion slloiiltl nlso he applied t,o t,hc sirrlilar co~~plcs in other nct,inidcs. Ho\vcvcr, it is 11ox~~ clcar fiorn rrlorc recent dnt,n for the dioxoncpt,~lniiim ions (sec Fiigcr nrltl Oct,ting [7GFUG/OET]) and t,llc dioxonranillrn

ions (sec Grcnt,llc et 111. [92GRE/FUG]) t,llat t,his corrcctiorl is far too large. Follo\~r- irlg Fngcr and Octt,ing, nrc tlo not apply any corrcct,iorl to t,llc "formal" pot,crlt,ials of Pcnncrrlan arltl .4sprcy [5OPEN/.4SP]; l)iit incrcasc sornc\~rhat the nnccrt,aint,y limits. Tllc srnall change in the potential diic t,o the change in standard st,at,c pressure fiorn 1 at,rn t,o 1 bar is entirely negligible in t,llc prcscnt casc. Thiis, for t,llc rcact,ion

this r e ~ ~ i c w oht,ains ArGm(\'.lO; 298.15 K) = (154.3 f 5.0) kJ . rnol-l. Il'hcn co1nl)inctl with t,llc cnt,halpy of t,hc same rcact,ion Af~;(.4m0z+) - AfH;(.4mO:) = (153 * 2.5) k.J.rno1-' and the st,arltlartl entropy of .41nO: sclcct,ctl in Scctiorl\:.2.4. t,llis gives Sk(.41nO:+; aq, 298.15 K) = ( 9 1 * 20) J . K-' .rrlol-'. This is in cxccllcnt agrccmcnt, with the valiic cst,irnatcd from t,hc cnt,ropy NpOz+ from the (corrected) work of Brarltl and Cobble [70BRA4/COB]. .4ccording to t,llc rrlctllod iiscd t,o correct for the diffcrcrlcc in the magnetic cont,ributions t,o t,llc cnt,ropy of t,hcsc ions, the cst,imat,c for the entropy of .4rnOz+ is -86.2 or -88.7 J . I<-'. rnol-'; nrit,h nnccrt,aintics of % 10 J . I<-'. rnol-'.

Tllc sclcct,cd ~ralnc is

S~(.krnO:+, aq, 298.15 K) = ( 8 8 * 10) J . I<-' . rnol-I

from ~vhich one obtains

AfG'k(.4m0;+. aq. 298.15 K) = ( 5 8 5 . 8 f 5.7) kJ . rrlol-'

V.3. Oxygen and hydrogen compounds and complexes

V. 3.1.1. Aq~reo~rs Anr laycirozidr conl,plr:cc.s

Thcrmotlynamic dat,a on .4rn(III) hytlrolysis have bccn compiled or rcvic\~rcd by a nurnl)cr of aiit,llors [76SCH. 78R.4I/SER, 80BEN/TE.4. 82.4LL. 84I<ER, 85PHI/PHI, 86KER/SIL. 86KIhI. 88hIOU/ROB, 89ROB; 92FUG/I<HO. 94JUN/EDE]. Only a fc\\. of t,hcrn. ho\vcvcr, att,cmptcd a crit,ical cxamirlatiorl of t,llc cxist,irlg information [86KER/SIL. 89ROB; 92FUG/KHO, 94.JUX/EDE]. Tahlc \'.4 sho\~.s t,llc nritlc vari- ahilit,y arltl iinccrtaint,ics of the rcport,ctl ~ ~ a l n c s of .4m(III) hydrolysis const,ant,s. They rcfcr t,o the rcact,ion

re-cval~lat,ion of the piil)lishctl dat,a is rnadc by t,his rcvic\v in cases nrhcrc tlis- crcpancics or rcsiilts of do~lht,fi~l int,crprct,at,ion n7crc reported. In gcncral, t,llcrc is no nniqiic st,at,ist,ical procedure for selecting the best rcgrcssiorl cquat,ion of cxpcrimcrlt,al dat,a. -4 great deal of pcrsorlal jiidgcrrlcnt is oft,cn a ncccssary part of t,llc mct,hotl. Possihilit,ics of bias in the cst,imat,cs may arise in t,llc case of very high intcrcorrcl. a t ' ,ion arrlorlg t,llc prcdict,or variahlcs. This review has used the sarne proccdiirc t,o select, the i)cst hydrolysis rrlodcl fiorn all sct,s of cxpcrimcrlt,al dat,a rcport,ctl by t,hc diffcrcrlt,

a~lt,llors. The proccdiirc first involvcd the fit,ting of all possil)lc hytlrolysis motlcls using the nonlincar rcgrcssiorl prograrnrnc NLIN of t,llc S.%S/ST.T softn~arc package [88S.kS] on a mainfiamc computer. This as t,hcrl follo~vcd by a scrics of irlt,crnnl corrlparisons to find the best cutoff point for t,llc niimhcr of prcdict,or varial~lcs. Tllc part,ial F-t,cst arltl the rcsidiial mean square n7crc nsctl as crit,cria for the asscssrncnt,. Tllc ~ ~ a l n c s of the hydrolysis constants rccalcnlat,cd by t,llis rcric\v from t,llc original cxpcrirncnt,al tlat,a arc given in Tahlc \'..5, ~vhcrc the rcport,ctl error lirrlit,~ rcprcscnt this rcvic\v's cst,imat,c of the 95%' confidcrlcc lcvcl.

hlajor diffic~llt,ics in t,llc cxpcrirncntal dct,crrnination of cqiii1il)riiim const,ant,s for .km(III) hydroxitlc cornplcxcs gcncmlly corrlc fiorn it,s grcat case of atlsorptiorl arltl prccipit,at,ion. hIost of t,hc cxpcrimcrlt,al work was carrictl out in the pH region ~vhcrc the first and the sccorltl hytlroxo species arc present. while only a fc\v dat,a have been rcport,cd on t,hc ncut,ral .%m(OH):3(aq). By analogy \\,it11 ncodyrni~lrn [iGB.kE/hIES]; .%llartl [8%.kLL] and Phillips et al. [85PHI/PHI] proposctl also the cxist,cncc of .%rn(OH),. The forrrlat,ion of this ncgat,ivcly cllargcd spccics ~voiild incrcasc t,llc .%rn(III) solubility in the high pH region. .% nnrnhcr of cxpcrimcrlt,al stiidics [83RAkI/STR. 84BER/KILI, 84KIhI/BER, 88ST.%/KIII, 88ST.%/KI112] have sho\\,n that s~lcll a sol~lhilit,y incrcasc does not occur at pH 5 13. The ol)scrvations by I'i- torgc and Tran The [91\'IT/TR.%] arc not considcrctl i)ccaiisc of t,hc grcat variat,ion of the ionic st,rcrlgt,ll during t,llcir cxpcrimcnt,~. Thiis. tllcrc is no cxpcrimcrlt,al cvidcrlcc for anionic hytlrolysis cornplcxcs of .%rn(III). .%lt,lloiigh polyniiclcar hydroxo- or 0x0-complcxcs coiild bc formctl in t,llc region irnmctliat,cly before precipitation, tllcrc is no critlcncc of t,llcir cxist,cncc. Spcct,roscopic rcsiilt,~ [84BER/KIII, 84KIII/BER, 88ST.%/KIII] siiggcst,irlg t,llc abscncc of polynnclcar complcxcs nrcrc inconcl~lsivc sirlcc tllcsc species arc not cxpcctcd t,o appreciably affcct spcct,ral shapes. This rcvic\v has cxcl~ltlcd t,llc prcscncc of polyn~lclcar spccics on a statistical hasis during t,llc cornpiit,cr rcfirlcmcrlt of cxpcrirncnt,al tlat,a [82SIL; 84BER/KIhI, 84KIhI/BER].

No systcrnat,ic stiidics have bccn rrladc ~vit,ll t,llc ionic strength varictl t,o allo\v cx- trapolation t,o t,llcrrnodynnrnic contlit,ions. Corrcctiorls for act,ivit,y cocfficicnts shonltl bc possil)lc ~vit,ll t,hc cqiiation derived from t,llc specific ion intcract,ion cqiiations (sec .kppcndix B. Eqs. (B.5) and (B.8)). Eq. (B.5) predicts a linear ionic st,rcrlgt,ll tlcpcndcncc. Figiircs \".2 and \".3 sho\v, llo\vcvcr, that t,hc cqiii1il)riiim tlat,a from Tahlc \".4; rcarmngcd according to Eq. (B.5), cl~lstcr in two tlist,inct regions of t,hc gmphs. .%c- cording t,o Korotkin [73KOR2, 74KOR], the ~ontradict~ory tlat,a might bc cxplainctl with a diRcrcnt cffcct of t,hc cations H+; Li+. Na+.K+ arltl XH: of t,llc background clcct,rolyt,c on .%m(III) hydrolysis. Ho~vcvcr. t,llc diffcrcncc hct,wccn t,llc logl$:, valncs; oht,aincd using t,hc specific ion int,cractiorl cq~lat,ions (Eq. (B.5) in .%ppcndix B); is too large t,o he accoiint,cd for by a rncdinrn cffcct,.

kinetic rrlctllod of analysis urns ~lsctl in Rcfs. [G911.kR/KIK, i2SHAk/STE, i3KOR%], nrit,h .%m spccics rrloving in the solution cit,hcr iindcr t,hc irlfl~lcncc of an clcct,ric field or hcca~lsc of t,llc solvent flo\v. .%ssnrning a slo\v rat,c of cqiii1il)r a t ' ,ion bct,\~~ccn t,hc varioiis .%m spccics, t,hc format,ion of distinct .km peaks urns entirely at,t,ribntcd t,o hytlrolysis rcact,ions. This review rcjcct,s this ass~lrnpt,ion hcca~lsc the rat,c of hydrolysis rcact,ions. nrhich involvc only dissociat,ion of prot,ons from l~onnd water rrlolcciilcs is cxpcct,ctl to i)c rapitl. Fiirt,hcrrnorc, it is likely t,llat adsorpt,ion-

Tahlc \'..4: Litcratiirc vnliics of cqnilibrinrn const,arlts (in logarit,llrrlic ilnit,s) for tllc reactions

.k~n(OH):~(s) + 3 H+ + + 3 H20(1) nrld

.krn"++n H20(1) + . k rn ( ( l~ ) f - " ) + , ,H+.

0.1 RI (H. Li) (iis [69DES/HUS] C104

5 X l O P M err1 [69\I..IR/KIK] (H.K)Cl

5 X l O P M err1 [72SH..I/STE] NHdC104

0.1 RI (H. Li) (iis [73HUS/HUU. C104 7GHUU/HUS]

0.1 RI LiN03 chr, [73KOR2] err1

0.2 RI NaC104 (iis [82UID] 1 M NaC1Od (iis [82LUN] 1 M NaC1Od pot [82N..II/CH..I] 0.1 RI NaC104 sol [82SIL] 0.7 RI NaCl (iis [83C..IC/CHO] 0.1 RI NaC104 sol [83EDE/UUC] 1:orr. t,o 0 sol [83R..II/STR] 0.1 RI NaC104 sol [84UER/KIRI]

0.1 RI NaC104 sol [84KIRI/UER]

0.5 RI NaC104 (iis [87R..IO/\I..IH] 0.1 RI NaC104 sol [88ST..I/KIhI.

(< 3.7 GUq/l) 88ST..I/KI\12] 0.1 RI NaC104

(44 - 185 GDq/l) 0.1 RI NaCl

(74 - 185 Gl3q/l) 0.6 RI NaCl

(74 - 185 Gl3q/l) 5 M NaC1Od 3 M NaC1Od sol [89P..IZ/KOC] 0.1 RI C10; err1 [89ROS/REI]

Tahlc I-.4 (rontiniicd)

5-28.6 ' i:orr. to 0 sol [SOFEL/R.iI] -2'i,3jf") ' clilut,ecl pot [SOPER/S.iP]

-11.1(&111 ' clilut,ecl sol [91\'IT/TR.i]

(a) Silva kept 10g~~;(~7l cnr~star~t (= -7.7) in t,lx least-sq~~ares fitt,ir~g of his solul~ility data. The vahle of log, \%-as taker^ frorr~ a. previous work. [83EDE/BUC] \%-here the first hy(iro1ysis i:onstant of Crn(II1) was rr~easllrerl 11y ~~otentiornetry (cf. rlppenclix A).

(11) For .irn(OH),, Silva reporte(i logl:[j4 < -34.9.

(c) Dat,a olltair~e(i frorr~ solul~ility rr~easllrerr~er~ts of .irr~On(s).

((i) Ecll~ilil~rillrn cor~star~t l o g l ~ l l , , ~ for t,lx reai:tior~: .irr~(C)H):~(s) + . i r r ~ " + + 3 O H .

(P) Stal~ility cor~st,ar~t 10g1~j[j:3 fnr the rer%<:ti~r~: .ir11~+ + 3 O H + .irr1(OH):3(aq).

(f) For .irn(OH),, Riiscl~ 6 . t 01. reporter1 logli;(17~ < -38 f 1.

(g) Ecll~ilil~rillrn cor~star~t logl~l l , , :~ for t,lx reai:tior~: .irr~(C)H):~(s) + .irr~(OH)a(acl).

(h) I'itorge ar~rl Tran The reporter1 loglo I' = -0.2 for t,lx eq~~ilit)ri l~rr~: . i~n(OH):~(aq) + O H + .irr~(OH);.

dcsorpt,ion processes of arncrici~lrn sl~ccics on t,hc stationary 1111asc int,crfcrcd nrit,h the r~len~~?rer~le l l t ,~ .

Ak~ncriciiim hydrolysis cqnilibrin n7crc st,~ltlicd using n solvcnt cxt,rnct,ion t,cchniq~lc by 11oth Dksirk. H~lssonnois and G~lillaiimorlt [GgDES/HUS] and Hnssonnois et al. [i3HUS/HUB] 11clo\v pH 5.9 in 0.1 I1 LiC104 sol~lt,ions. They assnrncd t,llc prcscncc of .4rnOHW in qiiantitics large crloiigh t,o protl~lcc mcas~lrnhlc deviations from the pH dcpcrltlcncc of dist,rih~lt,ion cocfficicnt,~ cxl~cct,ctl in t,llc prcscncc of .4rn"+ only. Rcannlysis of the dnt,n by t,his rcvic~v cxcliidcd t,his for st,nt,istical reasons.

Tllc ~ ~ a l n c s of log,>/, for n = 1 nrltl 2 at 0.1 hI ionic st,rcrlgt,ll rcport,cd 11y the sarnc research groiip for dist,inct soliillilit,y cxl~crirncnts [84BER/KIhI. 84KIII/BER, 88ST.4/KIII] cover nearly tllrcc orders of rnagnit,~ltlc (sec Figiircs I:.% and \:.3). How- cvcr. a rcanalysis of t,llc dnt,n [84BER/KIhI; 84KIII/BER] rrladc by t,llis rcvic~v indicated t,llat a rnajor disagrccmcnt cxist,s only for log,,',tj. This discrcpnncy appcnrs t,o bc related t,o a cllangc of t,llc solid phnsc ~vit,ll pH, r : j .4ppcndix .l. hlodcl calc~llations l>clo\~r pH 8 nrcrc irlscrlsit,ivc t,o :il. suggesting a srrlall conccnt,rnt,ion of .4rnOHW oorcr- ~vhclrncd ~vi th t,llc prcdorrlinnrlt .4rn(OH): (c$ Ta11lc 17.5). Sol~lhilit,y rncnsnrcrncnt,~ using .kmOa(s) cnrlrlot bc used for a qnnnt,it,at,ivc cl-alnnt,ion of hytlrolysis const,nrlt,s bccn~lsc t,llc dissolution rcact,ions coiild not 11c itlcnt,ifictl.

Silvn [82SIL] nnalyscd the pH tlcl~cndcncc of .4rn(OH):j(cr) sol~lhilit,y in 0.1 I1 NaCl(14 in t,crrrls of four hydroxitlc cornplcxcs. Tllc clairn for the species .4rn(OH):3(nq) nrld .krn(OH)T is rcfiit,cd by this rcric\v Ilccaiisc t,hc cxl~crirncnt,al point,s nhovc pH 8.5, inflncnt,ial in fit,ting the clloscn rnodcl; nrcrc irnpropcrly ovcr\~rcigllt,cd.

Tllc puhlicat,ion by St,adlcr and Kirn [88ST.4/KIII] is t,llc rnajor cont,ribntion t,o the st,~idy of 2'1.km(OH):j(s) soliillilit,y at high pH. hlcns~lrcrrlcnts wcrc rnadc in vnrioiis

Tahlc \".5: \'al~lcs of cqllilihrillrn constants (logarit,llmic ilnit,s) for the rcact,ions .%1n(0H):~(s) + 3 H+ + .4rn"+ + 3 H20

and .%rn"++n H20(1) + OH)!-") + , ,H+

as rccalc~llatcd by t,llis rcvic\v from the original cxpcrirrlcnt,al tlat,a (sec .%ppcndix -4).

Arn(OH):3(s) ArnOH2+ ..Irn(OH): ..Irn(OH)a(aq) t hlecli~~rn Referer~ce (phase) ("c)

-7.3 i 0.4 -15.0 f 0.2 25 1 M (NaC104) [82LUN] -7.2 i 0.2 -15.0 f 0.3 25 1 M (NaC104) [82N..II/CHA]

17.5 i O.G(ar11) 22 corr. t,o 0 [83Ri\I/STR] 15.9 i O.G(cr) -6.9 i 0.G -15.1 f 0.6 25 0.1 \I (NaC104) [82SIL] 13.7 i 0.2('!) -14.7 f 0.2 25? 0.1 \I (NaC104) [84BER/KIhI] 13.9 i 0.2('!) -14.3 f 0.3 25? 0.1 \I (NaC104) [84KIhI/BER] 15.5 i ( ) -7.0 i 0.4 -15.1 f 0.4 -26.4 i 0.5 25 0.1 \I (NaC104) [88STA/KI\I]

ionic mctlia (0.1 hI and 5 11 XaC104; 0.1 11, 0.6 hI and 3 h1 NaCl), and at increasing radiation ficltls. Tllc cl-mtliation darnage affcct,ctl t,llc particle size of t,llc prccipit,at,cs ~vithont changing the chemical nat,urc of the solllt,ion species. Forrrlat,ion of .%rn(\') only occnrrcd in 3 hI XaC1 bccansc of t,llc prcscncc of oxitlising mtlicals. The analysis of t,llc dat,a obtaincd in 0.1 h1 XaC104 llsctl ':II, ':IZ, and ':I:j as i)cst prcdict,or variahlcs (Table \'.5).

Rai et al. [83R.4I/STR]; ~vorking \vith an arnorpho~ls solid in 1.5 X 10-" h1 CaCIZ, rcport,ctl a rrliich higher arrlcriciiim solubility. .%lt,l~oiigl~ t,hc curve fitt,ing analysis urns irlscnsit,ivc t,o t,llc first hydrolysis const,ant,, an upper lirrlit \!,as assigned t,o t,llc ~ralnc of yl. The proposed ~ ~ a l n c s for ':l2 arltl arc lo\vcr t,han sclcctcd in t,llis rcric\v. Tllc diffcrcncc may bc at,tril)iit,cd t,o a pH dependent cllangc of t,llc soliil)ilit,y controlling solid phase in Ref. [83R.4I/STR].

\'al~lcs for ':II in 0.7 hl XaC1 [83C.%C/CHO] and in 0.5 hl XaC104 [87RA%O/hI.4H], and for :l2 in 0.2 11 NaC104 [82BID] wcrc oht,aincd by solvcnt cxtract,ion. -4lt,ho1lgh t,llcy arc of the correct ortlcr of rnagnit,udc, t,llcy have not hccn irlcllltlcd in the set of tlat,a iiscd t,o calciilat,c thcrmodynarnic constants; hccallsc of cxpcrirncnt,al ~llort,~omirlgs (cf. .%ppcndix .% on discussiorl of sclcct,ctl rcfcrcnccs).

Hytlrolysis cqnilibria in 1 h1 XaC104 nrcrc irlvcst,igat,ctl by Liindqvist [82LUN] arltl by Nair, Cllander and Joslli [82N.4I/CH.4] using, rcspcct,ivcly. solvcnt cxtractiorl and pot,cnt,iornct,ry. In l)oth cases; rrlodcl calciilat,ions assnrncd only t,hc forrrlat,ion of A%~nOH". Ho~vcvcr. rcint,crprctation of t,hc dat,a by this rcric\v finds statist,ically significant cvidcncc also for .%rn(OH): (cf. Tahlc \:.S).

Tllc rcsnlt,s of Pnziikllin and Kocllcrgirl [89P.4Z/KOC] arc not considcrctl in t,llis rcvic~v for the reasons spccifictl in .%ppcndix .%.

Thcrrnodynarnic data car1 he dcrirctl fiorn the sclcct,ctl set of hydrolysis const,arlt,s

Figure 17.2: Lit,crat,urc dat,a (cf. Tal)lc 17.4) for t,llc cq~lilihri~lrn .%m3+ + H20(1) + .%mOH2+ + H+

plott,cd accortling t,o Eq. (B.5). Filled circles tlcnotc the original cqnilibrinrn const,arlt,s in cxpcrirncntal st,~ltlics that arc re-cval~lat,cd in t,llc prcscrlt rcvic\v as dcscrihcd in the t,cxt and in .%ppcndix .%. For t,hc sake of clarit,y. t,llc const,ant from [89P.%Z/KOC] at 3.5 111 NaC104 (log,,'~'ll + 4 0 - log,, ( I H ~ ~ = -5.28) is not prcsc~lt,ctl i11 t,his gmph.

8

0 0.2 0.4 0.6 0.8 l

Ionic strength, rr~olal

a t 0.1 I1 and 1 hl ionic st,rcrlgt,ll (Tal)lc \:.S) on bchalf of Eq. (B.5) in .%ppcntlix B. Ho~vcvcr. t,hc dat,a arc too sparse t,o allo\v an acciiratc least,-square cxt,rapolation t,o zero ionic st,rcngt,h. To this purpose, cxpcrirncnt,al mcasllrcrrlcnts sho~lld bc nndcr- taken at other ionic strengths. Conscqncnt,ly. cqiiilibrinrn const,arlt,s in Table \".5 arc scparatcly cxtrapolat,cd t,o infinite diliit,ion. Sincc t,llcrc arc no intcract,ion cocfficicrlt dat,a for .%m3+; .%rnOH2+ anrltl .%m(OH):; the corrcct,ion has l)ccn rnadc by taking t,llc dat,a for trivalent lanthanitlcs, and for t,ypical di- and rnonovalcnt ions, cf. .%ppcndix B, Scct,ion B.1.4. t,ogct,hcr \vith the val~lc for E(,+, This gives the follo\~.ing cst,imat,ctl ~ ~ a l n c s in sodium pcrchlorat,c media:

( I l l r = l) = (0.04 * 0.05) kg . rnol-' ( I l l r = 2) = ( 0 . 0 4 * 0.07) kg . rnol-' : ( I l l r = 3) = ( 0 . 0 7 * 0.07) kg . rnol-'

A% nrcightcd average of t,llc rccalciilat,ctl and t,llcn cxtrapolat,cd ~ ~ a l n c s of v:, gives log,,;;'l," = ( 6 . 4 * 0.2) arltl log,$," = ( 1 3 . 9 * 0.1). .%lt,hoiigh the calcnlat,cd iinccrtaint,ics arc statist,ically correct. it is possiblc t,hat t,llc act,ual iinccrtaint,ics arc rrliich

Figure 17.3: Lit,crat,urc dnt,n (cf. Tal)lc 17.4) for t,llc cq~lilihri~lrn .%m3+ + 2 H20(1) + .%rn(OH): + 2 H+

plott,cd accortling t,o Eq. (B.5). Filled circles tlcnotc the original cqnilibrinrn const,nrlt,s in cxpcrirncrlt,nl st,~ltlics t,llat arc re-cxi~,lnnt,ctl in t,hc present rcvic~v as dcscrihcd in the text and in .%ppcntlix .%. For t,llc sake of clarit,y. t,llc constant from [89P.%Z/KOC] at, 3.5 rn NaC1(14 (log,,',i2 + 6 D - 2 log,, OH,() = -11.66) is not presented in t,his gmph.

- 2 log,, OH,^ -12

larger. Tllc val~lc for t,hc first hydrolysis constant implies a higher st,nhilit,y for .%m((IH)2+

tllarl rcport,ctl in previous rcvic\+rs on nrrlcriciiim nrltl larlt,hnrlidc hytlrolysis. For cxarnplc, vnliics of log,>/," = ( l 0 . 5 ) . -7.5 nrltl -6.6 have l)ccn sclcct,ctl, rcspcctircly, by Fuger [%FUG]. .%llartl, Olofsson and Torstcnfclt [84.%LL/OLO] and hIoiilirl et (11.

[88hIOU/ROB]. Bacs nrltl hIcsrrlcr [76B.%E/hIES] assigncd n vnliic of log,,'"l," = -8.0 to Ntl(II1) (a chemical annlog~lc of .%rn(III)). \+,hilc Rartl [85R.%R3] sclcctcd n x~alnc of -8.25 for Eii(II1). hlorcovcr, .%rnOHW +nrns rcjcct,cd on st,nt,istical gro~lrltls in the re-cvnliiation of t,llc cxpcrirncrlt,nl tlat,a of Rcfs. [84BER/KIhI. 84KIII/BER], snggcst,ing t,hnt .%rnOHW +nrns not an important species in t,hcsc cxpcrirncnt,~, i .e . , t,llat, log,;:l, 5 log,;'& = (log,>/2 - log,>/,). This result also fnvors a lo\+rcr st,al)ilit,y for .%mOH2+ and n x~alnc for log,;i,l," near -7.0. The reason for t,llc appnrcnt discrcpnncy is iinkno~vn and rnay bc diic t,o iinrccogniscd syst,crnatic errors in some of the cxpcrirncnt,al tlat,a. F~lrthcrmorc; tliffcrcnt proccdnrcs exist t,o cnlcnlat,c confidcncc int,crvals of prcdict,or x~ariablcs in non-linear rcgrcssiorl analysis. Indccd. slightly tliffcrcnt nnccrt,nint,ics have l)ccn oht,aincd usirlg different st,at,ist,ical computer packages. Thcrcforc, it was felt t,llat it ~voiild bc rrlorc rcalist,ic t,o sclcct the nn~vcigllt,ctl nv-

cragc of t,hc ~ ~ a l n c s cxt,rapolat,ctl t,o I = 0. i.e.. log,$/," = ( 6 . 4 * 0.7). nrhcrc the nnccrt,ainty has bccn assignctl t,o covcr the rrlaxirrl~lrn rangc of cxpcct,ancy.

It is difficult t,o tlccitlc nrhct,hcr t,hc val~lcs of log,,'~,I," l)clong t,o tliffcrcnt parcrlt tlist,ribntio~~s. .% tliscrcpancy rnay exist hct,\~~ccn the dat,a in Ref. [82SIL] arltl [88ST.%/KIII], and t,llc rcrnaining valiics. .% nrcightcd average of log,>/," = ( 1 4 . 4 * 0.3) and ( 1 3 . 8 f 0.1) can bc calciilat,ctl, rcspcct,ivcly, fiorn t,hc first and the sccond set of data. Tllc nn~vcight,ctl average of t,hc t,~vo val~lcs gives log,$; = ( 1 4 . 1 * 0.6) ~vhcrc t,hc ~lnccrt,ainty has bccn assignctl t,o covcr the rnaxirniim rarlgc of expectancy.

Tllcrc arc not rnany cq~lilihri~lrn dat,a for .%m(OH):3(aq). The ~ralnc sclcct,ctl by this review is that rccalc~llatcd from soliil)ilit,y data rcport,cd by St,adlcr arltl Kirn [88ST.%/KIII] and cxtrapolat,cd to infinite diliit,ion. IIorc acc~lrat,c dct,crrninations of hytlrolysis cqiii1il)ria in the alkaline pH region arc rccornmcntlcd.

This rcric\v sclcct,~ t,llc follo~ving st,andard cqnilibri~lrn constants (cf. Table 111.2):

Tllc st,arltlartl Gihhs cncrgics of format,ion lla~rc i)ccn calc~llatcd t,o he

Fignrc \".4 sho\~rs the ionic st,rcrlgt,ll tlcpcndcncc of t,llc re-c~i~,lnat,ctl and original lit,cratiirc val~lcs of log,>/, (cf. T;~l)lcs \'.0 arltl \:.4) accortling to t,hc spccific ion int,craction prirlciplcs dcscrihcd in .%ppcndix B, cf. Eq. (B.O). .%lthongh this Fignrc does not illustrat,c the sclcctiorl proccdiirc for the ~ralnc of t,llc cqnilibrinrn const,ant,; '"I,", at, I = 0; it sho~vs ncvcrt,hclcss t,hat t,hc rccalc~llatcd T ~ ~ ~ I I C S of v1 given in Table 17.5 do follo\v the ionic st,rcrlgt,ll tlcpcndcncc prctlictcd by t,llc cst,imat,ctl specific intcract,ion paramct,crs in Scct,ion B.1.4. -4 linear fit of the original lit,crat,urc val~lcs (fillet1 circles in Fignrc 17.4) nro~lld irlstcatl rcqiiirc a val~lc of E ~ ~ ~ ) ~ ~ + , ( : ~ ~ ) ~ ) N 0 . 4 kg . rnol-l, ~vhich nro~lld bc inconsist,crlt ~vit,ll t,llc ~ ~ a l n c s of specific ion intcract,ion cocficicrlt,~ for tlivalcnt ions. nrhich arc in t,llc range +0.09 5 E 5 +0.89, cf. Tal)lc B.3 arltl Scctiorl B.1.4.

Tllc tlist,ribntion of dissolved species in t,hc arncricinrn(II1) hydroxitlc systcrn in st,andard aqncoiis soliit,ions (i.e.. at I = 0) at 298.10 K is illiist,ratcd in Figure \:.5 for t,hc range 6 5 pH 5 1%. This diagram sho\~rs that .%rnOHW is a rclat,ivcly rrlinor species prcdorrlinat,irlg only in a pH rarlgc of abo~l t one unit,, cont,mry to t,hc ot,hcr species in this syst,crn. Fiirt,hcrrnorc. increasing ionic st,rcngt,h rcdiiccs the acitlit,y rangc in \vhich .%rnOHW +>rcdorninat,cs, as sho\vn in Fignrc \:.6. .% distril)iit,ion diagrarn for t,hc hydrolysis of .%rn(III) in 0.1 I1 NaCl(14 solutions is prcscnt,cd in the loxvcr part of Figiirc l'..$.

Tllc val~lcs for the sccorltl and third hydrolysis const,arlt,s of amcricinrn(II1) sclcct,ctl hcrc fall in t,hc rangc of ~ ~ a l n c s sclcct,ctl in ot,hcr rcvic\~rs for .%rn(III). arltl lanthanitlc(II1) hydrolysis. For example. for .%rn(OH): and .%~n(OH):~(ac~) Fngcr

Figure \'..4: Eq~lilihri~lrn const,ant,s for rcact,ion: .11n3+ + H20(1) + -4rnOH" + H+ at 25°C in XnC104 soliit,ions plott,cd accortling to Eq. (B.5). Open circlcs corrc- spontl to t,hc ~ ~ a l n c s re-cvnliiatcd in t,llis rcvic\v and given in Tal)lc \".5; ~vhilc filled circlcs corrcsporltl t,o t,hc original ~ ~ a l n c s reported in t,hc litcratiirc. cf. Table \".4 (nrit,ll tllc ~lrlccrt,aintics incrcascd by n factor of 1.96 in ortlcr t,o npproximnt,c tllc 95% ii~~ccrtai~lt,y 1 c ~ ~ 1 ) . For incrcascd rcadnhilit,y, t,llc symbols arc nrbit,rarily shift,ctl < f 0.014 rnol/kg) along tllc X-axis. The solitl line represents Eq. (B.5) \vit,ll (-

log,,'"l," = ( 6 . 4 f 0.2) and AE = (0.04 f 0.05) kg . mol-l. Tllc nssociatcd iinccrtaint,ics arc given by t,llc dott,cd lines.

Iorlic strength, rrlolal

[92FUG] rccomrrlcndcd log,,',i," = ( 1 4 . 8 * 0.5) and siiggcst,ctl, by analogy \vit,ll ;" 0 Ntl(III), a val~lc of log,, )l, = -26.5 for .Irn(III). For t,hc sarnc cq~lilihri~lrn const,nrlt,s

.Illartl; Olofsson nrltl Torstcnfclt [84.4LL/OLO] sclcct,ctl -16.5 nrltl -26.5 rcspcc- ti~rcly, while hIoiilirl et al. [88hIOU/ROB] preferred -14.6 and -23.6. It rrliist l)c pointed oiit,, ho~vcvcr. t,llat t,llcsc const,ant,s cxtcnd over n rnrlgc of n fcxv logarit,llrrlic nnit,s.

H~lhhcrt et 111. [7GHUB/HUS] report A,H,(\'.ll. rr = 1,298.15 K) = 65 kJ . rnol-l. Ho~vcvcr. tl~lc t,o t,hc scnrcit,y of t,hc cxpcrimcrlt,al dnt,a and t,hc narro\17 pH rnrlgc iiscd (cf. .Ippcndix .I) this rcvic\v does not consider tllc ~ n l ~ l c s rcport,ctl by Hnbbcrt et 111.

as rclinhlc.

V. 3.1.2. Aq~reo~rs Anr (V) oarad ArrajVI) hydrozirle conl,ple:ces

Cohcrl has dcscrihcd t,llc inst,nhilit,y of .4rn(I7I) sol~it,ions [i2COH]. Tllc forrrlat,ion of .Irn020H(aq) was assnrncd by Kirn et 111. [85hI.IG/CAIR; 86BUP/II.IG, 88KIhllBLC. 88ST.I/I<IhI, 88ST.4/KI112] in t,hcir int,crprct,nt,ion of amcricinrn solnbilit,y mcasllrcrrlcnts in nqllcons soliit,ions corlt,ninirlg significant cllloritlc conccn- trations. This is tlisciissctl in Scctiorl 17.3.2.5. Tananncv proposed tllc cxistcncc

Figure \".5: Calciilat,ctl dist,rih~lt,ion diagram of amcrici~lrn spccics at 25°C in standard aqiicolls solutions (I = 0) in t,llc range 6 5 pH 5 12. Tllc prccipit,at,ion of solid phascs is not considcrcd. The dott,cd curves rcprcscnt t,llc nnccrt,aint,y range of each calciilat,ctl fract,ion accordirlg t,o the riilcs of error propagation, r:j Eq. (C.18).

0.6 Fraction

0.4

Figure 17.6: Calciilat,ctl ionic st,rcngt,h dcpcndcncc of the distril)iit,ion of .%m3+; .%mOH2+ and .%rn(OH):; at 25°C in XaC104 solutions. Tllc prccipit,at,ion of solid phascs is s~lpprcsscd. The curves rcprcscnt t,hc acidity at ~vhich t,~vo aqllcons arncrici~lrn spccics have the S ~ I ~ C co~~ce~lt , rat io~l , a11d arc calcnlat,cd nrit,h the specific ion irlt,cractiorl cqiiations of .%ppcndix B. For clarity, neither ~lrlccrt,aintics nor t,llc ciirvc for log,& arc plott,cd in this diagram.

log,, r r r ~ + 7 . 2

7 . 6

I I I I I

-

-

-

l. P / g,, 1 - log,;il, - - - -

- A ~ O H ~ + -

i',,

J log,"'K2 = log,,12 P log,";,o, -

- Arn(0H): -

I I I I I

of .%mOa(OH)!:-'"1 ~vit,ll r , = 1 . . . 4 [9OT.%N2] and of . % ~ O ~ ( ( I H ) ~ - " ) also ~vit,ll r , = 1 . . . 4 [89T.%N] basctl on sl)cct,rophot,ornctric rrlcasllrcrrlcnts in strongly alkalinc soliit,ions. Xo t,hcrrnodynarnic dat,a car1 i)c rccorrlrrlcntlcd for any of t,llcsc cornplcxcs.

V.3.2.1. Tlre arnericilrrra-oxygen system

It is st,ill not possiblc t,o give a dcfinit,~ phasc tliagmrn for t,llc .%rn (1 syst,cm, sincc the principal st,udics arc far from consist,cnt,. Chikalla and Eyring have invcst,ignt,ctl the syst,cm usirlg roorn- and high-t,cmpcmt,urc X-ray tcchniqncs [G8CHI/EYR] and have also rncasnrcd t,llc oxygen tlissocint,ion pressures arltl tlcrivcd part,ial cnt,llalpics arltl crlt,ropics for 1.8 < O/.%rn < 1.99 from 1139 to 1445 K [GiCHIIEYR]; while Sari arltl Zamorarli [iOS.%R/Z.%hI] have matlc DT.4 rncasiircrncnt,~ for 1.Gi < (]/.%m < 2.00 and cxarrlinctl ccrarnographs for a nritlcr rarlgc of cornposit,ions. Ho\vcvcr, sincc it is irnpossil)lc t,o q~lcnch t,hc llypost,oichiomct,ric fliiorit,c phase; while t,llc rcact,ions irlvolving oxides at lower (]/.%m arc very sluggish, room-tcrnpcrat,~lrc X-my patt,crns and ccrarrlograplls arc difficiilt t,o int,crprct. In atltlit,ion, t,llc rclat,ivcly short half-life of 2'1.%m, ~lsctl in all t,llcsc stiidics, means t,llat any suht,ly ordered phases sirrlilar t,o those in the corresponding lanthanitlc oxidc systcrns arc iinlikcly t,o bc ohscrrctl diic to t,hc mtliation self-darnage (l)iit sec bclo~v). -4 possihlc phase tliagmrn consist,crlt, with Inany of t,llc obscrvat,ions of the major st,udics and nrit,h kno~vn hchavioiir of the PII (1 arltl Ln O syst,crns is sho\~,n in Figure \'..7.

Tllc rnajor fcat,urcs arc a l~road fcc flnorit,c phase .%mOa-,(m) nrhich ccrt,ainly ahorc 1300 K [iOS.%R/Z.%lI], and possil~ly allore 1150 K [G7CHI/EYR]. extends from .%m01,(i5(~r) t,o .%mOa(cr). .%t 1o11~r t,cm~cl.at,~lrcs, t,hcrc is probably a hrc phasc ~vit,ll a rarlgc of homogcncit,y aro~lrltl .%mOl,(i(cr); l)iit t,hc phase rclat,ionsllips in this region arc very far fiorn clcar. Tllc st,oichiomct,ric scsq~lioxitlc car1 exist in t,wo and possil~ly tllrcc of t,hc cryst,al st,riictiircs atlopt,cd by t,llc larlt,harlidc oxitlcs, sec Scctio11 \'..3.2.2.

Lyalynshkin et o,l. [8GLY.%/SUD] have sllo\vn t,llat ~vhcn hcatcd in a closet1 capillary \\,it11 finely-po\~rdcrcd SiOZ(s). .%rnOa(cr) st,arts t,o tlccornposc to lo\~rcr oxitlcs at, tcrnpcratiircs appreciably lo\vcr t,harl for pure .%rnOa(cr) ~lrltlcr t,llc samc condit,ions. This was at,tril)iit,cd t,o t,llc forrrlat,ion of reducing gases such as H2(g) from radiolyt,ic dccornposition of vapoiirs o~lt,gassctl fiorn t,hc silica. The samc a~lt,hors also siiggcst, that an irlt,crrrlcdiat,c phase forrrlcd iindcr t,llcsc condit,ions urns a rho1nl)ohctlml oxidc . % 1 n 0 ~ , ~ ~ ( c r ) . hascd on split,ting of t,hc 220 rcflcct,ions of the filrltlamcrlt,al fc,c st,riictiirc. b11t this concliision ncctls t,o he confirmctl.

A%kimot,o [Gi.%KI] claims to have prepared .%mO(s) by llcat,irlg "t,cns of rnicrograms" of arncrici~lrn mct,al in a scalctl q~lart,z capillary nrit,h t,llc st,oichiomct,ric arnoiint, of (scparatcly hcat,cd) .%g20(s). .%lthongh it urns irlt,crltlcd t,o heat t,hc .%rn(cr) t,o -850°C, the actiial rcact,ion t,cmpcmt,urc as rrliich highcr. sincc t,hc qiiart,~ capillary

t Earlier versior~s of Sect,ior~s 17.3.2.1. V.3.2.2 ancl V.3.2.3 \%-ere p111)lished i r ~ t,lle v ~ l l l ~ r l e edited t)y Corclfi~nke and Kor~ir~gs [9OCOR/KON]. This. horvever. contained a m1rr11)er of misprints m11i~:h 11ave t ~ e e r ~ c:orrect,e(l i r ~ the C:Ilrrent, r~ersior~.

Figurtl l . : Tc:ntilt,ivc: ;~mc:ricaiilm-osygcln ph;l.sc: diagram (rc:visc:rl from [SOCC>R/II;ON]).

I S fcc Am O 2 -,

l I l ,----, 1 L/* CC l CC

h;-],cl rc:cryst,nllist+i. R grtxy brit t.lr procl~~c: t 1v;l.s foilncl to hilrrr an f c ~ : s t r ~ ~ c : t urtx. wit,h a = 5.1145 X 10 " m. 1-0 filrt,hrr an;-llysis of thr prod1lc.t was possihl(:. RmlV(cr) has il similar SilCl(c3r) st,ructilrc: with a. = 5.00 X 10 " m. It sc:c:ms lilctlly tll;-l,t t.his 1v;l.s iln Rm((1,N) (m) solid solilt,ion: similar t,o t,hr so-c;-lll(:d plnt.onium mnnoxirlr which is now 1cno)n-n t,o I-)(: ;-I, Pi1 ((.I,(I) :X) (m) ph;l.sc:. C) t.hc:r rt:port,s of ;-l, ph;-l,sr with t,hr SilCl(cbr) str~~c:turtl and ;-I, lilt,ticac: p;l.rilmc:tcxr i~milncl 5 X 10 " m had prtlviously lhrc~n givt:n l>y Zilc~hnri;-l,st~n [4!I)Z:l(.12] ~ h o c~xilmint~cl m;-l,t c~i;-ll of unlinown provtxnnncbcx. ;-],nil 1,IcTVh;l.n [G 1 h,ICSJT] : clnring his i1.t t.cxmpts t,o prtxp;-l,rtx ;-l,mtlricium mt1t.;-11.

Si11c.c. non(: of t.hc:stl stildic:s show convincing c:vid(:nc:c: that :lmO(cr) is st.;-],l-)lr as il

pnrtX hilllc ph;-l,stl. it, is not c~onsidc:rt~cl f ~ ~ r t h r r .

;It low tcXmpc:rilt8ilrt:s. thr ~ t~o ic~ l~ io~n t~ t~r ic~ st~sq~~iosid(:, Rn~~C)~(c : r ) , has t.hc: c:ilhic: h c ~ r;-l,rt~-c~;lrth typcl-C h,Inp03 stmruc:turtx. sp;-l,ccx gronp I;l.3, with n, = 11.03 X 111 l' In ;-~,roili~rl 300 I<: [53TEhl/D:lI.;, Ij8CHI/E\-R]. It transforms n t. ;l, t.cxmpc:r;l.tilrc: h(:tn-c:c:n 973 imrl 11 73 K [G4T,ViIL2: i5I<EL/BE.R] t,o t.hc: r;-l,rt~-c~;lrth typr-:l L L ; O ~ (cr) hc:s;-l,gonill

st,rllct,llrc, spacc gronp P31n1, nrit,h (1, = 3.817 X 10-" and c = 5.971 X 10-" rn. Tllc rrlonoclirlic B-form of t,llc scsqnioxidc rnay be stable l)ctn~ccn the C and -4 forrns; 1~1 t it is prol)ably a mct,nstablc phnsc stabilised by rrlirlor impurities, pnrtic~llarly Srrl nrld ot,hcr lnrlt,hnrlidc clcrrlcnt,~ [68CHI/EYR, 7311.11; 74BER/T.W, 75KEL/BER]. Hcxngonnl .4m20:3(cr) mclt,s at (2478 * 15) K [73CHI/IICN].

Tllc cnt,halpy of formation of llcxngonnl .4rn20:j(cr) was rcccnt,ly rncnsnrcd by tlissoliit,ion in hytlrochloric acitl in n rrlicrocalorirrlctcr [85110R/SON].

AfH:(.4mLOj. cr, 298.15 K) = ( 1 6 9 0 . 4 * 8.0) k.J . mol-'

Tllcrc arc no cxpcrirncntal heat cnpacit,y dnt,n, and all t,hc val~lcs arc cst,imnt,ctl from the ~ ~ a l n c s for Cc20:j(cr) and P ~ i ~ O : ~ ( c r ) . t,llc lnt,t,cr at 298.15 K only.

C,",,(.11n~0~, cr. 298.15 K) = (117.5 f 15.0) .J . K-' . rrlol-l

S:(.4mL03. cr, 298.15 K) = (160 f 15) .J . K-' . rnol-'

from t,llc valllc for t,hc P U ~ O : ~ ( C ~ ) , 163.0 J . K-' . mol-l [81FLO/TET]. Prclirninnry calciilnt,ions of n revised t,rcnt,rrlcnt of t,llc ~raporisat,ion dnt,n for nrrlcriciiim oxides dissolved in plllt,orliiim oxitlcs [66.4CK/F.412] suggest t,hc ~ralnc rnay be sornc\vhnt, lower (150 .J . K-' . rnol-l).

Tllc Gil)l)s cncrgy of forrrlat,ion is cnlcnlat,cd from t,llc sclcctcd cnt,llalpy of forrrlat,ion nrld entropy.

AfGm(.1rn2(Ij, cr. 298.15 K) = ( 1 6 1 3 . 3 * 9.2) k.J . rnol-'

Tllc dioxide; .1rn02(cr), cryst,alliscs in t,hc fcc fliioritc st,riictiirc. spacc gronp Frn3m, with (1, = 5.377 X 10-" rn [68CHI/EYR]. Like Inany ot,hcr flllorit,~ oxitlcs it can exist, with a large deficit of oxygen, the lat,t,icc paramct,cr increasing nrit,h dccrcasc in oxygcn content.

Tllc cnt,hnlpy of tlissoliit,ion of .1rn02(cr) in 0.5 11 H2S04 - 0.1 h1 K1 solution has bccn rncnsnrcd by hIorss and Fuger [81110R/FUG]. They corrlbincd this vnliic ~vit,ll their mcasllrctl cnt,llalpics of mixing of aqncoiis .4mC1:j, HC1 nrltl H2S01 solutio~ls t,o correct for t,hc cffcct,s of t,llc mctliiim, to obtain finally t,llc cnt,halpy of dissolllt,ion of A1~n02(cr) in n 0.55 h1 HC1 sol~lt,ion. Follo~ving 1Iorss and Fiigcr [81hIOR/FUG].

~ v c use t,hc infinite dil~lt,ion valiics for aqllcons I and I,, sincc t,hc cffcct,s of the cxt,rapolnt,ion t>o irlfirlit,c diliit,ion will bc similar. I\'it,h AfHk(I-. aq.298.15 K) =

( 5 6 . 7 8 * 0.05) kJ . rrlol-' [89C(IX/I\:.%G]; and l ,Hk = ( 5 . 0 * 0.5) k.J . mol-l for the rcactiorl

at infinite dil~lt,ion [76P.%R/I\:.%G]; \IT firltl AfHk(I,, aq,298.151<) = -(51.8*0.5) k.J. rnol-'; nrhich ~vit,ll t,llc cnt,halpy of formation of .%m3+ in 0.55 hI hydrochloric acitl solut,ion at 298.15 K: ( 6 1 6 . 5 f 1.3) k.J .moll intcrpolat,cd from the tlat,a of [7%FUG/SPI]; cf. Scct,ion 17.2.2, gives

l f H ~ ( . l r n O L . cr. 298.15 K) = ( 9 3 2 . 3 f 3.0) kJ . rrlol-'

~vhcrc t,llc nnccrt,aint,y has hccn increased t,o allo\v for t,hc iinccrtaint,y in the cnt,halpy of transfer of .%rn"+ from siilphnric to hytlrochloric acid sol~lt,ions in t,hc prcscncc of I-.

Tllcrc arc no cxpcrirncnt,al hcat capacity dat,a and t,hc ~ ~ a l n c s arc cst,imat,ctl fiorn the ~ ~ a l n c s from Cc02(cr) and Pii02(cr). The cst,irnat,ctl hcat capacit,y is given by the rclation

C,",(.%rn02. rr, 298.15 K) = (66.17 * 10.0) J . I<-' . mol-l

Tllc cst,irnatc of t,hc st,andard cnt,ropy by I\:cst,riirn and G r o n ~ & l [62I\'ES/GRO] (83.7 J . I<-' . mol-l) is almost ccrt,ainly t,oo high. Their cstirrlat,c for P1102(cr), before t,llc heat capacit,y urns rncasiircd. urns 82.4 J . K-' . mol-l corrlparcd ~vi th the cxpcrirncnt,al valiic of 66.1 J . K-' . rnol-l. Ilk cst,irrlat,c

S:(.%m02. rr, 298.15 K) = (67 * 10) J . I<-' . rnol-'

from the ~ ~ a l n c s for the ot,hcr mcas~lrctl actinitlc dioxides. This val~lc is also consist,crlt, with preliminary calcnlat,ions of the vapori~at~ion data for arncrici~lrn oxidcs tlissolvcd in pliit,oninrn oxidcs [66.%CI</F.%I].

Tllc Gibbs cncrgy of forrrlat,ion is tlcrivcd fiorn t,llc sclcctcd cntllalpy of forrrlat,ion and entropy.

lfG;(.%rnO2. cr. 298.15 K) = ( 8 7 4 . 5 * 4.3) kJ . mol-l

V. 3.2.4. Solid Arra(II1) hydrozirles

.% nnrnhcr of sol~lhilit,y stiidics have i)ccn rcport,cd for prccipit,at,ctl .%m(OH):j(s). Con- flicting data arc, ho\~~crcr, proposed for t,llc follo~ving rcactiorl (($ Tahlc 17.4):

Tllc diffcrcncc in log,, (\'.l%) ~ ~ a l n c s car1 bc rationalised by part,iclc size consitlcrat,ions and possil)lc cllangcs in t,hc solid hytlroxidc phase.

A%~n(OH):j(s) is gcncmlly prcparctl by addit,ion of l~asic rcagcnt,~ t,o .%rn(III) soliitions. The amorphous hydroxide formctl init,ially at roorn tcrrlpcrat,~lrc ant1 at,rno- spheric prcssiirc then t,rnrlsforrrls t,o a cryst,allinc phase. Tllc rat,c of t,llis t,mnsforrna- tion tlcpcnds on soliit,ion corrlposit,ion ant1 acitlit,y. t,cmpcmt,urc, radiolysis, dct,ails of prcparat,ion and prct,rcat,rncnt of the precipitate.

hlilligan et al. [68hIIL/BE.4] and Hairc et o,l. [77H.I\I/LLO] fo~lrltl t,llat rapid drying of freshly prccipit,at,ctl "I ' .%I~(OH):~(~) at room t,crnpcrnt,urc yields a st,ablc arnorphoiis solid consist,ing of very srnall part,iclcs (1.5 t,o 2 nrn). -4gcing under ~vat,cr aft,cr an initial hcat,ing at 80°C for 90 rrliniit,cs leads inst,cad to a cryst,allinc st,riictiirc. as indicat,ctl by clcct,ron diffi.act,ion of 5-n~cck aged s~lspcnsions [6811IL/BE.%]. Elcct,rorl rnicroscopy ol)scrvations sho~vcd. ho\vcvcr, that cryst,allinc rod-like part,iclcs alrcatly exist in a fliiid sol aged only for 2 hours at 25°C [7iH.%I/LLO]. Tllc ageing proccsscs continue for ~vccks ant1 arc accclcrat,ctl at higher tcrnpcratiircs. Silva [82SIL] rcportcd that cornplct,~ conversion rcq~lircd 3 nrccks boiling in 5 h1 NaOH ~lrltlcr reflux condit,ions. Tllc crystallisation t,imc was rcdiicctl t,o 3 t,o 4 days if the siispcnsion urns cvaporat,cd to near tlryncss. Rod-like st,riictiircs of approxirnatcly liarn diamct,cr ant1 10pm lcrlgt,ll wcrc forrncd. In a paper st,ill in press at t,hc rrlorrlcnt that t,llc t,llc final draft of t,his book as cornplctcd, lIorss and IVilliams [94hIOR/I1:IL] rcport,cd on the preparation ant1 charact,crisnt,ion of a rrlorc crystalline ":j.%~n(OH):~(s) t,llan fo~lrltl by Silva [82SIL]. .% prccipit,at,c of .%rn(III) oxalat,c first calcincd to .4rn02(s) in air. was t,hcrl rcdnccd t,o .%~n~( I :~ (s ) ~lrltlcr H2(g) at 800°C ant1 finally hydrat,cd in the prcscncc of st,carn at 225°C. Rai et al. [83R.$I/STR] rcportcd t,llat an increase of pH accclcrat,cs the transformation rat,c of .%m(OH):j(arn) at roorrl t,cmpcmt,urc.

Tllc dcst,rnct,ion of cryst,allinit,y by self-irmtliation was st,udicd by Hairc et (11. [i7H.%I/LLO]. The rat,c of t,llis process dcpcntlcd on the spccific actirit,y of the isotope ilsctl. In piire nrat,cr, the cornplct,~ dcgratlat,ion rcqiiircd 1 day ~vit,ll 2'4Cm(III) (specific actirit,y 3 X 10" hIBq/mg) ant1 5 rrlont,lls nrit,h "'.4rn(III) (specific act,ivit,y 120 hlBq/rng). In t,llc latt,cr case cryst,al tlamagc as critlcnt already aft,cr t,wo ~vccks. Unlike the fresh arnorphoiis prccipit,at,c. the prodiict of dcgratlat,ion did not, rcgcncrat,c cryst,allinit,y lipon hcat,ing. .% hydrous oxitlc phase was s~lggcstcd t,o forrn.

Tllc tlist,inct,ion bct,~vccn arnorpllons ant1 cryst,allinc .%m(OH):j(s) may l)c arnbign- 011s. Rat,hcr t,llan a cont,iniions n c t n ~ x k of polyniiclcar species, the freshly prccipit,at,ctl arnorpho~ls body of .%m(OH):j(s) can be considcrcd an agglorncratc of very srnall crystals too mirl~lt,c t,o give difiact,ion lines but visible by clcct,rorl rnicroscopy (the 1.5 to 2 nrrl part,iclcs sec11 by ililligan et o,l. [68hIIL/BEA%]). Tllc ageing proccsscs allo\v aggregation t,o larger rotls and t,hc appearance of difiact,ion pnt,tcrns [82SIL]. Tllc vario~ls st,~ldics in t,llc literatlire cannot dcscribc t,llc d issol~~t io~l process (l.i.12) \vitll a nniqiic solubility const,ant (cf. Table 17.4); bccansc of the cornplcx ageing bchavioiir of .4rn(OH):3(s) snspcnsions. .41t,ho1lgh amcricinrn t,rihytlroxidc appears t,o be formctl in all cases. it is difficult t,o explain \vhy so diffcrcnt val~lcs n7crc ol)t,ainctl. Possil)lc reasons for t,hc lo\vcr valiics of rcport,ctl in Rcfs. [84BER/KIiI, 84KIiI/BER] arc t,hat t,hc cq~lilibri~lrn was not att,ainctl diiring t,hc rncasiircmcnt,s or that a diffcrcrlt, phase involving format,ion of oxo i)ridgcs as present,. The valiic foiind by St,atllcr ant1

Kirn [88ST.%/KIhI] is in agrccrrlcnt \vit,ll t,hnt oht,airlctl by Silvn [82SIL] for cryst,nllinc rnntcrinl. but no chnrnct,crisat,ion of t,llc final prccipit,atcd prodiict urns nccornplishctl. Based on cnlorirrlct,ric rncasiircrncnt,s of t,llc cnt,hnlpy of solution of 2'".%m(OH):j(cr) in 6 11 HC1. and on entropy vnliics cst,imnt,ctl by analogy \vith rare cart,h hydroxitlcs. hlorss and il'illiams [94hIOR/Il:IL] calc~llatcd a. solubility constant 'h':,, nearly tllrcc orders of mngnitiidc lo\vcr t,hnrl rcport,cd by Silva [8%SIL]. This may reflect the different i)chnvionr of nrcll-cryst,alliscd and rnicrocrystallinc .%I~(OH):~(S).

Tllc st,~ltlics of Paznkhin and Kochcrgin [89P.%Z/KOC] and of Pcrshirl nrltl Sapozll- nikowa [SOPER/S.%P] arc tliscardcd by t,his rcvic\v for the reasons spccifictl in .%p- pcrldix .l.

\Vhcn a single solid phase is in cqiii1il)riiim \vith the nqllcons soliit,ion, t,hc sol~lhilit,y of .%m(OH):j(s) can i)c cxprcsscd as.

This irnplics t,hnt solubility curves oht,aincd in t,llc prcscncc of .%I~(OH):~(S) of tliffcrcnt sol~lhilit,y prodiicts shonltl i)c cxprcssctl as t,hc sarnc filrlct,ion of [H+] as long as t,hc samc aqiicolls spccint,ion of arncrici~lrn occiirs in t,llc diRcrcnt soliit,ions. In Figure I".$ t,hc sol~lhilit,y dnt,n of nrncriciiim(II1) hytlroxidc in 0.1 h1 NaC1(14 [82SIL; 84BER/KIII, 84KIhI/BER, 88ST.%/KIhI] arc plott,cd accortling t,o Eq. (17.13). 11s- irlg t,llc rccnlcnlat,cd val~lcs of t,nkcn from Tal)lc \'..5. I t can i)c sccn t,hnt all dat,a point,s fall on the samc curve. Deviation of t,llc data a t pH 2 8 from Rcfs. [84BER/KIII, 84KIII/BER] indicates that cit,llcr cq11ilil)riiim is not rcnchcd, or tllcrc is n conversion of t,hc solid t,o n diRcrcnt phase. The solid line in Figiirc 17.8 urns calciilnt,ctl nrit,h t,llc sclcct,ctl set of st,andard cqiii1il)rinrn const,nrlt,s (cf. Table 111.2); cxt,rnpolnt,ctl to 0.1 I 1 NaC104 usirlg t,hc specific ion irlt,crnct,ion cqnnt,ions t1cscril)cd in .%ppcndix B; as ~vcll as the nssociatcd nnccrt,nint,y.

In principle. all the solubility constants in Tnhlc \'-.S coiild l)c iiscd for the purpose of thcrmotlynamic calciilnt,ions. H o \ ~ ~ c ~ ~ c r , t,his rcric\v prefers t,o cvnliiatc t,hc Gil)l)s cncrgy of forrrlat,ion of .%rn(OH):3(cr) fiorn the dnt,n of Silvn [8%SIL]. Only this aiit,llor condnct,ctl a carefill chnrnct,crisat,ion of t,hc solid phase.

Tllc sclcct,cd sol~lhilit,y const,ant for .%m(OH):j(cr), cf. Tnhlc 17.5 and .%ppcntlix -4, is tlliis

log,, 'h'~;,(\'.12; .%I~(OH):~ . cr; 298.15 K) = 15.2 f 0.6.

Figure \'..8: Sol~lhilit,y mcasllrcrrlcnts of .4rn(III) hydroxitlc in 0.1 hI NaC1(14 soliitions at 25'C from Rcfs. [82SIL; 84BER/KIhI. 84KIhI/BER. 88ST.4/KIII] plot,t,ctl as "log,, [.4rn] ,.,,, - 1 o g l n R K s S . - log,,[H+], \vhcrc for each cxpcrimcrlt,al stiidy the corresponding valiic of "K,,, is t,akcn fiorn Tal)lc \'..5. Tllc cont,iniions curre represents the val~lcs calciilat,ctl nrit,h t,llc sclcct,cd set of cqnilibri~lrn constants (cf. Table 111.2) cxt,rapolat,ctl to 0.1 I1 NaC104 usirlg t,hc specific ion irlt,cract,ion cqnat,ions t1cscril)cd in Akppcndix B; and the tlot,t,ctl curves show the associated ~lnccrt,aintics. Tllc I~ot- torn diagram sho\~rs t,llc calcnlat,cd acidit,y ranges of prcdorninancc for each .4m(III) species ~lrltlcr t,hc sarrlc corltlit,ions as t1cscril)cd ahol-c.

2 7

6 m 1 8 9 10 11 12 13

- log,, [H+]

Fraction 0.6 0.4

6 m 1 8 9 10 11 12 13

- log,, [H+]

Tllc val~lc proposed by 1Iorss nrltl TVilliarns [94hIOR/T\'IL], nearly t,llrcc orders of rrlngrlit,~ltlc lo\vcr than t,llat sclcctcd here; as in disagrccrrlcnt ~vit,ll their prcdict,ions based on t,llc rclat,ivc basicity of nct,inidc nrltl lnrlt,hanidc hydroxitlcs as a fiinctiorl of ionic size. For t,llis reason, 1Iorss nrltl TVilliarns [94110R/I\'IL] rccorrlrrlcndctl n working ~ralnc for log,, 'I%':,, of (14.5 f 2), nrhich tliflcrs slight,ly from hut is consist,crlt, wit11 t,hc val~lc rccorrlrrlcndctl by t,llis rcric\v.

Tllc t,~vo st,udics using a nrcll charact,crisctl nrrlorpho~ls americium hydroxitlc [83R.%I/STR. 85NIT/EDE2] rcport,cd sirrlilar solnbilit,ics at pH zz 7. .4lt,ho1lgll tllcrc arc some difficiiltics in intcrprct,ing t,hc tlat,a by Rai et 111. in the fill1 pH range (cf. .%ppcndix -4); t,his rcvic~v sclcct,~

log,, 'h'~;,(\'.12; .%I~(OH):~; nrn. 298.15 K) = 17.0 f 0.6.

From t,hc soliil)ilit,y constants for .41n(OH):~(cr) and .%m(OH):3(am). t,llc follo~ving Gihhs cncrgics of formnt,ion arc derived:

lfGk(.4rn(OH):3; nrn. 298.15 K) = ( 1 2 1 3 . 1 * 5.9) kJ . mol-l

AfGm(.%~n(OH):3; cr, 298.15 K) = ( 1 2 2 3 . 4 * 5.9) kJ . mol-l

Tllc only cxpcrimcrlt,al data on the cnthalpy of formation of .41n(OH):~(s) has hccn rcport,ctl in the paper by hIorss and i\'illiams [94hIOR/I\:IL] still in press at the rrlorrlcnt t,hnt the final draft of t,his book urns cornplct,cd. Tllc nut,hors gave a ~ralnc of AfHg( .4~~~(OH):3; CI; 298.15 K) = ( 1 3 7 1 . 2 * 7.9) kJ . mol-l. It has t,o i)c strcssctl hoxvcvcr that t,llis ~ralnc refers to n solid ~vhich rnay cxhibit a dcgrcc of cryst,allinity different than that of t,llc .%1n(0H):~(s) iiscd by Silvn [82SIL] and rccorrlmcrltlcd by this rcvic\v.

V. 2 . 5 Anr (IV) o,nrl Anr (V) h,ydrozirles

Tllcrc arc very fc\v st,~ltlics of nrrlcriciiim hydroxitlcs of oxidnt,ion st,at,cs higher t,hnrl (111). Proccdiircs for the prcparat,ion of .%m(I\') and .%rn(\') prccipit,nt,cs in alk;~- line solutions ~vi th nt,tcrrlpt,s t,o cllaractcrisc the corrcsporltling aqncoiis species wcrc rcport,ctl by Pcnncrnan. Colcrrlan and Kccnan [61PEN/COL]. by Collcn [7%COH] nrld by Tananncv [90T.4N]. Kirrl et o,l. [85hl.4G/C.%R, 86BUP/hI.%G; 88KIII/BUC, 88ST.4lKI11, 88ST.4/KI112] mcas~lrctl t,llc sol~lhilit,y of "I ' .%I~(OH):~(~) in 3 and 5 11 NaC1. The high dose rates of o.-radint,ion protl~lcctl t,hc oxidnt,ion of .4m(III) t,o .%m(\:). as cvidcrlccd by spcctroscopic t,cchniq~lcs. For the rcnct,ion

the vnliic of log,, hrs." = ( 9 . 3 f 0.5) was obtaincd i ~ o t h in 3 hI nrltl 5 h1 NaC1. In nlkalinc solutions, t,llc follo~ving cq~lilihri~lrn as nssiirrlcd

for nrhich log,, 11(\'.15, 3 h1 NaC1) = (1.5 * 0.5) [8S11A%G/C.4R] and log,, fi1(\'.15, 5 h1 YnCl)= (1.7*0.6) [88KIhI/BUC, 88ST.%/KIhI] were proposed. H o \ ~ ~ c ~ ~ c r , accortl- irlg t>o t>hcsc vnliics. very lit,t,lc .4rn020H(n(l) shonltl bc prcscnt in t,llc solutions. This

review tlocs not accept tllcsc val~lcs hcca~lsc of t,llc lack of st,rnct,ural characterisation of t,hc solid and other cxpcrirncntal ~hort ,~omings, cf. .kppcndix .l.

No tlat,a arc sclcctcd for .km(I\:). (1') and (\'I) hydroxitlcs. Est,imat,cs may l)c rrladc by analogy \\,it11 ot,llcr actinitlcs.

V.3.2.6. Terrrcxry arad qucxte~raary cxrrael.%c%'i~,vr o:c%cies

r r j Crystallog~n,plaic data

Sclliilz and Pcrlrlcrnarl [86SCH/PEX] have s~lrrlmariscd t,llc crystallogmphic st,rnct,urcs of t,hc niimcrolls ternary and qnat,crnary oxide phases cont,ainirlg .krn(II7), .km(\') arltl .k~n(\:I); and Tal)lc \:.6 has hccn abst,mct,cd fiorn their Tal)lc 8.3. Fnrt,hcr dct,ails of t,llc prcpnrat,ion and properties of t,hcsc oxitlcs car1 bc ol)t,ainctl fiorn t,hc original rcfcrcnccs qiiotcd by [8GSCH/PEN].

h ) Tlrerrraodylrrcxrraic data

Tllc only thcrmotlynamic data for t,llc t,crnary oxitlcs arc t,hc cnt,halpics of formation of the pcrovskit,c-t,ypc compo~lrltls Ba.kmO:3(cr) and SrAk~n0:3(cr); mcas~lrctl by Goutli- akas et 111. [90GOU/HAkI]. Ba.kmO:3(cr) was prepared frorn BaC0:3(s) and .krn02(s) at, tcrnpcratiircs up t,o 1350 K and it,s X-ray pat,tcrn i as indexed as a psc~ltlo-cubic ccll wit11 rr = 4 . 3 6 7 ~ 10-" rn; alt,ho~lgll it probably has a tlist,ort,ctl str~lct,~lrc. Sr.k~nO:~(cr) was forrrlcd from t,llc co-prccipit,at,cd oxalat,cs at 1100 K, and its X-ray patt,cr11 was irltlcxctl as an ort,horhombic ccll corrlparc t,hc idcaliscd cubic st,rnct,urcs given in Tahlc \".6. For t,llc calorirrlct,ric rncasnrcrncnt,~, t,hc t,crnary oxidcs nrcrc dissolrctl in an aqncoiis rrlixt,urc of 1 h1 HC1 and 0.1 h1 KI. Using auxiliary tlat,a corlsistcnt ~vit,ll those iiscd in t,hc prcscrlt work, Golidinkas et al. [!IOGOU/H.kI] dcrirctl t,llc follo~ving T ~ ~ ~ I I C S for the c~lt,halpics of forrnat,ion of t,llc ~)cro~~skit,c-t,ypc oxides:

Tllcsc ~ ~ a l n c s correspond to t,llc follo\~.ing cnthalpics of rcact,ion frorn .km02(cr) arltl hfO(cr): ( 6 4 f 5) kJ . mol-l for Af = Ba; arltl ( 1 6 * 5) k.J . rnol-' for ,\I = Sr. Tllc apprccial)ly lo\~rcr st,ahilit,y of t,hc Sr compo~lrltl oxitlc follo~vs sirrlilar hchavioiir for the analogous pcrovskit,c oxidcs of BaO(s) and SrO(s) nrit,h Zr02(s) and Cc02(s).

No nc~v dat,a have l)ccn pnblishcd sirlcc Flot,o\~r et 111. [84FLO/HAkS] rcvic\~rcd the phase diagram and t,hcrrnodynarnic dat,a for t,llc .km-H system and our asscssrrlcnt has ut,iliscd sorrlc of the dat,a cstirrlat,cd t,hcrcin.

Tahlc \'..G: Crystallogmphic dnt,n for t,crnary and qiint,crnnry oxitlc phases (adapted f rom [$GSCH/PEY, Tnhlc 8.31).

Cryst,al Space Gro111) ancl Lattice pararr~eters xlO1"/rn P l~ase Syrnrnetry S t r ~ ~ c t ~ ~ r a l Type 11 h c angle

<u-.irnN1)04 ,(j-.irr1Nl)O4 .irn".:j:jTa,O:j (er) rlrnTa04 (er) . i r r~Nl)TiO~ (<:I) rlrnTaTi0,j (cr) rlrnScO3 (er) .irnPa04(<:r) SrAirnO:3(cr) S-r l r r~O~ (er) Sr.irnnOq ( s ) ( ~ ) Da r l r r~O~ (er) Da:3,irnOs (<:I) ~a.. lrna04(s)(~' Da2,irnNl)Os (<:I) Da2.irnTaOH(cr) Da2,irnPaOfi(cr) LiArnOa (s)fa' ~in,\rn0:3 (S) (a) Lia.irnO4 (cr) Li4.irnOS (cr) LiH.irnO,j (cr) Lii.irnOfi (cr) Lis.irnOfi (cr) Li,irn(\lo04)a (cr)

tetragonal llrxagorlal tetragonal orthorhornl)i<: tetragonal orthorhornl)i<: tetragonal psrll(i0- tetragorlal

rnonoclini<: tetragonal tetragonal rnonoclini<: orthorhornl)i<: orthorhornl)i<: orthorhornl)i<: fc1: <:ul)i<: <:ul)i<:

tetragonal tetragonal llrxagorlal llrxagorlal llrxagorlal tetragonal

rnonoclini<: fc1: fc1: llrxagorlal tetragonal

tetragonal

(a) Strl~ct,llre rlot krlo~vr~

Olson and hliilford [660LS/IIUL] and Rotltly [73ROD] have sho~vn t,llat t,hcrc arc t,wo solid hydridcs of arncriciiim, .%mH2+,(cr), \vitll a \'cry ~vidc range of hornogcncit,y fiorn a hytlrogcn st,oichiornct,ry slight,ly less t,harl 2 to at least 2.7; ant1 .%mH:3(cr). .%l>ovc 700 K .%rn(cr; (I) begins t,o dissolve apprcciablc amo~int,s of hydrogen. as docs t,hc fcc .%m(cr. L/) at llighcr t,crnpcratiircs. In the t,wo st,~ltlics mcnt,ioncd, hydrogcn prcssiircs wcrc rncasiircd as a filnct,ion of r = H/.%rn ( r . = 0 t,o 3) and t,crnpcratiirc (773 t,o 1073 K for [660LS/IIUL] iising 2'1.%m, ant1 748 t,o 115% K for [73ROD] using "'3.%~n). In hot,ll stiidics, an invariant dipllasic ficltl as fo~lnd l>ct,~vccn .%m ~vit,ll tlissolvcd hytlrogcn ant1 .%rnHZ-,(m). Frorn H/.%m =W 1.9 t,o 2.7, t,llc single-phase .%mH2+I(er) is stable. In l)oth t,llcsc fields, cq~lilihri~lrn urns easily cst,ahlishcd. .%l)owc H/.%m = 2.7; .%~nH:~(cr) cxist,s in cqnilibrinrn nrit,h hytlrogcn sat,urat,cd .%mH2+,(cr); t,llc hydrogen prcssiircs in this region snffcr fiorn considcrablc hyst,crcsis; ant1 no rclial~lc prcssiircs can bc given. Flot,o\v et al. [84FLO/H.%S] have prcscnt,ctl a schcrnatic phase diagram based in t,llcsc rcsiilts.

r r j Crystal strurturr

.%1nH2+,(cr) cryst,alliscs in t,hc fc,c CaFz fluorit,~ st,riict,urc, spacc groiip Frn3rn, ~vit,ll a latt,icc pararnct,cr ~vhich tlccrcascs as H/.%rn incrcascs. Tllc qnot,ctl valiics arc

Lo~vcr Phase Boundary 5.349 [660LS/IIUL] 1.96 5.344 f 0.0010 [73ROD] 2.34 5.341 f 0.002% [73ROD] 2.67 5.338 f 0.004 [660LS/IIUL]

Tllc asscssctl thcrmotlynamic propcrt,ics for .%rnH2(cr) arc calc~llatcd from t,llc hydrogen prcssnrcs for t,llc tliphasic region .%rn(cr; sat,uratcd ~vi th hydrogen) + .%mH2-i(cr), ~vhich arc ass~lrncd t,o apply t,o t,hc reaction .%m(cr) +HZ(g) + .%rnH2(cr). The iinccrtaint,y in the cxpcrimcnt,al pressures, part,icnlarly at lo\v prcssiircs, docs not ~varmnt, a rrlorc cornplct,c analysis.

Tllc cxpcrirncntal prcssnrcs for the dipllasic region .%m(cr) + .%rnHZ-,(m) mca- siircd by Olson and hliilford [660LS/hIUL], ilsirlg '".%rn. and by Roddy [73ROD] agrcc \ ~ ~ l l at t,crnpcratiircs aroiind 1100 K, but t,llc earlier mcasllrcrrlcnts arc ahoiit, a fietor of two llighcr at 773 K. for an nnkno\~rn reason. In analysing tllcsc tlat,a. \IT

have arccpt,cd t,hc T ~ ~ ~ I I C S for t,llc standard entropy ant1 heat capacit,y for .%rnHZ(cr)

S:(.lmH2, cr. 298.15 K) = (48.1 * 3.8) J . K-' . mol-l

C,";,(.4rnH2. cr) = (24.8 + 4.5 X ~ o - ~ T / I < ) .J . K-' . rnol-'

(298.15 t,o 1200 K)

C,",,(.lmH2, cr. 298.15 K) = (38.2 * 2.5) J . K-' . mol-l

Tllcsc give lfS;(.lrnH2, cr. 950 K) = 147.3 J . K-' . rnol-', as cornpared t,o t,hc val~lcs of 137.7 and 156.2 .J . K-' . mol-l calciilat,ctl frorn t,llc st,~ltlics by Olson and ilnlfortl [66OLS/hlUL] and Roddy [73ROD] rcspcct,ivcly.

Tllc cnthalpy of formnt,ion of .4mH2(cr)

AfH:(.lmHL. cr, 298.15 K) = ( 1 7 5 . 8 * 15.0) k.J . mol-l

is then dcrivcd frorn t,llc Gil)l)s cncrgy of forrrlat,ion a t 1165 K

AfGm(.lrnHL, cr. 1165 K) = 8 . 3 4 0 k.J . rnol-I

dcrivcd frorn t,hc concordarlt valiics (at t,his t,crnpcratiirc) for t,hc cq~lilihri~lrn hydrogen prcssiirc in t,hc tliphasic region ol)t,ainctl frorn the cq~iations given in the two stiidics not,cd above.

hlost of t,hc nnccrt,aint,y in t,llc cnt,halpy of forrnat,ion arises from the iinccrtaint,y of lfS;(.lrnH2, cr). Tllc Gil)l)s cncrgy of formnt,ion is calc~llatcd frorn t,hc sclcctcd cnt,llalpy of formation and cnt,ropy.

AfGm(.lrnHL, cr. 298.15 K) = ( 1 3 5 * 15) k.J . mol-l

r r j Crystal structurr

. l ~ n H : ~ cryst,alliscs ~v i th a hcxagorlal str~lct,~lrc. Sirlcc a t close t,o arnl)icnt prcssiircs, it is only st,ahlc a t lo\v tcrnpcrat,~lrcs, t,llc X-ray pr?t,t,crns arc 11ot good cno~lgll t,o define the corrlplctc str~lct,~lrc, hut it is prcsiimahly t,hc same as P~lH:~(cr ) . spacc groiip P6:3/rn~nc, .lsN;~,:~(cr) t,ypc. Tllc lat,t,icc parameters arc rr = (3.764 f 0.0044) X

10-In, (: = (6.763 * 0.0073) X 10-'Or11 [73ROD].

. l~nH:~(cr ) is forrrlcd only sluggishly a t low tcrrlpcrat,~ircs (e.g. > 200 h at 125°C arltl 0.92 bar), and ncit,llcr Olsorl and hliilford [660LS/hIUL] nor Roddy [73ROD] conltl oht,ain any cqnilibrinrn pressures pcrt,aining t,o t,his phase. No rcliahlc thcrmotlynamic dat,a can tllcrcforc he given.

Tahlc \".i: Lit,crat,llrc valncs of cqllilihrillrn const,ant,s for t,hc formation of .%rn~!:-'") cornplcxcs.

sol 0.1 M HC104 23 (lis 0.5 M NaC104 25 (lis 1 M NaClOl 25 en~f 0.1 M NaC104 25 f 0.5 (lis 1 M NaClOl 25 (lis 1 M NaClOl 10

25 40 55

ix 0.1 M NaC104 25

(a) For t,hr reai:tior~: ArnF: + E + ArnF:3 (all), Fray reports logl, I<; = (3.11 & 0.0'7)

V.4. Group 17 (halogen) compounds and complexes

.%S proccdiircs for the cst,imat,ion of t,hc cnt,halpics of format,ion and standard entropies for arrlcriciiim halidc corrlpoiinds arc used cxt,cnsivcly in this review; and sirlcc t,llcsc cstirnation procctlllrcs arc the sarrlc for all t,hc llalitlc cornponnds. tlat,a sclcct,ion for all the aqllcons llalitlc cornplcxcs is tlisciissctl first in Scct,ion \'..4.1; while t,hc discussion of t,hc tlat,a sclcct,ion for all t,hc llalitlc compollrltls is postponctl t,o Scct,ion 17.4.%.

Tllc nnrnhcr of cxpcrirncnt,al stiidics on .%rn(III) cornplcxat,ion ~vi th fllloridc ions is rclatircly limit,ctl. They wcrc mainly tlcsignctl to dctcrrrlinc possil)lc corrclat,ions ~vit,ll analogo~ls corrlplcxcs of 4f clcrncnts. The cqnilibrinrn const,ant,s for the rcact,ions

rcport,ctl in Tal)lc \".i arc considcmhly larger than for the corresponding aqllcons corrlplcxcs ~vi th chloride ions (cf. Table \:.8). The valncs rcport,ctl by Choppin et o,l. in Rcfs. [69JON/CHO, 75DEG/CHO] arc disrcgardctl in t,his review l)ccaiisc t,llcy rcfcr to prclirninary ~vork. The rcact,ions (\'.16) arc charactcriscd by a positive cnt,halpy tcrrn. Tllcsc arc irltlicnt,ions t,hat t,llc .%mF!:-'") cornplcxcs arc prcdorninantly inner- sphere, in cont,rast t,o the ot,hcr .%rn(III) halidc corrlplcx species.

Conclllsivc critlcncc exists for the forrrlat,ion of t,llc first t,wo flnoritlc cornplcxcs. .%ziz and Lylc [69.%ZI/Ll-L] rcport,cd cqnilibrinrn data for .%rnFW+; .%mF: arltl

.%~nF:~(aq), at I = 0.5 hI. .% liqnitl-liqnitl part,it,ion t,cchniqiic \!,as ~lsctl in the range of F conccnt,ration fiorn 1 X 10-l t,o 4 X 10-" hI. Xash and Clcvclarltl [84N.%S/CLE%] fo~ind no cvidcrlcc for t,hc cxist,crlcc of the t,llirtl complcx up to a F conccnt,ration of 8 X 10-" h1 in a 0.1 hI pcrchlorat,c rncdi~lrn. Ionic strength effects alone cannot, explain t,hc observed diffcrcncc. Corrcct,ions to t,hcrmotlynamic condit,ions st,ill yicltl \'cry discordant valiics of L/; and L/,". Tllc tlat,a of Ref. [69.%ZI/Ll-L] arc rcjcct,cd by t,his rcvic\v. bccansc t,hc cxt,ract,ion mcchanisrn of .%rn(III) species in t,hc organic phase was not \ ~ ~ l l characterised.

Tllc cxpcrirncntal dat,a of Clloppirl arltl Unrcin [76CHO/UXR] and Nash and Clcvc- land [84XA%S/CLE2] arc ~lsctl to calc~llatc t,llc thcrmodynarnic valiic of loglo~,". Tllc first st,al)ilit,y const,ant dct,crrrlincd by hlakaroxi~,. St,cpanov and Shcstakov [73hl.4K/STE] is not incl~ltlcd in t,llc sclcct,ctl dat,a set bcca~lsc t,hc clcct,rornigration rrlctllod ~lsctl tlocs not appear t,o bc siifficicnt,ly acciirat,c for qiiantitatirc measure- rrlcnts of t,his type.

Extrapolat,ion t,o irlfirlit,c diliit,ion is pcrforrrlcd by nsing cst,imat,ctl valiics of ion irlt,cractiorl cocfficicnt,~ (cf. .%ppcndix B. Scct,ion B.1.4), obt,aining l ~ ~ \ ~ . ~ ~ ~ ; ~ , , = ~ ) =

( 0 . 1 2 f 0.1) kg . mol-l and ! l ~ ( ~ . ~ ~ ; ~ , , = ~ ) = ( 0 . 3 6 * 0.1) kg. rnol-l, ~vhich rcsiilts in

calciilat,ctl as the ~ln\~~cight,cd average of t,llc two accepted valiics [76CHO/UNR; 84N.%S/CLE%].

For t,llc sccond formation rcact,ion. this rcvic\v sclcct,s t,llc cq~lilibri~lrn const,arlt, proposed by Nash and Clcvcland [84N.%S/CLE%], oht,ainirlg

Cont,mry t,o t,llc sclcct,ion in t,hc I.lE.4 rcvic\v [92FUG/KHO], no val~lcs arc rccorn- rrlcndctl for t,llc format,ion of .%mF:3(aq) bcca~lsc t,llc only cxist,irlg dat,a by [54FE.%] and [69.%ZI/LYL] arc rcjcct,cd by the prcscrlt rcvic~v as cxplainctl prcvionsly arltl in .%ppcndix .%.

Tllc Gibbs crlcrgics of format,ion calc~llatcd nsing t,llc aiixiliary dat,a for .4rn"+ arltl F arc

lfGm(.4rnF2+, aq, 298.15 K) = ( 8 9 9 . 6 * 5.3) k.J . mol-l lfGk(.4rnF:, aq, 298.15 K) = ( 1 1 9 4 . 9 * 5.1) k.J . mol-l

Choppin and Unrcirl [76CHO/UNR] dctcrmirlcd A,Hm(\:.16, rr = 1) = (27.6 * 2.1) k.J . rrlol-l at I = 1 hl. The ~ ~ a l n c s dct,crrrlinctl by Nash and Clc~~cland [84N.%S/CLE%] at I = 0.1 I1 arc l,Hm(\'.16.n = 1) = (22.9 * 1.6) kJ . rnol-' and !l,Hm(\:.16, rr = 2) = (24 * 5) kJ . rnol-l. .%ltho~lgh no major shortcorrlings can bc idcrlt,ificd in t,hc cxpcrirncntal procctl~lrcs of Rcfs. [76CHO/UNR. 84N.%S/CLE%] this r e ~ ~ i c w does not rccorrl~rlcnd any c~lt,halpy ~'a111e bc~aiisc of t,llc imccrt,aint,y in the irlfliicncc of tcrrlpcrat,~lrc on actirit,y cocfficicnt,~.

V.4.1.2. Aqfreo~rs Anr clalorirae corralilezes

hlost of the availahlc dat,a on cornplcx forrrlat,ion of A%~n(III) nrit,h chloride ions wcrc puhlisllcd in t,hc sixt,ics. Sincc this t,imc a 111lrnl)cr of rcvic\~rs have appcarctl, but they arc restricted mainly t,o dat,a compilations. Rcccnt c~i~,lnat,ions of litcratiirc dat,a arc rcport,ctl in Rcfs. [92FUG/KHO; 88CH.%/ROB].

Eqnilibrinrn dat,a for t,llc cornplcxat,ion rcactions

arc given in Tahlc I,..$. Tllc cxistcncc of t,hc species .%rnCl'" and -4rnCl: is ~vcll cstahlishcd. .%nion cxchangc rncasnrcrncnt,~ in very highly conccnt,rat,ctl mctlia indicated t,llc prcscncc of negatively cllargcd species, prol)ably -4rnClT [56\V.4R/IVEL, 66hI.4RI. On t,llc basis of spcct,ropllot,omct,ric stiidics, higher order corrlplcxcs wcrc claimctl t,o l)c stable only in non-aqiico~ls solvcnt,~ [67RY.%; 70hl.4R/BOhI; 72B.%R/KOT]. hlarcns ant1 Borrlsc [70hl.4R/BOhI] calclllatcd the st,cpnisc forrnation constant of .%rnCc; bot,h in propylcnc carl)onat,c ant1 in acct,onit,rilc-siiccino- nit,rilc rnixt,llrcs. H o \ ~ ~ c ~ ~ c r , t,llcsc arc constants for non-aqncoiis rrlcdia and t,llcrcforc of lirrlit,cd iisc in t,llis rcric\v.

Tllc .4rn(III) cllloritlc corrlplcxcs arc so weak t,hat rclat,ivcly high conccnt,rations of cornplcxing ligantl arc rcqllircd to get a rncasiirablc variat,ion of the int,cnsivc propcrt,ics rrlonit,orctl tllroiigho~lt the cxpcrirncnt,~. The rat,io of nrat,cr t,o salt in conccnt,rnt,ctl rncdia is far lo\vcr t,han in diliit,c sol~lt,ions. Urltlcr tllcsc circllrn- st,anccs; t,hc rcplaccrrlcnt of a ~ ~ ~ a t c r rnolccnlc in t,hc inner coortlination sphere of the rrlct,al ion by a chloride ion slloiild he c~lllanccd. .%ccortling t,o 1Iarclls ant1 Shiloll [6911.%R/SHI]. oiit,cr-sphcrc intcract,ions have w r y lit,t,lc cffcct on t,hc al~sorption hands in the .%m(III)/chloridc systcrn. On t,his basis, t,llc spcct,ral changcs ohscrrctl at high ligand conccntrat,ions nrcrc ascribctl t,o t,llc prcscncc of inner-sphere corrlplcxcs [64SHI/II.%R; 69hI.4R/SHI; 69B.%R/hIIK]. Ho\vcvcr; l)ccaiisc of t,llc cx- tcnsivc cllangc of ionic st,rcngt,h; it is tlifficnlt t,o tlist,ingnish ~l~~ambigiionsly i)ctn~ccn corrlplcxat,ion cffcct,s and act,ivity effects. This considcrat,ion applies also t,o t,llc N1IR invcst,igat,ion by I'tlovcnko, Kolokl't,sov and Stcbnnov [66I.'DO/I<OL] ant1 I'tlovcnko and St,chllrlov [69I.'DO/STE], to t,llc soliil)ilit,y stiidy of hlarcns [67hI.%R] and t,o the clcct,ropllorcsis rncasnrcrncnt,~ of 1Iarirl [691IA%R2].

Tllc tcrrlpcrat,~lrcs at \vhich t,llc cxpcrimcrlt,~ wcrc carrictl oiit vary bct,~vccn 20" ant1 30°C; cf. Tal)lc IT.$. Xo cnt,halpy rncasnrcrncnt,~ arc available to correct loglopl t,o 25°C. H o \ ~ ~ c ~ ~ c r , by analogy ~vit,ll EnC12+ [63CHO/UXR]; t,hc t,crnpcratiirc dcpcrltlcncc of l o g l o ~ ~ l is cxpcctcd t,o he 11cgligil)lc ~vit,llin t,hc in\-cstigat,cd range. Tllc convcrsion to rnolality llrlit,s is not st,raight,for\~~ard hccallsc of t,llc continno~ls variation of the ionic mctlia at fixed ionic strength. For cxarnplc, t,llc niimcrical valiic of rnolality in the 4 11 Na(C104,C1) rncdinrn iiscd by Sckinc [64SEI<, 65SEKl changcs from 4.95 rn in t,llc al)scncc of cornplcxing ligands t,o 4.37 m in t,llc NaC1 solution. hlorcorcr, the conccnt,rat,ion dcpcndcncc of int,craction cocficicrlt,~ cannot i)c ncglcct,ctl at siich high ionic st,rcngt,hs. Thcrcforc, no tlat,a from cxpcrirrlcnt,~ at I = 3 h1 [82FUK/K.%\V,

Tahlc \".8: Lit,crat,urc ~ ~ a l n c s of cqnilibrinrn const,ant,s for t,hc rcactior~ .%m3+ + n C 1 + .%rnCl;-").

prx sol

"I'

er11 "I'

0.206 M HC1 ' P 0.35 [56WAR/WEL] 0.5 M HC1 ' f 0.24 4 M H(ClO4>Cl) 20 -0.16+0.02 -0.74+0.1 [62GRE] 1 M H(CIOIIC1) 22 + 1 -0.05 + 0.1 [62PEP/MAS] 1 M H(ClO4>Cl) 26 + 1 -0.05 + 0.05 [64BAN/PAT] 1 M Na(ClO4,Cl) 26 + 1 0.15 + 0.03 4 M Na(ClO4,Cl) 25 -0.15 + 0.07 -0.69 f 0.10 [64SEK1

65SEKl LiC1; var ' P 0.032 -0.97 [66VDO/KOL] 0 25 f l -0.45 f 0.04(") [67MAR]

al1(1 40 f l (H;Li)Cll var 25 + 1 -1.99 + 0.05 [69BAR/MIK] HC1; var 15 1.0 0.34 [69MAR2] LiC1; var ' P -2.2 + l 4 . 7 0 f 0.06 [64SHI/MAR1

69MAR/SHI] LiC1; var ' f 0.26 + 0.12 -0.05 f 0.29 [69VDO/STE] 1 M H(ClO4>Cl) 30f 0.1 -0.14+0.02 -0.52+0.04 [71KHO/NAR] 1 M Li(ClO4;Cl) -0.25+0.02 1 M Na(ClO4,Cl) 0.02 + 0.02 -0.37 f 0.05 1 M N H I ( C ~ O I > C ~ ) 0.12+0.02 0.03 f 0.02 3 M (LilH)(C104,C1) 20 -0.26+0.02 -0.66+0.04 [82FUK/KAW,

85SAT/MIT]

(a) This corlstar~t refers t,o t,he sol~~t)ilit,y process rlrnC1a . :1:H20(s) + ArnC1: + C 1 + :r:HaO(l).

85S.%T/IIIT] and at I = 4 h1 [62GRE, 64SEK; 65SEK] arc iiscd in t,llc prcscrlt annl- ysis. For t,llc rcrrlainirlg data, t,hc plot of (logloi/l + 6D) nccordirlg to t,hc specific ion irlt,cractiorl t,llcory sho\vs no ol~vio~ls trend \vith ionic st,rcngt,h. .%lthongh a rrlcdi~lrrl effect on stability const,ant,s urns somct,irrlcs observed [64B.%N/P.%T; ilKHO/X.%R]; tllcsc diffcrcrlccs arc srnallcr t,llan t,llc scat,t,cr in the dnt,n oht,nincd in H+ or Na+ containing rncdia. This set of data [561V.%R/\VEL, 62PEP/hI.%S. 64B.%N/P.%T, ilKHO/N.%R] is used t,o cnlcnlat,c loglo[/,". Ext,rnpolat,ion t,o in fin it,^ tlilntion nrit,h n ~vcight,cd linear rcgrcssiorl procctl~lrc is innppropriat,~. This rcvic\v corrcct,~ t,llc dnt,n at diffcrcnt ionic strengths usirlg an cstirrlat,cd T ~ ~ ~ I I C of AE. By co~rll)ini~lg cxpcrirncntal and cst,imnt,ctl intcract,ion cocfficicnts ( c : j .%ppcntlix B), this rcvic~v oht,ains AE = ( 0 . 2 2 f 0.1) kg . rrlol-l and ( 0 . 1 3 * 0.1) kg . rrlol-l for t,llc H(C104.C1) nrltl the Xn(CIOI,C1) mctlia, rcspcct,ivcly. The nnccrt,ninty is incrcnsctl to *0.1 l)ccaiisc of t,hc npproximnt,ion corlccrning E ( - ~ ~ ( : ~ ~ + , ( : ~ ~ ~ ) . The dcr i~~cd set of thcrmody~lami(;

T ~ ~ ~ I I C S for Rcactio~l \".l7 appears to hclo~lg to t,hc sarrlc parent distril)iit,ion. Thns. the \+,cight,cd nvcragc is ncccpt,ctl:

log,, ,l,"(17.1i.n = 1.298.15K) = 1.05*0.06

Tllc rccorrlrrlcndctl ~ralnc of t,hc st,nrltlartl Gibbs cncrgy of formnt,ion is cnlcnlat,cd to bc

AfGm(.4rnClL+. nq. 298.15 K) = ( 7 3 5 . 9 * 4.8) k.J . mol-l

No ~ ~ a l n c s for log,, 9," arc sclcct,cd. Tllc intcrprct,at,ion of the solrcnt cxtractiorl mca- siircrrlcnt,~ rnadc by Khopkar nrltl N ~ ~ , r ~ ~ , y a n n ~ k t , t y [71KHO/X.%R] cannot he t,akcn as dcfinitirc (cf. -4ppcntlix -4). .4lthongh Grcntllc [62GRE] and Sckinc [64SEK. 65SEK] folind cvidcncc for t,hc formnt,ion of very \+mk .%rnCl; species, t,llis revie\+, prefers not, to nsc t,hc rcport,ctl val~lcs of log,, 'l2, ~ C C ~ I I S C t,hcir ~orrect io~l to I = 0 from a rrlixctl ionic rncdinrn of high ionic st,rcngt,h is not sllfficicrlt,ly acciirat,c.

Stahilit,y const,ant tlat,a arc available for pcrchlorat,c cornplcxcs of .4m(III) only. Sol- ~ ~ c n t cxt,rnct,ion rncnsnrcrncnt,~ appnrcnt,ly irltlicnt,ctl t,hat weak -4rn~10:' species for111 l>clo\+r 2 h1 Cl(];; \+,it11 cqllilihrillrn const,nrlt,s ill = (0.86* 0.06) at ionic st,rcngt,h 2 I1 fixed nrit,h HBFl [i2B.4I/CHO], nrltl 9: = (4 * 0.9) as cstirrlat,cd by Lcbctlcv nrltl hlaziir in NaC104 rrlcdin of variable conccnt,ratio~~s [81LEB/II.%Z]. Cclctla. Holllh nrld Srrliroiis [74CEL/HOL] found no sigrlificnrlt effect of C10; on clcct,rornigration ~~clocity mcasllrcrncnts.

Tllc formnt,ion of the nqllcons outer-sphcrc cornplcx .%rn(C1O4): was rcport,ctl in the prcscncc of cxccss pcrchlorat,c ions 111) t,o 8 rn [81LEB/II.%Z]. The reported t,llcrrnodynnrnic const,ant at 25°C is 9," = (2.0 * 0.1). Tllc positjive cnt,halpy and entropy

ho+n~cvcr, that t,llc pcrchlorat,c corrlplcxcs arc prcdorninant,ly inner-sphcrc Tllc large change of ionic st,rcrlgt,ll ncccssnry t,o invcst,igatc corrlplcx forrrlat,ion

rrlakcs t,llc cxt,rnpolnt,ion t,o in fin it,^ dilllt,ion cxt,rcrncly siisccptiblc t,o error. Thns. no clcar tlist,irlct,ion can bc rnadc hct,\+~ccn very \+mk complcxation cffcct,s and lnrgc ~rarint,ions of nct,ivity cocfficicnts. Bccansc of tllcsc considerations, this rcric+nr does not rccorrlrrlcnd cqnilibrinrn const,nrlt,s for any of t,hc arncricillrn pcrchlorat,cs,

V.4.1.3. Aqfreo~rs A n r m hronricies arad iodides

Only a fc+v st,udics ntltlrcsscd corrlplcx forrnation of .%m(III) nrit,h hrorrlidc and ioditlc ions. Slliloll et 111. [64SHI/hI.%R. 69SHI/GI\-] sho\vcd by spcct,ropllot,omct,ry the forrnation of t,llc first t,~vo llalidc cornplcxcs in highly corlccntrat,cd soliit,ions. Tllc cqlii1il)riiim const,nrlt for the forrnation of t,llc inner-sphcrc cornplcx .%rnBi" +nrns rcport,ctl to he l ~ g ~ ~ ~ ~ = ( 3 . 3 * 0.1). -4s tlisciisscd in .4ppcndix .%; it is difficiilt to dist,ingnish hct,\+~ccn cornplcxat,ion nrltl act,ivit,y cffcct,s in such conccnt,rnt,ctl rncdia ([LiBr] 2 8.7 hl). Fnknsa~va et d. [82FUK/K.\'] nrltl Sat,o et 111. [85S.4T/hIIT]

rcport,ctl loglo fil = ( 0 . 5 2 f 0.04) and log,, fi2 = ( 0 . 5 5 * 0.03) for t,llc l)romitlc corrlplcxcs of arncrici~lrn(III) in 3 11 Li(C104.Br) at 220°C. Ext,rnpolnt,ion t,o I = 0 is llarnpcrcd by the vnriat,ion of t,llc aniorlic composit,ion of t,hc rncdinrn tl~lrirlg the cxpcrirncnt,~. Thcrcforc. no val~lcs arc sclcct,ctl.

V.4.1.4. Higher ozirlation stcxtes of arnericilrrn

No t,llcrrnodynnrnic tlat,a arc avai1al)lc on the format,ion of .%m(I\'); (1') n1~1 (1'1) halitlc complcxcs.

High conccnt,rations of fl~loridcs ions nrcrc foiind t,o st,nhilisc .%m(I\') in nqllcons soliit,ions [Gl.%SP/PEN> 73\'.%R/B.%Y]. Tllc close corrcspondcncc bct,~vccn t,llc nh- sorptiorl spcct,riim of tllcsc sol~lhlc .%m species and that of solitl .%rnF4 siiggcst,~ the cxist,cncc of .%rnF4(aq). Sirrlilar ol)scrvations nrcrc rnadc for .%rn(\'I) [82KEL]. How- cvcr. no t,hcrrnodynarnic tlat,a arc avai1al)lc.

Dioxonrncriciiim(\:) urns found t,o he present in 3 hI nrltl 5 11 NaC1 solutions because of radiolyt,ic oxidnt,ion of .%m(III); hut no cornplcx formation urns ol)scrvcd [85hI.%G/C.%R. 88ST.%/KIhI]. Tllc out,cr-sphere cornplcx bct,~vccn .%rnO;+ and Brr was postiilnt,ctl t,o bc an intcrmctliatc in t,llc rcdnct,ion process of .%m(\:I) t,o .%rn(\') by i)romitlc ions [77C00/\V00]. Ho\vcvcr, no cq~lilil)riiim dnt,n wcrc reported.

Tllcrc arc rather few cxpcrirncntal st,~ltlics from ~vhich acc~lrnt,c t,hcrrnodynnrnic dnt,n for nrrlcriciiim hnlidcs car1 he tlcrivcd:

Ho~vcvcr. bccansc of t,hc syst,cmnt,ic t,rcnds in the thcrrnodynarnic hchavioiir of the nctinitlc clcrncnt,~, rcliablc val~lcs of hot,ll t,llc cnt,halpy of formnt,ion and t,hc cn- tropy of many arncrici~lrn llalitlcs have hccn dcvclopcd, part,iciilnrly by Fiigcr et (11. [83FUG/P.%R] in t,hc rrlost rcccnt rcric\v of t,llc t,hcrmochcrnist,ry of the nct,inidc hnlidcs. Sincc very lit,tlc t,hcrrnodynnrnic information on arncrici~lrn hnlidcs has hccn puhlisllcd sincc that rcric\v, the prcscnt val~lcs arc derived prcdorninantly fiorn t,llis work. \\,it11 sorrlc nrnplification of t,llc high-t,crnl)cratiirc propcrt,ics. and considcrnt,ion of sorrlc ntltlit,ionnl cornpoiinds.

Sirlcc the proccdiircs [83FUG/P.%R] for t,hc cst,irnat,ion of the cnt,hnlpics of forrnation nrltl st,andard cnt,ropics of t,hc hnlidcs arc t,hc sarnc for all the halidcs. t,hc dct,nils nrld rclcxi~,nt dnt,n used arc givcn hcrc, and only t,hc dcrirctl val~lcs givcn in t,hc later text,.

Tahlc \'.g: Dnt,n used t,o cst,imnt,c !lfHg(.4mX:j, c:r; 298.10K). \:alncs arc in k.J.mol-l nrld rcfcr t,o 298.10 K.

r.(Rls+)/(lO-'" 111) 1.025 1.010 1.000 [76SHA] ArHi,(,(hlW+, aq) -489.1 1 3 . 8 -527.2 i 2.1 -592.0 i 2.1 [7GFUG/OET] H ( 1 : ) -1502.1 15.0 -1585.7 i 3.0 [83FUG/PAR] ArHi,(,(hlCl:3. cr) -866.0 i 3.8 -959.8 i 1.7 [83FUG/PAR] H ( B r ) -698.7 i 4.2 -730.5 i 2.1 -792.9 i 2.1 [83FUG/PAR] A r H i , (M?, cr) -46'7.4 i 4.2 -513.0 i 2.1 -579.9 i 2.5 [83FUG/PAR]

V.4.2.1.1. Estirraation of entlrcxlpies of forrraation

Considcrnt,ion of thcrmotlynamic data for the actinitlc hnlidcs sho~vs t,llat plot,s of the cnt,halpy diffcrcrlcc ( l fHg(hlX: j ; cr, 298.15 K) - lfH;(I13+, nq, 298.15 K)) (~vhcrc hl = U, Np; Pi1 nrltl X = F. Cl; Br, I). as n filrlctiorl of t,llc ionic radius of the hI"+ ion, arc very close to linear sec for cxarnplc Figiirc 2 in t,hc earlier rc- T ~ C T V by Fuger [82FUG]. It is t,hcrcforc assnrncd t,llat t,his linear fimct,ion can i)c cxt,cndcd t,o incliidc amcricinrn. This assilrnpt,ion car1 bc t,cst,ctl for .4rnC1:j(cr), for nrhich a rcliablc cnthalpy of formnt,ion is a~~ailablc. Tllc cst,imnt,ctl vnliic is lfH;(.4mC1:j. cr; 298.15K) = -(970*7) k .J .mol l ; as cornpared ~vi th t,llc cxpcrimcn- tal ~ralnc (sec Scctiorl 17.4.2.3.2) of ( 9 7 7 . 8 * 1.3) k.J . rnol-l. Tllc ~ ~ a l n c s cst,imnt,ctl in t,llc t,cxt arc t,hcrcforc jiltlgcd t,o i)c qilit,c rcliablc n.it,hin rnt,hcr conscrr. a t ' ,IT - C error linlit,s hascd on the corrlhincd ilrlccrt,aintics of the tlata ilsctl in t,hc cstirrlat,ion procc- durc. Tllcsc dnt,n arc siimrrlariscd in Table \'.g. Tai)lc \".l0 silrrlmnrizcs t,llc valilcs nsctl t,o cst,irnatc !lfH;(.4mF4, cr, 298.15 K) by sirrlilar proccdiircs i~ i i t ilsirlg valilcs for t,lloriiim in place of ncpt,nniilrn nrltl dioxides as xvcll as the aqncoiis ions. It may bc not,ctl that sorrlc of t,hc vnliics in Tal)lcs \'..9 and \'..l0 for t,llc NI) nrltl Pi1 spccics will not bc idcnt,ical nrit,h those t,o he sclcct,cd in fort,llcorrling XE.4 rcvic~vs, sirlcc the latt,cr volilrrlcs arc not finalized at t,llis tirnc. Ho\vcvcr the diffcrcrlccs will not i)c large; and t,hc effect on t,llc cst,irnatcd vnliics for t,llc .41n species will bc ~vit,llin the cstirnatcd iinccrtaint,ics.

Tllc valilcs for t,llc corrcsporltling qilant,it,ics of t,hc amcricinrn spccics used in the cstirnations arc: r(.41n"+) = 0.970 X 10-In rn; r(.4rn4+) = 0.850 X 10-" rn [76SH.4] nrld t,llc follo~ving cnt,hnlpics of formnt,ion dcrirctl in this ~vork:

Tahlc \'..10: Dat,a iiscd t,o cstirrlat,c lfH;(.I1nF4. cr; 298.10K). \;?liics arc in k.J.mol-l and rcfcr t,o 298.10 K.

(a) This va111r is it,srlf an rstirnate.

Tllcrc arc no mcas~lrctl ~ ~ a l n c s of the entropies of any arrlcriciiim halidc. Tllcsc val~lcs arc tllcrcforc all cst,imat,ctl, follo\~.ing [83FUG/P.$R] and carlicr ~vorkcrs, from the T ~ ~ ~ I I C S for t,llc halidcs of t,hc other act,inidc clcrncnt,~, often by rclat,irlg t,hc diffcrcrlcc in cnt,ropy to t,llc 111lrnl)cr of urlpaircd clcctrons; assuming a spin-only contril)iit,ion t,o the cnt,ropy.

Tllc t,rifl~loridc arltl tctrafliioridc of americium and the six-valcnt .$m02F2(cr) arc ~vcll cst,ahlisllcd cornponnds. arltl tllcrc is co11sitlcral)lc cvidcrlcc t,hat t,llc llcxafl~loridc .I1nFfi(cr) can bc forrrlcd iindcr st,rongly fl~lorinating conditions.

Tllcrc arc a 111lrnl)cr of cornplcx fl~loridcs cont,aining thrcc-, four- arltl fivc-~i~,lcnt, arncricinrn; \~rllosc st,rnct,urcs and mct,hotls of preparation lla~rc hccn siimrrlariscd by Sclliilz and Pcnncrrlan [86SCH/PEN]. Sincc t,hcrc arc no t,hcrrnodynarnic data for tllcsc t,crnary cornpoiinds, t,hcy arc not considcrctl fiirt,llcr in t,his rcvic\v.


.Imcricinrn t,rifl~loridc has the hexagonal LaF:3(cr) t,ypc cryst,al st,riictiirc. t,hc t,ypc in ~vhich all t,hc carlicr actinitlc and Inany lanthanitlc t,rifliioridcs cryst,allisc. This st,riictiirc as tlisciissctl in tlct,ail by Taylor [76T.II-]. The real st,riictiirc is a dist,ort,ion of t,llc idcalisctl fi~lly-capped t,rigonal prism, ~vi th t,wo rnolccnlcs per unit ccll, spacc groiip P6:3/rn~nc. S~lhscq~lcnt work, discnsscd by Taylor [76T.$Y]. i~ldicat,cs that the true ccll contains six rrlolcciilcs; ho\~~crcr, it is st,ill not clcar nrhct,hcr t,llc spacc group is P3cl or P6:icrn; corresponding t,o sligllt,ly diffcrcrlt tlist,ortiorls or t,llc smaller ccll. Tllc rcfincrrlcnt of t,llc rlciit,rorl difiact,ion data gives the sarrlc R-factors for each st,r~lct,~lrc. The latt,icc pararrlctcrs given by .Isprey; Kccnarl arltl Kriisc [60.ISP/I<EE]

have t,ll~ls IICCII C O I I V C ~ ~ , ~ ~ t,o t,his larger cell (by mnlt,iplying the n paramct,cr by A); (1, = (7.044 * 0.002) X 10-". c = (7.225 * 0.002) X 10-In m.

h ) Erathn,lpy of fofol.rnn,tiorr arad entfol.opy

.% ~ralnc for t,hc st,arltlartl cnthalpy of forrnation of nrncricinrn t,rifl~loridc was cst,imnt,ctl by Fuger et al. [83FUG/P.%R] by the proccdiirc not,cd in Scct,ion \'.4.2.1.1 t,o he:

AfH:(.%mF3. rr, 298.15 K) = ( 1 5 8 8 * 13) k J . rnol-'

This val~lc is preferred t,o that of 1 6 0 5 kJ . rrlol-l cst,imnt,ctl by LIorss [86110R] by a slightly diRcrcnt proccdiirc from t,hc syst,crnatics of t,hc lant,llanidc as \!,cl1 as the actinitlc trihalidcs. Ho~vcvcr. as noted by Llorss; t,llc corrclat,ions involving the crlt,llalpics of solution of t,hc trihalidcs arc rnt,hcr irregular for the clcrrlcnt,~ Xd t,o En, (nrhich have similar rrlolnr vol~lrrlcs t,o . % I ~ F : ~ ) ; nrhcrcas t,llc correlation of Fngcr et (11. [83FUG/P.%R]; involving actinitlcs only, gives cxccllcrlt prctlictiorls in all cases (for N ~ x : ~ ( c r ) as \!,cl1 as .%mX:3(cr)) \vllcrc it has i)ccn t,cst,ctl.

Tllc st,arltlartl cnt,ropy is cst,irnatcd (sec Scct,ion \:.4.2.1) t,o i ~ c :

S:(.%mF3. rr, 298.15 K) = (127.6 f 5.0) .J . K-' . rnol-l.

This val~lc is very close to t,hnt cst,imnt,ctl by assurrling t,llc cnt,ropy of form. a t ' ,ion of .%mF:3(cr) is t,llc snrrlc as t,hnt of P~ iF :~(c r ) (&S: = 2 3 2 . 5 J . K-' . rnol-' [83FUG/P.%R]), narncly 127.1 .J . K-' . rnol-l.

Tllc Gil)l)s cncrgy of forrnation is calc~llatcd from the sclcctcd cnt,halpy forrrlat,ion nrld entropy.

AfGk(.4rnF,3. rr, 298.15 K) = ( 1 5 1 8 . 8 * 13.1) kJ . rrlol-l

Carniglin and Ciinningllam [55C.%R/CUX] rncnsnrctl the vapour prcssiirc of nrn- crici~lrrl trifliioridc from 1126 t,o 1469 K by the cffi~sion rnct,hod. nsing tantal~lrn cells; nrltl target collcct,ion of t,hc cR~lsnt,c. Tllc mass of cffiisat,c \!,as cnlcnlat,cd from t,llc 0-radiomct,ric assay of t,llc targct ,~ nsing t,llc half-life of "I'.%rn given by Hollander, Pcrlmnrl nrltl Scnhorg [53HOL/PER]. Thcsc aiit,llors in fact gave val~lcs of 470 nrltl 475 y for t,hc half-life of 2".%m, so it is assnrncd t,llat Carniglia nrltl C~lnningllam [55C.4R/CUN] iiscd n ~ralnc of 472.5 y. Ho\vcvcr, t,llc preferred ~ralnc today is (432.7 f 0.5) y; [86\:4N; li.l27], so all t,llc pressures of .%~nF:~(g) given by [55C.%R/CUX] arc rctl~lccd by a fact,or of (432.71472.5) = 0.916.

In one scrics of cxpcrirncnt,~, tnrin cffiision cells \!,ere iiscd to cornpare t,llc vnpoiir prcssiircs of P~iF:~(cr) and .%mF:3(cr). The rncnsnrcd prcssiircs of P~iF:~(cr) \!,ere closc to those dct,crrrlincd by Pllipps e t al. [50PHI/SE.%]. ~vhich ngrcc nrit,h cnrrcnt,ly ac- ccptcd val~lcs [83FUG/P.4R], indicating t,hnt t,llc gcncral calihrnt,ion of t,llc mcas~lrirlg syst,cm \!,as not scrionsly in error.

It shonltl he rlot,cd t,llat dcspit,c t,hc great care taken to cxcliidc oxygen fiorn the np- pnrat,us, t,hc snrnplcs of P~ iF :~(c r ) aft,cr the cffi~sion cxpcrirncnts \!,ere invarinhly fo~lrltl

to cont,ain sorrlc oxyflnoritlc; ho~vcvcr. Carniglin nrld Ciinningllam [50C.%R/CUX] not,cd t,llat this \!,as iinlikcly t,o affect t,llc vapour pressure mcasllrcrrlcnts apprccial)ly.

Tllc cxpcrimcnt,nl val~lcs for the vaporisation of .%rnF:j(cr) for the assnrncd process

.%mF (rr) + .%mF 3 (g) (1-.18)

can bc fit,tcd by the linear cxprcssion bct,~vccn 1140 and 1469 K to

giving

Tllc cxpcrirncntal point at t,llc lo\!~st t,crnpcratiirc (1126 K) deviates noticeably from this and has l)ccn orrlit,t,ctl from t,hc fit,ting.

Carniglia and Cnnningharn [05C.%R/CUN] rlot,cd t,llat the dcrirctl cnt,ropy of sub- linlat,ion is consist,cnt \!,it11 t,hc rrlonorrlcric snblimnt,ion nssiimctl, rnt,hcr than a more corrlplicat,cd vnp~risat~ion process. t,lloiigh srrlall nrrlourlt,~ of dirrlcr rnolccnlcs co~lld i)c prcscnt in t,hc vapour.

Tllc cnt,ropy of snblimnt,ion for the corresponding vaporisation of LTj(cr) at 1300 K; the rncan t,cmpcmt,urc of t,hc rncasiircrncnt,s. calc~llat,ctl from t,hc thermal fimct,ions give11 by Glushko et al. [82GLU/GUR]; is 191.0 .J . I<-' . rnol-'. Ho~vcvcr. it \~ronltl bc cxpcct,cd that t,hc cnt,ropy of .%mF:3(g) \~ronltl bc appreciably srnallcr than t,llat, of UF:j(g) o\ving to srrlallcr clcct,ronic cont,ribntions, so t,llis is consist,cnt nrit,h the cnt,ropy of vaporisation obtaincd fiorn t,hc stiidy by Cnrniglia and C~lnninghnrn. In order t,o correct t,llc mcasllrcrrlcnts of Cnrniglia and Ciinningllam [05C.%R/CUN] t,o room t,cmpcmt,urc, it is t,llcrcforc nssiimctl t,llat t,hc cnthalpy and cnt,ropy corrcctions to 298.15 K arc t,llc same as those for t,llc vnporisat,iorl of UFt3(cr) [82GLU/GUR]:

Tllc val~lcs for t,llc s~lhlirrlat,ion of .%rnF:j(cr) to .%rnF:j(g) at 298.15 K arc t,ll~ls

Tllc tlcrivcd cnt,hnlpy of forrrlat,ion ant1 cnt,ropy arc:

AfH;(.%mF3, g. 298.15 K) = ( 1 1 6 7 f 15) kJ . rrlol-l S;(.%mF3, g. 298.15 K) = (334f 11) J . K-' . mol-l

Tllc lat,t,cr vnliic is consist,crlt \!,it11 a gasco~ls rrlolcciilc ~vit,ll sirrlilnr molcc~llar pararnc- tcrs as t,hosc of LTj(g) [82GLU/GUR] ; but \!,it11 n smaller clcct,ronic contril)iit,ion t,o the entropy. Tllc standard cnt,ropics at 298.10 K (for 1 bar st,andard st,nt,c pressure) for UFt3(g) and P u F : ~ ( ~ ) arc 347.4 J . K-' . mol-l [82GLU/GUR. 80HIL/GUR] ant1 336.2 .J . K-' . rrlol-l [85HIL/GUR], rcspcctircly.

Tllc Gil)l)s cncrgy of forrrlat,ion is cnlcnlat,cd frorn t,llc sclcctcd cnt,llalpy of forrrlat,ion nrld entropy.

r l j Mieltirrg point

Burnct,t [66BUR] reported the rrlclt,irlg point of a sample of .41nF:~(cr), prepared by rcact,ing t,llc hydrat,c of .4mF:3 prccipit,nt,ctl fiorn corlccntrat,cd HF solution ~vit,ll NH4 . HF2 at 400 K; t,o he (1666 * 20) K; \vllcn snpport,ctl on n rnolyhtlcniim lloltlcr in a graphite fiirnacc.

Tllc sol~lhilit,y prodiict ol)t,ainctl nrit,h t,hc sclcctcd ~ra111c of AfG'$(.4mF:3, cr. 298.15 K) is

.41nF:~(cr) + .km"+ + 3 F- log,, 11,,0(298.15 K) = -13.3 f 2.5

.Is discnsscd allore, t,his ~ralnc is derived frorn the cst,imnt,ctl val~lcs of t,llc sclcctcd cnt,llalpy of formnt,ion and t,hc cnt,ropy of the solid phase. The arncrici~lrn sol~lhilit,ics calciilnt,ctl ~vit,ll this sclcct,ctl val~lc for I%'s.o arc ortlcrs of rnagnit,~ltlc higher t,hnrl the nrncricinrn conccnt,rations rcport,cd by Fcny [54FEA] and by Nash and Clc~~cland [84N.%S/CLE%] for fliioridc sol~lt,ions having [ClO;] % 0.1 h1. Ho\vcvcr, it is not, ccrt,ain t,llat t,hcsc solutions nrcrc indccd in cqnilibri~lrn ~vi th cryst,nllinc nrrlcriciiim triflnoritlc rather t,llan an arnorphoiis (or c ~ ~ c n hydrat,cd) trifliioridc (cf. .4ppcndix -4). Tllcrcforc t,llc sclcctiorl rnadc by t,llis review car1 not he confirmctl ~vi th solubility dnt,n.

0,) Crystal structurr

.41ncricinrn t,ct,raflnoritlc has t,hc rrlonoclirlic UF4 t,ypc cryst,al st,riictiirc. spacc group C2/c. (I, = 12.538 X 10-l' rn; 11 = 10.516 X 10-l' rn. c = 8.204 X 10-" m, = 126.18" [i3A4SP/H.41].

Tllc standard cnthalpy of formnt,ion of .4mF4(cr) has bccn cst,imnt,ctl by two (rclat,cd) corrclnt,ions: Fngcr and Pnrkcr [83FUG/P.4R] iiscd t,llc snrrlc proccdiirc as iiscd for the t,rihnlidcs, nnrncly correlating AfHm(hIF4. cr) - AfH,(h14+; nq) nrit,h t,llc at,omic radius of t,hc mct,nl ion. for hI = Th; U. Pn, ~vhich; ~vi th t,hc vnliics noted in the int,rotl~lct,ion, Scctiorl \'T.4.2.1.1, gives a ~ralnc of ( 1 7 2 0 f 25) k.J . rrlol-l for the cnt,halpy of formation of .4mF4(cr). The extrapolation is less sat,isfactory in t,llis

case, sincc AfHk(.4rn4+; nq, 298.15 K) is not cxpcrirncntally ~vcll tlcfincd. .4 rclnt,ctl corrclnt,ion is t,o plot l f H g ( h l F 4 ; cr) - AfH;(IIO2; cr) also against t,llc ionic rntliiis of t,llc h14+ ion, ~vhich gives a ~ralnc of ( 1 7 0 5 * 15) kJ . rnol-l. Tllc sclcct,ctl ~ralnc is

AfH;(.%mF4. rr, 298.15 K) = ( 1 7 1 0 * 21) k J . rnol-',

~vhich is consist,crlt ~vi th t,hc scrni-qunnt,it,nt,ivc tlccorrlposit,ion mcasllrcrrlcnts discnsscd 1>c10\17.

Tllc ~ralnc of the standard cnt,ropy cstirrlat,cd by Filgcr et (11. [83FUG/P.%R] by the procedure rlot,cd in Scctiorl \'..4.2.1.

S:(.4mF4. rr, 298.15 K) = (148.5 f 5.0) .J . K-' . rnol-l.

is csscnt,ially identical to t,hnt cst,imnt,ctl by assuming t,llc cnt,ropy of formation of .I1nF4 is t,hc same as t,llat of PiiF4(-312.7 .J . I<-' . mol-l) [83FUG/PAIR]; nnrncly 148.2 .J . K-' . rnol-l.

Tllc Gil)l)s cncrgy of forrrlat,ion is cnlcnlat,cd frorn t,llc sclcctcd cnt,llalpy of forrrlat,ion nrld entropy.

AfGk(.4mF4, cr. 298.15 K) = ( 1 6 1 7 * 20) k J . rnol-'

Clliidinov and Clloporov [70CHU/CHO] mcas~lrctl t,llc vapour pressure of .IrnF4(cr) by t,hc cff~lsion rrlct,llod frorn a rlickcl cell. H o \ ~ ~ c ~ ~ c r ; t,hcir .4rnF4(cr) as prepared in sit,u by t,llc rcact,ion of F2(g) nrit,h .4rnO2(cr) at a pressure of < 1 at,rrl for 4 days at G73 K. This rcactiorl is kno~vn to give .4rnF4(cr) [54.4SP] in agrccmcnt ~vi th the rclcxi~,nt t,hcrrnodynarnic data. The rcs~llt,s fiorn n first riin in t,llc appnmt,us gave prcssiircs ~vhich above 800 K nrcrc lo\vcr t,hnrl cxpcct,cd from t,llc norrrlal cxtrapola- tion from lo\vcr t,cmpcmt,urcs. -4ftcr a fi~rt,llcr fliiorinat,ion, ho\vcvcr, the t,ot,nl vnpoiir prcssiirc gave n satisfact,orily linear rclat,ion hct,\~~ccn loglop and l/ T up to 4 2 5 K. .Ihowc t,his t,cmpcmt,urc, t,llc vapour dccrcascd ~vit,ll increasing t,cmpcmt,urc, intlicnt,- irlg tlccornposition (or rcnct,ion) of the .IrnF4(cr). .4rnF4(cr) is indccd 11ox~~ kno\1,11 to st,art to dissociat,c apprccial)ly at allout t,his t,cmpcrat,~lrc; as tlisciissctl more fi~lly 1>c10\17.

Their [70CHU/CHO] cqiiation for the vapour prcssnrc ~lrltlcr t,llcsc conditiorls is

log,,p(bnr) = 1 1 9 1 1 / T + 6.564. frorn 729 to 908 K

corresponding t,o the Gibbs cncrgy of snblimnt,ion of

for the nssiimctl process

.IrnF4 (cr) + .IrnF4 (g). (1-.19)

Tllcrc arc no rclial~lc thermal filrlct,ions for cit,llcr .41nF4(cr) or .4mF4(g) nrit,h ~vhich the entropy of snblimnt,ion of 126 J . I<-' . mol-l car1 l)c compnrctl, hut l,,,S for

the corresponding rcnct,ion involving iiraninrn (~vhich is certainly prcdorninantly n sirnplc cvnporat,ion) is allout 192 .J .K-'. mol-l; using the t,hcrrrlal fimct,ions given by Fiigcr et o,l. [83FUG/P.4R] for UF4(cr) and Glnshko et (11. [82GLU/GUR] for UF4(g) (Cav syrnmct,ry). It is iinlikcly that t,llc cnt,ropy of vnporisat,ion of .4rnF4(cr) \~ronltl differ by more t,hnrl 20 J . K-' . mol-l from this ~ralnc. so it rnay he that the rcactiorl rncnsnrcd by Chndinov and Choporov [iOCHU/CHO] urns rrlorc complicnt,ctl t,hnrl the sirnplc vnp~risat~ion to .IrnFl(g).

In fact,, t,llc rcact,ion

considcrctl by Cll~lt l ino~~ nrltl Choporov [iOCHU/CHO] t,o ncco~lrlt for t,hc dccornposition allore 950 K is t,llcrrnodynnrnici~~lly fxonrablc cvcn at low tcrnpcrat,~lrcs, so co111tl have led to some rctl~lct,ion in the vapour pressure of .4mF4(cr); pnrtic~llarly on the first run, nrhcn sorrlc ~lrlrcactcd .IrnOZ(cr) co~lld have l)ccn present. Ilorcovcr. Gihsorl and Hairc [88GIB/HAII] snggcst,cd t,llat rlickcl cells react nrit,h the fliiorinc cvolvcd from .4rnF4(cr). cqnivalcnt t,o t,hc rctl~lct,ion of .IrnFl(cr) by Ni(cr), ~vhich is of coiirsc t,hcrrnodynarnicnlly favo~lmhlc at all tcrnpcratiircs. Tll~ls rlickcl conltl lose it,s passivity at t,llcsc tcrnpcrat,~lrcs, perhaps by rcactiorl of t,hc rlickcl fliioridc filrrl wit11 .4mF:3 (cr) or .4mF4(cr).

Sirlcc the propcrt,ics of .4rnF4(g) arc of rrlinirrlal irnport,ancc for the prcscrlt piir- poses, t,llis species is not considcrctl filrtllcr in t,llis cornpilnt,ion.

Tllc siiggcst,ion of Clliidinov and Choporov [iOCHU/CHO] that .4mF4(cr) loses fill- orinc at t,crnpcratiircs allore W 1000 K according to the rcact,ion

has rcce~lt,ly IICCII co~lfirrrlcd ~cmi-(l~la~lt,it,at,iv+ by Gil~son and Hnirc [88GIB/H.41]. Tllcsc nut,hors hcat,cd W 5rrlg of .IrnFl(cr) in n (leaking) L&(cr) cffi~sion ccll in n tantal~lrn filrnncc lentling t,o n q~ladr~lpolc mass-sl)cct,rornct,cr. Fliiorinc gas urns itlcntifictl in the vnpoiir, cvcn at t,llc l o ~ ~ ~ s t t,crnpcrat~~rc of t,llc stiidy ( W 850 K). On heating to 1000 K t,hc F2(g) signal disappeared. Tllc rnass-spcct,rornctcr employed co111tl not dctcct species ~vit,ll rrlass nnrnhcrs as high as t,hosc for nrrlcriciiim fliioridcs. . I~nF:~(cr) (idcnt,ificd by X-ray tliflraction) urns fount1 t,o bc prcscnt in t,llc Kniidscn ccll aft,cr t,hc cxpcrirncnts, in an arnoiint approxirnat,cly equal to the start,ing arnoiint,.

From t,hc tlct,ails of the cxpcrimcnt,~. in ~vhich all t,llc .IrnFl(cr) as corlvcrt,ctl irlt,o . I~nF:~(cr) in n few mirl~lt,cs at 1000 K, it is cstirrlat,cd that the prcssiirc of F2(g) in their (leaking) cffi~sion ccll urns 3 X 10-50 5 X 10-">nr; the p(FZ) calc~llatcd fiorn the sclcct,ctl data at 298.15 K; cxt,rnpolnt,ctl to 1000 K \vithont any C,,, corrcct,ion is 5 X lO-")ar.

In t,llcir cxpcrimcnt,~. Clliidinov and Choporov [iOCHU/CHO] used a larger snrnplc of .4mF4(cr); and an appreciably smaller cff~lsion orifice. so t,hcy \~ronltl have convcrt,cd only part of their sarnplc t,o .41nF:~(cr), leading t,o a lo\vcr prcssiirc of .4rnF4(g) (diic

to lack of sat,uration in t,llc Kniidscn cell), hut not t,o complct,c tlccornposition t,o arncricinrn t,riflnoritlc. as in the cxpcrimcrlt,~ of Gillson and Hairc [88GIB/H.%I].

If t,hc stiidy of Cll~lt l ino~~ and Choporov [iOCHU/CHO] represents, c ~ ~ c n approxirnat,cly, t,llc vapour pressure of .4rnF4(cr); t,llc F2/.4mF4 rat,io in the vapour orer .41nF:~(cr) + .4rnF4(cr) is allout 10, siiggcst,irlg t,hat .4mF4(cr) ccrt,ainly ~r:~,l)orizcs rnainly by dccornposit,ion.

Jonniaiix [79JOU] has st,~ltlicd the vaporisat,ion and rcdcposit,ion of arrlcriciiim fill- oridcs in gascoiis flnorinc in a nickel t,~lhc \!,it11 a t,cmpcmt,urc gradicnt at prn(g) = 1 and 5 bar. Tllc volat,ilization \!,as ass~lrncd t,o occur f ~ i o , the tctrafliioridc. They report, crlt,llalpics of adsorpt,ion of 251 and 349 kJ . rrlol-' a t t,hc t,~vo pressures, but it is far from clcar t,o n~hicll precise process or processes tllcsc valiics rcfcr.

Fargcas et al. [8GF.$R/FRE] have st,~ltlicd t,llc vaporisation of arncricinrn corrlpoiinds in atmosphcrcs of HF(g); F2(g) (I)oth of t,hcsc \!,it11 ant1 nrit,ho~lt 02(g) ) a11d BF3 + F2 gases. follo\~~ctl by dcposit,ion in a t,~lhc \!,it11 a t,crnpcrat,urc gradicnt r~lrlrling from 1073 to 123 K. Tllc posit,ion of tlcposition of any volat,ilc compo~lrltls along t,hc tcrrlpcrat,~lrc gradient tiil)c \!,as itlcnt,ificd radiomct,rically. F:~rgcas et o,l. [86F.%R/FRE] not,ctl t,llat, the position (and tlliis tcrnpcrat,~lrc) of tlcposition is st,rongly corrclat,cd nrit,h the type of volat,ilc species (,\IFi, .\IOaFZ, etc.), tlcpcnding litt,lc on t,hc mct,al AI. Frorn their cxpcrirncnts, t,hcy siiggcst t,llat arncrici~lrn is dcposit,ctl as hot,ll .4rnFi(s) arltl .41nFli(s). lIorc dcfirlit,ivc idcnt,ification of t,hc forrrlatiorl of .4rnF5(g) ~voiild i)c very ~vclcornc.

Drohichcvski et al. [80DRO/PRU] s~lggcstcd t,llat .4mFli can l)c forrrlcd in hot,ll the condcrlsctl and gascoiis st,at,cs by the rcact,ion of KrF2 \vit,ll -41nF:~ in anhydrous HF at 313 to 333 K. They \!,ere not a l~lc to isolate any pure arncrici~lrn fliioridc fiorn this rcact,ion, but found t,hat 241.4m, itlcnt,ificd by its 7-spcct,riim, was present in the vapour, that \~,hcn t,hc solvent urns cvaporat,cd. a (lark bro~vn solitl vaporised t,o give a vapour \vit,ll a symrnct,ric infia-red active al)sorpt,ion peak at (604 f 3) cm-' (t,hc sirrlilar peaks of UFfi(s) and PnFli(s) lie at 624 and 615 cm-'; rcspcctircly); arltl that on hydrolysis this solitl yicldctl .4m0;+ in sol~lt,ion, all of nrhich. t,hcy siiggcst,, irltlicat,cs t,llat a volat,ilc higher arrlcriciiim fliioridc; prol)ably .4rnFfi. car1 bc formctl nntlcr st,rongly flnorinat,ing condit,ions. The tcrrlpcrat,iirc gradicnt cxpcrirrlcnts of Far- gcas et 111. [8GF.$R/FRE]. nrhich also siiggcst t,llat 0.04%' .4rnF6(g) car1 l)c forrrlcd in an at,rrlospllcrc of BF:3(g) + F2(g), lla~rc bccn tlisciisscd in Scctiorl \.'.4.2.2.3. Ho\vcvcr rrlorc rcccnt,ly Gihsorl and Hairc [92GIB/H.41] \!,ere iinablc t,o dctcct t,hc forrrlat,ion of a volat,ilc arrlcriciiim fliioridc cit,hcr by rnass-spcct,romct,ric or radiorrlctric analysis ~vhcn .4111O2(cr), .4mF4(cr) or .4rn(cr) wcrc hcatcd in flnorinat,ing agcnt,s such as F2(g); F2(g) + BF:3(g) and ClF:j(g) + BF:j(g).

at 298.15 K to be +(6i* 21) kJ .m&'. by analogy ~irith riit,l~cninrn, arltl Gil~son arltl Hairc [92GIB/H.%I] give t,llc sarnc cstirrlat,cd valiic, ~vit,lloiit an nnccrt,aint,y. This is probal~ly not a t,ot,ally independent cst,irnatc, sincc [92GIB/H.%I] mcrcly rcfcr to the rrlctllods iiscd by [80DRO/PRU] and [86110R] in tlcscribing t,hcir o\1~11 asscssrrlcnt procedure. I\'it,h this cnthalpy of rcact,ion, t,llc fiact,ion of .%rnF6(g) in cqnilibrinrn with .%mF4(cr) arltl F2(g) at 1 bar ~voiild l)c 10-In t,o 10-"at 300 t,o 400 K. but, ~ v o ~ ~ l t l ; of coiirsc; be higher in rrlorc st,rongly fliiorinat,ing at,rnosphcrcs. Tllc i)alancc of cvidcrlcc probal~ly point,s t,o .%rnF6(g) being formed. at least t,ransicnt,ly. in s~lcll at,rnosphcrcs. -4 rcpct,it,ion of t,hc cxpcrirrlcnts of [80DRO/PRU]; but iising ":3.%rn; with it,s lo\~rcr irradiat,ion flux; nro~lld be valiial~lc.

Dioxoamcricinrn(I'1) flnoritlc. .%rn02F2(cr); 11,as cl~aract,criscd by Kccna~l [68KEE]. It is formctl by t,hc act,ion of an HF/F2 mixt,urc on sotliiim arncricyl(\'I) acetate, initially at liqnitl X2 tcrnpcrat,~lrc, but finally at room t,cmpcmt,urc. X-ray pat t ,c r~~s of the protl~lct aft,cr cvaporat,ion of t,hc solrcnt indicat,ctl t,llc prcscncc of a phase ~vit,ll a llcxagorlal st,rnct,urc, spacc group Rzm, U02F2 t,ypc. ~vit,ll rr = 4.136 X 10-In rn; c = 15.85 X 10-" rn. isost,riictiiral nrit,h t,llc other act,inidc(\T) oxyfl~loridcs.

No filrtllcr inf~rrrlat~ion is available on t,his cornpo~lntl.

r r j Li o,nrl No, corn,po?rrrcis

Pcnncrrlan et o,l. [GiPEN/KEE] lla~rc prcparctl the compo~lrltls LiF . .%mF4(cr) arltl iNaF . G.%rnF4(cr) by hcat,ing cllloritlcs nrit,h t,hc appropriat,~ cat,ion ratio in clcmcrlt,al fluorine at 350°C for 16 h. Tllc st,riictiircs and lat,ticc paramct,crs of tllcsc phascs arc:

Li.%mF5(cr); t,ct,mgonal. LiUF5-type, spacc groiip 141/a. rr = (14.63 f 0.02) X

10-" rn. c = (6.449 * 0.005) X 10-" rn.

Krusc and .%sprcy [62KRU/.%SP] have prepared the .%rn(II7) corrlplcx fliioridc Rl~~.%rnF(~(cr) by t,rcat,ing .%m(I\') hydroxitlc or .41n(\') carbonates nrit,h conccn- tratcd RbF HF solutions. Orarlgc pink cryst,als of Rb2.%mFfi(cr) wcrc found t,o

have a11 ort,horhorr11)ic cell \vith latt,icc paramct,crs (1, = (6.98 * 0.0%) X 10-" rn; h = (12.09 * 0.02) X 10-l' rn; (: = (7.56 * 0.02) X 10-l' m.

Tllc corrcsporltling N:I, and K cornpounds of U and Th 11ax.c hcxagorlal syrnmct,ry, 1~1 t the larger Rh+ iorl caiiscs n slight dist,ort,ion t,o the overall ort,horhornl)ic syrnmc- try, but t,llc distort,ing infliicncc is so weak that t,llc cryst,als tend to rcrcrt to higher syrnrnctry by t,~vinning.

V.4.2.3. Anrericiurn chlorides

.lrncricinrn is the first nct,inidc clcrrlcnt for nrhich corrlmorl truly divalcnt corrlpoiinds arc st,al)lc; nrltl l)oth the dicllloridc nrltl t,llc t,ricllloritlc of nrncriciiim, as \ ~ ~ l l as the trixi~,lcnt oxychloridc .lrnOCl(cr), 11ax.c l)ccn \ ~ ~ l l charnct,criscd.


.lrncricinrn dichloridc; prcpnrctl (t,ogct,hcr \vit,ll .lmC1:j(cr)) by t,hc rcact,ion of nrncr- ici~lrrl mct,nl \vith HgC12(s) has t,llc ort,horhornl)ic P1)C12(cr) t,ypc crystal st,riictiirc. spacc groiip Pnmn, n = 8.963 X 10-" rn; 11 = 7.573 X 10-" rn. c = 4.53% X 10-" rn; Bayljarz [73B.-].

hlorss [86hIOR] cst,irnatcd t,hc cnt,hnlpy of forrrlat,iorl of .4rnC12(cr) t,o bc 6 5 4 k.J . rnol-'; \vitll an ~lnkrlo\vn ~lnccrt,ainty, hascd on t,llc assiimption t,llat t,hc hypot,hct,ical cnt,halpy of soliit,ion is sirrlilnr t,o t,llat of SrnC12(cr). t,llc lanthanitlc dicllloritlc \vith the sarnc ionic rntliiis of t,llc cat,ion as amcricinrn in nrncricinrn dichloridc. Ho\~~cx~cr, sirlcc this involrcs t,hc highly iinccrtain val~lc of the cnt,halpy of forrrlat,ion of .4ri"(nq), the rrlost that car1 prohal~ly i)c saitl of the cnt,hnlpy of formation of .lmC12 is that it is likely to i)c rrlorc rlcgnt,ivc t,hnrl 2AfHk(.4rnC1:j. cr)/3, narncly 6 5 2 kJ . rnol-l.


.lrncricinrn trichloridc has t,llc hexagonal UC13(cr) t,ypc cryst,nl st,rnct,urc, spncc group P6:j/rn. (1, = 7.38% X 10-" rn; (: = 4.214 X 10-" m, as tlct,crrrlinctl from single crystal X-ray tliflraction tlat,a by Burns and Pctcrson [70BUR/PET]. This is the st,rnct,ural type in \vhich all t,llc kno~vn act,inidc t,ricllloridcs cryst,allisc.


Tllc cnt,halpy of soliit,ion of .4rnC1:j(cr) in 0.001 nrltl 1.5 11 HC1 solutions urns rncnsnrcd by Fiigcr nrltl Cnnningharn [63FUG/CUN]. Il'hcn corrlhincd \vit,ll t,llc cnt,hnlpy of

soliit,ion of o.-.4rn(cr) in t,hc same soliit,ions (~vhcrc the infinite dilllt,ion ~ralnc has hccn nsctl for the 0.001 h1 HC1 solution), and the cnt,llalpics of forrnation of t,hc chloride ion [89COX/II:.kG] and Parker. Ilkgmnn nrltl Garvin [76P.4R/IVAkG], the tlcrivcd val~lcs for t,llc cnt,halpy of forrnation of -4rnCl:j arc ( 9 7 8 . 2 * 1.7) and ( 9 7 7 . 8 * 1.3) k.J . rnol-'; rcspcct,ivcly (sec [83FUG/PAkR] for dct,nils). Follo\ving [83FUG/P.4R] the T ~ ~ ~ I I C acccpt,cd is

AIH:(.4rr~ClJ, cr. 298.15 K) = ( 9 7 7 . 8 f 1.3) kJ . rrlol-l

Tllc standard cnt,ropy is cstirrlat,cd (sec Scctiorl 1'.4.2.1) t,o bc

S;(.4rnClI, cr. 298.10 K) = (164.8 * 6.0) J . K-' . mol-l.

This ~ralnc is close t,o that cst,imnt,ctl by nssiimirlg t,llc cnt,ropy of forrnation of .4mC1:j(cr) is t,llc snrrlc as that of UC1:j(cr) (AfSk = -225.8 .J.K-'.rnol-' [83FUG/PAkR]), nnrncly 164.2 .J . K-' . rnol-l.

Tllc Gii)i)s cncrgy of forrrlat,ion is cnlcnlat,cd from t,llc sclcctcd cnt,llalpy of forrrlat,ion nrld entropy.

lfG;(.4rnClI. cr. 298.15 K) = ( 9 1 0 . 7 f 2.3) kJ . rnol-'

Tllc heat capacit,y at 298.15 K is cst,imnt,ctl t,o bc similar to t,hnt of UC1:j(cr) [89COR/KOX] t :

C,",(.4rnCli, cr. 298.10 K) = (103 * 10) J . I<-' . rnol-'

TVcigcl nrltl Kohl [851\'EI/KOH] rncasiircd t,hc rrlclting point,, TflIs = (991 * 5) K nrltl the cnt,halpy of filsion of .4mC1:j(cr) iising a corrlmcrcinl DT.4 appnmt,us.

Their val~lcs arc acccpt,cd. but nrit,h increased nnccrt,aintics

Tllcrc is t,oo much iinccrtaint,y in the heat cnpacit,ics of solid and liqiiid .4mC1:j t,o nt,tcrnpt n rncaningfiil cxt,rnpolnt,ion of t,llis valllc t,o 298.10 K.

TVcigcl nrltl Sllllstcr [85IVEI/SCH] att,cmptcd t,o rrlcasllrc the vapour prcssiirc of .k~nCl:~(cr) by n variant of t,llc st,nt,ic i~oiling-point rncthod, using very srnall nrnonnts of arrlcriciiim trichloridc trapped iindcr a rnolyhtlcniirn cup flont,irlg in a hat,ll of liqiiid

t Tlle vallle of Ci,,,,(UCla,cr.298.15 K) in T a l k 111.1 of t l ~ e llrar~il~rr~ NE.&-TDD review

[92GRE/FUG, p.361 is erroneolls, cf. the clis<:llssion in .&ppenclix D, p.348

tin. Their dcscriptiorl of t,hc cxpcrirncnt,al diffic~llt,ics, plus the nnrncroiis qiiitc apprcciahlc corrcct,ions lvhich have t,o i)c applied t,o t,llc rncasnrcd static pressure, siiggcst, that this t,cchniq~lc is ccrt,ainly difficult to nsc on a rnicro-scale. This is borne oiit, by t,llc cxt,rcrrlc variation in t,hc rcsnlt,ing prcssiircs. The aiit,llors carried oiit seven riins: nrithin riins. indiritl~lal points dcliatcd fiorn a linear loglop 71s. 1 / T plot by up to a factor of t,wo in t,llc prcssiirc. and hct,l~~ccn runs, t,hc pressures at the same tcrnpcratiirc differed by up t,o a fact,or of t,cn. hlorcovcr. lvith arnoiint,~ of 100 t,o 200 iag of amcricinrn t,ricllloritlc (prepared from arncriciiim tlioxitlc) ~lrltlcr a 110 cup, in contact lvit,ll hydrogen-rcdiicctl Sn(1) at t,crnpcrat,nrcs 111) t,o 1343 K; t,hcrc can

oxychloridcs do not form a part,, if not t,llc major part. of t,hc rncasnrcd pressures. Gi~rcn t,llcsc prol)lcrns, and t,llat the pressures derived by Ilkigcl arltl Schnst,cr;

loglop(1098 t,o 1343 K) = 7.8 - 11826/T(har) arc allout t,wo orders of rnagnit,~ltlc higher than those of pliit,oninrn t,richloritlc. it sccrrls ~inlikcly t,llat t,hcsc rcprcscnt the xral)ollr ~ ~ C S S I I ~ C of arrlcrici~l~n t,richloridc, a11d 110 fiirt,llcr trcatmc~lt of the rcsiilts is at,t,crnpt,cd.


.kmcricinrn oxychloritlc .krnOCl(cr) has t,hc t,ct,ragonal PIjFC1 type crystal st,riictiirc. spacc groiip P4/nrnrn. n = 3.99 X 10-" rn. c = 6.77 X 10-l, m [04KOC/CUN]. This is the st,rnct,ural t,ypc in lvhich all t,hc kno\vn IIOX actinitlc oxyhalitlcs crystallise.

h ) Tlrrrrraodylrrcxrraic data

Tllc cqiii1il)riiirn constant of the rcact,ion

was stiidictl by Koch and C~lrlrlingharrl [04KOC/CUX] from 682 t,o 880 K, and by TVcigcl arltl Il:ishnc~vsky [76Il:EI/Tl'IS]. iising bot,h 2'1.4rnC1:j(cr) (from 767 to 864 K) and "'3.4rnC1:j(cr) (frorn 75% t,o 854 K). The rcsiilts of t,hcsc t,llrcc st,~ltlics arc in cxccl- lent agrccmcnt,, and all t,hc cqiii1il)riiim constants arc fit,tcd to one linear cxprcssion

log,, li,(17.%l. 682 to 880 K) = 6.676 - 4360/T(har).

for the Gibbs cncrgy for the ahovc rcact,ion. To ut,ilisc this cxprcssion t,o calc~llatc t,hc st,andard propcrt,ics of .krnOCl(cr) at,

298.10 K. t,llc heat capacit,y charlgc for t,llis rcact,ion rrlllst l)c cst,imat,ctl. For t,his, the

heat capacity of .4rnC1:j(cr) is assiimctl t,o i)c t,hc sarnc as that of UC1:j(cr) and t,llat, of .4mOCl(cr) is t,akcn to bc a srrlootll curve; bct,~vccn 298.15 arltl 1100 K;

based on ~ ~ a l n c s calc~llatcd fiorn C,";,(3U02 + U + 2UC1:j)/G. If the cnt,llalpy and cnt,ropy of the hytlrolysis rcact,iorl arc taken to he t,hosc at the

rrlcarl tcrrlpcrat,~lrc of t,hc t,~vo st,udics 781 K; t,hc corrcct,ions to 298.15 K arc:

Wit11 t,hc val~lcs given above for .4mC1:j(cr) ant1 the COD.4T.I Key I'al~lcs [89COX/I1~.IG] for H20(g) arltl HCl(g), t,llc final vah~cs for .4rnOCl(cr) arc

_lfH~(.I~nOC1. cr. 298.15 K) = ( 9 4 9 . 8 * 6.0) kJ . rnol-' S;(.IrnOCl. cr. 298.15 K) = (111+10) J . K-' . mol-l

Tllcsc valiics arc slight,ly diRcrcnt from t,hosc given by Fngcr et al. [83FUG/P.%R] ~ v h o iiscd a constant heat capacity tliffcrcncc of 6.3 J . K-' . mol-l for t,hc hydrolysis reaction (17.21). Tllc major nnccrt,aint,ics in t,hc cnthalpy of format,ion arltl entropy indcctl corrlc fiorn t,hc heat capacity corrcct,ion.

Tllc Gil)l)s cncrgy of forrrlat,ion is calcnlat,cd from t,llc sclcctcd cnt,llalpy of forrrlat,ion and entropy.

AfGm(.IrnOC1. cr. 298.15 K) = ( 9 0 2 . 5 * 6.7) k.J . rnol-'.

Corrlplcx chlorides of -4rnCl:j nrit,h one and t,llrcc moles of CsCl have hccn idcntifictl, together nrit,h a scrics of corrlpoiinds 1l'f~.4rnCl~(s) (111 = K. YHA. RI)) and t,hc qnat,crnary halidc Cs2N:~,.4rnC16. Data for t,llc cnt,halpy of formation of the latt,cr compo~lrltl arc avai1al)lc.

V.4.2.3.4.1. Terno,nl chlorides CsArraCl4, CS, AnrClfi, M2ArnCl: (M = K. NH4, Rh)

Cs.4mC14(s) and C ~ : ~ . 4 m C l ~ ~ ( s ) wcrc prepared by Bagnall, Laidlcr and Stc~vart, [68BAIG/L.41] from acitlic aqncoiis solutions; their st,rnct,urcs arc not kno\vn. Tllc pcnt,achloridcs have been t1cscril)cd arltl charact,criscd by Sclllcitl et o,l. [87SCH/hIOR]. Solutions of ":j.I~nCl:~ in hydrochloric acitl nrcrc rrlixctl \\,it11 the solid alkali cllloridc and evaporated t,o tlryncss a t 200 300°C ~lrltlcr a st,rcam of HCl(g), t,o yield t,an- ycllo\v po\\,dcrs of the t,crnary chloritlcs. X-ray cxa~ni~lat,ion indicat,cd t,hcy have an ort,horhornl)ic cryst,al st,rnct,urc, spacc group Pnrna, isot,ypic \\,it11 K2PrC15(cr) arltl

Table \".11: Lat,t,icc pararnct,crs for amcrici~lrrl t,crnary cllloritlcs

many ot,hcr sirrlilar lant,llanidc arltl actinitlc compo~inds. Tllc latt,icc pararnct,crs of tllc americium corrlpoiinds arc given in Tahlc \".11.

Tllc arnrnoni~lrn corrlpoiind forrrls a convcnicnt int,crrncdiary for t,hc synthesis of .41nCl:~ (m).

V.4.2.3.4.2. Qucxte~raary chloride Cs2NaArnCln,

Scllochrccllt,~ et al. [89SCH/GEN] have charact,criscd Cs2Xa.4mClfj(cr) arltl rncasnrcd it,s cnthalpy of solution in 1 molal hydrochloric acitl sol~lt,ion.

Cs2Na.4rnClti(cr) was foiind t,o have t,llc fcc itlcal-cryolit,c str~lct,~lrc, spacc group F1n31n. \vitll (I, = 1 0 . 8 5 4 6 ~ 10-ln~rl for a sample containing "I'.41n. This is significant,ly smaller t,harl t,hc pararrlctcr rcport,ctl by Sodcrllolrrl et 111. [86SOD/EDE] for a sarnplc containing ":3.4~n; t,hc reason for t,his diffcrcncc is not clcar.

Schocbrccht,~ et 111. [89SCH/GEN] rncasiircd t,llc cnthalpy of sol~lt,ion of t,hc "l-4rn corrlpoiind in an 1 hI HC1 soliit,ion t,o i)c ( 5 1 . 6 2 f 0.85) kJ . rnol-I' a t 298.15 K. \VC have accepted all tllc auxiliary dat,a iiscd by Schocbrccht,~ et al.. except for l fHg(CsC1, cr. 298.15 K); for nrhicll ~ v c prefer tllc ~'a111c ( 4 4 2 . 3 1 f 0.16) kJ . 11101-I'

siiggcst,cd by Glushko et al. [82GLU/GUR] rat,hcr t,han tllc valiic proposctl by Parker [76P.4R/\V.4G]. ( 4 4 2 . 6 9 * 0.04) kJ . mol-l, sirlcc t,hc forrrlcr ~ralnc is csscnt,ially in agrccrrlcnt ~vitll all tllc cxpcrirncntal data corlsitlcrcd by tllc COD.4T.4 Key \;?l- ncs Task Group, Cox et 111. [89COX/II:.4G]. Tllc tlcrirctl cnthalpy of format,ion of Cs2N:~,.4mC16(cr) is

Tllc st,arltlartl cnt,ropy and heat capacity at 298.15 K have been cst,imat,ctl in t,llis review by ass~lrning t,llat t,hc tliffcrcnccs fiorn slims of tllc const,it,ucnt cllloridcs arc close t,o zero:

Tllc Gil)l)s cncrgy of forrrlat,ion is cnlcnlat,cd from t,llc sclcctcd cnt,llalpy of forrrlat,ion nrld entropy.

V.4.2.3.5. Molten so,lt .sy.strrns

Tllcrc arc n niimbcr of stiidics on t,llc tlist,ribntion of actinitlcs in rrlolt,crl cllloritlcs [74hl.%R/SPI, 91hI.%R] and on the clcct,rocllcrrlicnl processing of nct,inidcs in molt,cn Ctl/KCl-Lip1 c~lt,cct,ic mixt,urcs [92KOY/.JOH, 93.ICK/SET] nrhich contain tlat,a on part,it,ion cocficicnt,s. Ho~vcvcr tllcsc st,udics arc outside the scope of t,his review nrltl will not i)c considcrcd fi~rt,llcr.

Bot,ll t,hc dibrornidc and tril)romitlc of nrncriciiim, as ~vcll as t,hc t,rivalcnt oxyhrornidc .ImOBr(cr) have hccn 117~11 chnmct,criscd. Bnyharz [73B.-] rcportcd t,hnt in the reaction of amcricinrn mct,nl nrit,h sufficient HgBr2(cr) to for111 approxirnatcly cqiial nrrlo~lrlt,~ of .%rnBr2(cr) and .%rnBr:j(cr); t,llc X-ray pat,t,crn of t,hc protl~lct in fact contained no lines at,t,ribntablc t,o t,hcsc cornpoiinds, hut sho~vcd lirlcs for an nnitlcnt,ificd phase. sirrlilar to that ol)t,ainctl by t,hc hytlrogcn rcdnct,ion of CfBr:j(cr). This possil)lc new phase clearly ncctls filrtllcr invcstigat,ion.


.Imcricinrn dihrornidc; prcpnrctl by t,hc rcact,ion of arrlcrici~lrrl rrlct,al and HgBr2(cr), has t,llc t,ct,rngonnl EuBr2(cr) t,ypc cryst,al str~lct,~lrc, spncc groiip P4/11, rr = 11.592 X

10-In rn; c = 7.121 X 10-In rn [73B.%l-1.

h ) Tlrrrrraodylrrixrraic data

Tllcrc arc no piil)lishctl t,hcrrnodynarnic tlat,a for this cornpound


.Imcricinrn tril)romitlc 11,as first prcpnrctl on t,llc rnicrograrnrnc scale by t,hc nct,ion of

.IIBr:j(cr) on .Irn02(cr), nrltl purified by s~lhlirrlat,ion [51FRI]. lIilligramrrlc nrnonnts of the t,rihrorrlidc of the longer-lived "".Irn isot,opc wcrc prcpnrctl by .Isprey; Kccnan nrld Krnsc [G5.%SP/KEE] from .%mC1:j(cr) nrltl arnrnoniiim hrorrlidc at G72 t,o 723 K in a strcarn of hydrogen. .%sprcy et o,l. confirmctl t,llc crystal st,riictiirc. first rcportcd by Zachariascn [48Z.%C], to bc t,hc ort,horhornl)ic P~iBr:~(cr) t,ypc, spacc group Crncrn;


Tllc st,andard cnt,halpy of format,ion and st,arltlartl cnt,ropy nrcrc cst,irnatcd by Fngcr et al. [83FUG/P.%R] by t,llc procctl~lrc rlot,cd in t,hc introdiictiorl (Section 17.4.%.1.1) and arc accepted in t,his rcvic\v.

AfHk(.%mBr:j. cr; 298.15 K) = (810*10) kJ . mol-l S;(.%mBr:j. cr; 298.15 K) = (%05*17) J . I<-' . rnol-'.

Tllc Gil)l)s cncrgy of forrrlat,ion calclllatcd from t,hcsc ~ ~ a l n c s is

lfG;(.4rnBrj, cr. 298.10 K) = ( 7 8 7 * 11) kJ . mol-l


.%mcricinrn oxyl)romitlc .%mOBr(cr) has the tetragonal Pl)FCl(cr) type cryst,al st,riictiirc, spacc group P41nrnrn. n = 3.982 X 10-" m, (: = 7.644 X 10-l, rn [79I\'EI/\VIS]. This is t,hc st,riictiiral t,ypc in ~vhich all t,llc kno\vn LIOX act,inidc oxyhalitlcs cryst,allisc.


Tllc cqiii1il)riiim constant of the rcact,ion

was st,udicd by Ilkigcl, I\'ishncvsky and Gllldncr [821VEI/I\'IS] from 719 t,o 890 K. Tllc cqiii1il)riiim constants from t,his st,~ltly arc fit,t,ctl t,o t,hc linear cxprcssion,

log,, hrP(I7.%2. 719 to 890 K) = 6.671 - 4408.3/T(l)ar)

for t,llc Gibbs cncrgy for t,llc allore rcact,ion. It will bc sccn that the cqnilibrinrn const,ant,s for the i)romitlc hydrolysis arc alrnost idcnt,ical ~vit,ll t,llosc for t,hc corrcspontling rcact,ion involving t,llc chlorides. I)cing on average abollt 15% lo\vcr in the tcrnpcratiirc range st,lltlicd.

Tllc heat capacity change for this rcactiorl is assnrncd t,o bc the same as t,llat, cst,irnatcd for t,hc rcact,ion involving chlorides. so the diffcrcnccs t,o convert t,o cnt,llalpy and entropy ~ ~ a l n c s at 298.10 K arc sirnilar:

Wit11 the val~lcs given nhovc for .I~nBr:~(cr) nrltl COD.4T.I Key \'al~lcs for H20(g) nrld HBr(g) [89COX/\V.4G] (cf. Tnhlc I\'..l). t,llc final ~ ~ a l n c s for .4mOBr(cr) arc

l f H ~ ( . I r n O B r . cr. 298.15 K) = ( 8 9 3 +12) k J . rnol-' S~(.IrnOBr. cr. 298.15 K) = (128 +20) J . K-' . mol-l

Tllcsc ~ ~ a l n c s arc slightly diffcrcrlt from those sclcct,cd in t,hc rcvic\v by Fiigcr et 111. [83FUG/PAIR] \17ho used a const,nrlt heat capacit,y diffcrcncc of 6.3 .J . I<-' . rnol-' for the hydrolysis rcactiorl (17.22). Tllc rnajor cont,ribntion t,o t,llc nnccrt,nint,ics given is irltlcctl t,hc heat cnpacit,y corrcct,ion.

Tllc Gil)l)s cncrgy of forrrlat,ion is cnlcnlat,cd from t,llc sclcctcd cnt,llalpy of form. a t ' ,ion nrld entropy.

AfG~(.IrnOBr. cr. 298.15 K) = ( 8 6 1 + 13) k J . rnol-'

Bot,ll t,llc tliiotlidc and t,riioditlc of arncrici~lrn. as \ ~ ~ l l as t,llc trivalent oxyiodidc .IrnOI(cr) have bccn ~vcll chnmct,criscd.


.Irncricinrn diiodidc is prepared [72B.I1-/.4SP] by t,llc actiorl of Hg12(cr) on nrncri- ciiirrl rnctal. The dixi~,lcncy of americium in t,his compoiind was corlfirrrlcd by mng- nct,ic snsccpt,ihilit,y mcasllrcrncnts. It has the rrlonoclinic E11I2(cr) type cryst,al st,riictiirc, spacc group Pc, P2/c or P21/c; rr = 7.677 X 10-" rn; 11 = 8.311 X 10-" rn; c = 7.925 X 10-" rn. i/ = 98.5".


Tllcrc arc no piil)lishctl t,hcrrnochcmical tlat,a for t,his cornpound, i)iit Bnyharz et 111. [72BAlY/.ISP] rcport,cd t,llat it mclt,s nrit,h dccomposit,ion at -973 K.


Based on rrlicrogrnrrlmc samples of t,hc strong ;!-cmit,t,ing 2'1.1m isotope, nrrlcriciiim triiodidc prcpnrctl by Fried [5lFRI] fiorn arncrici~lrn dioxitlc nrltl .411:j(cr) urns first report,ctl [48Z.4C] t,o cryst,nllisc in t,llc ort,horhornl)ic P~iBr:~(cr) t,ypc str~lct,~lrc. Ho\vcvcr, in rrlorc rcccnt work using the more easily llandlctl "".Irn isot,opc. .4sprcy, Kccnan

nrld Krnsc [64.%SP/KEE, 60.%SP/KEE] prepared .%~nI:~(cr) from .4rnC1:3(cr) and nrn- rrloni~lrrl iodide at 672 to 723 K in a st,rcnrrl of hydrogen; its st,rnct,urc as found to l)c hcxagonal BiI:3(cr) t,ypc. They n7crc 1l11al)lc t,o conxrcrt t,llis t,o an ortllorllorrlhic phase, at any t,cmpcmt,urc from 673 t,o 1173 K. hlorc rcccnt,ly Hairc et 111. [83H.%I/YOU] have sho\1711 t,llat the t,riioditlc prepared from t,llc rnct,nl nrltl iodine at 300°C has the ort,horhornl)ic P~iBr:~(cr) st,riictiirc. while snrnplcs prcpnrctl fiorn .%~nBr:~(cr) or .%~nCl:~(cr) and HI(g) allore 600°C had t,llc hcxagonal BiI:3(cr) str~lct,~lrc. Tllcrc is n rcvcrsihlc t,ransition l)ctn~ccn t,hc polyrnorphs at 673 * 30 K, but t,llc corlvcrsion of the high tcrrlpcrat,~lrc hcxagorlal phase t,o t,llc low tcrnpcratiirc ortllorllorrlhic phase is xrcry sliiggish; so t,hc hcxagonal phase can easily l)c qncnchcd t,o roorrl tcrnpcrat,~lrc, e.g. from the rnclt. Siil)scqiicntly Hnirc et al. [80H.%I/BEN] s h o ~ ~ ~ d t,llat the convcrsion of t,hc hcxagorlal str~lct,~lrc to t,hc ort,horhombic also occiirs by t,hc imposition of n pressure of 2 GPa at nrnl)icnt t,crnpcratiirc. in accord ~vi th t,hc considerably smaller molar vol~lrrlc of t,llc lnt,tcr.

Tllc lnt,ticc pnrnrrlctcrs for the two phases given by [83H.%I/YOU] arc:

lo\v t,cmpcmt,urc phase. ort,horhombic P~lBr:~(cr) t,ypc, spncc gronp CrnCrn; (L = 4.28 X 10-In rn. 11 = 13.94 X 10-" rn. c = 9.974 X 10-In rn.

high t,crnpcratiirc phase; hcxagonal BiI:3(cr) t,ypc. spncc gronp Rz. 11, = 7.637 X

10-" rn. c = 20.91 X 10-" rn.

Tllcir paramct,crs for the ort,horhornl)ic phase ngrcc nrit,h t,hosc rcport,cd by Zachari- nscn [48Z.%C] ~vit,llin t,llc rather large nnccrt,nint,ics of the latt,cr; t,llosc of t,llc llcxagonal phase arc appreciably grcat,cr (by 1.8 nrltl 2.9%) t,llan those rcport,cd by -4sprcy nrld co-~~wrkcrs [64.4SP/KEE. 65.4SP/KEE]. The rcnsorl for t,his discrepancy is riot,

known hot,ll st,udics iit,ilizcd the longer-lirctl ":3.4rn isot,opc. so radiat,ion darnagc is not likely to i)c the caiisc.

h ) Eratho,lpy of fofol.rno,tiorr arad entfol.opy

Tllc st,andard cnt,halpy of formnt,ion and st,nrltlartl cnt,ropy nrcrc cst,irnatcd by Fngcr et 111. [83FUG/P.%R] by the procctl~lrc not,ctl in t,llc introdiictiorl and arc sclcct,ctl in this rcvic\v.

AfH;(.4rr~IJ, cr. 298.15 K) = ( 6 1 2 f 7) k.J . 11101-l

S;(.4rnII, cr. 298.10 K) = (234 f 20) .J . K-' . rnol-I

Tllc Gil)l)s cncrgy of forrrlat,ion derived from t,llcsc val~lcs is

lfGm(.4rn13, cr. 298.10 K) = ( 6 1 3 f 9) k.J . mol-l


Bayl~arz et al. [i2B.4YlA%SP] prcpnrctl nrrlcriciiim oxyioditlc by llcnt,irlg .%rn12(cr) in rrloist air at -673 K. .4rnOI(cr) has t,hc t,ct,rngonnl PbFCl(cr) t,ypc crystal st,riictiirc.

spacc groiip P4/nrnm, rr = 4.011 X 10-l', c = 9.204 X 10-" rn [7%BAlY/.1SP]. This is the st,rnct,ural t,ypc in ~vhich all t,hc kno\vn IIOX actinitlc oxyhalitlcs crystallise.

h ) Tlrerrraodylrrcxrraic d a t a

Tllcrc arc no piil)lishctl t,hcrrnodynarnic tlat,a for this cornpound.

V.5. Group 16 (chalcogen) compounds and complexes

Tllcrc arc no cxpcrimcrlt,al stiidics involving t,llc t,hcrmotlynamic propcrt,ics for arncri- ciiirrl chalcogcnidcs. so t,llis review s~lrrlmarizcs t,llc prcparat,ivc arltl st,riictiiral dat,a for tllcsc phases, but inclndcs a fcxv cstirrlat,cd ~ ~ a l n c s for the entropies of t,llc rnonochalco- gcnitlcs.

Tllc rnonosiilphitlc. a "s~lhstoichiornctric scsqnisnlphidc" (~vith a composit,ion close t,o .11n:~S~(cr)); the true scsqnisnlpl~idc arltl the s~lhstoichiomct,ric disiilphitlc arc kno\~rn. Tllc so-called L/-scsq~lis~lll)llidc is t,rcat,cd nrit,h the oxys~llphidcs.

Damicn [ilD.4h'l] obtained a phasc nrit,h t,llc fc,c XaCl(cr) t,ypc st,rnct,urc, spacc group F1n31n. mixed nrit,h t,hc .4rn:3S4(cr) phasc, (~vhich Damicn callctl :-.11n~S:~); by heating the scsqiiisiilphitlc in vac~l~lrn (N 10-"orr) at 650°C. By analogy nrit,h other actinitlc clcrncnts; this urns assnrncd t,o he t,llc rnonosiilphitlc, but the precise corrlposit,ion is not kno\vn. The lat,ticc paramct,cr of this prcs~lrnably s1ll~)l~iir-sat,nratcc1. corrlposit,ion was 5.592 X 10-" rn.

Tllc latt,icc paramct,cr of t,llc single-phase .11nS(cr) prepared by Charvillat et (11.

[iGCH.k/BEN] fiorn st,oichiomct,ric amo~lrlt,s of arncriciiim hytlritlc and snlph~lr urns 5.600 X 10-l' m. Tllcsc aiit,llors also prepared t,hc diphasic mixt,urc of .11nS(cr) + .11n:~S~(cr) aft,cr Damicn. finding a lat,ticc pararnct,cr increasing from 5.592 X 10-" t,o 5.618 X 10-" rn as the annealing t,cmpcmt,urc was increased fiorn 800°C t,o 1100°C. This may irltlicnt,c an apprcciahlc range of homogcncity for this phase.

During this hcat,ing, tllcrc urns a continno~ls loss of \~,cight,; arltl at 1300°C, no rnonosnlphidc as present. This rnay he diic to prcfcrcnt,ial loss of .1m(g) fiorn the rnonosnlphidc:

or loss of .1rnS(~). The forrrlcr sccms rrlorc likely, sincc as Darrlicrl 171D.1hI1 not,ctl, the dccornposition of -4r1l~S:~(cr) at as lo\v a t,crnpcratiirc as 650°C implies that .11n~S:~(cr) is apprccial)ly less st,ahlc than t,hc corresponding P11 and NI) compo~lntls. This,

together ~vit,ll t,llc higher volat,ilit,y of clcmcrlt,al .%m. conltl lcatl t,o t,llc congriicntly vaporising composit,ion in t,llis syst,crn being near .%rn:jS,(cr).

Tllcrc arc no cxpcrirncnt,al thcrmotlynamic tlat,a for .%mS(cr); but Gronvoltl, Dro~vart, and i\i.st,riim [84GRO/DRO] cst,imat,ctl the st,andard cnt,ropy t,o bc

S;(.krnS. cr. 298.15 K) = (92 * 12) J . K-' . mol-l.

Damicn [ilD.%h,l] prepared . k ~ n ~ S : ~ ( c r ) on t,hc 50 mg scale by heating arrlcriciiim hytlritlc nrit,h t,hc st,oiclliorrlct,ric arnoiint of s~llphiir at 500°C. Rcactiorl urns cornplct,c in four days t,o give a black po\~rdcr nrit,h an X-my pat,t,crn ~vhich coiild i)c irltlcxcd as an ortllorllorrlbic cell. ~vit,ll rr = 7 . 3 9 ~ 10-In, h = 3.98 X 10-In and c = 15.36 X 10-" rn. Tllc str~lct,~lrc is assiimctl t,o i)c the sarrlc as t,hat of P ~ l ~ S : ~ ( c r ) ; narrlcly the (Y-CC~S:~ type spacc groiip. Tllc sarnplc prol)ably cont,ainctl some .k~n:~S,(cr).

Tllcrc arc no cxpcrimcrlt,al thcrmotlynamic data for . k ~ n ~ S : ~ ( c r ) ; l)iit hloskvin [73hIOS, 73hIOS21 has cstirrlat,cd t,llc st,andard cnt,ropy arltl heat capacity of .%mZS3(cr) to bc 133 arltl 244 J . K-' . rnol-', rcspcct,ivcly. Tllcsc arc apprcciably diRcrcnt fiorn the cxpcrirncnt,al valiics for U2S:j(cr) [84GRO/DRO]. 190 and 133.7 J . K-' . rnol-'; and may not bc w r y rcliablc.

This phasc was first idcntifictl by Zachariascn [48Z.%C; 49Z.%C2]; it has t,llc cubic T l ~ : ~ P ~ ( c r ) st,rnct,urc. hlorc recently it has bccn prepared by Darrlicrl [ilD.%hl] rho called it y- .k~n~S:~) ; by t,llc tlccornposition of t,llc scsq~lis~llphidc in vaciiiim. Fnr- thcr work by Charvillat et al. [iGCH.k/BEY] s h o ~ i ~ d t,hat t,llc lat,ticc pararnct,cr of t,his phase incrcascs nrit,h t,llc t,crnpcratiirc of tlccomposit,ion. siiggcst,irlg t,hat it probal~ly has a range of composit,ion. Even the lligllcst lat,t,icc pararrlctcr fo~lrltl by [iGCH.%/BEN] (8.434 X 10-In m by dccomposit,ion at 1300°C) is appreciably lo\vcr than foiind by Zachariascn (8.445 X 10-In m).

TVhcn Darnicn and Jovc [71DAkII/JO\'] llcat,ctl arncricinrn hydridc nrit,h cxccss snlpll~lr in a Pyrex t,ubc at 400°C for orlc \ ~ ~ c k ; t,hcy foiind a coarse black rnat,crial ~vhich contained a tctragorlal phasc ~vit,ll rr = 3.938 X 10-" and (: = 7.981 X 10-In rn. Tllc int,cnsit,ics of the X-ray patt,cr11 s~lggcst that t,llis phase has a PSCII~O-cc11 of the C11~Sb(cr) t,ypc; spacc group P4/nmrrl similar t,o the snbst,oichiornct,ric pl~lt,orliiim dis~llphidc; ~vi th t,llc cornposition hISl,9(cr). Yo analysis of t,hc corrlpoiind urns rnadc, so t,hc exact composit,ion is not kno\vn.

Tllcrc arc t,~vo oxysnlphidcs kno\vn, .%m20aS(cr). and a phnsc rclat,cd t,o t,llc scsqiiisiil- phidc, .%rnloOS14(cr).

This phase urns prepared by Hairc nrltl Fahey [77H.%I/F.%H] by rctl~lcing .%m(III) oxys~llphatc . % I ~ ~ ~ O ~ S O ~ ( C ~ ) in H2/.%r at 800°C. TVcll-cryst,allisCd sarrlplcs ~vere oht,ainctl in as short a t,imc as 2 h. .%rn2(12S(cr) is isost,rnct,ural nrit,h hexagonal La20aS(cr), spacc gronp P31n. \vitll n = 3.910 X 10-l' and c = 6.77% X 10-" m.

h ) Anrlo OS11 (cr)

This compo~lrltl urns prepared by Damicn. hlarcon ant1 .Jovc [72D.%h'l/hl.%R] by heat,- irlg .%rnaS:3(cr) arncrici~lrn disiilphitlc in vac~l~lrn in a plat,iniirn cr~lciblc. .%~n~S:~(c r ) is forrrlcd at 850°C; on filrtllcr hcat,ing to llOO°C, n t,ct,rngonnl phase ~vit,ll rr =

14.87 X 10-" and (: = 19.73 X 10-" m is formctl. Tllc similar pliit,oninrn nrltl lan- tllarlidc phascs nrcrc first t,ho~lgllt to he polyrnorphs of t,llc scsqnisnlphidcs. hut Cnrrc, Lariicllc nrltl Bcsan~orl [iOC.%R/L.%R] sllo\~~ctl t,hnt they wcrc oxys~llphidcs nrit,h the corrlposit,ion hIloOS14(cr), ~vi th spacc gronp 141/ncd. Tllc nrrlcriciiim cornpound is nssnrncd t,o i)c similar.

l\lakovlcv nrltl Kosynkov [56Y.%K/KOS] first reported sorrlc qiialit,at,ivc spcct,rophot,o- rrlctric ol)scrvations on t,hc forrrlat,ion of amcricinrn-s~lll)l~atc cornplcxcs. Tllcrc arc fcxv rclinhlc qnnnt,it,at,ivc stiidics nvailablc in t,hc lit,crat,~lrc on the arncrici~lrn(III) s~llphatc syst,cm, and all of tllcrrl rcfcr t,o soliit,ions of lo\v pH (pH 5 3.6, cf. Tal)lc \'.l%). Only cxt,rnct,ion tcchniqiics such as cation cxcllangc [60LEB/PIR, 64B.%N/P.%T; 67N.41; 68A%ZI/Ll-L. 68N.411 nrltl solrcnt cxtractiorl [64SEK, 65SEK2. 67C.%R/CHO, 68A%ZI/Ll-L. 78R.%O/B.%G. 80KHO/hI.%T] as ~vcll as clcct,rorrligrnt,iorl [SOROS/REI] wcrc iiscd to dct,crrrlinc the composit,ion nrltl t,hc st,nhilit,y constants of t,hc corrlplcxcs forrncd. No solubility rncasiircrncnt,s wcrc rcport,ctl. . % r n ( ~ ( I ~ ) ~ ~ - " " ((rr = 1 nrltl 2) nrld .%rn(HSO1): species have l)ccn s~lggcstcd t,o interpret the various cxpcrirncrlt,nl dat,a.

Tllc data listed in Tal)lc \'.l% rcfcr t,o cqnilibrin of t,llc t,ypc

Tllc cation-cxchnngc cxpcrirncnt,~ pcrformctl by Lcbctlcv. Pirozllkov and l\lakovlc~r [60LEB/PIR] at I = 0.75 nrltl 1.5 I1 wcrc irlt,crprctctl assnrning t,hc formation of the .%mSO: nrltl .%rn(S04); complcxcs. The scarceness of t,hc cxpcrirncntal tlat,a nrltl the narrox~~ conccnt,rnt,ion range invcstigat,cd at I = 1.5 hI does not allow n rclinhlc

Tahlc \".12: Litcratiirc cqiiilillriiim constants for t,hc arncrici~lrn(III) siilphat,c syst,cm.

hletl~ocl hlecli~~rn pH t("C) log,, ,& log,, Referer~ce

cix 1.5 \I N H ~ ( x ( ~ ) , S04) - 4 20-25 0.75 RI N H ~ ( x ( ~ ) . s o 4 )

cix 1 M H(ClOq,HS04) 0 26f l 1 M 1Ua(C104, SO4) 3

(iis 1 M 1Ua(C104, S04) 3-4 25 (iis 2 M 1Ua(C104, SO4) 3 25 f 0.1

~~ ~ ~ ~

55 1.65&0.06 2.38&0.10 cix 1 M H(ClOq,HS04) 0 27 1.22&0.01 (11) [671U..II, 681U.411

1 M 1Ua(C104, SO4) 3 1.49&0.01 2.36&0.01 (iis 0.5 \I Na(C104, S0q) 3.6 25 f 0.5 1.86&0.01 2.83&0.02 [68..IZI/LYL] cix 1.86&0.01 2.80&0.03 (iis I + 0 3 25f0.1 3.76&0.11 5.64&0.10(') [72\ICD/COL] (iis 1 M H(ClOq,HS04) 0 25f0.1 1.82&0.01("' 3.12&0.01("' [78R..IO/U..IG]

2 M H(ClOq,HS04) -0.3 1.711 f 0.004(") 3.04 & 0.01(") (iis 1 M 1UH4(C104, S0q) 3 30 1.72&0.02 [8OKHO/\I..IT] err1 0.1 \I Na(ClO4, SOq) 2.8 25 2.50&0.3 3.6&0.4 [9OROS/REI]

5.5 2.50&0.2 3.1&0.7

(a) Lellerlev, Pirozl~kov arlrl Xakovlev [GOLEB/PIR] report illat t,lle ionic: strengt,h was kept <:on- s tar~t t)!. acl(iition of arrlrrlor~illrr~ cl~lorirle or perchlorat,e.

(11) Nair reports log,, Ii = (0.54 & 0.03) for: Am" + 2HS04 = rlrn(H2SO4):. (c) R1c:Dorvell ancl Colerrlar~ report log,, ,& = (5.29 f 0.05). ((i) The stallility corlstarlts of Ran et al. [78R..IO/U..IG] for t l ~ e rrac:tior~s: Am" + 71 HS04 +

(:4-211) .4rn(S04),,, + rr H+, \%-ere cornl~inerl with t , l~e protonat,ion cor~star~t of S O ; 11sec1 1137 Rao f ! t al. (log,, Iil = 1.18 arlrl 1.08 at I = 1 arlrl 2 \I res~~ect,ivel!.) to give t l ~ e vallles presentecl in illis Ta11le.

dct,crrrlinat,ion of t,llc t,llc cqnilibrinrn const,arlt,s which arc tllcrcforc tlisrcgardcd by this review. F~lrthcrmorc; bccansc the aiit,llors did not specify t,hc composit,ion of the ionic rrlcdia ilsctl; the log,, ill val~lc at I = 0.75 hI is not inclndctl in t,llc cxtrapol a t ' ,ion to I = 0 pcrforrrlcd by t,his rcric\v.

Bansal. Patil and Sharrna's rcsnlt,s [64B.%N/P.%T] arc not sclcctcd 11y this rcric\v, as t,hc rcport,ctl val~lcs rcfcr to iin~~iil~lishctl nwrk by Nair and ilklch.

Nair [GiN.$I. 68X.%I] ~lsctl a dissociation const,arlt of HSO, not corlsistcnt \\,it11 the auxiliary dat,a atlopt,cd in t,hc NE.$ rcric\vs. arltl t,hcrcforc his cxpcrirncntal data arc rcint,crprct,ctl usirlg loglo lil = (1.22 * 0.03) at I = 1 11. Tllc rcs~llt,s oht,aincd at, pH = 3 arc not affcct,ctl by t,llc acitl const,ant,. .$t pH = 0; t,hc dcpcrltlcncc of the part,it,ion tlat,a nrit,h [SO:-] indicat,cs t,hc prcscncc of .%rnSO:. Tllcrc is no cvidcncc of .%m(HS04): formnt,ion; thiis, t,his rcvic\v does not support t,llc cxistcncc of the arncricinrn l ~ y l r o g c n - i i l h a t cornl~lcxcs.

Figure \:.g: Extrap~lat~ion to I = 0 of cxpcrirncntal data for t,llc cqiii1il)riiim const,ants of formation of .lmSO:. accordirlg to rcact,ion (\'.23), nsing the specific ion irlt,cractiorl cqnat,ions (($ .%ppcndix B). Both cxpcrirncnts ~vit,ll [H+] 2 1 hI (U) arltl [H+] < 1 mhl (e) arc plott,cd. The rcs~llt of t,llc ~vcight,cd linear rcgrcssion for the cxpcrirncnt,~ ~vit,ll [H+] 5 1 rrlhI is sho\17n as a straight line, arltl t,hc dot,tcd lirlcs rcprcscrlt t,llc iinccrtaint,y range.

Rcirlt,crprct,at,iorl of t>lic solvcnt cxt,ract,ion data of Rao et o,l. [78R.%O/B.%G] nsing an acid constant for HSO; consist,crlt nrit,h t,llc dat,a in Chapt,cr 11'; leads to slight,ly different format,ion constants (cf. .%ppcndix .l).

Tllc rc-cval~lat,cd va111cs fiorn Rcfs. [67N.%I; 68N.41. 78R.%O/B.%G] and t,l~c cqni- lil~rinrn const,arlt,s frorn all other rcfcrcnccs list,cd in Tahlc \:.l2 cxccpt [6OLEB/PIR, 64B.%N/P.%T] arc convcrt,cd to rrlolal iinits t,o perform an cxt,rapolation usirlg the specific ion irlt,cract,ion c:q~lat,ions of -4ppcntlix B. Tllc corrected st,al)ilit,y const,arlt,s oht,ainctl at [H+] 2 1 11 (0, Figiirc \:.g) and [H+] 5 l rn11 (e, Figure \'.g) sccm not to i)clong t,o the sarnc parcrlt distril)i~t,ion. Tllc apparent discrepancy, i)ctn~ccn pH 5 O and pH -- 3 dat,a, rnay he at,t,ribntcd t,o the diffcrcncc in ionic rncdia iiscd (H+/HSOj/ClOj arltl Ya+/SO:-/ClO J) . Tllc lack of tlat,a oht,aincd in corlccntrat,cd acitl soliit,ions tlocs not allo117 a rclial~lc cstirrlat,c of t,llc pH irlfl~lcncc on the snrn of ion irlt,cractiorl cocfficicnts; .LE; and cvcn t,lloiigh the rcsult,~ of Rao et al. [78R.%O/B.%G] (I = 1 arltl 2 11 H+/HSOT/C~OT) arc considcrctl sat,isfactory by t,llis rcvic~v; they will not i)c incl~ltlcd in t,hc cxt,rapolation to I = 0. The ~vcight,ctl linear rcgrcssion, pcrforrrlcd on pH 2 3 tlat,a. rcsnlt,~ in

log,, ?,"(l-.23,298.15 K) = 3.85 * 0.03

and AE, = (-0.16 * 0.03) kg . mol-l. The sclcctctl ~ralnc for log,, 9," is close t,o

Tahlc \'..13: \;?liics of t,hc forrrlat,ion const,ant,s for .%m(SO4), ol)t,ainctl at pH= 3 cxt,rnpolnt,ctl t,o I = 0. The cqnilibrinrn const,ant,s, rcport,ctl in Tnhlc \'.l2 in rrlolnr nnit,s, have hccn corlvcrt,ctl t,o rrlolal urlit,s in accordancc ~vi th Eq. (11.3%). Tllc * tcrrrls corrcsporltl t,o n 95% iinccrtaint,y.

Rcfcrcncc hlcdinrn t,/("C) log,, i/2 log,, p,"

the x~alnc (log,,iy = 3.82) ol)t,ainctl by Bidoglio et (11. [87BID/T.%X] and t,o the cq~iilil)riiim constant dctcrmirlcd cxpcrirncnt,ally at I 5 0.1 11 by hIcDo~vcll nrltl Colcmnrl [7%hICD/COL]. The slight diffcrcncc is due to t,hc fact t,hnt Bitloglio pcrforrrlcd t,hc regression t,o I = 0 usirlg rrlolnr (inst,cad of rnolnl) iinits for the ionic st,rcngth. Frorn the dct,crrrlincd vnliic of AE, nrltl t,llc ion irlt,crnct,ion cocficicrlt,~

,(:lO; nrltl E ( ~ ~ + , ~ , , ; - ) given in .%ppcndix B t,his rcric\v oht,nins: ~ ( . ~ ~ ~ ~ ) z ,c:1o,) =

(0.22 f 0.08) kg . rnol-l. ~vhich is in gootl agrccmcnt ~vi th t,llc sclcct,cd cstirrlat,c for E-vnliics for the int,cractiorl bct,~vccn pcrclllornt,c and complcxcs of nrrlcriciiim ~vit,ll clcct,ric charge of +l (cf. Scctiorl B.1.4).

No rclial~lc cxtrapolat,ion t,o I = 0 11 can bc ol)t,aincd from t,llc scatt,crcd .%m(SO4), formation const,ant,s. F~lrthcrmorc; no critlcncc of .%rn(S04), was fo~lrltl in the pH% 0 rcs~llt,s reported in [68N.%I]. ~vhich is in cont,rntlictiorl nrit,h t,llc st,udy of [78R.%O/B.%G], pcrforrrlcd under similar contlit,ions. cf. .%ppcndix -4. -4s t,hcrc is no apparent reason for such discrcpnncy, this review cxtrapolat,cs to zero ionic st,rcngt,h only t,llc vnliics of log,, obtaincd at pH zz 3. using t,llc specific ion irlt,crnct,ion cqiiations of .%ppcntlix B. nrltl !k2 = (-0.30 f 0.08) kg. rnol-'. Tllc rcsnlt,s arc prcscrlt,ctl I l 3 Tllc val~lcs of Sckinc [64SEK. 65SEK21, Nair [67N.%I. 68N.%I] nrltl Khopkar and hlathiir [80KHO/hI.%T] do not agrcc nrit,h t,hc data by Dc Carvalho nrld Choppin [GiC.%R/CHO]. Bccn~lsc tllcrc is no appnrcrlt rcnsorl t,o prefer one set, of data oxrer t,llc other. an iinn~cightcd axrcmgc of all tllcsc cqnilibrinrn const,ant,s is sclcct,ctl, nrltl the iinccrtaint,y nssigrlcd t,o cover t,llc range of cxpcctation of all sclcctcd T'>I,~I~cs:

log,, ,/,"(IT.23. 298.15 K) = 5.4 * 0.7

~vhich is in good ngrccrrlcnt ~vit,ll t,llc val~lc cxpcrimcnt,ally tlct,crrrlinctl by hIcDo~vcll nrld Colcrrlan [72hICD/COL].

It sho~lld i)c rrlcntiorlcd t,llat t,hc cxpcrirncntal dnt,a iiscd for tllcsc cnlcnlat,ions rcfcr

to slight,ly diRcrcnt t,crnpcratiircs (cf. Tal~lc 17.13). H o ~ ~ ~ c ~ ~ c r , the st,~ltly of Dc Carvalho and Choppin [GiC.%R/CH02] sho~~rs t,hat the tcrnpcratiirc cffcct,s on t,llc ~ ~ a l n c s of the cqlii1il)riiim const,arlt,s arc not large in t,his t,cmpcrat,urc mngc.

Tllc sclcct,cd Gibbs cncrgics of formation arc calculated t,o he

AfG$(.%mSO:, aq, 298.15 K) = ( 1 3 6 4 . 7 * 4.8) k.J . mol-l AfGm(.krn(S04),, aq, 298.15 K) = ( 2 1 1 7 . 5 * 6.3) k.J . mol-l

Tllc cqnilibrinrn const,arlt,s rcportcd by Dc Carvalho and Choppin [67C.%R/CHO, 67C.%R/CH02] (cf. Tal)lc \:.12) arc llsctl t,o tlct,crrnirlc the cnthalpy arltl entropy changes. .k nrcightcd linear rcgrcssiorl of '.l11 p , ?IS. 1/T(K-l)" leads t,o t,llc follo~ving non-st,antlartl val~lcs:

at I = 2 11, pH = 3 and 298.15 K. The val~lcs for the forrrlat,ion of .krnSO: agrcc with l,Hm;I = (18.4 f 3.3) k.J . rnol-' and l,Sm;1 = (88 f 13) J . I<-'. rrlol-' rcportcd in Ref. [GiC.%R/CH02].

Hydrat,cd and anhydroiis .%m(III) snlphat,cs, .%mZ(S04):j. raH20(cr) (n = 0,5,8). arltl the t,rixi~,lcnt oxysiilphat,c (.%mO)zS04(cr). lla~rc l)ccn prcparctl. Ycllo\17-pink crystals of .%mZ(S04):j. 8H20(cr) wcrc obtaincd by cvaporat,iorl of a 5 hI soliit,ion; t,hcy crystallise in the rrlonoclinic system; spacc groiip C2/c \vith rr = 13.619 X 10-" rn; h = 6.837 X 10-" rn. c = 18.405 X 10-In m, 9 = 102.67" [72BUR/B.-]. On the basis of analyscs for .%m, S O : arltl ~vat,cr l\lakovlcv et al. [58Y.%I</GOR] snggcst,cd t,llc prccipit,at,c oht,aincd by t,hc atltlit,ion of ct,hanol t,o a solllt,ion of .%rn(III) in 0.5 11 HzS04 was the pcntahydratc; no fi~rt,llcr charact,crization 11,as rnadc. Hall arltl hlarkirl [57HAkL/hI.4R] have rcport,cd t,llcrrrlogrnvimct,ric rcs~llt,s for t,llc tlchydrat,ion of Ak~n2(S04):3 hydrates. and sho117cd that the s~llphat,c corlt,crlt of t,llc ~vhit,c product, forrrlcd at 550 - 650°C corrcsporltlcd to anhydrous .%m(III) siilphat,c. Tllc oxysiilphat,c of .%rn(III). (.%rn0)2S04(cr), 11,as obtaincd by Hairc and Fahcy [7iH.%I/F.%H] by st,opping t,llc calcinat,ion of t,llc .%m(III) snlphatc hytlmt,cs in air at 750°C; it has a body-ccnt,crctl ort,horhornl)ic cryst,al strllct,lirc nrit,h (I, = 4.225 X 10-In rn; h = 4.103 X 10-In rn; (: = 13.328 X 10-In m. Tllc precise spacc groiip has not hccn cst,ahlishcd.

Fcdosccva and Bndant,scva. [89FED/BUD] s~lggcst t,hc prodiict of nit,ritc rcdiictiorl of .%m(\:I) siilphat,c soliit,ions at nnkno\~rn pH t,o br an iinspccificd hydrate of the .km(\:) snlphat,c. Ho~vcvcr t,llc X-ray difiact,ion patt,crn of t,his phase 11,as qnit,c dist,irlct from the 117cll-cst,al)lishctl NI)(\') analogiic, so t,his idcntifi~at~ion is far fiorn ccrt,ain.

I'Iakovlc~~ nrld Kosyakov [58Y.%K/KOS] rcport,ctl t,llc cxist,cncc of .4rn(III) t1oiil)lc siilpllat,cs of type 1\ I .%rn(S0~)~ .:rrH20(s) (~vith ,\I = K, Rh, CS nrltl T1) as ~vcll as K:3.4r~~(S04):3 .H20(s). KX.%~~12(S04)7(~) and Tlx.%m2(S04)7(s).

Tllc monosclcnidc, a "siil)st,oichiornct,ric scsqnisclcnidc" (nrit,h a cornposition close t,o . % ~ n : ~ S c ~ ) nrltl t,hc snbst,oichiornct,ric disclcnitlc arc kno\~rn.

Damicn nrltl \Vojako\~rski [75D.4hl/\VO.J], nrltl Char~~il lnt et n,l. [76CH.%/BEN] prc- pared a phase ~vi th t,hc fcc NaCl(cr) t,ypc str~lct,~lrc, spacc group Frn3rn, rrlixctl ~vit,ll the .4rn:3Sc4(cr) phase, by llcnt,irlg t,llc hydridc nrit,h sclcrliiim in cq~limolar rnt,io at, 800°C in vnciiiim ( W 1 0 - T o r r ) for 24 h, follo\~~ctl by annealing the prodnct,~ in nlii- rrlinn crncil)lcs at 1100°C. By analogy ~vit,ll ot,llcr actirlidc clcmcnt,~. t,his was ass~lrncd to i)c t,llc rnonosclcnitlc. l)iit the precise composit,iorl is rlot kno~vn. Tllc lat,t,icc pn- rarnctcr of t,his prcsnrnal~ly sclcni~lrn-sat,~lmtctl cornposit,ion was 5.821 X 10-" m. On fi~rthcr llcnt,irlg t,o 1250°C. t,llc morlosclcrlidc as no longer ohscrrctl.

Tllcrc arc no cxpcrirncntal t,hcrrnodynarnic tlat,a for .%rnSc(cr); l)iit Gronvoltl, Dro~vart and Ilkstr~lrn [84GRO/DRO] cst,irnatcd t,llc st,andard entropy to i)c

S:(.%mSc. rr, 298.15 K) = (109 f 12) .J . K-' . rnol-l.

hlit,cllcll and Lnrn [70hIIT/L.%II] first prepared this phase, mixed ~vit,ll nrlot,llcr nnidcntifictl phase, from cqiiirnolnr arnoiint,~ of nrncricinrn and sclcni~lrn llcnt,ctl first, to W 200°C, and nnncalcd at 1000 and t,llcn 800°C. Tllc rnajor phase had n hcc st,r~lct,~lrc. Th:3P4-t,ypc. spncc group I43rl, n = 8.782 X 10-" rn; and as ass~lrncd to bc .%~n:~Sc~(cr) . Darnicn nrltl \Vojako\~rski [75D.%hI/\VO.J], nrltl Cllarvillat et (11. [76CH.$/BEN] also prepared this phase t,ogctllcr nrit,ll .%mSc(cr) by rcnct,ing nrncri- ciiirrl hydridc ~vi th sclcrliiim and nnncaling at 1100°C. They report a sornc\vhnt larger lat,t,icc pararnct,cr of 8.799 X 10-" rn.

\Vhcn Damicn nrltl .Jovc [71D.%II/.JO\'] llcnt,ctl arncriciiim hydridc nrit,h cxccss sc- lcrli~lrn in a Pyrex tiil)c at 673 K for one \ ~ ~ c k t,hcy fo~lrltl a coarse black mnt,crial ~vhich corlt,aincd a t,ct,rngonnl phase ~vit,ll n = 4.096 X 10-" and (: = 8.347 X 10-" rn.

Tllc int,cnsit,ics of the X-ray patt,cr11 sllggcst that t,llis phase has a psc~~do-~c l l of the C1i2Sb(cr) t,ypc; spacc group P4/1l1rlm, sirrlilar t,o the ~~11>st,oiChiorr1ct,l.iC pl~lt,o~liiim disclcnidc, \vith the corrlposit,ion h l S ~ ~ . ~ ( ~ r ) . Xo analysis of t,hc cornpound as rnadc; so t,hc exact composit,ion is not kno\vn.

Tllc rnonotclliiridc, .%~n:~Tc~(cr) ; t,hc scsqnit,cllnridc, t,hc siil)st,oichiomct,ric ditclliiridc and t,llc t,rit,cllnridc have been itlcnt,ificd.

Damicn arltl \Vojako\~rski [75D.4hl/\VO.J], arltl Char~~il lat et o,l. [76CH.%/BEN] prc- parcd a phase \vith t,hc fcc NaCl(cr) t,ypc str~lct,~lrc, spacc group Frn3rn, rrlixctl \vit,ll the .%~n:~Tc~(cr) phase, by hcat,ing the hydridc nrit,h t,cllllri~lrrl in cqnirnolar ratio at, 800°C in vaciiiim (-- 10-"orr) for 24 11; f o l l o \ ~ ~ d by annealing t,hc prodiicts in alinnina cr~lciblcs at 1200°C. By analogy nrit,h ot,hcr actinitlc clcrncnts, this urns as- siirrlcd t,o bc t,hc rnonotclliiridc, hut t,llc precise composit,ion is not kno\~rn. Tllc lat,ticc paramct,cr of t,his prcs~lrnably tclliiriiim-satiiratcd cornposition as 6.171 X 10-" rn.

Tllcrc arc no cxpcrirncntal t,hcrrnodynarnic data for .%rnTc(cr), but Gronvoltl, Dro\vart and Ilkstrllrn [84GRO/DRO] cst,irnatcd t,llc st,andard entropy to i)c

S;(.%rnTc. cr. 298.15 K) = (121 * 1%) J . I<-' . rnol-',

based on cst,imat,ctl lat,t,icc and rrlagnct,ic contril)lit,ions of 104.6 [62\VES/GRO] arltl 16.7 J . K-' . mol-l; rcspcct,ivcly.

hlit,cllcll and Larrl [70hIIT/L.%II] first prepared this phase, mixed \vit,ll arlot,llcr nnidcntifictl phasc, from cqllimolar arnoiint,~ of arncriciiim and t,cllllri~lrrl hcatcd first, to % 420°C. and anncalcd at 1000 arltl t,llcn 800°C. Tllc rnajor phase had a l ~ c c st,riictiirc, T l~ :~P~- t ,ypc , spacc groiip 143t1, rr = 9.393 X 10-" m arltl was assnrncd t,o i)c . % ~ n : ~ T c ~ (cr) .

Darrlicrl and i\:o,jako~vski [75D.%hI/\\'OJ], Charvillat et al. [7GCH.$/BEN] also prc- parcd t,llis phasc t,ogctllcr \vith .%mTc(cr) by reacting arrlcriciiim hydridc \vith t,cl- lllriiim and annealing at 1100°C. They rcport,cd a rat,hcr larger lat,t,icc pararrlctcr of 9.404 X 10-" rn. This phase is also t,llc dccorrlposit,iorl product of higher arrlcriciiim tcllnridcs above 900°C [72D.%hI/CH.%]. They s~lggcst,ctl that t,llis phase has an apprcciahlc rarlgc of hornogcncit,y, sincc it,s lat,t,icc paramct,cr incrcasctl \vit,ll annealing tcrn1)cratiirc from 9.382 X 10-In m at 900°C t,o 9.420 X 10-" m at 1100°C.

Damicn [72D.%hI] obtaincd a tctragorlal phasc ~vit,ll rr = 4.366 X 10-" arltl c = 8.969 X

10-l' rn by thermal tlissocint,ion of .41nTc:~(cr) in vaciiiim at 400°C. Tllc irlt,crlsit,ics of t,hc X-ray pat,tcrn s~lggcst that t,his phasc has a pseudo-cell of t,llc Cn2Sh(cr) type, spacc group P4/nmrn, similar t,o the siil)st,oichiomct,ric pl~lt,orliiim dit,cllnridc. Xo analysis of the cornpound cor as rnadc; so t,hc exact cornposition is not kno\vn. hut, by analogy nrit,h P~lTc~-,(cr) it was assiimcd to be ~11b~t,oiChiorr1ct,l.iC. S ~ ~ b s c q ~ ~ c ~ l t , l y Bums. Damicn and Hairc [79BUR/DA411] prepared 2'".4rnTc2-,(cr) from t,hc clcrrlcnt,~ at 550°C for 20 h and removing cxccss Tc by tlist,illat,ion. Rcfirlcmcrlt of t,llc crystal st,r~lct,~lrc was corlsistcnt ~vit,ll 27% ~~aca~lc ics in one of t,llc tnro Tc lat,t,iccs. suggesting the composit,ion as . 4 r n T ~ ~ . ~ : ~ ( c r ) . Tllc lat,t,icc parameters of t,hc tctragorlal cell wcrc (1, = 4.358 X 10-In and (: = 9.027 X 10-In m.

Damicn [72D.%hI] obtaincd a tctragorlal phasc ~vit,ll rr = 4.339 X 10-" arltl c = 2.557 X

10-% lby vapour phase rcactiorl of cxccss Tc (Tcl.4rn = 3.5) and americium hydridc at 350°C for 5 d. -4ftcr removal of ~lrlrcactcd Tc by tlist,illat,ion. t,hc \~,cight incrcasc corrcspondcd t,o a cornposition of .4mT~:~ . Ho\vcvcr. t,llc line irlt,crlsit,ics snggcst,cd that t,hc phase is isost,rnct,ural ~vi th X d T ~ : ~ ( c r ) (Norling arltl St,cinfink [66NOR/STE]) and t,hat its true syrnrnctry is ort,horhombic. spacc group Crncm, nrit,h t,llc rr and 11

paramct,crs csscnt,ially cqiial.

In their st,udy of t,hc t,hcrrrlal tlccornposition of .4mTc2(cr); Char~rillat and Damicn [i2DA4II/CH.4] fo~lrltl that in t,llc X-ray pat,t,crn of t,hc rnajor comporlcnt .41n:~Tc~(cr) oht,ainctl by hcat,ing to 900°C, tllcrc n7crc four atltlit,iorlal lines ~vit,ll cl-spacings close to t,llosc of four of the st,rongcst lirlcs of P ~ l ~ O ~ T c ( c r ) . It S C C I ~ S likely t,llcrcforc t,llat, .4m202Tc(cr) was forrncd, prcs~lrnably by rcactiorl with silica. in this stiidy.

V.6. Group 15 compounds and complexes

V.G. 1. Nitrogen corn,po?rrrci,s arad conl,ple:ces

Tllcrc arc no cxpcrimcrlt,al st,udics involving t,hc t,hcrmotlynamic propcrt,ics for arncrici~lrn pnict,idcs. so this review snrnrnarizcs t,llc prcpamt,ivc and str~lct,~lral tlat,a for tl1csc phases.

Only t,hc rrlononit,ridc has hccn idcnt,ificd. -4s rlot,cd i)clo\v, c ~ ~ c n in t,llc prcscrlcc of arnrnonia/hydrogcr~ rnixtiircs; ~vhich corrcsporltl t,o qnit,c high cffcctirc rlit,rogcn prcssiircs. no higher nit,ridcs nrcrc foiind t,hat correspond to t,llosc in t,hc earlier actinitlc clcrncnt-nitrogcn systems.

A%kimot,o [Gi.%KI] 11,as t,llc first t,o report tllc prcparat,ion of a phase ~vit,ll tllc NaCl(cr) st,riictiirc. spacc group Frn3rn, by hcat,ing, in scalctl q~lart,z t,ubcs, cit,llcr arncricinrn hydridc arltl arnmonia at 800°C for 30 rninut,cs, or arncricinrn po\~rdcr (oh- taincd by tlccornposition of tllc hydridc) nrit,h rlit,rogcrl at 750°C for 1 h. Sirlcc only 100/ag of .%m was used, no filrtllcr analysis urns possil)lc. The lat,t,icc pararnct,crs of tllc black protl~lct,~, assnrncd t,o he .$rnN(cr), nrcrc 5.000 X 10-" arltl 5.005 X 10-l, rn rcspcct,ivcly. ~vit,ll an nnccrt,aint,y of 0.005 X 10-l' rn.

Cllarvillat et al. [75CH.%/BEX, 76CH.%/BEX] rcpcat,ctl t,llc prcparat,ion from nitrogen (600 Torr pressure, 550°C. 12 h) firltling a phasc ~vitll tllc slightly smaller lat,ticc paramct,cr of (4.995*0.002) X 10-l' rn; as lla~rc Radchcnko et al. [82R.$D/RY.%] using 70% N2(g) + 30%' Ha(g) at 800°C. ~vho fo~lrltl rr = (4.991 t,o 4.993) X 10-" m for tllc single phasc prodiicts. In rlcitllcr of tllcsc stiidics \!,ere any filrtllcr analyses carrictl

It is clcar from t,llc mct,hotl of preparation t,llat thcsc '~rnononit,ridc" phases may ~vcll contain dissolved oxygen

.% prclirninary report by Ciiillcrdicr, hl~lsikas arltl hIart,caii [77CUI/IIUS] on tllc corrlplcx forrrlat,ion hct,\~~ccn arncriciiim(II1) and azidc ions, was f o l l o ~ ~ ~ d by Ph.D. thesis [81CUI] and t,hc piil)lications by hliisikas et o,l. [8OhIUS/II.%R; 8311US/CUI], ~vhich report t,hat solvcnt cxtractiorl cxpcrirncnt,~ yielded log,, 'll = 1.3; log,, i12 = 1.6 and log,, = 1.4, arltl al)sorpt,ion spcct,ropllot,omct,ric rncasnrcrncnt,~ rcsiiltcd in log,, 'll = 1.0 and log,, 92 = 1.4. Tllc papers by hlnsikas et 1x1. irltlicnt,c t,llat tllc sl)cct,ropllot,omct,ric cxpcrimcrlt,~ nrcrc pcrforrrlcd at I = 5 11, nrit,ho~lt st,at,irlg clearly ~vhich i)ackgroiind clcct,rolyt,c was used, alt,ho~lgll Cnillcrdicr [81CUI] indicates t,llat, sodiiim pcrclllorat,c 11,as crnployctl.

Choppin and Barber [89CHO/B.%R] pcrformctl a solvcnt cxt,ract,ion st,~ltly at pH =

5.9 and I = 0.5 h1 XaC104, involving a fc117 rare cart,hs arltl act,inidcs. For arncriciiirn; t,hcy obtaincd log,, ill = (0.67 f 0.05) at 25°C. Clloppirl and Barhcr ol)t,ainctl A,H,(CrnN;+, I =0.5) = (15.1 f 2.8) kJ . mol-l from a tcrrlpcrat,~lrc variat,ion stiidy irlvolving Cm3+.

Tllc specific ion intcract,ion cqnat,ions (cf. .%ppcndix B) arc not appropriate to pcr- for111 ionic st,rcrlgt,ll cxt,rapolations for t,hc st,~ltly rcport,ctl in [8OhIUS/II.%R; 81CU1, 83hIUS/CUI]. arltl t,hc constant reported by Clloppin and Barber [89CHO/B.%R] is atloptcd. .% ~ralnc of AE = ( 0 . 1 * 0.1) kg . rrlol-l is dcrirctl from t,hc follo~ving

W - cstirnatcs: E ( . ~ ~ ~ : + ; ~ : ~ ~ ~ ; ) W L ( ~ ~ ~ ~ ~ ~ ~ + ~ ~ ; ) = (0.39 f 0.04) (cf. Scct,ion B.1.4), arltl E ( ~ ~ ; , , + ) = (0.0 * 0.1) [92GRE/FUG. 1i.267]. This rcric\v assiimcs t,llat tllc iinccrtaint,ics rcport,cd in [89CHO/B.$R] arc *l st,arltlartl deviation. Tllc ionic st,rcngt,h corrcctiorl yields:

log,, ,1,"(298.15 K) = l . G i * 0.10

~vhcrc t,llc nnccrt,aint,y has hccn increased to reflect t,llc 95%' corlfitlcncc l c ~ ~ l . Tllc Gihhs cncrgy of format,ion is calciilat,ctl to l ~ c :

V. G. 1.3. Anrericiurn raitrite corn,plezes

Rao, Kiis~lrnaknrnari and Pat,il [78R.%O/I<US] pcrforrncd a solvent cxt,ract,ion stiidy on t,llc cornplcxat,ion of .%m(III) arltl Cm(II1) by nit,rit,c ions. For arrlcriciiim they report log,, PI = (0.96*0.03) at 1 I1 NaC1(14 arltl 25°C. Tllc acid const,arlt of nitroils acitl urns mcasllrctl under the samc contlit,ions: log,, K I = 2.86. TVhcn cxt,rapolat,ctl to I = 0 iising the cqnat,ions in .%ppcndix B; t,llc acid constant (log,, Ii," = 3.10) agrccs \vit,ll t,llc valiic sclcct,ctl by Grcntllc et o,l. [92GRE/FUG], cf. Tal)lc I\:.2. This

2+ . rcvic~v sclcct,~ t,hc format,ion const,arlt for .$rnY02 reported by Rao, Kiis~lrnaknrnari and Patil [78R.%O/I<US] aft,cr cxt,rapolat,ion to I = 0 (again using the cqiiations in .$ppcndix B) arltl increasing the nnccrt,aint,y t,o *0.2:

log,, ,/,"(298.15 K) = 2.1 * 0.2

No Gibbs energy of forrnation can bc calciilat,ctl bcca~lsc t,llcrc is no sclcct,cd ~ralnc for the NO, ion.

V.G.1.4. Anrericiurn raitrcxte corn,po?rrrcis arad conl,ple:res

V.G. 1.4.1. Aqi~,r.eo?rs o,nrericiurn raitrcxtes

Tllc arncrici~lrn(III)-nit,ratc systcrn has hccn invcstigatcd by solrcnt extraction; rnainly in 1.0 I1 HN0:3-XC104 mctlia (\vhcrc X = H. Ya; Li or NH4); as prcscrlt,ctl in Ta- ble I7.14. The cxpcrimcrlt,al mcasllrcrrlcnts nrcrc irlt,crprct,ctl assiimirlg t,llc forrrlat,ion of .%rnNOi+ and .$~n(N(l:~):. Tllc corresponding st,al-)ilit,y constants irltlicnt,c t,hat the nit,rat,c corrlplcxcs arc \vcak. It is t,llcrcforc difficiilt to distingllisll bct,~vccn cornplcx forrnation and changcs in t,hc act,ivit,y factors of t,llc soliit,cs callsctl by t,hc (oft,cn largc) changes in solllt,c conccnt,mt,ion. Hcncc, this rcvic\v relics only on the dat,a ol)t,ainctl for the .$rnY~;+ species accortling t,o

and corlsitlcrs that t,llcrc is no clcar cvidcncc of the cxist,cncc of higher cornplcxcs. Early qllalit,at,ivc spcctrophotornct,ric ohscrvat,ion by l\lakovlc~r and Kosyakov

[56\i.%K/I<OS] critlcncctl t,hc forrrlat,ion of arncrici~im-nit,ratc cornplcxcs. alt,ho~lgh the corrlposit,ion of t,llc corrlplcxcs urns not rcport,cd. Tllc cat,ion-exchange tlat,a oh- taincd by Lcbctlcv. Pirozhkov and l\lakovlc~r [6OLEB/PIR] rcvcalcd t,hc cxistcncc of the .%mNO:+ cornplcx. Lahr and Knoch [70L.%H/I<NO] found cvidcncc for t,llc for- rrlntiorl of . $ r n ( ~ ( l : ~ ) ~ - " ) ( = l ) Ho\vcvcr, w r y largc charlgcs in t,hc solllt,ion corrlposit,ion wcrc matlc in t,llis st,~ltly (0 to 8 11 and t,llc tlat,a rrlight perhaps also he cxplaincd by act,ivit,y fact,or variat,ions. Tllc samc rcasorling can he applied to Rcfs. [66GI\:, 69SHI/GI\-1. Chiarizia, Dancsi and Scil~ona stiidictl t,llc compct,it,ivc corrlplcxat,ion of .$rn(III) in YH:/SCN-/N(l, rncdia [73CHI/D.$N] and irlt,crprctcd their rcsnlt,s assiimirlg t,hc format,ion of .%rn(~CN)f-'") (n = 1.2.3) arltl .%rnNOi+ cornplcxcs. Tllc thiocyanat,c dat,a cont,rntlict all prcviolls ohscrvat,ions. arltl this rcvic~v rcjcct,~ the corresponding cqiii1il)riiim ronst,ant,s for t,llc thiocyanat,c corrlplcxcs (c f . Scct,ion \:.7.1.4). and disregards t,llc proposed log,, Pl(NO,).

Tahlc \.'.14: Lit,crat,urc cqnilibrinrn corlst,nrlt,s for t,hc .%mcricinrn(III)-rlitri~,t,c syst,cm, nccortlirlg t,o t,hc rcactiorls

(3 -n ) .%rn"+ + rr XO: + .%1n(N(1:~), .

rr \Ietl~o(i Rle(ii~xn(~' pH t ( " C ) log,, in Referer~ce

1 rix 1.0 RI NH~x(" '

(a) ..I significant arrlollrlt of t,lle a r~ ior~ in t l ~ e l)ackgro~~nrl electrolyte was s~~l)stit,l~t,ecl l)$ NO; in tllese stll(iies.

(l)) Let~eclev, Pirnzhkr~v and hkovlev [GOLEB/PIR] report tllr~t t,lle ir111ic st,re11gt11 \%-as kept, <:onstant t)!. acl(iition of arr~rrlor~illrr~ cl~lorirle or perchlorate.

(c) 17r~111e ol)tainr(i in t,l~is review l)$ a. reinterpretation of origirlal rlat,a (cf. rlppenclix A).

Tllc cqiii1il)riiim const,ant from t,hc rcint,crprctation of t,hc solvcnt cxt,ract,ion dat,a of Bansal; Patil arltl Sharma's [64B.%N/PA1T] (cf. .1ppcndix -4) arc in agrccrrlcnt ~vit,ll the rcs~llt,s of Pcppartl, hlason and Hiichcr [62PEP/hl.%S], t,llosc of Choppin arltl Strasik [G5CHO/STR], arltl those of Khopkar and Namyanankntt,y [7lKHO/XA1R]. Tllc corrcsporltling valiics of l ~ g ~ ~ ~ ~ arc accepted by t,his revie\\,. Thcsc cqnilibrinrn const,ant,s arc convcrtcd t,o rrlolal iinits arltl cxt,rapolat,ctl to zero ionic st,rcngt,h using the specific ion irlt,cract,ion cqnat,ions (cf. .1ppcndix B) ~vit,ll AE = (-0.06 * 0.06) kg. rnol-'. .%n nnccrt,aint,y of *0.1 has hccn assigned t,o all logln L/, ~ ~ a l n c s in ortlcr t,o take irlt,o accollrlt t,hc charlgc of t,hc aniorlic cornposit,ion of the rncdia. For t,hc same reason. an nn~vcight,ctl axrcmgc of t,hc tlat,a corrected t,o I = 0 is pcrformctl, yielding:

log,, ,1,"(17.24. 298.15 K) = 1.33 * 0.20

It shonltl he rrlcntiorlcd t,hat the cxpcrimcrlt,al dat,a llsctl for t,his calcnlat,ion rcfcr to slight,ly diffcrcnt t,crnpcratiircs (cf. Tahlc \:.14). No rcliahlc cnt,halpy dat,a arc availahlc in t,hc lit,crat,~lrc; and t,hcrcforc t,his review corlsitlcrs t,llat an increased 1111- ccrt,ainty of f 0.20 is rcprcscnt,at,ivc of t,hc crcnt,ual (minor) t,crnpcratiirc effects on the cqiii1il)riiirn const,ant,s.

Tllc Gil)l)s cncrgy of forrrlat,ion is calcnlat,cd t,o bc

AfGk(.%mNO:+. aq. 298.15 K) = ( 7 1 7 . 1 * 4.9) kJ . rnol-'

\'asil'cv et 111. [75\'.1S/.%ND] stiidictl the .%m(\:I) NO, syst,cm in 0 5 [HXOt3] 5 18 h1 sol~lt,ions iising a spcctrophotornct,ric tcchniqnc and s~lggcstcd t,hc form. a t ' ,ion of .%rn02(N0:j)~-n) (n = 2, 3). \;?sil'cv 1't (11. i~lt,crprct,ctl t,hcir I I I C ~ S I I ~ C I I I C I ~ ~ , ~ at, [HXO:3] < 10 h1 accortling t,o t,hc follo\~.ing rcact,ion

.1rnOZ(H20)~+ + 2 NO, + .%m02(NO:j)2(H20)2(aq) + 4 H20(1)

with log,, fi2 = (3.93 f 0.04). .Is it is not possiblc t,o cxt,rapolatc data from this high and ~rarying ionic st,rcrlgt,ll t,o I = 0 \\,it11 t,llc specific ion int,cractiorl approach, t,llis cqlii1il)riiirn const,arlt is not sclcct,cd in t,llis rcric\v.

No ot,llcr invcst,igat,ions of .1rn(I\'/\:/\'I) NO: arc found in the lit,crat,~lrc.

a i l 1 111. [90\:.%S/K.%L] prcparctl hytlmt,ctl .%rn(III) rlit,rat,c by dissolving the oxide in 8 h1 HNO:j. The solllt,ion as first cvaporatctl and t,hcrl dried llrltlcr Hc(g), to give a ycllo\~r-rose .11n(N(l:~):~.:r;H~O precipitate. Tllc allt,hors llsctl diffcrcnt thermal analysis (DT.1) t,o st,udy the thermal tlccornposition of t,llc prepared solid:

.%m(XO:3):j(s) i .1rn(I2(s)

~vhich irltlicat,cs that .1rn(III) is oxidised t,o .%m(I\') during t,hcrrrlal dccomposit,ion. Frorn t,llc area of t,hc DT.1 ciirvc for t,llc t,hcrrnal dccornposition, the allt,hors cst,imat,ctl the standard heat of formation of t,hc anhydroiis cryst,allinc .%rn(III) nit,ratc:

l f H ~ ( . l ~ n ( N O : j ) : j . cr; 298.15 K) = ( 6 4 0 * 100) kJ . mol-l.

.Is not crloiigh cxpcrirncnt,al arltl cornpiit,at,ionnl dct,ails arc given in Ref. [90\'.1S/KA1L]. this valiic car1 not he rccornrncndctl.

Tllcrc arc fc\v rcliablc st,~ltlics availablc in t,hc l i tc ra t~~rc on amcricinrn corrlplcxat,ion by phosphate anions; and rrlost of tllcsc st,udics nrcrc pcrforrrlcd on sol~lt,ions of low pH arltl fairly high corlccntrat,ion of phosphoric acid. Expcrirncnt,al st,~ltlics of cqni- liljria in t,hc amcricinrn phosphoric acid systcrn arc complicat,ctl by t,llc prcscncc of scvcral cornpcting ligands: H:jP04(a(l), H2PO;, HPO: and PO:-. Tcchniqiics s~lcll as cat,ion cxcllangc [GGBORIELE, 71hIOS2], spcctrophot,ornctry [79LEB/FRE2] arltl solvent cxt,ract,ion [86R.%O/II.%H. 88R.%O/hI.%H] h x c l)ccn iiscd to dct,crrrlinc the corrlposit,ion and t,hc st,ahilit,y const,arlt,s of the amcrici~lrn(III) pllospllat,c cornplcxcs. Tllc rnono- and dihydrogcn phosphate corrlplcxcs .%mHPO: arltl .%~(H~Po~)!:-") ( r r = 1 to 4) have l)ccn snggcst,cd t,o int,crprct t,llc varioiis cxpcrirncntal data (cf. Tahlc \".15).

In order t,o rcanalyzc all the availablc lit,crat,urc dat,a (Tal)lc \'.l5 arltl .%ppcndix .%) the frcc ligarltl conccnt,ration, [H,PO!~'-~~)] was corrlp~it,cd nsing t,llc sclcct,ctl prot,onation const,ant,s of phosphate (Table I\'.%) and the corresponding spccific intcract,ion cocficicrlt,~ (Tal)lc B.4). Eqiii1il)riiim const,arlt,s oht,ainctl in rcint,crprctations of cxpcrimcrlt,al dat,a given in sclcct,cd rcfcrcnccs wcrc analysctl nsing t,hc spccific ion intcract,ion cq~lat,ions (cf. .%ppcndix B) and valiics of E (-am( HpPOa );,, q+71(p-3)

.(:lO;) cst,imat,ctl

in Scctiorl B.1.4. Orlc of t,llc limit,at,ions of the specific ion irlt,cractiorl rrlctllod (c$ .%ppcndix B)

is that it only takes int,o acco~lrlt the irlt,cract,ions hctn~ccn ions of diRcrcnt chargcs ~vhilc disrcgardirlg int,cractiorls ~vit,ll ~lnchargctl species. This assnrnpt,ion is sufficient in rrlost of t,llc cxpcrirncnt,al condit,ions cnco~lrlt,crctl in t,hc lit,crat,urc for I 5 4 11. Ho~vcvcr. at higher conccnt,ration of a neutral species, in t,his case H:jP04(aq); the ion- nc~it,ral int,cractiorl shonltl he corlsitlcrcd [iGPIT/SIL]. Bcca~lsc t,llc appropriat,~ ion- nc~it,ral intcract,ion cocfficicnt,~ arc not kno~vn for the arncrici~lrn pllospllat,c syst,cm, it is not possiblc t,o rrlakc t,llc proper corrcctiorls t,o zero ionic st,rcngt,h. This rcric\v ncvcrt,llclcss decides to corlsitlcr the data collcct,cd at [H:3P04] 2 4 h1; but cannot, irlcl~ltlc the rcs~llt,ing stability const,ant,s in t,llc t,ahlc of sclcct,ctl st,andard rcactiorl dat,a (Table 111.2).

Borisov et al. [GGBOR/ELE] st,~ltlicd the .%rn(III)-phosphate systcrn; at I = 0.2 11 NH4C104; usirlg a cation cxcllangc resin. Tllc vnriat,iorl of t,hc tlist,ribntion cocficicrlt, 71,s. [H2PO;], at pH = 2; 3 and 4; indicates t,llc format,ion of .%rnH2PO:+. Tllc sarnc cxpcrirncnt,al t,cchniqnc as ~lsctl by hloskvin [ilhIOS%] at 1.0 h1 NH4C1 arltl

(:3-n) a t pH = 0.3 and 1.8, proposing t,hc cxist,crlcc of t,llc four complcxcs .%m(H2P04),,, wit11 n = 1 t,o 4. Tllc cat,ion cxcharlgc tcchniqiic appears ho~vcvcr inadcq~lat ,~ t,o s t , ~ ~ d y this syst,crn ~vhcrc scvcral pot,cnt,ial ligands (PO:-. HPO: and H2PO;) may for111 various cat,ionic complcxcs. Hcncc, the tlat,a of Borisov et o,l. [66BOR/ELE] arltl hloskrin [7111052] can not i)c sclcctcd in t,his review, cf. .%ppcntlix -4.

Lcl)cdcv et al. [79LEB/FRE2] st,udicd the spectral changcs in t,hc arncrici~lrn ah-

Tahlc \.'.15: Litcratiirc cqiii1il)riiim constants for t,hc arncrici~lrn-l)l~os~)l~atc syst,cm

Metho(1 Ionic Media pH t ('C) loglo References

cix cix cix cix "I'

cix 1.0 M NHlCl 0.3. 1.8 ? 2.10 [G'JMOS, 71MOS21 cix I 1 0 ? 3.63 [G'JMOS] "I' 1 to 13 M 0 to 1 23 3.72 + 0.02(') [79LEB/FRE2]

cix 1.0 M NHlCl 0.3. 1.8 ? 2.85 [G'JMOS, 71MOS21 cix I 1 0 ? 5.62 [G'JMOS]

cix 1.0 M NHlCl 0.3. 1.8 ? 3.40 [G'JMOS, 71MOS21 cix I 1 0 ? 6.3 [G'JMOS]

Tahlc \-.l5 (continnctl)

Met,hocl Iol~ic Media I'H t ("C) log,, [j References

pot 10 to 15 M 0 to l 23 14.2 + l [79LEB/FRE2] H(C104, HaP04)

(a) Valile correct,ed fiom I = 0.5 M NHlClO4 to I = 0 by the ailthors of the original pi~l)licat,iol~ [86RAO/MAH] using t,he Davies eqilation.

(1)) Rao r t al. [86RAO/MAH] report the followil~g valiles at 0.5 M NH4C104 for the fi)rmat,iou of AmHPO:: loglobl(pH = 7) = 3.60 and 3.92> and loglo (il (pH = 8) = 2.41 and 4.14.

(c) Valile corrected t,o I = 0 1)y the ailthors [79LEB/FRE; 79LEB/FRE2] and it correspon(1s therefore t,o (io. Because of t,he extreme col~cent,ration coll(1i- tions, t,he reaction involves the exchange 11etwee11 ligall(1s all(1 solvation water moleci~les; ancl the correspol~(iing e(l11ilit)rilim const,ant was also correct,ed for the variat,iou in water act,ivit,y

sorptiorl hand a t 506 nrrl protl~lccd by HaPO; complcxnt,ion. a t high conccnt,rations of phosphoric acitl: 0.1 5 [H:3P04] 5 13 11. Tllc ionic strength in tllcsc soliit,ions is cstirnatcd t,o i)c (0.35 f 0.10) 11 from the cnlcnlat,cd dissociation of H,P04(aq) irlt,o H2P0,. -4s tlisciissctl in -4ppcntlix -4. t,llis data arc not corlsitlcrcd tl~lc t,o t,llc cxt,rcrrlc

Rno. hlahnjnn and Natarajan [86R.4O/hI.4H] contl~lct,cd a solvcnt cxt,ract,ion cxpcrimcrlt iising a liquid cnt,ion cxchnngcr. They rrlcns~lrctl t,hc tlist,ribntion cocficicrlt, a t diffcrcrlt t,ot,al phosphnt,~ conccnt,rnt,ions (at 30°C nrltl 0.5 hI NH4Cl(14). They irlt,crprct,ctl their rcsnlt,s assuming the prcscncc of .IrnH2PO:+ (at pH = 2 and 3) nrltl .ImHPO: (at pH = 7 nrltl 8). Tllc rcanalysis of the cxpcrirncnt,al dnt,n ngrccs wit,ll the forrrlat,ion of the first dihytlrogcn pllospllat,c complex, but this rcric\v corlsitlcrs tha t the cxpcrirncnt,al dnt,n ol)t,ainctl in rlciit,rnl ant1 \~rcnkly hasic sol~lt,ions might siiffcr from syst,crnatic errors, and filrtllcrmorc t,llc st,oichiornctry of the prctlomirlant, corrlplcx (.4mHPO: or .IrnP04(aq)) can not i)c dct,crrrlinctl nnnrnl)ig~loiisly fiorn the nvailnhlc data (cf. -4ppcntlix -4); llcncc t,llc cqiii1il)rinrn const,nrlt for t,hc form. a t ' ,ion

of .%rnHPO: listed in Tahlc \'.l5, is tlisrcgardcd by this rcvic\v. Similar corltlit,ions (pH = 2 arltl 7, and I = 0.5 hI NH4Cl(14) Ivcrc llsctl by Rao. 11ah~1,,jan arltl Yat,amjan in another stiidy [88R.%O/II.%H] t,o invcst,igatc the effect of t,cmpcmt,urc variat,ion (at 10; 20 and 41°C). Tllc allt,hors i~ascd t,hcir concliisions on t,llc chcrrlical rrlodcl prcscrlt,ctl ~ r c ~ i o i i s l y [86R.%O/hI.%H]. For t,hc sarrlc reasons this review sclcct,~ only the data oi)t,ainctl at pH = 2, and concliidcs that the cxistcncc of .%rnHPO: is not, clearly proven in the st,lltlics of Rao et 111. [86R.%O/h~I.%H, 88R.%O/hI.%H].

For the cqllilihrillrn:

the stability const,arlt from [86R.%O/hI.%H] at 30°C and I = 0.5 h1 is convcrt,cd t,o rrlolal iinits arltl cxt,rapolatcd t,o zero ionic st,rcngt,h usirlg the specific ion intcract,ion cqliations, cf. .%ppcntlix B. yielding t,llc follo~ving sclcct,ctl valllc:

~vhcrc t,hc llnccrt,ainty has i)ccn increased t,o t,akc int,o accollrlt t,hc t,crnpcratiirc tliffcrcncc. Tllc Gibbs energy of formation is calclllatcd to i)c

Tllc dat,a of Rao, hlahajan arltl Natarajan's obtained at diffcrcrlt tcrrlpcrat,~lrcs [86R.%O/hI.%H; 88R.%O/II.%H] yicld for rcact,ion (\:.25): A,H,,, = (14f 6) kJ.rnol-' and A,S,,, = (82f 19) .J.I<-'.rnol-' a t 25" arltl I = 0.5 h1. Bccallsc of t,llc iinccrtaint,y in t,hc inflncncc of t,crnpcratiirc on act,ivity cocfficicnts, the cqllilihrillrn constants arc not cxt,rapolat,ctl to I = 0 t,o obtain st,arltlartl valiics for t,hc cnthalpy and entropy of corrlplcx format,ion. F~lrthcrmorc; the t,cmpcmt,urc T-ariation of log,, ill is small arltl of t,llc same ortlcr of magnitiidc as t,llc iinccrtaint,y in the intlividnal ~ ~ a l n c s of the cq~iilil)riiim const,ant,s.

l \ la~lir et o,l. [69Y.%N/GI\'] stiidictl the st,ahilit,y of higher oxidat,ion st,at,cs of arrlcriciiim in 4 to 16 h1 H:3P04 sol~lt,ions; usirlg spcctrophotornctry. Tllc aiit,llors rcport,ctl t,llat, arlodic oxidat,ion of t,hc init,ial .%rn(III) solution lead to .%rn(\'I) in [H:3P04] 5 5 11, ~vhilc .%m(I\') as forrrlcd at higher phosphoric acitl conccnt,ratio~~s, \vitll a rnaxi- rrllim oxitlat,ion yicld at [H:3P04] % 12 hI. This qllalit,at,ivc inf~rrrlat~ion indicates t,llat, the cxpcrirncnt,al tlct,crrrlinnt,ion of t,llc .%rn(I\:)/.%rn(III) and .%rn(\'I)/.%rn(\') rcdox pot,cnt,ials is possii)lc in phosphat,~ rncdia. Erin et 111. [75ERI/SH.%] dcrnonst,ratcd that .%rn(I\:) conltl also bc protlllccd in solutions nrit,ll [H:3P04] 5 5 by oxidat,ion of .%m(III) f o l l o ~ ~ ~ d by chromnt,ographic separation using col~lrrlns filled ~vit,ll zirconillrrl phosphat,c.

Tllc formal pot,cnt,ial of the .%rn(I\:)/.%rn(III) conplc as mcasllrctl by 1-anir et 111.

[iO\i.%N/GI\'] in 11.5 t,o 14.5 11 H:jP04 soliit,ions. obtaining E"(I\:/III) = (1.75 * 0.01) 1' ?iel:s?rs SHE at 25°C. Yngcnt et o,l. [71NUG/BAfi] rcport,ctl a valllc of 1.78 l:,

rncasnrcd in 10 h1 H:jP04 solllt,ions at 25°C. referring t,o nnpnblisl~cd work by .J.R. Stokcly and R.D. Baybarz. hlyasoctlov et o,l. [77hIY.%/LEB] rncasiircd E"(I\'/III) =

(1.800 f 0.005) and (1.770 * 0.005) 1.' in 12 arltl 15 h1 H:jP04 sol~lt,ions; rcspcctircly. .l11 t,hcsc cxpcrirncnt,al rcsnlt,s indicat,c that the corlditiorlal rcdox pot,crlt,ial in high phosphoric acid corlccntrat,ions ([H:jP04] > 11 hl) is E"(I\.'/III) = (1.77 * 0.02) 1' ?iers,i~,,s SHE.

Tllc corrlplcx format,ion of .%m(I\') nrit,h H2PO; has l)ccn stiidictl by Lcl)cdcv et l [iSLEB/FRE%] who rncasiircd t,llc oxitlat,ion potcntials of t,hc .%m(I\')/.%rn(III) couple in 10 t,o 15 hI H:3P(I4 solutions. Using the st,al)ilit,y const,arlt,s for the .%m(III) cornplcxcs, . ~ I ~ H ~ P o : + and .krn(H2PO4);; rncasnrctl sl)cct,rophot,ornctricnlly in the sarnc stiidy, cf. Tahlc \'..15; Lchcdc~r et al. oht,ainctl loglo 9: = (14.2 f 1) for the follo\~.ing rcact,ion:

Ho~vcvcr. as discllsscd in .kppcndix -4, it is not possil)lc t,o scparat,~ rncdia cffcct,s from corrlplcx forrrlat,ions in t,hcsc highly corlccntrat,cd soliit,ions. and an cqnilibrinrn const,ant for t,his rcact,ion can not i)c rccomrrlcndcd by t,his rcvic\v

TVhilc in aqiicolls solutions clcctrochcrrlical oxitlation of .%m(III) t,o .%m(I\') is folind t,o t,akc place at high H:3P(I4 corlccntrat,ion (> 10 hI); cf. Ref. [79LEB/FRE2]; in acct,orlit,rilc rrlcdia this oxidat,ion occurs at [H:jP04] = 0.3 t,o 2 hl [87PER/LEB]. Tllc stabilisation of tctravalcnt arncricillrn is ccrt,ainly important. hut the reported T ~ ~ ~ I I C S arc not considcrctl hccallsc of t,llc non-aq~lcous rncdia.

Tllc formal potential of the .krn(\'I)/.%rn(\.') collplc urns rncasiircd by 1-anir et l [70\i.%N/GI\'], ol)t,aining E"(I7I/\') = (1.34 f 0.07) 1' ?iel:s?rs SHE, in 0.5 t,o 4.3 11 H:jP04 solllt,ions at 22°C. Lcbctlcv et 111. [79LEB/FRE] st,~ltlicd t,llc amcricyl-

at [H:3P04] 2 0.1 hl. The val~lcs of log,, p," for:

wcrc follrltl to he (3.3 * 0.1) and (4.61 * 0.05) by spcctropllotornct,ric arltl pot,cnt,io- rrlctric t,cchniq~lcs rcspcctircly. The cxpcrirncntal dat,a arc not adcqnat,c t,o prove the proposed cllcrrlical rnodcl. and t,his cqiii1il)riiim const,ant is not rccorrlmcrltlcd by t,llis review.

hlarcns et o,l. [721IAkR/Y.%Y] cxi~,lnat,ctl the effect of phosphoric acitl mctlia on t,hcir previous mcasllrcrrlcnts of t,hc forrrlal pot,crlt,ial for .%rn(I\')/.%m(III) [iOY.kN/GI\'] t,o oht,ain a ~ralnc of t,hc st,arltlartl rctlox pot,cnt,ial, Eo(I\.'/III), using st,al)ilit,y const,arlt, cst,irnatcs (fiorn analogo~ls larlt,harlidcs and act,inidcs) on assiimctl st,oichiomct,rics for the cornplcxcs. Ho\vcvcr, t,hcsc t,ypcs of correlations arc nnrcliablc owing t,o the lack of any tlircct cvidcncc on t,llc .krn(II7; 1'; \.'I) spcciat,iorl in phosphoric acitl soliit,ions. Rclial~lc cvaliiations of t,llc standard pot,crlt,ials E0(I\.'/III) arltl Eo(\.'I/\') arc t,lllls not possible fiorn t,hc available rncasiircrncnt,s in phosphat,c mctlia.

Elcsin et (11. [GiELEILEB] stiidictl the cornplcx forrrlat,ion of arncricillrn and ot,hcr trixi~,lcnt act,inidcs ~vit,ll t,rirnct,al)llosl)lloric acid, H:jP:309, iising an ion cxcharlgc t,cchniqiic (0.2 I1 NH4C104; 25°C). .%t,; pH = 2 and 4; two corrlplcxcs n7crc siiggcst,ctl t,o dcscril~c the cxpcrirncntal rcslllt,~: . % ~ n P : ~ O ~ ( a c ~ ) and A%~nHP:jO:. Tllc format,ion const,ants at I = 0.2 hI for t,hcsc corrlplcxcs wcrc rcportctl to l)c log,, ill = (3.48 f 0.04) and (3.3 * 0.2) rcspcctircly. No rclial~lc auxiliary dat,a (prot,onat,ion const,ant,s for P:jOi-) arc available and t,llcrcforc t,llcsc cornplcxcs arc not incliidcd in the sclcctcd

DiRcrcnt Soviet inx~cstigat,ions have rcport,ctl t,hc prodiiction arltl stabilisation of tetra-, pcnt,a- and hcxavalcnt arrlcriciiim in aqiicolls potassiiim ~)l~os~)l~otiingst,atc solllt,ions. KloP211:17061 [iGS.%P/SHI, 76S.%P/SPI, 77KOS/TIhI. 80hIIL/LIT, 82ERI/KOP, 82KUL/LEB. 83ERI/KOP, 8GERI/KOP], based on t,hc follo~ving rcdox reartion srhcmcs:

2.4rn(17) + .%rn(II-) + .%rn(171)

.i111(ITI) + .i111(111) + .%rr1(17) + .i111(II7)

( I ) + 11(111) + 2.i111(11T)

hlilyllkova, Litvina and hlyasoctlov [8OhIIL/LIT] rcport,cd log,, i12 = 5.4 and 9 for t,llc .%rn(III) arltl .%rn(II7) corrlplcxcs . % ~ ~ ( P ~ I I : ~ ~ c ) ~ ~ ~ ) : ~ and rcspcct,ivcly. Tllcsc cqllilibrillrn const,ant,s, apparcnt,ly obtaincd at roorn tcrnpcrat,~lrc, wcrc calclllatcd fiorn sl)cct,rophot,ornctric tlat,a on soliit,ions of varying ionic rncdillrn. This rcvic~v does not rccomrrlcnd val~lcs for any of t,hcsc intcract,ions.

V. 6.2.2. Solid arnerici?rrn p1rosplaonr.s corralio~i~,nrls

Only t,hc monophosphidc has bccn itlcnt,ificd, cxrcn in t,llc prcscrlcc of cxccss pllospllo- 1'11s.

Cllarvillat et (11. [i5CH.%/BEN; 7GCH.%/BEN] llcat,cd arncricillrn hydridc ~vit,ll cxccss rctl phosphorus at 580°C for 3 days, finding a single-phase prodiict ~vi th the NaCl(cr) str~lct,~lrc, spacc group Fm31n. \vitll a lat,ticc paramct,cr of (5.7114*0.0003) X

10-l' rn. .%gain. oxygen contarnination is possible. bllt is prol)ably less serious t,harl with t,hc nit,ritlc.

Kcllcr arltl TValt,cr [65KEL/I1:.%L] have prccipit,at,ctl Arn(II1) phosphates by addit,ion of diliit,c solllt,ions of Na2HP04 or (NH4)2HP04 to nrcnkly acid .%m(III) solutions. Tllc hytlmt,c corlt,ains up to 0.5 H 2 0 per rrlolc of .%rnP04 and crystallises ~vi th a hexagonal unit cell rr = (6.99 * 0.01) X 10-l, rn; (: = (6.39 * 0.01) X 10-" m. Tllc light pink cornplctcly anhydroiis .%mP04(cr) is forrrlcd by calcinat,ion allore 200°C, and has the

rrlonoclirlic ThSi04-type lat,t,icc, spacc group P%,/11 \vit,ll rr = (6 .73f 0.02) X 10-" rn; h = (6.93 f 0.02) X 10-l, rn; c = (6.41 * 0.02) X 10-l' rn. 9 = 103.83". This has an apprccial)ly higher dcnsit,y t,harl the hydrate.

Rai et al. [92R.$I/FEL] pcrformctl a solubility st,~idy of 2'".4m(III) in phosphate rncdia. The cxpcrirncnt,al tlat,a at pH< 3 n7crc int,crprct,cd accortling t,o the follo~ving reaction

.4rnP04 . rHLO(nrn) + .h3+ + P O : + r H,0(1) (I- 26)

This rcric\v sclcct,~ t,hc soliil)ilit,y const,arlt ol)t,ainctl by Rai et 111. [S%R.II/FEL] ~vit,ll the ~lnccrt,ainty incrcascd to f 0.6 log,,-unit,s (cf. -4ppcndix .I):

log,, h':,,(\-.26,%98.15 K) = 2 4 . 7 9 f 0.60

Tllc tcrrlpcrat,~lrc at \vhich t,llc cxpcrirrlcnts nrcrc pcrforrrlcd urns not specified by Rai et d., hut t,llc incrcascd ~lnccrt,ainty will compcnsat,c for possil)lc tcrrlpcrat,~lrc cffcct,~. Tllc corrcsporltling val~lc of &Gm for .4rnP04(arn; hydr) car1 not bc sclcctcd by t,llis rcric\v dnc t,o t,hc ~lnkno\vn stoichiornctry of the solid phase.

Ternary phosphates of .4rn(I7I) ~vit,ll the gcrlcral formula 1l 'I .4rn0~PO~ . . ~ H ~ ( l ( c r ) ; (0 < rc; < 3) arltl (AI = NH4; K. R11 and CS) \\,ere prepared by La~valdt et 111.

[82L.4TV/hI.4R] fiorn .4rn(I7I) in 2 hI rlit,ric acid sol~lt,ions by addition of 0.1 hI H:3P(14 and I \ I L C 0 3 ( ~ ) to obtai11 a pH of 3.5. The lcrnon-ycllo\v compo~lrltls lla~rc a t,ct,ragonal st,r~lct,~lrc, spacc groiip P4/nrnm or 14/rnrnrn \\,it11 n = (6.91 t,o 6.99) X 10-" rn; c = (8.82 to 9.06) X 10-l, rn. Tllc R11 arltl CS cornpo~lntls may lla~rc sorrlc 111 replaced by H.

Only t,llc monoarscnidc has bccn itlcnt,ificd, c ~ ~ c n in the prcscncc of cxccss arsenic. Cllarvillat arltl Darnicn [i3CH.4/DAIII] hcatcd sorrlc amcricinrn hydridc ("l'.Irn)

with cxccss arscrlic in a Pyrex tiil)c at 600 K for one nrcck. Tllc X-ray diffi.ar,t,ion pat,t,crns of t,hc protl~lct (W 50 mg) irltlicnt,ctl the prcscrlcc of arsenic arltl an fcc phase. .Ift,cr vaporisat,ion of t,hc cxccss arsenic, the latt,icc pararnct,cr of the fcc phase, NaC1- type, spacc group Frn3m, was n = 5.873 X 10-" m after annealing at 1000°C for 10 h. By analogy ~vit,ll the corrcsporltling ncptiininrn and plntoni~lrn phases. t,his urns

Rotltly [i4ROD] rcpcat,ctl t,his prcparat,ion using t,llc longer-lived 2'".4m isotope, and various heat t,rcat,rncnts. Hc found t,llc follo\~.ing lat,t,icc pamrnctcrs: (5.880 * 0.001) 10-" m aft,cr heating of 675°C for 1 h arltl at 400°C for 7 d. arltl (5.880 * 0.002) 10-" rn aft,cr annealing at 1000°C for 10 h. Tllc lo\~rcr lat,t,icc pararnct,cr aft,cr arlncaling at 1000°C rnay of coiirsc rcs~llt fiorn sorrlc oxygen contarnination; as noted by Roddy.

Kcllcr and JValtcr [65KEL/JV.%L] have obt,aincd t,hc .%m.%s04(cr) by calcinat,ion at, 1000°C of t,hc precipitate fiorn mixing .%~n(N(l:~):~ and (NH4)2H.%~04 soliit,ions. It, has the rrlonoclirlic ThSi04-type lat,t,icc, spacc gronp P21/11 ~vit,ll n = (6.89 * 0.02) X

10-l' rn; h = (7.06 * 0.02) X 10-" rn; c = (6.62 f 0.02) X 10-" m, = 105.5". Ternary arscnatcs of .%rn(J'I) ~vit,ll the gcncral forrrliila ,\l.%mO2.%sO4 . . ~ H ~ ( l ( c r ) ;

(0 < rc; < 3) arltl (AI = NH4; K. R11 and CS) n7crc prepared by La~valdt et (11. [82L.%JV/hI.%R] from .%m(\:I) in 2 h1 nit,ric acid soliit,iorls by addit,ion of 0.1 hI H:3.%s04 and I \ I L C 0 3 ( ~ ) to obtai11 a pH of 3.5. The lcrnon-ycllo\~r compo~lrltls have a t,ct,ragonal st,r~lct,~lrc, spacc groiip P4/nrnm or I41rnrnm \vitll n = (7.09 t,o 7.15) X 10-" rn; c = (8.93 t,o 17.73) X 10-" rn. Tllc R11 and CS corrlpoiinds rnay have sorrlc .\I rcplaccd 1)y H.

No t,hcrrnodynarnic tlat,a arc availa1)lc for the arscrlat,cs of arncrici~lrn

Tllrcc nrlt,irrlonitlcs have 1)ccn itlcnt,ificd: .%rn4Sb:3 (cr); arltl .%rnSl)(cr) and .%1nS1)~(cr); the tlct,ailcd phase rclat,ionships arc not kno~vn.

Tllc mixed corrlpoiind .%mSbTc(cr) is also tlisciisscd in Scct,ion 17.6.4.1.4.

Charvillat et n,l. [75CH.%/BEN] obtaincd t,llis phase by hcat,ing arrlcriciiim hydridc with ant,imony in a molar rat,io of 4:3 in a scalcd cvacnat,ctl t,ubc at 550°C for 7 days. Tllc X-my tliflraction pat,t,crns of t,llc protl~lct indicated t,hc prcscrlcc of t,~vo pllascs. an fcc phase, NaCl(cr) type, ~vi th rr = 6.240 X 10-" rn; arltl a bcc phase of type (a&) Th:3P4(cr). spacc group I4rl nrit,h rr = 9.2392 X 10-" rn. Phases of t,llis type arc nrcll-kno\vn in t,hc lantllanitlc-antirr~o~~y syst,crns.

hlit,cllcll arltl La111 [70IIIT/L.%h'I] first prepared t,hc rrlorlonrlt,irrlonitlc. bot,ll 1)y arc- rrlclt,irlg t,llc clcmcnt,~. arltl by hcat,ing cqnirnolar arnoiint,~ of t,hc clcrrlcnts at 630°C for 1 h in an cvac~lat,cd quartz caps~llc.

This phase has also bccn idcrlt,ificd by Roddy [74ROD]. usirlg ":3.%rn; and Charvillat, et n,l. [76CH.%/BEN]; 1)y rcact,ing the clcrrlcnts nrit,h or \vithont hydrogcn in scalcd containers.

A%~nS1) has t,hc nsiial XaCl(cr) fcc st,riictiirc. spacc gronp Fm31n. \vitll a pararnct,cr bct,\~~ccn 6.2380 X 10-" and 6.241 X 10-" rn. tlcpcntling on the heat trcatmcnt or possibly purity. Tllc as-cast rnat,crial had a slightly larger pararnct,cr of 6.2426 X

10-l' rn [iOhIIT/L.%II].

.%1nSb2(cr) as prepared by Charvillat et n,l. [77CH.%/D.%II] by rcact,ion of cxccss ant,irnony arltl amcricinrn hytlritlc in a scalcd qiiart,z tiil)c at 700°C. .%nncaling for 7 d. as rcq~lircd to ol)t,ain nrcll-cryst,alliscd protl~lct,~. Tllc str~lct,~lrc was fo~lrltl t,o i)c ort,horhornl)ic ~vit,ll (1, = 6.18 X 10-"; h = 6.05 X 10-l' arltl c = 17.59 X 10-l' m. Based on t,llc analogoils compo~lrltl of pl~lt,oniiim, for nrhich sirlglc cryst,al X-ray pict,urcs wcrc taken. the st,rnct,urc is taken t,o that t,o LaSb2(cr). spacc gronp Crnca.

Tllc precise corrlposit,ion (ant1 oxygcn content) of this phase is not kno\vn.

Charvillat et n,l. [77CHA%/D.4h~l] also prcparctl t,llc rrlixcd antirnonidc-t,cll11ric1.c~ by reaction of st,oichiomct,ric arnoiint,~ of .%mSb(cr) and Tc(cr) in q~lart,z t,~lhcs at 750°C for 7 (l. It has t,hc t,ct,ragonal (anti) Cii2Sb(cr) st,riict~~rc, spacc gronp P4/nmrn, ~vit,ll (1, = 4.326 X 10-"; (: = 9.17 X 10-" m. .%gain; t,hc prccisc corrlposit,ion is not kno\~rn.

Only t,llc monol)ismnthidc has l)ccn idcntifictl. This phase was obtaincd by Rotltly [74ROD]; usirlg "'3.4rn; by rcact,ing the clcrrlcnt,~

with or nrit,ho~lt hydrogcn in quartz t,~lhcs. Tllc final rrlixtiirc cont,ainctl arrlcriciiim rnctal and an fcc phase. NaCl(cr) st,riictiirc. spacc groiip Fm31n. \vitll n = 6.338 X

10-l' rn (975°C for 2 d) or 6.335 X 10-l' m (as ahorc 800°C for 14 (1). No higher corrlpoiinds n7crc foiind.

V.7. Group 14 compounds and complexes

Tllc phase diagram of t,hc .%rn-C syst,crn has not hccrl cstablisl~cd in any tlct,ail; hut, the "monocarl>itlc" and scsq~licarbitlc have bccn idcnt,ificd. IVorkcrs at Enratorn [73EUR] prcparctl samples of arncrici~lrn carbitlcs by carl>ot,hcrrnic rctl~lct,ion arltl by arc mclt,ing. Sarnplcs of overall cornposition .4rnCl.04 and . % I ~ C ~ , ~ ~ anncalcd at, 1000°C for 24 h. corlt,aincd an fc,c XaC1-type phase ~v i th n = 5.02 X 10-l' rn. rrlixctl with a scsqiiicarhidc phase having a slight,ly smaller lat,ticc paramct,cr than that noted l>clo\~r. .41t,ho1lgh t,hc precise corrlposit,ion and oxygcn and nit,rogcn contents of the fc,c phase nrcrc not cst,ahlishcd, it is prcsiimahly t,llc rrlonocarhidc .%mC(cr).

A%~ncriciiim scsqnicarl)idc has l)ccn prcparctl by LIitchcll arltl Larn [7OIIIT/L.4L~I%]. It is isostr~lct,~lral ~vit,ll P ~ ~ c : ~ ( c r ) ; spacc group I?3tl, n = (8.2757f 0.000%) X 10-l' rn for a sample anncalctl at 1000°C for 1 h. Tllc prccisc cornposition urns not cst,ahlishcd.

From the syst,cmat,ics of t,llc actinitlc carbides. Hollcy et al. [84HOL/R.%N] have cstirnatcd t,hcrrnodynarnic propcrt,ics of -4r11~C:~(cr) 1171lich ~orrcspond to:

'C. C e C W

% E e Z

-e 6 D

4 2 3 e 3 :: e U

-2 +2 D 6 e S i a Z

E a .c- U .c- i C

E T

Q5 1

& S

Tahlc \'..16: Lit,crat,urc cqiii1il)riiirn const,arlt,s for t,llc arncrici~lrn(III)-carho~~atc-~vi~~t~cr syst,cm.

Met,hocl Ionic t logloK Reference Mecliinn ("C)

sol 0.1 M N a C 1 0 ~ 25 2.74 + 0.17 [84SIL/NIT] sol 0.1 M N a C 1 0 ~ 25 2.77 + 0.15 [85SIL] sol I 1 l1 25 2.53 + 0.16 [85SIL]

sol 0.1 to 0.3 M NaC10J 25:' -21.03 + 0.11 [84BER/KIM] sol I 1 l1 '? -22.5(") [SOFEL/RAI] sol 0.1 M N a C 1 0 ~ 25 -18.70 + 0.12 [92RUN/MEI]

sol 3.0 M N a C 1 0 ~ 20 -15.08 + 0.15 [89ROB] sol 0.1 M N a C 1 0 ~ 25 -14.945 + 0.09 [91MEI/KIM] sp 0.1 0.3 M NaCIOl 25 -14.85 + 0.05 [91MEI/KIM] sol 0.1 M N a C 1 0 ~ 22 -14.785 + 0.05 [91MEI/KIM2] sol 0.1 M N a C 1 0 ~ 25 -14.725 + 0.09 [92RUN/MEI] sol 0.1 M NaCl 21 -17.1 f 0.15 [93GIF/VIT] sol 4 M NaCl 21 -15.2 f 0.2 [93GIF/VIT]

sol 0.1 M '? -18.32(~) [85KIM, 85KIM21 I 1 l1 '? -17.56(~) [85KIM2]

sol I 1 l1 '? -17.38(~) [86AVO/BIL]

(lis 1.0 M N a C 1 0 ~ 25 5.81 + 0.04 [82LUN] rlrl 1.0 M N a C 1 0 ~ 25 5.3 f 0.4 [82LUN] sol 0.1 to 0.3 M N a C 1 0 ~ 25:' 5.08 + 0.92 [84BER/KIM] sp 0.1 M N a C 1 0 ~ 22.5 6.69 + 0.15 [89NIT/STA] sp I 1 l1 25 8.16 + 0.10 [89NIT/STA] sol 3.0 M N a C 1 0 ~ 20 5.45 + 0.12 [89ROB]


Metho(1 Iol~ic t logloK Reference Me(ii11n1 ( " c )

sol I + 0 '?

sol 0.1 0.3 M NaClOl 25 sp 0.1 0.3 M NaClOl 25 sol 0.1 M NaCl 2 1 sol 4 M NaCl 2 1

clis clis enl sol sol sol sol S11 sol sol

0.2 M NaClOl 1.0 M NaClOl 1.0 M NaClOl 0.1 to 0.3 M NaClOl 3.0 M NaClOl I + 0 0.1 0.3 M NaClOl 0.1 0.3 M NaClOl 0.1 M NaCl 4 M NaCl

sol 0.1 to 0.3 M NaClOl 25? sol 3.0 M NaClOl 20 sol I + 0 '?

sol 0.1 M NaCl 2 1 sol 4 M NaCl 2 1


Metllo(1 Iol~ic t logloK Reference Me(ii11n1 ("c)

sol 0.1 to 0.3 M NaClOl 25? 12.15 + 0.15 [84BER/KIM]

sol 0.1 to 0.3 M NaClOl 25? 18.29 + 0.17 [84BER/KIM]

(lis 0.2 M NaClOl 25 15.57 + 0.08 [82BID] sol 0.1 to 0.3 M NaClOl 25? 16.16 + 0.14 [84BER/KIM]

(a) Felrr~y. Rai arlrl Fl~lt,or~ [SOFEL/RAI] <:ornt)ir~e(i t,l~eir soll~l~ilities a t pH> 6.5 X%-it,h tllose of Silva 185SILl t,o ol~tain t,l~is solul~ility cor~st,ar~t.

(1)) These ~x111es refer t,n snll~l~ility experir~ler~ts perforrrled by V i t ~ r g e [84\TT] \%-it,hir~ t l ~ e RIIRAGE project. Hc~\%-ever, \Tit,(>rge clid 11nt pul~lish hirrlself the reslllts frorr~ the t,reat,rrler~t of t,lle rlat,a.

formation of t,llc first and sccorltl i)icarhonatc, t,hc sccorltl carbon at,^ arltl t,hc rrlixctl hytlroxy-carl~onntc .4rn(CO:j)20H" cornplcxcs. L~lntlqvist [82LUN] and Nitschc, Starltlifcr and Silva [89NIT/ST.4] sho\~~ctl iising two diffcrcrlt CO2 part,ial prcssiircs tha t t,hc bicarl)onat,c cornplcxcs must bc much weaker t,harl reported by Bidoglio; hcncc, t,llc int,crprct,at,ion of the cxtractiorl dat,a sccrrls t,o i)c in error and t,llc stability const,ant,s init,ially rcport,ctl [82BID] arc not considcrcd in t,llis revie\\,. The only qnal- it,at,ivc information avai1al)lc from t,hc dat,a of Bidoglio [82BID] is t,llc prctlomirlancc of .4rn(CO:j), a t 8 5 pH 5 9 and 4 . 4 5 log lo[C0~-] 5 3 (cf. -4ppcntlix -4). ~vhich is in agrccrrlcnt nrit,h t,llc ohscrvat,ions of Lnndqvist. Robo~lch. and hlcinrath and Kirn [82LUX, 89ROB, 91IIEI/KIhl].

L~lntlqvist [8%LUX] st,~ltlicd amcricinrn corrlplcxat,ion in carbon at,^ mctlia iising a solvent cxtractiorl t,cchniqllc a t I = 1.0 I 1 (NaC1(I4) and rcport,cd t,hc forrrlat,ion of .4mCO: arltl .11n(C( l :~)~ . .41t,ho1lgh HCOT urns t,hc prctlomirlat,ing ion of the carl)onat,c syst,crn iindcr t,llc cxpcrirncnt,al condit,ions (pc:o, = 0.1 arltl 1.0 at,rn); tllcrc was no cvidcncc for . ~ ~ ~ ( H C ( I : ~ ) P - " ) cornplcxcs.

Bcrnkopf and Kirn [84BER/KIII] rcport,cd solnbilit,y mcasllrcrrlcnts of a solid ~vit,ll st,art,ing composit,ion .11n(OH):~(s) a t I = 0.1 and 0.3 11 NaC1(14, pc:o, = lO-".\at,rrl (cf. Scct,ion \:.7.1.%.2.a). Bcrnkopf arltl Kirn intcrprct,cd their solubility data assllrning

(3-9, . (:3-an), the prcscrlcc of hydroxitlc (.4m((IH), ; 7, = 1; 2. 3), carl)onat,c (.4r11(C0:~),,, . r , = l , % , 3) arltl rrlixcd hydroxy-carbonate (-4rn(0~),(~0:~)f-'-""). , i , = 1 . 2 arltl

r , = l ,%) cornplcxcs. The solitl phase was assiimctl t,o he .k1nC0:~OH(s). This rcric\v considers t,llat the t,ransforrrlat,ion of t,llc initial solid. A I ~ ~ ( O H ) : ~ ( S ) + ' ~ . ~ I ~ C O : ~ O H ( S ) " , may he slo\v ant1 it may have occ~~rrcd tl~lring t,llc cxpcri~rlcnts (cf. .4ppcntlix -4); and tllcrcforc t,hc rcport,cd cqiii1il)riiim const,ant,s from this stiidy arc not considcrctl in the sclcct,ion proccdnrc.

Rao. hlahajan ant1 Nat,ar:~,,jan [88R.4O/hI.kH] reported arncrici~lrn(III) solrcnt cxtract,ion cxpcrimcnt,~ at pH = 6 and 7 and at I = 0.5 hI. This rcvic~v rcintcrprct,~ the dat,a sho~ving t,llat t,llcsc cxpcrirrlcnts rcrcal t,hc cxist,cncc of carhonatc corrlplcxcs (cf. .kppcndix .l), nrhich is in agrccrrlcnt ~vit,ll other cxpcrirncntal ol)scrvations prcscnt,ctl in t,hc litcratiirc. Thcrcforc, t,hc stability constants for t,llc i)icarhonatc corrlplcxcs rcport,ctl in [88RAkO/hI.4H] arc rcjcctcd by t,his rcric~v; cf. Scct,ion \'.7.1.2.1.1).

Nit,schc. Standifcr and Silva [89NIT/ST.k] tlct,crrrlincd the format,ion const,ant of .kmCO: in 0.1 hl NaC1(14 soliit,ions by ahsorptiorl sl)cct,rophot,ornctry. No cvidcncc was fo~lrltl for t,llc cxistcncc of amcricinrn hi carbon at,^ cornplcxcs.

Rohoiich [89ROB] rncasiircd t,llc sol~lhilit,y of .km2(CO:3):3(cr) as a filnct,ion of car- bonatc conccnt,rat,ion at I = 3 h1 XaC104. Tllc solubility dat,a n7crc analysed in tcrrrls of carl)onat,c cornplcxcs ( . k r n ( ~ ( l : ~ ) ~ - ~ ' " ) ; r , = 1. 2, 3) and a soliil)ilit,y product, for .4rn2(CO:3):3(cr) (cf. Scct,ion \'.7.1.2.2.1>). No cridcncc of .km(CO:3): forrrlat,ion was foiind by sl)cct,rophot,ornctry in t,llc 0.1 t,o 3.0 h1 Na2CO:3 mngc. Tllc cqnilibrinrn const,ant,s rcport,cd by Robo~lch (cf. Tal)lc \'.16) arc re-cval~lat,cd by t,his review. .Is the dat,a obtaincd by Rollouch [89ROB] in l~atch cxpcrimcnt,~ (log,,[C0:-] 2 -3.5) can equally nrcll he t1cscril)cd ~vit,ll the solubility of .l\rn2(CO:3):3(s) or .k1nC0:~OH(s), only t,hc cqnilibrinrn constants nncq~livocally resulting fiorn t,llc rncasiircmcnt,s at, const,ant pc:(),, i .e. log,, 9," and log,, 1%':,,(\'.36); arc iiscd in t,llc sclcct,ion proccdiirc.

hlcirlrat,h and Kim [9lhIEI/KIII] invcst,igat,ctl t,hc arncrici~lrn corrlplcxat,ion in car- bonatc rncdia. pcrforrrling sol~lhilit,y and spcctroscopic cxpcrirncnts. The dat,a collcct,ctl at ionic st,rcngt,hs of 0.1 and 0.3 hI NaC104, at pH = 6 t , ~ 9, ant1 ~lrltlcr a controllcd CO2 partial pressure (pc:(), = 0.01 at,rn) nrcrc intcrprct,cd by the forrrlat,ion of Ak~nCO: and .k~n(C(l:~)?. Tllc stability constants ol)t,ainctl from the soliil)ilit,y dat,a rcport,ctl by hlcinrath and Kim agrcc nrit,h t,llc re-cvaliiation pcrformctl by t,his rcric\v (cf. n i x 1). Tllc val~lcs of ill and fi2 rcportcd in [91hIEI/KIhI] arc t,llcrcforc irlcl~ltlcd in t,hc sclcct,ion proccdnrc. Tllc valiic of 'l2 dctcrmincd sl)cct,rophot,ornctri- cally is ho~vcvcr disrcgartlcd (cf. .kppcndix -4). Tllc ~ralnc for t,hc soliil)ilit,y product, of .km2(CO:3):3(cr) is tlisciissctl in Scct,ion \.'.7.1.2.2.h.

Tllc sol~lhilit,y of ":3.k~nCO:30H(cr) in carl)onat,c rnctlia urns invcst,igat,ctl by Fclrny. Rai ant1 Fiilton [9OFEL/R.41]. over ~vidc ranges of [CO:-], [HCOT] and pH val~lcs. .Is sllo\~~n in Figiirc 3 of [9OFEL/R.41]. t,hc aiit,llors irlclutlcd t,hc sol~lhilit,y dat,a rcportcd by Silva and Xit,schc [84SIL/NIT. 85SILl during t,llc fit,t,ing of their own sol~lhilit,y dat,a. This review considers irlstcatl the cq~lilihri~lrn const,arlt,s for rcact,ions

(:3-an) .kmCO:30H(cr) + H++(rr - 1) C O : + ( C l 3 ) , , + H20(1) (\:X)

oht,ainctl cxcl~lsivcly from solubility tlat,a of Fclmy, Rai ant1 F~llt,on (cf. tlisciission of Ref. [SOFEL/R.kI] in -4ppcntlix -4). Tllc st,cp\visc cq~lilil)riiim const,ant,s for carl)onat,c corrlplcxat,ion ant1 16. dcrirctl from ~ ~ a l n c s of 1%'s,,(\:.27)) arc incl~ltlcd in the sclcct,ion proccdnrc.

Figure \".10: Extrapolat,ion to I = 0 of litcratiirc cqiii1il)riilm constants [82LUN; 89NIT/ST.4. 91IIEI/KIhI] and the rcirlt,crprctcd ~ra111c fi.0111 [89ROB] for t,hc forrnation of .4mCO:, nccordirlg t,o

.4111"+ + CO:- + .411lc(1:, using the specific ion intcract,ion cqnnt,ions (cf. -4ppcndix B). Tllc (lashed lines rcprcscrlt t,hc ~lnccrt,ainty 1imit)s cst,irnatcd by this rcvicx~r. cf. Eq. (\'.28).

Giffiut and \'it,orgc [93GIF/\TT] reported cqiii1il)rinrn const,ant,s for t,llc forrrlat,ion of A4~n(CO:3)p-2'") (n = 1 t,o 3) from an int,crprctation of their soliil)ilit,y dnt,n at 0.1 nrld 4 11 NaC1. cf. Table \".16. Ho~vcvcr. dnc t,o t,llc lack of dct,nils in t,llis puhlicat,ion, the rcport,cd cq~lilihri~lrn const,nrlt,s can not he crctlit,cd in t,llis review; cf. -4ppcndix -4.

Tllc val~lcs of log,, L/, fiorn Rcfs. [82LUN; 89NIT/ST.4; 91hIEI/KIkI] nrltl the rcint,crprct,ctl val~lc from [89ROB] arc cxtrapolat,cd t,o I = 0 iising t,hc specific ion interaction cqnntions 3 r d tllc rvcightcd linear rcgrcssion procctlllrc as tlcscril)cd in .4ppcndiccs B and C (cf. Figure: \:.10). The cxt,rnpolat,ion is pcrforrrlcd ~vit,ll n ~ralnc of AE, = -(0.24f 0.05) kg.11101-l oht,aincd from t,llc ion intcract,ion cocficicrlt,~ given in Scctiorl B.1.4. Tllc rcsiilt of t,llc cxtrapolat,ion to I = 0 for -4rnCO: yicltls:

I I I I I I

log,, ,/,"(298.15 K) = 7.8 f 0.3 (1.28)

-

This ~ralnc agrccs ~vithin t>h(: nnccrt,nint,ics \vitll t,llc constants given by hlonlin et aL [HSAIC)U/ROB] (log,, g," = 7.6). Nitschc; Stantlifkr ant1 Sill-a [89NIT/ST.4] (log,, i / y = (8.16 * 0.10)); nrltl the val~lc cst,irnatcd hy Cantrcll [88C.4N] (log,, 9," = 7 - 1 . 1 ) .

- . -

Tllc vnliics of t,llc sccorltl stcp~visc cq~lilihri~lrn const,nnt,, IjL; from Rcfs. [82LUN; 91hIEI/I<IhI, 90FEL/RA41] arc convcrtcd t,o rrlolnl urlits nrltl cxt,rapolatcd t,o zero ionic

[9l\lEI/KI\I], sol

I I I I I I I

st,rcngtll \!,it11 the specific ion intcract,ion cqnnt,ions of -4ppcntlix B. Tllc !,E ~ralnc for t,his rcnct,ion is oht,aincd fiorn t,hc cst,imnt,ctl ion irlt,crnct,ion cocfficicnts given in Scctiorl B.1.4 ( A E ~ = ( 0 . 1 4 * 0.07) kg . mol-l). Tllc \~rcigllt,cd average of t,hc tllrcc T ~ ~ ~ I I C S of log,, IjLO yields:

Tllc val~lc of t,hc t,hird st,cp\visc cqiii1il)riiim const,ant,, I%':j. oht,aincd by Fclrny. Rai nrltl Fiilt,on [90FEL/R.41] is sclcctcd

~vhcrc t,hc ~lnccrt,ainty has bccn increased bccansc of t,llc iinkno~vn t,cmpcmt,urc of this stiidy. Tllcsc st,cpnrisc cqiii1il)riiim constants lead t,o the follo~ving sclcct,ctl val~lcs for the overall forrrlat,ion const,ant,s:

log,, ,/,"(298.15 K) = 12.3 * 0.4

log,, ,!:(298.15 K) = 15.2 * 0.6

Tllc ~ralnc of log,, L/," ngrccs \vit,ll t,llc ~ ~ a l n c s sclcctcd by LIoiilirl et o,l. [88LIOU/ROB], (log,, i/; = 11.8); and \vith the vnliic cst,imnt,ctll)y Cnrlt,rcll [88C.%Y] (log,, p," = 12.8).

Tllc Gibbs crlcrgics of formnt,ion for t,hc cnrbonatc corrlplcxcs of arncrici~lrn(III) derived fiorn the sclcctcd formation const,ant,s arc:

As an illiist,ration; Figure \'..l1 sho~vs t,hc distril)iition of carhonatc cornplcxcs of .km3+ in compct,it,ion nrit,h the hydrolysis prodnct,~.

Forrrlat,ion constants for t,llc first t,~vo hicnrbonat,~ corrlplcxcs of amcricinrn wcrc rcport,ctl by Bitloglio [&?BID]. cf. Tal~lc \:.16. H o \ ~ ~ c ~ ~ c r , the first stability const,ants appears too lnrgc corrlparcd \vith log,, fi,(~l,fHCOi+) = 2 t,o 3 for ~l'f = 1- [85SP.4. 92GREISP.41. .\I = La [81CIAk/FER] and for other rare cart,hs [9011:00; 87C.%Y/BYR. 93LEE/BYR]. Liindqvist [82LUN] and Nitschc, Standifcr nrltl Silva [89NIT/ST.4] sho\~~ctl t,hnt,, if t,llc hicnrbonat,~ forrrlatiorl const,nrlt,s of Bidoglio wcrc correct. t,hcsc species nro~lld lla~rc l)ccn dctcct,ctl in t,llcir cxpcrimcnt,~. F~lrthcrmorc; the re-cvnliiation of t,llc dist,rih~lt,ion cocfficicnts reported by Bidoglio [82BID] indicates that . k ~ n ( C ( l : ~ ) ~ as t,hc prcdorninant amcricinrn complex in the aqiicolls phase (cf. -4ppcntlix -4).

Alt,lloiigh HCOT as t,llc prctlomirlat,ing ion of the carhonatc systcrn in t,llc sol- ~ ~ c n t cxt,rnct,ion cxpcrirncnt,~ pcrformctl by Liindqvist [82LUY], t,hcrc no cvidcncc for . ~ I ~ ( H C O : ~ ) ~ ~ - ' " ) corrlplcxcs (cf. previous Scct,ion).

Figure l : Calciilat,ctl tlist,ribntion diagrarns for tllc aqiicolls arncrici~lrn(III) hytlroxidc-carho~~atc systcrn at I = 0 arltl 25°C. Tllc diagrarns lla~rc hccn calcnlat,cd using t,llc sclcctcd cqnilibrinrn constants in Tahlc 111.2 for a fixed partial prcssiirc of COa(g) (upper tliagmrn) arltl for a const,arlt l c ~ ~ l of t,ot,al inorgarlic carbon (lower dingmrn). Solid pllasc precipitation has hccn snpprcsscd in t,llcsc calc~llations.

Rno. hlahajan and Natarajan [88R.%O/hI.%H] interpreted t,hcir solrcnt cxtractiorl cxpcrirncnt,~ at pH = 6 and 7 and at I = 0.5 h1 assuming the forrrlat,ion of .krnHCO;+ nrld .k1n(HC0:~):. This review re-cxi~,lnnt,cs the tlat,a sho~ving that t,llcsc cxpcrirncnt,~ rcvcal irlstcntl t,llc cxist,cncc of carl)onnt,c cornplcxcs (cf. .%ppcndix .l). Thcrcforc, cvcn if the cqnilibrinrn const,nrlt,s rcportcd in [88RAkO/hI.4H] for the 1)icarbonatc corrlplcxcs appear t,o be of t,hc right order of mngnitiidc, t,hcy arc ncvcrt,hclcss rcjcct,ctl 1)y t,llis review.

E~vart et 111. [92E\\:.%/ShII] 11sctl a chcrrlical rrlodcl incllltling t,hc cqllilibrillrn const,ants for .krn~CO;+ and . ~ I ~ ( H C O : ~ ) : sclcctcd 1)y Phillips et o,l. [88PHI/H.%L] (~vhich origirlat,c fiorn t,hc x~alncs rcportcd 1)y Bitloglio [%?BID]). t,o fit the amcricinrn conccn- tratiorls mcasllrctl in "concrct,c cq~lilibmt,ctl nrnt,crs". Ho~vcvcr. diic to cxpcrimcrlt,al sllortcorrlings in t,hcsc rncnsnrcrncnt,~, no q~lant,it,at,ivc information can be cxt,rnct,cd from the dnt,n, cf. the discllssiorl of Ref. [86EIVAk/H01\'] in .kppcndix .l.

This rcric\v concl~ltlcs t,hnt t,llcrc is no cxpcrimcrlt,al cvidcrlcc ~vhich can prove the cxist,cncc of nrrlcriciiim 1)icarbonatc complcxcs. Fnrt,hcr cxpcrimcrlt,al work is ncccssary before t,llc rcalit,y of tllcsc complcxcs in aqncoiis solllt,ions is cst,al)lishctl

Scvcral authors 11ax.c snggcst,cd t,hc formnt,ion of mixed carbo~~atc/l~ytlroxiclc cornplcxcs of amcricinrn:

Bcrnkopf nrltl Kirn [84BER/KIhI] proposctl the forrrlat,ion of t,hrcc rrlixctl cornplcxcs (.k1nC0:~OH(aq). .%mCO:j(OH), nrltl .km(CO:3)zOH2-) t,o explain t,hcir solubility data.

Bidoglio [82BID] ass~lrncd t,llc prcscncc of .%m(CO:j)20H" in t,llc analysis of his solvent cxt,ract,ion tlat,a.

Shiloh. Givon and lInrclls [69SHI/GI\-] proposctl the complex .%m(CO:3):j0H4- t,o cxplnin t,hcir sol~lbilit,y dnt,n.

Enrnrt et o,l. [86E\V.%/HO\V; 8iCRO/EII'.k] nsctl the cllcrrlicnl motlcl proposed 1)y Bcrnkopf and Kirn [84BER/KIhI]. acljjnst,ing the cqllilibrillrn const,ant,s for .%rnCO:j(OH); and .%rn(CO:j)20H" t,o fit t,hc arncricillrn corlccntrat,ions mcasllrctl in "concrct,c cqllilibrnt,ctl nrnt,crs".

Ho~vcvcr. the tlisciissions in Scctiorls \'..7.1.2.l.n and \'..7.1.2.%, and in .%ppcndix -4, sho\17 t,llat all the ax7ailal)lc cxpcrimcrlt,al dnt,n can be rcintcrprct,cd nrit,h t,hc assnrnp- tion t,llat only nrrlcriciiim carl)onnt,c cornplcxcs and/or hydrolysis prodnct,~ arc formctl in aqiicolls soliit,ions.

Fiirt,hcr cxpcrimcrlt,al ~vork is nccdcd t,o corlfirrrl or tlcny t,hc cxistcncc of rrlixctl .km(III) hydroxy-carbonate corrlplcxcs in nqllcons soliit,ions.

in non-cornplcxing aqiicolls rncdia. it hccorrlcs qiiitc stable in carl)onnt,c soliit,ions. hloskvin and Poznyakov [79110S/POZ] rcport n coprccipit,at,ion stiidy (using Fc(II1)

hytlroxidc as the host solid phase) of several act,inidcs(\:) as a filrlct,ion of t,hc conccn- tratiorl of some ligands in XH4C1 soliit,ions at pH -- 8.5. For .4rn(I7), Iloskrin nrltl Poznynkov report log,, ill = (2.02 f 0.09) for:

at I = 0.25 h1; and (20 * %)"C. .%lthongh t,llis stiidy rcrcals an irlt,crnct,ion l)ctn~ccn .%m(\:) nrltl cit,llcr carhonatc or bicarl)onnt,c, the cxpcrirncrlt,nl cvidcncc is not con- cliisi~~e as t,o t,llc composit,ion of t,hc COII I~)~CXCS formed. This cq~lilihri~lrn const,nrlt is tllcrcforc rcjcct,ctl by this review.

Giffiut and \'.itorgc [93GIF/\'IT] stiidictl the solnbility of 241.%m in 0.1 and 4 11 NaC1 solutions at 21°C. Tllc larger soliil)ilit,y in the conccnt,rnt,ctl cllloridc soliit,ions was intcrprct,cd as t,hc mtliolyt,ic oxidnt,ion of .%rn(III) t,o .%m(\:). nrltl the sol~lhilit,y curve at 4 11 NaC1 was irlt,crprctcd ~vi th the format,ion of two .4rn(I7) carl)onnt,c cornplcxcs:

for ~vhich t,llcy rcport log,, ill = (5.5 f 0.3); log,, fi2 = (8.9 * 0.4). Giffaiit n11d I'itorgc also clairrlcd t,hnt t,llcsc cornplcxcs wcrc in cqnilibrinrn ~vit,ll Xn.%m02CO:j(s). Ho~vcvcr. o\ving t,o t,hc lack of dct,nils in Ref. [93GIF/\'IT]. t,llc rcport,cd cqnilibrinrn const,ant,s can not i)c crctlit,cd in t,llis rcric\v, cf. .%ppcndix .%.

Tllc apparent norrnal pot,crlt,ial of t,hc .%rn(\'I)/.4rn(I7) coilplc urns mcas~lrctl by Simnkin et o,l. [74SIhI/I7OL]: Eo(\'I/\') = (0.90 f 0.01) 1' 71s. SHE in 1 I1 K2C(13 soliit,ions at 20°C. Lat,cr Simnkin [iiSIhl] rcport,cd that t,llis norrrlal pot,cnt,ial urns irldcpcrltlcnt of the corlccntrat,ion of Na2CO:j (E"(I7I/\:) = 0.90 1' ?IS. SHE). hut t,llat, it dccrcascd ~vit,ll t,llc conccnt,rnt,ion of K2CO.3 [i7SII.I]. Boiirgcs et al. [83BOU/GUI] pcrforrrlcd carcfiil spcct,ropllot,omct,ric and pot,crlt,iomct,ric rncasiircrncnt,s of t,llis rcdox couple in carhonatc rrlcdin at 25°C. Tllc appnrcnt rlormnl pot,crlt,ial urns foiind t,o l)c irltlcpcrltlcnt of [CO;-] in 2 11 NaHCO:j-NaCO:3 rnixt~~rcs: E"(I7I/\') = (0.975*0.01) 1' 71s. SHE. hlyasocdov et o,l. [8GhIY.%/LEB] reported E0(\:I/\') = (0.910 f 0.003) 1' 71s. NHE for 3 hl I<,CO:j solutions.

Tllc apparent norrnal pot,crlt,ial of t,llc .%rn(I\')/.%m(III) co~lplc has bccn rncnsnrcd in [N:I,HCO:~ + Xn2CO:3] = 2 I1 solutions: E0(I\'/III) = (0.9% * 0.01) 1' 71s. SHE at pH = 9.7 [82HOB/S.4hI]. nrltl E"(I\'/III) = (0.924 * 0.01) 1' 71s. SHE at 25"C, [CCIi-] = 1hI [83BOU/GUI]. Tllc potential of t,llc .4rn(I\')/.%m(III) conplc as fo~lrltl by Boiirgcs et al. [83BOU/GUI] to tlccrcnsc nrit,h t,llc corlccntrat,ion of t,hc carl)onnt,c nrliorl in t,llcsc [NaHCO:j + Xn2C0:j] = 2 h1 solutions. Ilynsocdor et o,l. [86hIY.%/LEB] rncnsnrcd Eo(I\'/III) = (0.870 * 0.00%) 1: ?IS. NHE in 3 hI KHCO:j/K2CO:3 soliit,ions.

Tllc rncasnrcrncnt,~ of Bonrgcs et al. [83BOU/GUI] for l)oth t,hc .%rn(\'I)/.%m(\:) and .%m(I\')/.4m(III) coiiplcs pcrformctl in 2 I1 NaHC0:j/Na2C0:j mctlia, lla~rc hccn rcint,crprct,ctl by Robo~lch [89ROB] assuming t,llc follo\ving cqiii1il)ria:

~vhich prcsllrnc t,llat . % ~ ( I \ ' ) ( c o : ~ ) ~ - , . % ~ ( \ : ) o ~ ( c o : ~ ) ant1 . ~ ~ ~ ( \ ' I ) O ~ ( C O : ~ ) ~ - arc the lirrliting complcxcs for the I\.', 1' ant1 \'.I oxitlat,iorl st,at,cs (as cxpcct,cd by analogy ~vi th U(I\:); NI)(\') ant1 U(\:I)-P11(\'1). rcspcct,ivcly). F~lrthcrmorc; the measure- rrlcnts of Bourgcs et al. sho~v t,llat . 4 r n ( ~ O : ~ ) ~ ~ is the Arn(II1) lirrliting complex, ~vhich confirms Shiloh. Gi~ron ant1 IIarc~ls's [69SHI/GI\'] obscrvat,ions, (cf. -4ppcntlix -4).

Basctl on t,llc rcdox reactions mcnt,iorlcd above, Fcrri, Grcnt,llc ant1 Salvat,orc [83FER/GRE] used t,llc data of Boiirgcs et 111. [83BOU/GUI] t,o calcnlat,c t,hc forrrlatiorl constant for t,hc cqiii1il)riiim

~vhich they report t,o l)c log,, fi:3(.%1n(\')) = (16.4 f 0.4) at I = 3 hI NaC1(14. This appears to bc a rnist,akc. ant1 t,his rcric\v hclicvcs that the rcport,ctl valiic corresponds inst,cad t,o rcactiorl (\:.29).

Grcnt,hc. Rohoiich ant1 \'.itorgc [86GRE/ROB] also ~lsctl t,llc dat,a of Boiirgcs e t 111.

[83BOU/GUI] t,o cstirrlat,c log,, 'lr, = 40 at an ~lnspccificd ionic st,rcngt,h for rcact,ion

Similarly, t,llis rcric\v rcint,crprct,s the dat,a of Bourgcs et al. [83BOU/GUI] ( c f . .%ppcndix .%) accortling t,o reactions (\'.29) and (\:.30) and sclcct,~ the follo\ving val~lcs at zero ionic strength:

log,, l<" (1-.30,298.15 K) = 20.1 * 0.9

E " ( \ - . ~ o , 298.15 K) = (1.19 * 0.05) 1..

It sllonltl he noted that t,hc result for rcact,ion (\'.%g) car1 he co1nl)inctl ~vit,ll the st,andard rctlox potential for the .%m0;+/.4rnO: coiiplc. ant1 t,hc formation rcact,ions for the carhonatc complcxcs:

l 1 h (1.29) = 1 l (1.31) + 1 ( 1 ( r ( ) ) / ( r ( I ) ) ) . .% ~ralnc for log,, lio(1'.31) = (27.0 * 1.5) car1 he calcnlat,cd from t,hc sclcct,ctl Gil)l)s crlcrgics in Tahlc 111.1, yielding:

This can l)c corrlparcd nrit,h the val~lc (14.2 f 0.3) \vhich is calc~llatcd from t,llc dat,a in t,hc ~lrarliiim NE.%-rcvicw [92GRE/FUG]. Corrlparisons ~vi th val~lcs for ncptiininrn and plntoni~lrn slloiild bc rnadc ~vllcn t,llc corresponding NE.%-rcvic\vs arc avai1al)lc.

Tllc rcs~llt for rcactiorl (1:.30) is corrlhincd nrit,h t,llc Gil)l)s cncrgy of format,ion for . ~ I ~ ( c o : ~ ) : and C O : t,o ol)t,ain

which is combined nrit,h t,llc sclcct,cd valiic for &G$(.%rn4+; aq, 298.15 K) t,o give:

.krn4+ + 5 C O : + .%rn(CO:j)g- log,, 'l,; = 39.3 * 2.1

This val~lc is comparahlc ~vit,ll t,llc analogous cqnilibri~lrn const,ant oht,aincd for urn- nium (log,, il,o = (34.0 * 0.9) [S%GRE/FUG]). Tllc large nnccrt,aint,y in t,llc val~lc of log,, 'l: given allore for t,hc forrrlat,ion of . % ~ ( C O : ~ ) ; arises from t,hc nnccrt,aint,y in the valiic of AfG$(.%m4+, aq, 298.15 K) obtaincd by t,llc cstirrlat,ion proccdnrcs tlis- c~lssctl in Scct,ion 1".2.3.

Only t,llcrrnodynarnic data for four amcricinrn carl)onat,c solids have hccn reported: .%mCO:j(lH(s) [84BER/KIhI. 84SIL/XIT; 85SIL, 88ST.%/NIT;

90FEL/R.%I. 9%RUN/hlEI] .%mZ(CO:3):3(s) [69SHI/GI\'. 89ROB. 91hIEI/KIhI. 9lhIEI/KIII2;

92RUN/hIEI, 93GIF/\TT] Na.k~n(C(l:~)~(s) [841?IT, 85KIh1, 85KIhI2, 86.%1'O/BIL] N ~ . ~ I ~ O ~ C O : ~ ( S ) [93GIF/\TT]

Tllc ~ ~ a l n c s of t,hc sol~lhilit,y prodiicts rcport,ctl in t,llc lit,cmt,urc arc given in Table 1'..16; p.149.

Aks dcscribctl in t,llc follo\~.ing t,~vo sections, the cxpcctcd partial pressure of C02(g) l>clo\~r ~vhich .%mZ(CO:3):j(s) will (perhaps slo\~,ly) he corlvcrt,ctl into .%mCO:jOH(s) is p(:o2 N 0.1 bar (cf. [9lhlEI/KIh12. 92RUX/IIEI. 921-iITI).

.kmcricinrn hydroxy-carhonatc displays t,~vo st,rnct,ural forms, ort,l~orhombic and hcxagonal. Tllc cell pararnct,crs of the ort,l~orhombic st,mct,urc arc n = 4.958 X 10-"; h = 8 . 4 8 7 ~ 10-" and (: = 7 . % 1 5 ~ 1 0 - ' ~ rn [85SIL]. Stantlifcr arltl Nit,schc [88STAk/XIT] rcport,ctl a cryst,allographic st,udy idcntifyirlg .k~nCO:~(lH(cr). prccipit,at,cd at 60°C

and pH = 5.9, cx11il)iting an llcxagonal st,rnct,urc. The corresponding cell pararrlctcrs arc a = 12.22 X 10-" ant1 c = 9.70 X 10-l' rn. Sol~lhilit,y st,~ltlics (cf. Tahlc \:.16) have hccn pcrforrrlcd only for t,llc ort,horhombic form.

Shiloh, Gi~ron and hIarciis [69SHI/GI\-] st,udicd tllc solubility of a chcrnically characterised .4mZ(CO:3):3(s) in 0.1 t , ~ 0.6 11 pot,assi~lrrl cnrbonat,c rncdia; tllc aiit,llors int,crprct,ctl t,hcir rcs~llt,s assiimirlg tllc forrrlat,ion of .41n(C(I:j):~0H'~. This rcric\v rcint,crprct,s t,hcir rcsnlt,~. taking into acco~lrlt t,llc infliicncc of t,hc ionic st,rcngt,h, ant1 proposes t,llc follo~ving cqnilibrinrn:

sllo\~ring t,hat . ~ I ~ ( C ( I : ~ ) ~ is tllc prcdorrlinant cornplcx 111) t,o [CO:-] = 2 11. Ho\vcvcr, from t,llcsc mcasllrcrrlcnts is not possil)lc t,o dctcrminc if t,llc solid phase in cqnilibrinrn wit11 t,hc carl)onat,c soliit,ions is .4rnC0:j0H(s) or .4rr12(C03):j(~), cf. .4ppcntlix -4.

Bcrnkopf and Kim [84BER/KIhI] rcport,ctl a sol~il)ilit,y product constant for tllc corrlpoiind .4mCO:jOH(s). Tllc ~ralnc urns oht,aincd from soliil)ilit,y rncasnrcrncnt,~ condnct,ctl in diliit,c i)icarhonatc rncdia (0.1 t,o 0.3 h1 NaC104). at const,arlt CO2 part,ial prcssiirc (pc:(), = 10-".%tm). and start,ing ~vit,ll .4m(OH):3(s). Tllc solid phase urns not charact,criscd but was assiimctl t,o bc .4rnC0:jOH(s). This review consitlcrs t,llat, tllc transformation of t,hc init,ial solid, .41n(OH):~(s) +'..41nC0:~OH(s)"; may l)c slow and it may lla~rc occnrrcd during t,hc cxpcrirrlcnts (cf. .4ppcndix -4); ant1 t,llcrcforc does not consitlcr tllc rcportcd sol~lhilit,y const,ant in t,llc sclcct,ion procctl~lrc.

Silva and Xit,schc [84SIL/XIT, 85SILl stiidictl t,hc solubility of arrlcriciiim in diliit,c carl)onat,c soliit,ions. Tllc cxpcrirrlcnts nrcrc pcrforrrlcd at constant ionic st,rcngt,h (I =

0.1 hl NaClO,), const,ant pH (pH = 6.12 f 0.03), and under controllcd COZ part,ial prcssiirc (pc:o, = 0.00792 at,rn). The solid phase. charactcriscd by it,s X-ray diffi.act,ion pat,t,crn to i)c ortllorllorrlhic .4mCO:jOH(cr).

Tllc solubility of amcricinrn in carhonatc mctlia >i7as also invcst,igatcd by Riindc, hlcinrat,ll and Kirn [92RUN/hIEI] ~lrltlcr cont,rollcd pc:o, at,rnosphcrc, nrit,h pH varying from 4 t,o G a t I = 0.1 11 NaC10,. .4rnC0:jOH(s) urns ass~lrncd t,o he st,al)lc at pc:(), =

3 X 10-' at,rrl by analogy ~vit,ll t,hc ncodyrniiim-carhonat,~ syst,cm [92RUN/hIEI]. Tllc solubility product re-cval~lat,cd fiorn Silva's st,utly (cf. ~disc~lssiorl of Ref. [85SIL]

in .4ppcndix -4) for tllc rcact,ion

as ~vcll as tllc val~lc rcportcd by R~lntlc. hlcirlrat,h and Kirn [92RUN/hIEI] arc cx- trapolatcd t,o zero ionic st,rcrlgt,ll using AE = (0.45 + 0.04) kg . mol-l as calcnlat,cd from t,llc sclcct,ctl ion intcract,ion cocfficicnt,~ (-4ppcndix B). Tllc solubility protl~lct,~ at I = 0 arc avcragctl t,o give

log,, I ~ , ( \ ' . 3 3 ; 298.15 K) = 2 1 . 2 f 1.4.

~vhcrc t,hc ~lnccrt,ainty has bccn assignctl t,o cover tllc rnaxirniim range of expectancy. Tllc tlcrivcd Gibbs cncrgy of formation is

AfGm(.lrnCO3OH, cr. 298.15 K) = ( 1 4 0 4 . 8 + 9.3) k.J . rnol-'

Tllc solubility const,ant,; log,, K:,,(I:.32) = log,,(I'~,,(I~.33) X ill) = ( 5 . 5 1 *0.08). dct,crrrlinctl by t,his review from the data of Shiloh. Gi~ron and 1Iarc1ls [69SHI/GII7] (cf. .%ppcndix -4); agrccs nrit,h the val~lc ol)t,ainctl \vit,h the sclcct,ctl cqnilibrinrn const,ants: log,,(h'~,,(I~.33) X ill) = ( 6 . 0 f 1.5). Ho\~~cvcr. as rrlcntiorlcd above. it is not possible from t,llc data in [69SHI/GII-] t,o concliidc nrit,h corlfitlcncc ~vhich is the solid phase in cq~lilihri~lrn.

Tllc cqnilibrinrn const,ant at 298.15 K for the rcactiorl

can i)c calciilat,ctl from the auxiliary data in Chapter I11 and from the valiics of log,, I ~ , ( 1 7 . 3 3 ) and log,, ';I~,(I'.l2):

log,, I%';(17.34. 298.15 K) = 4.2 * 1.5

~vhich rcsnlt,s in a C02(g) cqiii1il)riiim partial presslire for the cq~lilihri~lrn i)ctn~ccn the t,wo solids in rcactiorl (17.34) of pc:(), = (0.6 * 2) X 10-' bar. This valiic is consistent ~vit,ll t,hc concliisions prcscrlt,ctl by I7it,orgc [92I'IT].

Shiloh, Givon and hlarcns [69SHI/GII-] st,~ltlicd the solubility of a chcrnically characterised .%mZ(CO:3):3(s) in 0.1 t , ~ 0.6 11 pot,assi~lrrl carbonat,c rncdia; the aiit,llors irlt,crprct,ctl t,llcir rcs~llt,s assiimirlg t,llc format,ion of .4rn(CO:j):30H4. Xc\~rt,on arltl Sullivan [85XE\V/SUL] rcintcrprct,cd t,llcir rcsnlt,~. t,aking int,o accoiint t,llc inflncncc of t,hc ionic st,rcngt,h, and proposed the follo\~.ing cqiiilibrinrn:

cvcr. from t,llcsc rncasnrcrncnt,~ is not possiblc t,o dctcrrrlinc \vhich is t,llc solid phase in cq~lilihri~lrn ~vit,ll t,llc carl)onat,c solutions: .%mZ(CO:j):j(s) or .4rnC0:jOH(s). cf. .%ppcndix .%.

Rohoiich [89ROB] rncasiircd t,hc sol~lhilit,y of .%~n~(CO:~) :~(c r ) as a fimct,ion of carl)onat,c corlccntrat,ion at I = 3 h1 XaC104. Two set of cxpcrimcrlt,~ wcrc pcrforrncd: orlc ~vhcrc t,llc total carhonatc conccnt,rat,ions wcrc kno\vn, and arlot,llcr using cont,rollctl C02(g) part,ial pressure. Tllc so1iil)ility dat,a nrcrc analyscd in t,crrrls of carl)onat,c corrlplcxcs ( .4rn(~(I:~)~~-"") , rr = 1; 2. 3) arltl a soliil)ilit,y protl~lct for .%~n~(CO:~) :~(c r ) . Tllc solitl phase was charact,crisctl hy it,s X-my tliflraction pat,t,crn. Tllc reported cqnilibrinrn constants (cf. Tal~lc \:.16) arc re-cval~lat,cd by this rcric\v (cf. -4ppcntlix -4).

hlcirlrat,h and Kim [911IEI/KIhI] stiidictl the solnbility of arncrici~lrn in carbonat,c mctlia. Tllc tlat,a n7crc collcct,ctl at 0.1 and 0.3 11 NaC1(14 ionic st,rcngt,h, pH =

6 t,o 9; iindcr pc:(), = 0.01 atm, and as intcrprct,cd by t,llc format,ion of .%mCO: and .%rn(COt3); in t,hc aqllcons solutions. The solitl phase urns cllaractcriscd as

. k~n~(CO:~) :~(c r ) by X-my difiact,ion, t,hcrrnograxirnctry arltl diffcrcrlt,ial thermal analysis. .% rcirlt,crprct,at,iorl of t,hcsc cxpcrirncnt,al data, (:f. -4ppcntlix -4, rcsiilts in val~lcs for cqiii1il)riiim const,ant,s nrhich agrcc \vith t,llosc originally rcport,ctl in [9lhIEI/KIII].

T\vo additiorlal invcst,igation of the soliil)ilit,y of arrlcriciiim in carl)onat,c rncdia have been rcport,cd by hlcinrath and Kim [9lhIEI/KIhI2] and R~lntlc. lIcinrat,ll arltl Kirn [92RUN/hIEI] iindcr controllcd pc:(),; \vit,ll pH varying from 4 t,o 6; at I =

0.1 h1 NaC104. .k~nCO:~(lH(s) was assiimctl [92RU1U/IIEI] t,o bc the st,ahlc phase at p(:(), = 3 X 10-' at,rrl by analogy \vith t,hc ncodyrninrn systcrn (cf. .kppcndix -4); ~vhilc at pc:(), 2 0.01 atm t,hc st,al)lc solid phase was ass~lrrlcd on t,llc sarrlc grounds t,o bc .krnZ(CO3),(s) [91IIEI/KIhI%, 92RUN/hIEI], which is in agrccrrlcnt \vit,ll prcvio~ls cxpcrirncnt,al obscrvnt,ions [84SIL/NIT; 85SIL, 89ROBl.

Giffiut arltl \'.itorgc [93GIF/\'IT] rcport,ctl so1iil)ility constants for . k ~ n ~ ( C ( l : ~ ) : ~ ( s ) from an int,crprctation of t,hcir solubility data at 0.1 and 4 11 1UaC1, cf. Table \'..16. Ho~vcvcr. dnc to t,hc lack of tlct,ails in t,his pnblicnt,ion, the rcport,cd x~alncs can not, bc crcdit,ctl in t,his rcvic\v. cf. -4ppcntlix -4.

Four val~lcs of the cq~lilihri~lrn constant for reaction.

arc considcrcd in this rcvic\v: t,hc re-cxi~,lnat,ctl corlst,arlt fiorn t,llc dat,a by Rohoiich [89ROB] (cf. .kppcndix -4). the val~lcs obtaincd by Ilcinrath and Kirn [9lhIEI/KIII, 9lhlEI/KIh12] from t,hcir soliil)ilit,y mcasllrcrncnts; and the val~lc rcport,cd by Riindc, hlcinrat,ll and Kirn [92RUN/hIEI]. Thcsc const,ant,s arc convcrt,cd t,o rrlolal nnit,s arltl cxt,rapolat,ctl t,o zero ionic strength usirlg t,llc specific ion int,cractiorl cq~lat,ions of .kppcndix B. Tllc val~lc ol)t,ainctl fiorn the tlat,a of Rohoiich [89ROB] is discrepant,. Tllc tliffcrcncc in t,cmpcmt,urcs sccrrls not large enough to cxplain t,llc disagrccrrlcnt, in t,hc val~lcs of Iq,(\:.36); and tllcrc is no apparent reason t,o prefer t,hc val~lcs fiorn Kirn et (11. over t,llosc of Rohoiich. Tllcrcforc an iinn~cigllt,ctl axrcmgc of t,hc four val~lcs is pcrforrncd. giving:

log,, I ~ , ( 1 7 . 3 6 ; 298.15 K) = 1 6 . 7 f 1.1

~vhcrc t,hc ~lnccrt,ainty has bccn assignctl t,o cover the rnaxirniim rarlgc of expectancy. Tllc Gihhs cncrgy of formation; is tlcrivcd to i)c

AfGm(.k~n2(C0j),j , cr. 298.15 K) = ( 2 9 7 1 . 7 * 15.8) k.J . mol-l

It shonltl he mcrlt,ioncd t,llat the sol~lhilit,y constant. log1nh ' , j ( .35) =

log1,(I ' , ( .36) X 1 ) = ( 3 . 6 8 * 0.08); dct,crrrlincd by t,llis rcric\v from t,hc tlat,a of Shiloh, Givon and IIarc~ls [69SHI/GI\'] (cf. .kppcndix -4). tliffcrs from t,hc val~lc oh- taincd nrit,h the sclcctcd cqiii1il)riiim const,ant,s: log1,(h'~,,(\~.36) X 9;) = ( 1 . 5 f 1.3). Ho~vcvcr. as mcrlt,ioncd above, it is not possil)lc from the tlat,a in [69SHI/GI\:] t,o concliidc \vith confidcrlcc nrhich is t,hc solid phase in cquilihri~lrn.

Tllc cqnilibrinrn const,ant at 298.15 K for the rcactiorl

Figure \'..12: Calc~llatcd sol~lhilit,y and prcdorrlinarlcc arca diagram for t,llc arncriciiirn(II1) hydroxitlc-carbo11;1,t,c syst,crn in t,llc range G 5 pH 5 10.5 as a fiinctiorl of the C02(g) partial prcssiirc. at I = 0 and 25°C. Soliil)ilit,y lirrliting phases arc irldicat,cd on t,hc graph.

[Aln],.,,. = 1V6 M

0

-1

log,, Pro,

-2

log,, (L",

may bc calciilat,ctl from the aiixiliary dat,a in Chapt,cr 111, and the ~ ~ a l n c s of log,, lq,(\'.36) and log,,';li,;o(\'.33):

log,, I<';(17.37.298.15K) = 0.4 * 1.8

~vhich rcsnlt,s in a C02(g) cqiii1il)riiim partial presslire for the cq~lilihri~lrn i)ctn~ccn the t,~vo solids in rcact,ion (\'.37) of p(:(,, = (0.16 * 1.2) bar. This ~ralnc is consist,crlt, with t,llc cxpcrimcrlt,al ol)scrvations in Rcfs. [91IIEI/KIII2; 92RUN/hIEI] and ~vit,ll the concliisions of \"it,orgc [92\TT].

Tllc lirrlit,~ cst,al)lishctl by t,llc val~lcs of log,, I<';(\"(\;37) and log,, 11;:(\'.34) arc sho\~rn in the prcdorrlinarlcc arca diagram in Figiirc \'.l2 for a total arncrici~lrn(III) conccn- tratiorl of 10-" hI in tlilntc soliit,ions at 298.15 K. Tllc soliil)ilit,y of arrlcriciiim under sirrlilar conditiorls is sho\~rn in Figure \'..13.

Kcllcr arltl Fang [69KEL/F.%X] invcstigat,cd t,hc t,hcrrnal dccomposit,ion of synt,hct,ic NaA~~n(C0: j )2(s) and N:1,:~.4rn(CO:~):~(s). Xo t,hcrrrlodynarrlic tlat,a arc availahlc on the last solid.

Figure \.'.13: Calcnlat,cd solubility diagram for t,llc amcricinrn(II1) hytlroxidc- carl)onat,c syst,crn in t,llc rarlgc 5 5 pH 5 11 and 8 5 log,,pc:o, 5 0, at 25°C arld st,arltlartl condit,ions (I = 0).

Scvcral piil)lications have appcarcd nrit,h val~lcs for t,llc soliil)ilit,y protl~lct of NaAk~n(C0:j)2(s) [85KIhI. 85KIhI2, 8GAk\.'O/BIL]. cf. Table I7.1G. Thcsc val~lcs arc based on sol~lhilit,y cxpcrirrlcnts pcrforrrlcd by \"it,orgc [84\.'IT]. H o \ ~ ~ c ~ ~ c r , t,hc cxpcrirrlcrlt,al dctails have not appcarcd in the open lit,cratiirc. Robo~lch [89ROB] characterised this solid by X-my difiact,ion in sorrlc of his cxpcrimcnt,~. but not crloiigh dct,ails wcrc given t,o allo\v a re-cvaliiation of his tlat,a (cf. -4ppcntlix .l). Due to the lack of cxpcrimcrlt,al dctails rrlcnt,ionctl above. a ~ra111c for the soliil)ilit,y prodiict of NaAk~n(C0:j)2(s) car1 not he rccorrlrrlcndctl by t,llis review.

Schiiltz and Pcrlrlcmarl [86SCH/PEN] list,cd t,llc arncriciiim solids rcport,cd in the lit,cratiirc. and TVcigcl [851VEI] (lid a crit,ical and cxllaiist,ivc rcric\v of the .km(\') and .4rn(I7I) carl)onat,c solids, ~vhich can i)c siimrrlariscd as follo\~rs:

Pcntavalcnt amcricinrn:

1. IIo~lo-cnrbo~lat,c solids of t,hc t,ypc l\l.km02CO:j(cr) (~vhcrc Af = KE(; Rh; CS, YHA) display a hexagonal syrnmct,ry, spacc group CGIrnrnc, rr = (5.10* 0.02) X 10-l' m, (: = (11.0 * 0.7) X 10-l' rn.

2. K:j.4rr102(C03)2(~) is a t,an prccipit,at,c fornlcd i11 3.5 I1 K2COt3 arrlcriciiim soliit,ions oxidised ~vit,ll ozone.

3. Tri-carhonatcs ~\f~.4n~02(C0:j) : j (s) (whcrc Af = KE(; CS; NH4) have also hccn reported, no cryst,allographic parnrrlct,crs arc avai1al)lc.

Hcxavalcnt amcricinrn: N~1,2i-2(.4rn0~+)(C(l:j)r of iinkno~vn stoichiornctry is readily forrrlcd ~vhcn adding rrlct,llanol t,o an Ak~n(\'I) 0.1 I1 YaHCOt3 solution. Sirrlilar prccipit,at,cs n7crc oht,aincd with Ca. and Ba cat,ions; l)iit no st,oichiomct,ric, or crystallogmphic tlat,a have hccrl rcport,ctl.

hlorc rcccnt,ly Giffiut and \'it,orgc [93GIF/\'IT] have st,udicd t,llc soliil)ilit,y of "lAkrn in 0.1 and 4 11 NaC1 solutions at 21°C. Tllc larger sol~lhilit,y in t,llc con- ccrltrat,cd cllloridc sol~lt,ions urns irlt,crprctcd as the mtliolyt,ic oxitlat,ion of .km(III) to Ak~n(\'); and t,llc soliil)ilit,y curre at 4 h1 NaC1 was int,crprct,ctl \\,it11 the follo~ving soliil)ilit,y cqiii1il)ria:

for ~vhich t,llcy report log," li,;o = ( 1 0 . 5 * 0.3). Giffaiit and I'itorgc also clairncd the formation of t,~vo .$m(\') carl)onat,c corrlplcxcs (.l\rn02CO: arltl . k r n ~ ~ ( C ~ : ~ ) ~ - ) . Ho~vcvcr. owing t,o t,llc lack of dct,ails in Ref. [93GIF/\'IT]. the rcport,ctl sol~lhilit,y const,ant car1 not bc credited in t,llis review; cf. .kppcndix -4.

C21ialit,at,ivc informat,ion on the irlt,cract,ion l)ctn~ccn arncrici~lrn(III) arltl cyanitlc ions was provided by Ciiillcrdicr et al. [77CUI/IIUS; 81CUI], ~vho report loglo PI % 4 at,

I = 5 hI and 25°C \vithont giving any cxpcrimcrlt,al dct,ails. hIorc cxpcrirncntal work is nccdcd t,o confirm t,llc cornposition and st,abilit,y of t,llc cornplcxcs forrncd. Xo ~ralnc can bc rccorrlrrlcndctl for this syst,cm.

Tllcrc arc scrcml scparat,ion proccdnrcs of lanthanoid arltl act,inoitl clcrrlcnts in aqiic- 011s t,hiocyanat,c mctlia. Ho\vcvcr, xrcry few direct cxpcrimc~lt,al dct,cr~rlinat,ions of the thcrrnodynarnic valiics of t,hc arncrici~~rn(III)- t l~io~;ya~~i~~t~c system lla~rc bccn rcportcd; and no critical compilations of tllcsc tlat,a sccm to exist,.

A%~ncriciiim complcxation by t,hiocyanat,c is qnit,c ~vcak; arltl it,s stiidy requires largc conccnt,rations of t,hc t,hiocyanat,c ligand. Thcrcforc. largc i)ackgroiind clcctrolyt,c corlccntrat,ions lla~rc been iiscd in ortlcr t,o kccp actirit,y cocficicrlt,~ nearly const,ant,. hIost invcst,igat,ions have i)ccn pcrformctl i)y solvent cxt,ract,ion using 1.0 or 5.0 hl NaSCN/XaC104 aqncoiis solutions. lIorloniiclcar species, such as .%mSCN2+, .%m(SCN);. .%~n(ScX):~(aq) and .$m(SCN),, have bccn snggcst,cd t,o irlt,crprct the different cxpcrirncntal rncasiircrncnt,s. according to:

( 3- n ) .%rn3++r, S C N + . $ I ~ ( S C X ) ~ . (1.38)

Table \'.l7 prcscnt,~ all t,hc st,ai)ilit,y constants (gl; 12, p:j and h,) rcport,ctl in the lit,- crat,llrc and t,llc cxpcrirncntal dct,ails: t,crnpcratiirc. pH, ionic mctlia and t,llc t,cchniqllc nsctl for t,llc invcstigat,ions. Ilk rlot,c t,llat Ref. [70KIN/CHO] is only a preliminary rcport of t,llc st,~ltly in [74KIN/CHO]. It slloiild be not,ctl that some authors rcport,cd the prcscrlcc of only .%rnSCN2+ and .%rn(SCX): (motlcl "[Il; 92") [65CHO/KET, ilH.%R; ilKHO/N.$R, 72H.$R/PET2, 74KHO/hI.%T]; \vhilc ot,hcrs rcport,cd that t,hc cornplcx .%rn(SCX): is 11cgligii)lc arltl irlt,crprctcd their dat,a assiimirlg t,hc forrrlat,ion of . % I ~ ( S C N ) : ~ ( ~ ~ ) (model "pI, p:j") [64SEK. 65SEK3. 74KIN/CHO] t . Hcncc. t,hc direct, corrlparison of st,abilit,y constants rcportcd in t,llc litcratiirc is hindered by t,llc fact, that cit,hcr or as not calcnlat,cd in several cases.

Tllc solrcnt cxtractiorl cxpcrimcrlt,~ pcrforrrlctl by Choppin and Kct,cls [65CHO/KET], display a tcrrlpcrat,llrc tlcpcndcncc opposit,c t,o t,llat rcport,ctl in later publicat,ions [72H.$R/PET. 74KIN/CHO]. Thcrcforc, t,llis work was not considcrcd by t,llis rcric\v.

Khopkar arltl Naraynnankiit,t,y [71KHO/X.%R] and Khopkar and hIat,ll~lr [i4KHO/lI.%T] st,udicd t,llc .%m(III) SCN- system; usirlg dinonylnapht,halcnc siilpho- nat,c liqnitl ion cxchangcrs. The variat,ion of t,hc dist,ribntion cocficicrlt ~ J S . [SCN-] was intcrprct,cd assllrning t,llc prcscrlcc of .%mSCN2+ arltl .%rn(SCX): complcxcs. Rc- analysis of the dat,a sllo\~rs t,llat a i)ctt,cr fit is obtaincd assllrning t,llc formation of . % I ~ ( S C N ) : ~ ( ~ ~ ) , inst,cad of .%rn(SCX):. Tllc complcxat,ion of arncricillrn by t,lliocya- nat,c ligarltls is rat,hcr weak and the tlct,crrrlinat,ion of t,llc st,abilit,y constants is very scnsit,ivc t,o changcs in t,hc chemical model. This rcvic~v considers that t,llc work of Khopkar et al. cvidcrlccs only t,hc cxist,cncc of .%rnSCN2+.

t It sl~ol~lrl t)e not,ecl horrever. t,klat r%-llile Kir~arrl arlrl Choppin ['74KIN/CHO] 11ser1 the .'(jl. Dai' rrlorlel t,o interpret tlleir rlat,a. tllejr only report,ecl rrallles of il.

Tahlc \''.l?': Expcrimcrlt,al cqllilihrillrn const,ant,s for tllc arncrici~lrn(III)-thiocyanat,c syst,cm.

hle tho~l Ior~ic 11H t log,, B1 lc)gl0 log,, ,& Referer~ce \~erli l lrn(~) ("C)

Tahlc \".l7 (continnctl)

hIet,l~orl Ionic pH t l o g l ( 1 log,, log,, (j:3 Referer~ce \ l e r l i~~ rn (~ ) ("C)

clis 5.0 RI NaC104 3.0 10 0.42&0.02 [74KIN/CHO] 25 0.60&0.05 40 0.68&0.02 55 0.72&0.02

(a) .i significant arrlo~lr~t of t,lle arlior~ in the l)ackgro~mcl elect,rolyt,e \%-as s ~ ~ I ) s t i t ~ ~ t e d I)$ S C N in tllese st~lrlies.

(I)) \:>L~IIPS c~rrected t,n I = 0 11si11g Dtxvies eq~lation. (c) Sekirle [64SEK. 65SEK31 reports log,, (j4 = 0.00 & 0.15

((i) \:>L~IIPS rligitisecl 11~7 illis review frorr~ Figure 12 and Figure 7 in Refs. [ i lHAR. 72HAR/PET] respect,ively (81. (j:3 rnorlel).

(P) \:>L~IIPS rligitisecl t)y t,k~is review frorr~ Figure 3 in Ref. [74KHO/hIiiT].

Harrrlon et al. [7lH.%R; 7%H.%R/PET] ohscrrctl t,hc spcct,ral chnrlgcs in t,llc 503 nrrl nrncricinrn al)sorpt,ion bnntl produced by SCN- cornplcxnt,ion. Tllc authors calc~l- lat,cd t,hc forrrlat,ion constant of .%rnSCN2+ and .%rn(SCN); fiorn t,llc spcct,rnl dnt,n. This rcvic~v corlsitlcrs that. l)ccaiisc of t,llc scatt,cring in the dnt,n, no rclinhlc concl~l- sion on t,llc cxistcncc of .%rn(SCY): and/or .4rn(SCN):3(aq) car1 he cxt,mct,cd. Hcncc. the st,al)ilit,y const,ant,s oht,aincd by Harmon et al. frorn their spcct,ropllot,omct,ric mca- siircrrlcnt,~ arc not acccpt,cd hcrc.

Chiarizia et o,l. [73CHI/D.%Y] st,~ltlicd t,hc cornpctit,ivc corrlplcxnt,ion in NH4SCY/- NH1N(I3 rrlcdin nrltl int,crprct,ctl t,llc t,lliocyanatc syst,cm assnrning t,llc forrrlat,ion of .%1nSCN2+; .%rn(SCY): and .4rn(SCN):3(nq) cornplcxcs. The rcsiilting spcciat,ion diagram irltlicnt,cs t,hnt, .%mSCN2+ and .%m(SCN):3(aq) arc t,hc prcdorrlinnrlt species. ~vhilc .%1nSCN2+ ncrcr cxccctls 5%'. This cont,radict,s all other cxpcrirncnt,al cvidcncc. nrltl thcrcforc. t,llc rcport,cd st,nhilit,y const,ant,s (logloi/,) arc disrcgnrdctl by t,his rcvic\v.

Lcl)cdcv and l\lakovlc~~'s ion cxcllangc st,~ltly [62LEB/Y.%K]. and Sckinc's [64SEK, 65SEK31. Kinard and Choppin's [74KIY/CHO] solvcrlt cxtractiorl cxpcrirrlcnts clearly cvidcrlccd t,hc cxistcncc of the .%rnSCN2+ nrltl . % I ~ ( S C N ) : ~ ( ~ ~ ) complcxcs. at high ionic st,rcngtll (I = 5 M). -4s the specific ion intcract,ion cqnnt,ions arc valid up t,o I zz 3 11, the corrcsponding st,al)ilit,y const,nrlt,s arc not cxt,rapolnt,ctl t,o zero ionic st,rcngt,h, nrltl tllcrcforc t,llcsc ~ ~ a l n c s arc not sclcct,ctl in t,his rcvic~v. c ~ ~ c n t,lloiigh t,llcy arc considcrcd rclinhlc.

A%t lo\vcr ionic strength (I 5 1 11) t,llcrc is sorrlc cxpcrimcrlt,nl critlcncc sho~ving the cxist,cncc of sorrlc ~vcnk corrlplcxcs .%rn(~cY)f-") ~vit,ll n > 1. l)iit rrlorc cxpcrirncrlt,nl work is ncctlcd t,o confirrrl t,hc st,oichiomct,ry of t,hc species formctl. Hcncc. the val~lcs of and p:3 rcport,ctl in t,hc lit,crat,urc at I 5 1 11, cf. Table I7.17, arc tlisrcgardcd by t,llis rcric\v, nrltl t,hc corrcsponding st,al)ilit,y corlstnrlt,~ arc not sclcctcd.

A%t,tcrnpt,s t,o invcst,ignt,c the formnt,ion of higher order t,lliocyanatc cornplcxcs, using tribntylphosphnt,c or q~lat,crnary amirlcs as cxt,ract,ing agcnt,~. indicated t,hc prcscncc

Tahlc \".18: Lit,cmt,urc rcvic\v of t,hc thcrmotlynarnic filrlct,ions for t,llc .%rn(III)- thiocynnat,c systcrn.

I t 1%1, D; &Glll 1, H,,, 4, S,ll Rrfrrrr~cr (RI) (.c) (kJ . rr~ol-l) (kJ . 11101-') ( J . K-' . rnol-l)

of aniorlic species .%rn(SCN); [64SEK. 65SEK3, 74KIN/CHO], but no rclial~lc st,n- bilit,y const,ant,s have hccn reported.

Tllc vnliics for the cqililihriilrn constant for .%mSCYW +lct,crrrlinctl at I = 0.5 11 by Lcbctlcv nrltl l\lakovlc~r [62LEB/YAkK] and at I = 1 h1 by Hnrrrlon et 111. [ilH.kR; i2H.%R/PET] and Khopkar e t d. [ilKHO/N.%R. 74KHO/hI.%T] arc cxtrapolat,cd t,o zero ionic strength (cf. .kppcndix -4) \vith t,hc specific ion int,cractiorl cqnnt,ions of .kppcndix B using = ( 0 . 1 5 * 0.05) kg . rnol-'. Tllc iln\~~cight,cd axrcmgc of the cxt,rnpolnt,ctl ~ ~ a l n c s yields:

Tllc Gil)l)s cncrgy of forrrlat,ion is dcrirctl t,o he

&Gm(.krnSCN2+, aq, 298.15 K) = ( 5 1 3 . 4 * 6.4) k J . rnol-'.

Table \'..l8 presents n litcratiirc rcric\v of thcrmodynarnic fiinctiorls for t,llc forrrlatiorl of .%mSCN2+, .%rn(SCN):, and .k~n(SCY):~(aq) complcxcs. -4s rrlcnt,ionctl earlier; t,llc stiidy of [65CHO/KET] is disrcgartlcd 1)y t,his rcvic~v bccansc it,s oppo- site t,cmpcmt,urc tlcpcndcncc of PI. Tllc cnt,halpy changes obtaincd in .%ppcndix .k

Tnhlc \".19: Str~lct,~lrnl tlat,a for amcricillrrl silicidcs

Phase Synnnet,ry Space Groiq) Iso-type Cell Parameters Co~npoi~n(l / (10-In ln)

from t,hc cqiii1il)riiirn const,nrlt,s dct,crrrlincd a t I = 1 LI by Harrrlon et o,l. [ilH.%R; i2H.%R/PET] and by Khopknr and Llathiir [74KHO/LI.%T] yicltl the follo\ving val~lcs:

1,H;(I7.38.r, = 1.I= lL1.29815K) = (5.5*7) k.J.rrlol-l

1,S;(I7.38. r, = 1. I = 1 LI. 298 15 K) = (23 * 27) J . K-' . rrlol-l

Extrapolat,ion of tllcsc cqllilihrillrn const,ant,s t,o I = 0 nccordirlg to t,llc cqnnt,ions of .%ppcndix B, f o l l o \ ~ ~ d by a \~,cight,cd linear rcgrcssion ,'ln ill 71s. 1/T(1C1)" const,rnincd with the sclcct,ctl ~ralnc of log,, p," = 1.3; n~ollld lead t,o t,llc follo\~.ing st,andard val~lcs a t 298.10 K: A,H;(\:.38, n = 1) = (10 * 12) kJ . rnol-' and 1,S;(\'.38. rr = 1) =

(G0 * 40) .J . I<-' . mol-l. Ho\~rc~~cr, t,llis rcric\v tlocs not rccorrlrrlcnd t,llcsc val~lcs bccn~lsc of t,llc iinccrtaint,y in t,hc infliicncc of t,cmpcrat,~lrc on actirit,y cocfficicnt,~.

V. 7.2. Silicon corralio'i~,nrls cxrrci corn,plezes

TVcigcl et o,l. [84TVEI/IVIT] lla~rc prepared t,llc four silicidcs of arncricillrn given in Tahlc 17.19. Tllc snrnplcs wcrc prcpnrctl by t,hc rcact,ion of "1.4rnF:j(cr) nrltl silicon in alnrnina crncil)lcs at 980 - 1200°C in vacllo. by t,llc follo\ving gcncrnl reaction:

Inhorrlogcnco~ls sarnplcs nrcrc re-anncalctl in vacno a t 1000 - 1200°C. The silicidcs wcrc charact,crisctl by high t,cmpcmt,urc X-ray diffi.nct,ion up to 900". Insnfficicnt

irlformnt,ion was oht,aincd to tlm\v a rclial~lc phnsc tliagmrn. l)iit all four silicidcs wcrc rcportcd t,o rrlclt l)ctn~ccn 1173 and l273 K; ant1 n possil)lc phase t,mnsforrna- tion in .krnSi(cr) urns ohscrrctl bct,~vccn 813 nrltl 943 K. Tllc phase relationships in the .km-Si syst,crn arc tlliis very sirrlilar t,o those in t,llc U-Si nrltl Pii-Si syst,cms. Tllc .4111Si~.~+~(cr) is probnhly a single phnsc region cxt,cnding from .k~n~Si :~(cr) t,o . k ~ n : ~ S i ~ (cx).

V.72.2. Aq?reo~r.s ixrrael.ici'i~,vr silicates

No t,hcrrnodynarnic data have l)ccn rcportcd in t,llc litcratiirc on nrrlcriciiim silicat,~ corrlplcxcs in aqiicolls solllt,ion nor have any species hccn dcrnonst,ratcd. Bccansc of n lack of data, t,llc t,rixi~,lcnt lanthanoids car1 not i)c nscd for gnitlancc. Cornplcxcs of the for111 F ~ s ~ o ( o H ) ~ + nrcrc prepared \vith t,rixi~,lcnt iron [71POR/\VEB].

V. 72.3. Solid arnerici?rrn silicn,te conl,po?rrads

Ikry lit,t,lc has bccn rcport,cd on silicat,~ cornpounds of arncrici~lrn. .4rnSi04(cr) urns rcport,ctl by Kcllcr [63KEL. 67KELI as having n t,ct,ragorlal st,rnct,urc \vit,ll t,llc llrlit, cell pnrnrrlctcrs n = 6.87 X 10-l' nrltl c = 6.20 X 10-" rn. Ho\~~cx~cr, t,ct,mvalcnt, .km is iinlikcly t,o i)c of irnport,ancc in nnt,ural aqiiat,ic syst,crns. High-t,crnpcratiirc solid st,nt,c rcact,ions in t,llc .krnnl-oxitlc-Si02 syst,crn car1 lcntl t,o cornpounds of the for111 .4rr19.:i:300.1i7(Si04)602(~r) (~vhcrc stands for vacancies in t,hc cryst,nl lat,t,icc) nrld .km8(SiOli)2(cr) [79.4LL]. sirrlilar to t,llc corrcspontling lnrlt,hnrloid cornpo~lntls. Tllc forrrlcr arc st,nt,ctl t,o cryst,nllisc nrit,h t,llc hcxagonnl apatite t,ypc of st,rnct,urc as do the polyoxidcs ~~~f1.krn9(Si04)li02(cr) and 1 \ l " . k r n ~ ( S i 0 ~ ) ~ O ~ ( c r ) . Bccaiisc of the similarit,!. in chemical bchavio~lr hct,\~~ccn t,hc t,rivalcnt act,inoids and lanthanoids, one 1vo111tl cxpcct nrncriciiim(II1) t,o forrrl n vnrict,y of corrlpoiinds nrit,h silica as tlo the rarc cart,lls [8GGSC/EYR]. Rare cart,h tlisilicatcs prccipit,nt,c as n gel fiorn soliit,ions of rarc cart11 cllloridc and silicic acid [77BOC/CH.k]. No data arc ax7ailal)lc on the soliil)ilit,y const,ant of any nrrlcriciiim silicnt,c cornpo~lntls.

Crystallogmphic informnt,ion for .krnGc04(cr) is giver1 in Table \:.6

V.8. Group 13 compounds

Crystallogmpllic informnt,ion for .k1n.410:~(cr) is given in Tal)lc 17.6

Tllc cxist,crlcc of T1.4rn(S04)2 . .TH~O(S) and T18.k1112(S(j1)7(~) has IICCII reported by l\lakovlcv nrltl Kosynkov [58YAkK/KOS] (cf. Scct,ion 17.5.1.2.2). No tl~crmotlynamic dat,a has hccn rcport,ctl on t,hcsc cornponnds.

V.9. Group 9 compounds

Fctlosccva ant1 B~ul:x,nt,scva rcport,ctl t,hc synthesis of t,hc arncrici~lm(\:) sulpllix,ttc compoiind Co(NH:3)6.%~n02(S04)2 .2H20(s) [89FED/BUD] (cf. Scctiorl \:.5.1.2.2). Xo thcrrnodynarnic tlat,a has hccn rcport,ctl on t,his cornl>o~lntl.

V.lO. Group 6 complexes

Crystallogmphic informat,ion for t,llc rno1yl)datcs and t,llrlgst,at,cs of arrlcricilim arc give11 in Tahlc \".6.

Tllc st,al)ilisat,ion of .$rn(I\:). .%m(\:) and .%m(\:I) by pllospllot,~lrlgst,nt,c ions in aqiic- 011s solutions is tlisciissctl in Scct,ion \'.6.2.1.3. p.144. In addit,ion. colnplcxcs of :lm(III) a,11<1 Am(I1:) \vit,l~ the anions TT:loO:~ ; P\T:~~O:; , . and Si\Vl,O:; arc mcn- tioncd in [89YUS; 89YUS/FED]. No t,hcrrnodynarnic data can l)c sclcct,cd for any of these systems.

V . l l . Group 5 complexes

Crystallogmphic informat,ion for t,llc t,crnary arltl q~latcrnary oxitlcs of arrlcriciiim arltl v:x,natli~~m, niolji~lm or t,:xnt,:x,lum arc given in T:\l)lc V.6.

V.12. Group 4 complexes

Crystallogmphic information for t,llc qllat,crnary oxidcs of arrlcriciiim and t,it,arliiim arc given in Tahlc 17.6.

V.13. Actinide compounds and complexes

Bart,schcr arltl Sari [83B.%R/S.$R] have rncasiircd t,llc oxygen pot,cnt,ials in Uo.s.%mo.sOa+x(cr) for bot,h hypo- and 11yl)cr-st,oichiorr~ct,ri<; oxides. 1.87 5 O/(U + .%m) < 2.09. hct,wccn 873 ant1 1573 K 1)y ccpilihrat,ion \\.it11 CO(g)/C02(g) and H2(g)/H20(g) mixt,urcs. Tllcsc rcsnlt,~ have been llsctl to dcrivc partial rrlolar crlt,llalpics and crlt,ropics of dissolllt,ion of oxygen in the oxitlcs (prcscnt,ctl only in the for111 of plot,s). The rcsnlt,~ arc cornpared t,o t,hc sirrlilar U-PII-O and U-Cc-O syst,cms [83BA%R/S.4R].

V l . 1 2 . Otlrer terrrcxry o,nrl qucxte~raary ozirles

Crystallogmphic inforrnat,ion for t,llc t,crnary arltl q~latcrnary oxitlcs of arrlcriciiim arltl prot,act,ininrn arc given in Tal)lc 17.6.

Tllc t,cndcncy of act,inidc(\') cations, IIO:, t,o int,cract \vit,ll certain cat,ions (rnost,ly rnliltichargcd) has bccn t1cscril)cd in Inany pnblicnt,ions using an array of tcchniqiics. rnainly al)sorpt,ion sl)cct,rophot,ornctry. prot,on spin rclaxat,ion, potcntiornctric t,cch- niqiics arltl Ramarl spcct,roscopy. Thcsc irlt,crnct,ions have bccn rcric\vctl by Grcntllc et al. in t,hc iiraninrn YE.%-TDB revie\\, [92GRE/FUG], nrhcrc it is not,ctl t,hat all rc1cxi1,nt stiidics before 1977 \\,ere cxt,cnsivcly rcvic\~rctl in Ref. [iSFRO/Rl-K].

Complcxcs of -4rnO: \vit,ll CO;+ arltl N ~ O ; +

wcrc rcport,ctl [81GUI/HOB. 82GUI/BEG] for I = 10 hI (pcrchlorat,c) arltl in rncdia of variable ionic strcngtll for t,hc species .4rnO:-UO$+. .%S discllsscd by Grcntllc et 111. [92GRE/FUG]; no dat,a can i)c rccomrrlcndcd for t,hcsc cat,ion associat,ion reactions.

V.14. Group 2 (alkaline-earth) and group 3 compounds

Crystallogmphic informat,ion for .%mS~O:~(cr) and for t,llc t,crnary and qnat,crnary oxidcs of arrlcriciiim arltl t,hc alkaline-earths arc given in Tal)lc \'..G.

V.15. Group l (alkali) compounds

V. 15.1. Trrrrcxry arad qucxte~raary ozirles

Tllc only t,hcrrnodynarnic dat,a for t,llc t,crnary oxidcs arc t,llc cnt,llalpics of forrrlat,ion of t,hc pcrovskit,c-t,ypc cornpollrltls Ba.%mO:3(cr) and Sr.%mO:3(cr). as discnsscd in Scctiorl \'..3.2.6. Cryst,allograpllic inf~rrrlat~ion for tllc ot,llcr t,crnary and qnat,crnary oxidcs arc given in Table \".6.

.% tlisciission on t,llc t,crnary flnoritlcs Li.%rnFS(cr). Yai..%~n(~F:jl(cr) and Rb2.%rnF~(cr) is presented in Scct,ion \'..4.2.2.6.

V.15.3. Terrrcxry arad qucxte~raary chlorides

.% discllssiorl on t,llc t,crnary chlorides Cs.4rnC14(cr), C ~ : ~ . % ~ r l C l ~ ~ ( c r ) ~ 1l~f~.4rrlCl~(cr) (AI = K. NH4, RI)) and t,llc qllat,crnary cllloritlc C~~Yn.%mCl(~(cr) is prcscnt,cd in Scctiorl \'..4.2.3.4.

Tllc cxistcncc of ~l ' f .%rn(SO~)~ . :r;H20(s) (nrit,h ~l'f = K. Rb and CS) as n~cll as K:3.%r~~(S04):j . H20(s) arid E(8.%mZ(S(j1)7(~) has bee11 rcport,cd by I-akovlc~~ arid Kosyakov [58Y.%I</KOS]. No t,llcrrnodynarnic dat,a has i)ccn rcport,cd on tllcsc cornpoiinds (cf. Scct,ion \:.5.1.%.2).

Ternary pllospllat,cs of .krn(I'I), I ~ I . % ~ I ~ O ~ P O ~ . . T H ~ O ( C ~ ) (\vitll 111 = I<, R1) arid CS) have hccn rcportcd by La~valdt et al. [8%L.%TV/hI.%R], cf. Scct;t,ion \:.6.2.%.2.

Ternary arscrlat,cs of .krn(I'I), ,\i.%mOa.%s0~ . .~HaO(cr) (\vitll ,\I = K, Rb arltl CS) have hccn rcportcd by La~valdt et al. [8%L.%TV/hI.%R], cf. Scct;t,ion \:.6.3.%.

Tllc .%rn(III) cornpounds N;~,.%rn(CO:~)~(cr) arltl Xa:3.%rn(C0:j):3(s); arc tlisciissctl in Scctiorl IT.7.1.2.2.c. The amcricinrn(I7) cnrbonat,cs: l\l.%mOaCO:3(cr). nrit,h 111 =

Na, K. Rh, Cr; I<:j.krn02(CO:3)2(s) and ~ \ l ~ . k ~ n O ~ ( C O : ~ ) : ~ ( s ) . \vit,ll ,\l = K and CS arc discllsscd in Scct,ion IT.7.1.2.2.d. ~vhcrc cari)onat,cs of arncricillrn(I'1) of nnkno\~rn st,oichiornctry arc also rncntioncd.

Chapter V1

Reference list

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[58BJE/SCH] Bje r r i l~n~ J.; Schwarzer~l)ach, G.> Si1li.n; L.G.; Stal~ility Const,arlts, Vol.1 8z 111 Lon(1on: Cllernical Society, 1958.

[58YAK/GOR] Yakovlev; G.N., Gort)el~ko-Grrlnar~ov~ D.S.; Zel~kova~ R.A., Razl~i tnoi~ V.M., Kazanskii; K.S.; A stildy of t,he (1oul)le sulfates of americium t)y means of their cryst,alline al~sorption spectra; Zhilr. Ol~schei K l ~ i n ~ . ~ 28 (1958) 2624 2637> in Rilssian.

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[GOLEB/PIR] Lel)e(lev; I.A., Pirozhkovl S.V., Yakovlev, G.N., Deterrnirlation of the composition ancl the il~stat)ilit,y col~stallts of oxalate; nitrat,e and sillfat,e complexes of Am"' all(1 Cm"' 11y the inetho(1 of ion exchange, Ra(1iokhi- ~n iya , 2(5) (1960) 549 558, ill Russian; Englisl~ trallsl.: pp.39 47.

[GOMOS/KHA] Moskvir~~ Kha l t i~ r in~ G.V., Gelnlar~, A.D., Illvestigat,iol~ of the colnplexing of trivalent americium in oxalate all(1 ethylene~iian~ine tetraacetate soli~t,iol~s 1)y the ion-exchange ~net,hocl~ Sov. Racliochen~.~ 1, 1 (1960) 69 76.

[61AKS/ERM] Aksrl'ril(1; N.V.> Erlm)lenkol V.I.> Hy(iroxi(1es all(1 1)asic chlori(1es of eu- ropiilnl; t,ert)ium, ancl hol~ni inn~ Russ. J. Inorg. C h e n ~ . ~ 6 (1961) 397 399.

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[61LEW/RAN] Lewis; G.N., Rall(ialll M.; Pitzerl K.S.> Brewer, L., Tl~ermo(lynanlics, 2nd e(i.> New York: McGraw-Hill, 19611 7231).

[GlMCW] M c W l ~ a l ~ , D.B.> Crystal st,ruct,ure am1 physical properties of arnericii~n~ ~net,al; Report UCRL-9695; Lawrence Radiation Lal~oratory, Berkeley, Californial 1961; 10011.

[GlPEN/COL] Pelnleman, R.A., Colenlal~; J.S., Keellal~; T.K., Alkaline oxi(1ation of americium: preparation all(1 reactions of Anl(1V) l?y(lroxi(1el J . Im~rg. Nilcl. Cllem.; 17 (1961) 138 145.

[GlPEP/MAS] Peppar(1; D.F.> Mason, G.W.> Hi~c l~er , I.> Stal~ility col~stant,s of certain lant,hani(le(III) and actinicle(II1) chlori(1e and l~it,rate complexes; Report TID-l4716 all(1 UAC-5777, 1961, 131).

[GlSTA/GIN] Starikl I.E.; Ginzl~ilrg, F.L.> State of rnicroan~oin~ts of ra(lioelen~erts ill dilute soli~t,iol~s; Ra(iiokhirniyal 3(1) (1961) 45 511 ill Russial~; E l~g l i s l~ transl. pp. 49 55.

[62DAV] Davies; C.W.> 1011 associationl Washillgtol~; D.C.: Bi~t,terwortl~s; 1962

[62GRE] Grellthe; I.> Chlori(1e colnplexes of tervalent americium, sllort comnnn~i- cation, Acta Chen~. Scan(1.; 16 (1962) 2300.

[62GRE2] Grellthe; I.> 011 t,he st,al)ility of the acetat,e, glycolate and tllioglycolate complexes of tervalert n~ rop i i l n~ and arnericiiln~; Acta Cllem. Scan(1.; 16 (1962) 1695 1712.

[62KRU/ASP] Kri~se; F.H.> Asprey, L.B.> A crystallil~e flm)ri(ie colnplex of tetravalert americium, Inorg. Cllem.; 1 (1962) 137 139.

[62LEB/YAK] Lel)e(lev; I.A., Yakovlevl G.N., Determination of the conq)osit,iol~ and inst,al)ility constallts of t,k~iocyar~ate complexes of Am(III), Cln(III), and Ce(II1) 1)y ion exchange; Sov. Ra(iioc11en1.~ 4 (1962) 273 275.

[62MCW/CUN] McWllal~; D.B.> Cinn~inghan~; B.B., Wallmann, J.C.; Crystal st,ruct,ure therlnal exl~ansiol~ and nleltir~g point of americium rnetall J. Im~rg. Nucl. Cllem.; 24 (1962) 1025 1038.

[62PEP/MAS] Pel)l)ar(i; D.F.> Mason, G.W.> Hi~cl~er , I.> Stal~ility col~stant,s of certain lant,hani(ie (111) alld act,il~i(le (111) clllori(1r alld nitrat,e conq)lexesl J. In- org. Nucl. Cheln., 24 (1962) 881 888.

[62VAS] Vasil'ev; V.P., Influence of ionic strellgtl~ on the installility constallts of complexes; Rilss. J. Illorg. Cheln., 7 (1962) 924 927.

[62WES/GRO] West,rum, E.F.; Jr., Gronvolcll F.; Chemical tllerrno(1ynanlics of the actinide elernel~t chalcogenicles, in: Tl~em~o(iyl~alnics of nuclear n~ater ia ls~ Proc. Synq). held 21 25 May, 1962; in V i e r ~ r ~ a ~ Vienna: Int,ernat,iol~al At,omic Energy Agellcy, 1962, pp.3 37.

[63CHO/UNR] Clloppin, G.R., Unreinl P.J.; Halide complexes of the lallthanicle ele- m e n t , ~ ~ J. Il~org. Ni~cl. C h e n ~ . ~ 25 (1963) 387 393.

[63FUG/CUN] F i~ge r~ J.; Cilnningharn, B.B., Heat,s of fornlation of Pu3+, Pi1C1:3(c), PitOCl(c), Anl"+> ~ l n C l : ~ ( c ) and AlnOCl(c), J. Illorg. Ni~cl. Cllem.; 25 (1963) 1423 1429.

[63KEL] Keller, C., Unt,ersi~clnn~gen iil~er (lie Gernlallate iln(1 Silikat,e cles Typs ABO4; Ni~kleol~ik, 5 (1963) 41 48, in German.

[64ASP/KEE] Asprey> L.B., Keenan> T.K.> Kruse, F.H., Preparat,iol~ and cryst,al (lat,a fix lant,hani(ie and act,il~i(le triiocli(iesl Im~rg. C h e n ~ . ~ 3 (1964) 1137 1140.

[64BAN/PAT] Bansal, B.M.L.> Pat,il, S.K.> Sharnla; H.D., Chlori(1e l~it,rate and sulpllate complexes of europiinn (111) ancl alnericiiln~ (111), J . Im~rg. Nucl. C h e n ~ . ~ 26 (1964) 993 1000.

[64IRV/KHO] Irving, H.M.N.H., Khopkar, P.K.> Tlle stal~ility of the chlori(1e colnplexes of ei~ropium, J . Inorg. Ni~cl. Cllem.; 26 (1964) 1561 1569.

Seki l~e~ T., Co111111ex for111ation of La(III)> Lu(II1) all(1 Am(II1) with oxalat,e, sulpllate, cllloricle ancl thiocyanate ions, J . Inorg. Nilcl. Cheln., 26 (1964) 1463 1465.

S l~ i loh~ M,> Mareus> Y.; Tlle chelrlistry of t,rivaler~t ~ ~ e p t i n ~ i i ~ n ~ pli~tonium all(1 americium ill hali(1e soli~t,iol~s; Report IA-924> Israel Atolrlic Energy Colnmissiol~, Sorecl Research Est ,a l~l .~ 1964; 261).

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Asprey> L.B.; Keellal~; T.K., Kruse, F.H.> Crystal s t r i~ct i~res of t,he t,rifli~- ori(les; trich1ori(1esl trit)ron~i(les; and tl.iio(licles of anlericiinn and ci~rium, Illorg. C h e n ~ . ~ 4 (1965) 985 986.

Clloppin, G.R.> Ketels; J . , Thiocyanat,e con~plexes of some t,rivaler~t lan- thanicle ancl actinide elemellts, J. Im~rg. Nilcl. C h e n ~ . ~ 27 (1965) 1335 1339.

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Keller, C.; Walterl K.H.> Darstellung, gittrrkollstant,en uncl chenliscl~e eiger~schaftel~ einiger terl~jirer oxide des pli~tonilims, americiiln~s iln(1 curi- illrls vonl typ Me"'X"04; J . Im~rg. Nilcl. Cheln., 27 (1965) 1253 1260, in German.

Sek i l~e~ T.> Solvent ex t rac t io~~ stil(ly of t,rivalent act,illide and lan~tl~al~i(le complexes in atlileoils soli~t,iol~s: I. Chlori(1e con~plexes of La(III), Eu(III), Lil(II1) and Anl(II1) in 4 M Na(C104); Acta Cheln. Stand.; 19 (1965) 1435 1444.

Sek i l~e~ T.> Solvent ex t rac t io~~ stil(ly of t,rivalent act,illide and lan~tl~al~i(le complexes in aqileous soli~t,iol~s. 11. Sillfate complexes of La(III)> Eu(III), LII( I I I )~ ancl Anl(II1) in 1 M Na(C104); Acta Chen~ . Scancl., 19 (1965) 1469 1475.

Sek i l~e~ T.> Solvent ex t rac t io~~ stil(ly of t,rivalent act,illide and lan~tl~al~i(le complexes in aqileous soli~tions~ IV. Tlliocyarlate colnplexes of La(III)> Eil(II1); Lu(III), and Am(II1) in 5M NaC104 soli~tions at 25'C, Acta Cllem. Scancl., 19 (1965) 1519 1525.

Stepanov, A.V.> Sl~veclov~ V.P.> Illvestigation of t,he l~yclrolysis of Ce(II1) 11y elect,romigration in nitrate soli~t,ions~ Rilssian J. Illorg. C h e n ~ . ~ 10 (1965) 541 542.

[66ACK/FAI] Ackermann, R.J.> Faircloth, R.L., Raiihl E.G.; Thornl R.J.> The evaporation 1)ehaviour of ~ ~ e p t i n ~ i i ~ n ~ (lioxi(ie, J. Im'rg. Ni~cl. C h e n ~ . ~ 28 (1966) 111 118.

[66ACK/FAI2] Ackermann, R.J., Fairclot,hl R.L., Rall(ll M.H.> A tllermo(1ynanlic stil(ly of the vaporization l~ehavior of the sul)st,oichiolnet,ric pli~t,oniinn (lioxi(1e pllasel J . Pllys. Cllem.; 70 (1966) 3698 3706.

[66BOR/ELE] Borisov; M.S.> Elesin, A.A., Lel)e(lev, I.A., Filirnonov, V.T.> Yakovlevl G.N., Illvestigat,iol~ of the complexing of trivalel~t actinides ancl lar~tl~al~i(les in phosphoric acid solutions, Sov. Ra(lioc11ern.; 8 (1966) 40 44.

[66BUR] Burnet,t; J.L., Melt,il~g 1)oillts of CnlF.3 and AlnF:j; J . Illorg. Nilcl. C h e n ~ . ~ 28 (1966) 2454 2456.

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[66GUG] Gi~gge l~ l~e i ln~ E.A.> Applications of statistical nlechanics, Oxford: C l a rendon Press, 1966> 2111).

[66MAR] Marci~s; Y.; Allion exchange of inet,al complexes-XV. Allion exchange alld anline extraction of lant,hani(ies ancl trivalent actinides fi-on1 chlori(1e soli~t,iol~s; J. Illorg. Nucl. C h e n ~ . ~ 28 (1966) 209 219.

[66NOR/STE] Norlillg, B.K.; Steinfink, H.; The cryst,al s t r i~c t i~re of neo(1ynium t,ritel- Ii~ricle, Im'rg. Cheln., 5 (1966) 1488 1491.

[660LS/MUL] Olsonl W.M., Mi~lfor(i; R.N.R., The alnrricii~n~-l~y(iroger~ syst,en~; J . Pllys. Cllem.; 70 (1966) 2934 2937.

[66VDO/KOL] V(lovel~ko; V.M.> Kolokol't,sovl V.B., St,et)ilnov, O.B., Relaxation processes ill complex forlnation. I. Copper ancl arnericiiln~ cl~loricles in aqile- 011s soli~t,iol~s; Sov. Ra(iioc11ern.; 8 (1966) 266 269.

[67CAR/CHO] De Carva111o; R.G., Chopl~i l~; G.R., Lai~thanicle alld act,il~i(le sulfate colnplexes: I. Deterlnillation of stal~ility col~stant,s, J . Im'rg. Ni~cl. C h e n ~ . ~ 29 (1967) 725 735.

[67CAR/CHO2] De Carva111o; R.G., Chopl~i l~; G.R., Lant,hani(ie and actinide sulfate colnplexes: 11. Deterlnillation of ther~m)(lynan~ic paralnet,ers, J. Inorg. Nucl. Cllem.; 29 (1967) 737 743.

[67CHI/EYR] Cl~ikalla~ T.D.; Eyrir~g, L.> Dissociation pressures ancl partial tllerrno(1y- llalrlic (li~al~tities fix arnericiiln~ oxides; J . Inorg. Nilcl. Cllem.; 29 (1967) 2281 2293.

[67CHO/KEL] Clloppin, G.R., Kelly, D.A.> Ward, E.H.> Tlle effect of cllallges in t,he iollic ~nediurn on the stat)ilit,y col~stant of E u ( N O : ~ ) ~ + , in: Solvent extraction chenlist,ry, Proc. Int. Conf. 11eld ill Gothent)i~rg (Swe(1e11) 1966 (Dyrssel~; D.> L i l j e n ~ i n ~ J . 4 . ; Ry(il)ergl J . , rtls.) Amst,er(lan~: Nort,h-Hollancll 1967, pp.46 49.

[67ELE/LEB] Elesinl A.A., Lel)e(lev; I.A., Piskumm, E.M.; Yakovlev, G.N., Conlplex fi)rmat,iou of an~erici inn~ ci~rium, and prolnet,hiinn wit,k~ trirnetaphospho- ric acid, Sov. Racliochen~.~ 9 (1967) 159 163.

[67KEL] Keller, C.> Tlle solicl-state cl~emistry of arnericii~n~oxi(les; in: Lantl~al~i(lr / . actinide chelnistry; Synq). 11eld 13 14 Sept. 1966; ill New Yorkl Advan. Cllem. Sex. No. ?l1 Washingtol~, D.C.: Anlericar~ Chenlical Society, 1967, pp.228 247.

[67MAR] Marci~s; Y., The soli11)ility of alnericii~n~(III) cl~loricle in concentrate(1 l i t l~ i i ln~ chlori(1e solutions, Ra(iioc11in1. Acts.> 8(4) (1967) 212 214.

[67NAI] Nairl G.M.> Americii~n~(III) sillfat,e colnplexes; Proc. Nucl. Radiat,. Cheln. Sylnl)., 11eld 6 9 March 1967; in Poona, Chenlist,ry Colr~rnittee~ Depart,. ~ n e n t of At,omic Energyl Goverlnnent of Ill(iia, ~111.405 410.

[67PEN/KEE] Pelnleman, R.A.> Keenan> T.K., Asprey, L.B., T e t r a and pentavalent actinide flm)ri(ie colnplexes, ill: Lant,hani(le/actir~i(ie cl~emistry~ Sylnl). 11eld 13 14 Sept,. 1966> ill New York, Advan. Cheln. Ser. No. 71; Washin~gtol~; D.C.: Americal~ Cllernical Society, 1967> pp.248 255.

[67RYA] Ryar~, J.L., Octahe(ira1 hexal~alicle complexes of the trivalel~t actini(iesl in: Lant,hani(ie/act,il~i(le chenlist,ry, Syrnp. help 13 14 Sept. 1966> in New York; Advan. C h e n ~ . Sex. No. ?l1 Wasl~illgton, D.C.: Anlericar~ Chelr~ical Society, 1967; pp.331 334.

[67WAD/WOL] Wade; W.Z., Wolf. T.; Preparation and sonle propert,ies of arnericiiln~ ~net,al; J . Inorg. Nilcl. Cllem.; 29 (1967) 2577 2587.

[68AZI/LYL] Aziz; A.> Lyle, S.J.> Naqvi; S.J., Cllenlical ecl11ilit)ria in arnericiiln~ and curiinn sulpllate ancl oxalat,e systelr~s ancl all application of a liquid scin- tillat,iou coilnt,il~g inet,hocll J. Illorg. Niicl. Cheln., 30 (1968) 1013 1018.

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[68BUR/ELL] Burnsl J.H., Ellisol~; R.D.> Levy, H., The crystal s t r i~c t i~ re of Na7ZrfiF31; Acta Cryst., B24 (1968) 230 237.

[68CHI/EYR] Cl~ikalla~ T.D.> Eyrir~g, L., Phase relationships in t,he an~ericiinn-oxyger~ systelr~, J. Illorg. Ni~cl. C h e n ~ . ~ 30 (1968) 133 145.

[68KEE] Keenan> T.K., Lattice col~stant,s of AlnOzF2(1)> Im~rg. Nucl. Cheln. Lett,., 4 (1968) 381 384.

[68MIL/BEA] Milligar~, W.O., Beasley, M.L., Lloycl, M.H.> Haire; R.G.> Crystallil~e americium trik?yclroxi(iel Acta Cryst,., B24 (1968) 979 980.

Nairl G.M., Americii~n~(III)-suilpl~atr colnplexes, Ra(iioc11in1. Act,&, 10 (1968) 116 119.

S tep l~ens~ D.R., S t r o n ~ l ~ e r g ~ H.D.> Lilleyl E.M., Phase (iiagran~; colnpress- it)ilit,y ancl resistance of arnericiiln~ as a f i~l~ction of pressilre; J . Pllys. Cl~em. Solids1 29 (1968) 815 821.

Aziz; A.> Lyle, S.J.; E(l i~il i l)r i i~n~ cor~starlts for ~(li~eouis fli~oro c0111p1exes of scan~li inn~ ytt,riinnl arnericii~n~(III) and ci~rium(III) t)y extraction illto (ii-2-ethylhexyl phosphoric acidl J. Il~org. Ni~cl. Cheln., 31 (1969) 3471 3480.

Barl~anel', YII.A.~ Mikhailova; N.K.> S t i ~ i y of t,he con~plex forlnation of A~I("') wit11 the C 1 ion in aqueoils solutions t)y the rnetho(1 of spectrophot,omrtry, Sov. Ra(iioc11ern.; 11 (1969) 576 579.

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Dksir4, B., Hussonm)is; M,> Gi~illainrn)n~t,~ R.> Dktermination (le la premiPre constal~te (i'l~y~lrolyse (ie l'an~t:riciiln~; (111 curiinnl (111 1)erkeliinn et clu cal- iforl~iiln~; C. R. Het)(l. Seal~ces Acad. Sci.; Ser. C; 269 (1969) 448 451, ill French.

G i ~ i l l a i ~ n ~ o l ~ t , R.; Ferreira (ie Miral~(ia, C., Galill; M,, Dktermination cle la premikre const,arlte ~l'hy(1rolyse clu c i~r i i ln~; C. R. Hel~cl. S4ances Aca(1. Sci.> Sex. C > 268 (1969) 140 143> in Frel~ch.

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M a r i r ~ ~ B.; Kikinclai; T. , Eti~(ie corn~)art:e (le l'hy(lro1yse (ie l'europiinn et, (ie l'arn4ricium en iniliei~ chlori~rt: pal. PlectrophorPse silr papier, C. R. Hel)(i. Skal~ces Acacl. Sci.> Sex. C > 268 (1969) 1 4; in Frencl~.

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S l~ i loh~ M,, Givon, M.; Mareus> Y., A spectrophot,ornetric s t i~dy of trivalent actinide complexes in soli~tions 111. Americiiln~ with l~romicle, io(licle, l~it,rate all(1 carl~onate l igan~ls~ J. Illorg. Nucl. Cllem.; 31 (1969) 1807 1814.

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Yal~ir, E.> Givon, M,> Marcils, Y.> Higher oxi(1atior1 st,ates of americiiln~ in phosphate soli~tions~ Im~rg. Nucl. Cllem. Letters; 5 (1969) 369 372.

Brandl J.R., Col)l)lel J.W.> The tl~ermo(iyl~alnic filnctions of neptilnium(V) all(1 ~ ~ e p t i n ~ i i ~ n ~ ( V I ) ; Inorg. C h e n ~ . ~ 9 (1970) 912 917.

Burnsl J.H.; Peterson> .J.R.> Refinen~ert of the cryst,al s t r i~c t i~re of AmC1:j; Acta Cryst., B26 (1970) 1885 1887.

Carrk; D.> Laruellel P.; Besanpll; P,, Crist,allocl~in~ie.- Strilctilre crist,alline (1e la prktel~(li~e variktk [j des si~lfi~res (1e terres rares (1e conq)osit,io11 PrloS140, C. R. Skances Hel~cl. Acacl. Sci., 270C (1970) 537 539, ill French.

Clli~(iinov, E.G.> Choporov, D.Ya.> Si~l~linlation of arnericiiln~ t,et,raflm)- ri(le; Sov. At. Energyl 28 (1970) 71 73.

Kinarc& W.F., Choppinl G.R., The t l~er~m)~lynamic of conlplexing of trivalent actinide ions t)y thiocyanat,e; Report TID-25671, Tallahassee; Flori(1a: Florida Stat,e Ulliversit,y, 1970> 131).

Lallr; H., Knocl~; W.> Bestirnnli~l~g von Stal)ilitit,skonstal~trl~ einiger Ak- tini(1enkomplexe: 11. Nitrat,. 1111(1 Chlol~i(ikolr1exe von Uran, Neptilnium, Plutol~ii ln~ 1111(1 An~ericiinn~ Ra(lioc11irn. Act,&, 13 (1970) 1 5; in Gernlal~.

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[7OMIR/POL] Mirom)vl N.N.> Polyashovl I.M.> Investigat,iol~ of the reaction for the for- lrlation of eurol~iinn l~y(lroxi(le; Russ. J . Illorg. Cheln., 15 (1970) 1 2.

[7OMIT/LAM] Mitchell; A.W.; Larn, D J . ; Crystal striict,ures of Aln-S l~~ Anl-Se ancl Aln- Te alloys near the e(li1iatolnic con~posit ion~ J. Nilcl. Mat,er.; 37 (1970) 349 352.

[7UMIT/LAM2] Mitchell; A.W.; Larn, D J . ; Tlle cryst,al st,ruct,ure of americium sestlilicar- l)i(le; J. Nilcl. Mat,er.; 36 (1970) 110 112.

[7USAR/ZAM] Sari, C., Zanloralli, E.> An investigatiol~ in t,he arnericiiln~ oxide syst,en~; J. Nilcl. Mat,er.; 37 (1970) 324 330.

[7UYAN/GIV] Yal~ir, E., Givonl M,, Marci~s; Y.> Direct (ietermination of the fornlal potelltial of the Anl(1V) Anl(II1) ancl Anl(V1) Anl(V) coilples ill pllosplloric acidl Inorg. Ni~cl. C h e n ~ . Lrtt,ers, 6 (1970) 415 419.

[71DAM] D a l r ~ i e r ~ ~ D., i v fi~rrn of arnericii~n~ ses(~i~is~ilfi(ie and americium im)m)sul- fi(lel Inorg. Nilcl. Cllem. Letters; 7 (1971) 291 297.

[71DAM/JOV] Dalrlier~~ D., Jove; J . , Americiiln~ disiilfi(1e ancl (iiselel~i(le; Im~rg. Nucl. Cllem. Letters; 7 (1971) 685 688.

[71GUI/DES] G i ~ i l l a i ~ n ~ o l ~ t , R.; Di.siri.> B.> Galill, M.> PremiPre const,arlte (l'l~y(lrolyse (ies lal~thani~les, Racliochen~. Radioanal. Let,tersl 8 (1971) 189 198> ill French.

[71HAR] H a r n ~ o l ~ , H.D., The t l~iocyal~ate al1(1 chloricle complexes of some trivalel~t actinides, P11.D. thesis ill inorganic chemistry, Urliversity of Telnlessee, Knoxville; Tennessee, ancl report ORNL-TM-3486, Oak Ridge Nat. Lab., Tennessee, 19711 1431).

[71 JEN] J e l ~ s e r ~ ~ K.A. (i:h(~rrrr(~rr)~ Nonlenclati~re of im~rganic chenlist,ry, 2nd HI.; IUPAC Colrlrnissiol~ on Nornel~clati~rr of Inorganic Cl~ernistry~ 0xfi)r~l: Pergalmm Press, 1971; 1101).

[71KHO/NAR] Khopkar; P.K., Nar;tyal~al~ki~tt,y, P.; Effect of ionic nleclia 011 the stabilit,y const,arlts of ch1ori(1el nitrate all(1 tlliocyallate colnl~lexes of arneri- ciinn(II1) all(1 euro~)iinn(III), J . Im~rg. Nilcl. Cllem.; 33 (1971) 495 502.

[71MOS2] Moskvir~~ A.I.; Investigation of the colnplex forlnation of trivalent 11111to- 11ii1n1; arnericiiln~; ancl c i~ r i i ln~ ill pllosphate soli~tions~ Sov. Racliochen~.~ 13 (1971) 688 693.

[71NUG/BAY] Ni~gellt, L.J.; B;tyl)arzl R.D.> Bi~rne t t ,~ J.L., Rya l~ ; J.L., Elect,ron tral~sfer all(1 f-(1 al~sorption 1)ancls of sonle lartl~ani(ie all(1 actinide colnl~lexes and the stan(lar(1 (111-IV) oxi(lat,iol~ pot,er~tials for each nlemt)er of the lan- thanicle all(1 act,illi(le series, J . Im~rg. Nlicl. C h e n ~ . ~ 33 (1971) 2503 2530.

[71POR/WEB] P o r k , R.A., Weller> Jr., The irteract,ion of silicic acid with iron(II1) and i~ r a l~y l ior~s i r ~ dili~te ~ ( l i ~ e o ~ i s soli~t , iol~s~ J. Inorg. Ni~cl. Cl~em.; 33 (1971) 2443 2449.

[71SIL/MAR] Sill611; L.G.; Martell, A.E., Stal~ility col~stant,s of metal-iou complexes; Si1pp1. No. 1; Special Pi1111. No. 25> Lon(1on: The Chelr~ical Societ,y, 1971, 8651).

[72BAI/CHO] Bais(lenl P.A., Clloppin, G.R., Kinarc& W.F.> 1011 pairing of Aln(II1) wit11 percl~lorate~ J . Il~org. Ni~cl. C h e n ~ . ~ 34 (1972) 2029 2032.

[72BAR/KOT] Barl~anel', YII.A.~ Kot,lin, V.P., Gorsky, A.G., I(1ertification of the octa- l~eclral con~plex ArnCl:; accor(1ing to the al~sorption spect,ra of Am(II1) in et,ham)l soli~t,iol~s of HCl, Doklacly Cheln., 202 (1972) 98 101.

[72BAY/ASP] Bayl~arz, R.D.> Asprey, L.B.; St,rouse, C.E., F i ~ k i ~ s l ~ i n ~ a ; E.; Divalent aln- ericiinn: T l ~ e crystal s t r i~c t i~re and rnagl~etic si~scept,il)ility of A d a , J . Il~org. Ni~cl. C h e n ~ . ~ 34 (1972) 3427 3431.

[72BUR/BAY] Burnsl J.H.> Bayl~arz, R.D.> Crystal s t r i~c t i~re of americium sillfat,e oc- tahy(lrat,e, 1m)rg. Cl~em.; 11 (1972) 2233 2237.

[72COH] C o l ~ e r ~ ~ D.> A~r~ericilim(VI) i r ~ 1)asic sohition, Il~org. Nucl. Cheln. Letters; 8 (1972) 533 535.

[72DAM] Dal r~ ie r~~ D.; An~ericiinn trit,elli~ri(le and (litelli~ri~le, Il~org. Nilcl. Cheln. Letters; 8 (1972) 501 504.

[72DAM/CHA] Dal r~ ie r~~ D.> Charvillat, J.-P.> Alnericiiln~ sest~i~itelli~ri~les, 1m)rg. Cheln. Letters; 8 (1972) 705 708.

[72DAM/MAR] Darnien, D.> mar col^; J.P., Jove, J .> The ''[j fi~rrn" of americium ses(li1isi11- pl~i(le; Il~org. Ni~cl. Chen~. letters; 8 (1972) 317 320.

[72EBE/SAB] Et)erle; S.H., Sat)ai~, C.S., The tl~ermo(lyl~alnics of Am(II1)-~~it,rilot,riacet,ic acid complexes; Ra(lioc11eln. Raclioal~al. Letters; 11 (1972) 77 87.

[72FUG] F i~ge r~ J .> Tl~ermo(lynan~ic propert,ies of sin~ple act,il~i(le compoi~n(ls, in: Lal~thani~les al1(1 act,il~i(les; MTP I l~ te r l~a t . Rev. Sci.> 1m)rg. C h e n ~ . ~ Ser. I> Vol. 7 (Bagnall, K.W.; d.)> Lonclon: Bi~t,terwortl~s; 1972, ~111.157 210.

[72FUG/SPI] F i~ge r~ J.> Spirlet,> J.C.> Miillerl W.; A new (letermination of t,he heat of soli~t,iol~ of an~ericiinn rnetal and the heat of fi)rmat,iou of various arneri- ciinn ions al1(1 conq)oin~(is; Inorg. Ni~cl. Cl~em. Let,tersl 8 (1972) 709 723.

[72HAR/PET] Ha rn~o l~ , H.D.> Pet,erson, J.R., McDowe11, W.J.> Colen~al~; C.F.> The tetrad effect: The thiocyanat,e complex st,al)ility const,ar~ts of some trivalent actini(lesl J . Inorg. Nilcl. Cl~em.; 34 (1972) 1381 1397.

[72HAR/PET2] Harmon, H.D.> peter sol^; .J.R.> Bell, J.T., McDowell, W.J., A spectropho- ton~etric st,ucly of the forlnation of americiinn t,k~iocyar~ate conq)lexesl J . Il~org. Ni~cl. C h e n ~ . ~ 34 (1972) 1711 1719.

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Marcils; Y.; Yal~ir, E.> Givon, M,> The stan(lar(1 1)oterltial of t,he anler- iciiln~ III/IV couple. An estirnat,e from the fornlal pot,ent,ial and colnplex stal~ilities ill pllosplloric acid; ill: Coor(1ination Chenlist,ry ill Soli1- tion (Hijgfeldt, E., ?(l.); Kilngl. Tek. Hijgsk. Hand . Nr. 265, Stockhohn: Swedis11 Nat. Sci. Res. Coinlcil, 1972, pp. 227 238.

McDowell, W.J.; Colelrlar~~ C.F.> Tlle sillfat,e colnplexes of some trivalel~t transplutol~iiln~ actinides alld nl ropi i ln~~ J . Illorg. Nilcl. Cllem.; 34 (1972) 2837 2850.

Sari, C.; Miiller; W.> Belledict; U,, P11ase transition of anlericiinn inet,al; J. Nilcl. Mat,er.; 45 (1972) 73 74.

Sllalinet,s> A.B., Stel~arnm~ A.V.> Investigat,iol~ of complex fornlation of the trivalel~t actinide and lant,hani(ie elelnent,s t)y the nletllo(1 of elect,ro- ~nigration. XVII. Hydrolysis, Sov. Ra~liocheln., 14 (1972) 290 293.

Asprey> L.B.> Hairel R.G., On t,he act,ini(ie tetraflilori(1e lat,tice paranle- ters; Inorg. Nilcl. Cllem. Lett.; 9 (1973) 1121 1128.

Batesl R.G., Deterrnirlation of pH, theory ancl practice, New York: Jol111 Wiley & Soils; 1973> 4791).

Bayl~arz, R.D.> Tlle 1)reparat,iol1 alld crystal st,ruct,ures of arnericiiln~ (iicl~loricle alld (lil)romicle, J . Inorg. Ni~cl. C h e n ~ . ~ 35 (1973) 483 487.

Cllarvillat, J.-P.> Danliel~; D., Anlericium monoarselli(1e; Illorg. Nucl. Cllem. Letters; 9 (1973) 559 563.

Clliarizia, R.> Danesil P.R., Scit)ona, G., Magon, L., Liqui(1 allion exchange of thiocyanat,e-nitratr act,illi(le alld lal~thanicle conq)lexesl J. In- org. Nucl. Cheln., 35 (1973) 3595 3604.

Cl~ikalla~ T.D.> McNeilly, C.E., Batesl J.L., Rasnlilsser~ J .J .> Higll-teln- peratilre phase tral~sfi)rmat,iol~s ill some lar~tl~al~i(le alld act,illi(le oxi(iesl in: Proc. Int,. Colloq. High Tenlperatilre Phase Transforlnations, C.N.R.S. P11t)l. No. 205, 1973> pp.351 360.

Ei~rat,om, Progress Report No. 15, Period January June 1973; Colnrn11- ~lication 3050 TUSR 15; Ellropean Institilte for Transilranium Elelnent,sl Karlsruhe, pp.106 114.

Hi~ssonnois~ M.; Hi11)ert; S.> Brillard, L., G i~ i l l a i~n~o l~ t , R., Dkterlnillation (ie la premikre const,arlte (l'l~y(irolyse (ie l 'einsteil~ii~n~; Ra(iioc11em. Ra- (iioanal. Let,tersl 15 (1973) 47 56> in Frencl~.

Korot,kil~, Yu.S., Hydrolysis of tral~si~l.aniinn elenlerts. 11. Hy(lro1ysis of alnericium(II1) alld curiinn(II1) in p i~ r e llit,ric acid solutions, Sov. Ra- (iiocllem.; 15 (1973) 682 685.

[73KOR2] Korot,kil~, Yil.S., Hy(lro1ysis of t r a n s i ~ r a l ~ i i ~ n ~ elemel~ts. 111. Hy(lro1ysis of alnericium(II1) ill the presellce of ions with positive al1(1 l~egative hy(1ra tion energies; Sov. Racliochen~.~ 15 (1973) 776 781.

[73MAI] Maier, D., Po1ylm)rphisln of an~ericiinn ses(li~ioxi~le and col~tril)utions t,o the st,al)ility of t,he rare eart,h oxi(lesl Report KFK-1844> Krrl~fi)rschi~ngzm- t r i ln~ Karlsrill~e~ Germany, 1973.

[73MAK/STE] Makaroval T.P., Stepal~ov; A.V.; Shrstakov; B.I.> Elect,romigration illvestigat,iol~ of t,he colnl~arative stal~ility of fli~oro-complexes of the MF2+ typeof certain rare-eartl~ ancl actinide elelnent,sl Rilss. J . Il~org. C h e n ~ . ~ l8 (1973) 783 785.

Moskvir~~ A.I.; Son~e ther~rn)~lynamic charact,eristics of the processes of fi)rmat,iou of actinide compoiln(1s in a soli(1 forln: I. Energy al1(1 ent,ropy of the cryst,al lat,ticel heats of forlnatiol~ al1(1 heats of soli~tion~ Sov. Ra- (iiocllem.; 15 (1973) 356 363.

Moskvir~~ A.I.; Son~e ther~rn)~lynamic charact,eristics of the processes of fi)rmat,iou of actinide conq)oin~(is in a soli(1 forn~: 11. Heat capacity and linear and 1)ulk tl~ermal-ex~)ansior~ coefficiel~ts, Sov. Racliochen~.~ 15 (1973) 364 367.

[73NUG/BAY] Ni~gel~t , L.J., Bayt)arz, R.D., Burnet,t; J.L., Ryal~; J.L., Elect,ron-tral~sfer al1(1 f (1 al~sorption l)al1(1s of some lal~thanicle ancl actinide colnplexes al1(1 t,he stal~(iar(i (I1 111) oxidation pot,ent,ial for each rnelr11)er of the lant,hani(ie al1(1 actinide series, J . Phys. C h e n ~ . ~ 77 (1973) 1528 1539.

[73NUG/BUR] Ni~gel~t , L.J., Bi~rnet t ,~ J.L.> Morssl L.R.> Correlation of some tl~ermo(ly- l~alrlic properties of the lal~thanicle a l~ ( l act,il~i(le n~etals, J. Cheln. Ther- ~m)clyn., 5 (1973) 665 678.

[73PIT] Pitzer, K.S.; Tl~ermo(lynan~ics of elect,rolytes: I. Theoretical 1)asis and general eqilat,iol~s; J . Pllys. Cheln., 77 (1973) 268 277.

[73PIT/MAY] Pitzer, K.S.; Mayorga; G.; Ther~rn)~lynan~ics of electrolyt,es. 11. Activ- it,y al1(1 osmot,ic coefficient,^ for strong elect,rolytrs wit11 one or 1)oth ions in~ivalel~t, J . Pllys. Cl~em.; 77 (1973) 2300 2308.

[73ROD] Ro~l~ ly , J.W.; The actinide hy(1ricles: The alnericium-hy(1rogr11 systelr~~ J . Il~org. Nilcl. C h e n ~ . ~ 35 (1973) 4141 4148.

[73VAR/BAY] Varga; L.P.; Baytmrz; R.D., Reisfel~l~ M.J.> Asprey; L.B., Electronic spec- t ra of t,he 5f" al1(1 5f%ctinicles: Am4+, Pu3+, Bk", CP+ ancl Es4+. The f"."il~terlne(liate spin-orl~it coi~plil~g (liagran~; J . Il~org. Nucl. Cl~em.; 35 (1973) 2775 2785.

[74BER/TAN] Bern(lt,> U,> Tanan~as; R.; Maier, D.; Kellerl C.> Z i~ r st,al)ilitit der ~ r ~ o r ~ o k - linen n~o(iifikation (ier sesquioxi(1e v011 arnericiiln~ 1111(1 europii l~n~ Im~rg. Nilcl. Cl~em. Letters; 10 (1974) 315 3211 in Gerlnan.

Cele~ la~ J. , Holilt), J . , Smirousl F.; A iom)phoret,ic st,ucly of t,he association of Pm3+ all(1 Anl"+ ions ill concelltrat,e(i solutions of calciinn percl~lorat,e all(1 llit,ratel Coll. Czecll. Cllem. Colnnl in~.~ 39 (1974) 3599 3602.

Dexl~ert ,~ H.> Carol P,, Dkterlnillation cle la s t r i~c t i~ re crist,allir~e de la varikti. A (les hy(lroxycarl)ol~ates (ie terres rares LnOHC0:j (Ln = Na), Mat,. Res. Bi111.~ 9 (1974) 1577 1586> ill French.

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Khopkar; P.K., Mat,hurl J.N., Thiocyal~ate colnplexil~g of some trivalel~t actinides ancl lal~thani~les, J . Inorg. Niicl. Cheln., 36 (1974) 3819 3825.

Kinarc& W.F., Choppinl G.R., Conlplexil~g of trivalel~t act,il~i(le ions t)y thiocyanat,e, J. Inorg. Nilcl. Cllem.; 36 (1974) 1131 1134.

Korot,kil~, Yu.S., Hy(lro1ysis of t,ransuranium elemellts: V. Hydrolysis of americium ancl ci~rium in perchloric acid soli~t,iol~s; Sov. Ra(iioc11em.; 16 (1974) 223 226.

Korot,kil~, Yil.S., Hy(lro1ysis of tral~s~iraniinn elemellts. IV. Sorpt,iol~ l~olm)geneit,y of inicroarnoi~nt,s of an~ericium(III), Sov. Racliochen~.~ 16 (1974) 218 222.

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Cllarvillat, J.-P,, Belledict; U,, Dalr~ien, D., Miiller, W., Preparat,iol~ et, ~)aramet,res (1e rnaille (le (li~el(li~es pllicti~res (l'americiiln~ et (1e ci~rilim, Racliochen~. Ra(lioana1. Let,tersl 20 (1975) 371 381, ill Frel~ch.

[75DAM/WOJ] Dalrlier~~ D., Wojakowski; A.; Prel)arat,iol~ et paralnet,res (le inaille cles ~m)m)seleniures et n~ol~otellurures cle ~lept,uniinn et (l'an~ericiinn~ Radio- chen~. Ra(iioana1. Lett,ers, 23 (1975) 145 154; ill French.

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[76WAR/MUE] Ward; J.W.; Miller; W.> K r a n ~ e r ~ G.F.> Tlle vapoi~r pressure of h igh pi~rit,y soli(1 an~ericiinn~ ill: Transplutoniinn 1975 (Miller, W.> Lin(lner; R., rtls.)> Anlster(1aln: North-Hollan(1, 1976> 11~1.161 171.

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[77HAI/LLO] Haire, R.G.> L loy~ l~ M.H., Milligan, W.O., Beasley; M.L., Latt,ice paralnet,ers of 2'4Cn~(OH):3 and the effect of self-irra(iiat,iol~ 011 crystalline 2'1Am(OH):j all(1 "'CIII(OH):~; J . Inorg. Nucl. Cllem.; 39 (1977) 843 847.

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[77SEL/KOS] Seleznev; A.G., Kosillil~; N.S.> Kosenkov, V.M., Sln~sl~akov, V.D.> St,ul)il~; V.A., Denleshkil~; V.A., 011 the 11olylnorphism of americium, Pllys. Met. Metall, 44 (1977) 180 183.

Sinlakin, G.A.> Real oxi(1ation potelltials of t,he coilples A r n ~ $ + / A r n ~ ; ; N~)o$+/N~)O: in soli~tions of potassiiln~ all(1 so(iii1n1 carl~ollates; Sov. Racliochen~.~ 19(4) (1977) 424 426.

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Gor(lon, S.; Millac; W.A.> Schmiclt; K.H., Sjot)lom, R.K.> Sullivan, J.C.> Pi~lse-ra(lio1ysis st,uclies of Americiiln~ ions ill aqileous perchlorate ~ne(lia> Illorg. C h e n ~ . ~ 17 (1978) 294 296.

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Mi~sikas, C.; Le Marois; G., Fit,oussi; R.; Cuillerdier, C.> Propert,ies and ilses of nitrogen^ and sillfi~r (lonors ligands in act,il~i(le separat,iol~s; in: Actinide separat,iol~s (Navratil, J.D.> Sclnllz, W.W.> rds.), ACS Symp. Ser. 117, Washin~gtol~; D.C.: A I I I ~ ~ . Cheln~. Soc.> 1980, pp.131 145.

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Gi~ i l l a i ln~e~ B.> Hot)art,> D.E.; Boi~rges, J.Y.> iiCat,iol~-eation" c0111p1exes of pent,avalent actinides: 11. S~)rctro~)hotoln~et,ric st i~(iy of complexes of Anl(V) with UO;+ al1(1 NI)O$+ in atlilrous perchlorate soli~t,iol~; J. Im~rg. Nilcl. Cl~em.; 43 (1981) 3295 3299.

Helgesol~; H.C., Kirkhan~; D.H.; Flowers; G.C., Theoretical precliction of the ther~rn)~lynamic 1)ehavior of atlileoils electrolyt,es a t 11igh pressilres and telnperat,ures: IV. Calcillation of act,ivity coefficiel~ts, oslm)tic coefficients; al1(1 apparel~t n~ola l al1(1 stan(lar(1 ancl relative partial n~ola l properties t,o 600°C and 5 kt), Anl. J . Sci.; 281 (1981) 1249 1516.

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Lel)e(lev; I.A., Mazi~r , Y.F., In~vest,igation of the con~plex fi)rmat,iou of alnericium(II1); c i ~ r i i ~ n ~ ( I I I ) ancl califi)rnium(III) wit11 perchlorate ions ill a(l i~eo~is sol i~t ion~ Sov. Racliochen~.~ 23 (1981) 291 299.

Morss, L.R.> Fuger> J.; Entl~alpy of fi)rn~ation of arnericiiln~ (lioxi(1e and a tl~errnocl~ernical est,ilnate of the elrct,rocle potel~tial An14+/Aln"+; J . Il~org. Ni~cl. C h e n ~ . ~ 43 (1981) 2059 2064.

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Allard; B., Solul~ilities of actinides ill i~eutra l or 1)asic soli~t,iol~s; ill: Ac- tinides in ~)erspect,ive (Edelsteil~; N.M.; rtl.); Oxford: Pergan~ou Pressl 1982, pp.553 580.

Bi(logliol G., Charact,erizat,iou of Anl(II1) con~plexes wit11 t)icart)onat,e al1(1 carl~onate ions a t groin~(lwater concentration levels; Ra(iioc11em. Ra- (iioanal. Let,tersl 53 (1982) 45 60.

Drever, J.I.> The georhelnistry of natural watersl Englewoocl Cliffs, N.J.: Prel~tice-Hall, 1982> 3881).

Erirll E.A.; Kopytov; V.V., Rykov, A.G., A st i~(iy of the il~teraction of alnericium(II1) and alnericium(V) in solutions of pot,assiinn tin~gstophos- p l~a te ~ I O P Z W 1 7 ~ ) R I ; Sov. Racliod~en~., 24 (1982) 280 287.

Fuger> J. , Tl~ermo(lynan~ic properties of the act,il~i(les: Cilrrel~t perspec- tives, ill: Actinides ill perspective (E(lelstein, N.M., d . ) > 0xfi)r~l: Perga- 1m)n Pressl 1982, ~1~1.409 431.

[82FUK/KAW] Fi~kasawa~ T . > Kawasi~ji, I.; Mitsilgasl~ira, T. , Investigation 011 the colnplex forlnation of some lal~thanoicls(III) ancl actinoicls(II1) wit,k~ chlori(1e al1(1 l)rolni(lel Bi111. Cl~em. Soc. .Japanl 55 (1982) 726 729.

[82GLU/GUR] Glushkol V.P., Gurvichl L.V.; Bergmal~, G.A., Veit,sl I.V.> Me(iveclev, V.A., K h a c l ~ k i ~ r i ~ z o v ~ G.A.> Yilngn~al~, V.S., Ther~rn)clynamic properties of in(livi(111al si11)stances (Gli~shko, V.P., l . ) : Vol. 4, Moscow: Naitka; 1982; in Rilssian.

[82GUI/BEG] Gi~ i l l a i ln~e~ B., begin^; G.M.> Ha ln~ ; R.L., Rarnan spectron~etric stil(1ies of "cation-cation" con~plexes of pent,avalel~t act,il~i(les in aclileoils percl~lorat,e soli~t,iol~s; Il~org. C h e n ~ . ~ 21 (1982) 1159 1166.

[82HOB/SAM] Hot)art,> D.E., S a ~ n h o u n ~ K.; peter sol^; .J.R.> S~)rctroelect,rochrlr~ical stil(1- ies of t,he act,il~i(les: Stal~ilization of Alnericii~n~(IV) in aqueoils carl~onate soli~t,iol~; Racliochiln. Acta, 31 (1982) 139 145.

[82JEN] J e l ~ s e r ~ ~ B.S.; Migrat,iol~ phenon~ena of ra(lionucli(1es into the geosphere; CEC Ra(lioact,ive Waste Managen~ert Seriesl Vol. 5, EUR-7676, Ch i~r , Swit,zerlan(l: Harwoocl Acaclen~ic Pi11)lishers; 1982> 1971).

[82KEL] Keller, C., Fli~ori(les of five- and six-valel~ce transi~ranium elen~erts; Che- ~niker-Zeiti~ng, 106 (1982) 137 142; in Gerlnan; Englisl~ tral~slat,iol~ in: Report LA-TR-86 211 Los Alalm)s Nat,iol~al Lat)orat,ory, 1986> 181).

[82KUL/LEB] Ki~ lyako~ Y.M.> Lel)e(lev; I.A.> Frellkel1, V.Y.; Trofin~ov; T.I.; Myasoe- (iov; V.F.> Electrocl~emical oxi(1ation of an~ericiinn(III) al1(1 certain reactions of an~ericiinn ions in potassium ~) l~os~) l~ot ,ungsta te soli~tions~ Sov. Racliochen~.~ 23 (1982) 674 679.

Laffitte, M. (chairrnnr~)~ A report of IUPAC colr~rnissiol~ 1.2 on tl~ermo(ly- ~~a ln ics : Not,ation for states al1(1 processes, significance of t,he word "st,an- (iar(i" ill chelr~ical tl~ermo(lynan~ics; and relr~arks on connrn)nly tal)illat,e(l f i~rms of t,hem~o(iyl~alnic funct,iol~s; J . Cheln. Ther~rn)clyn., 14 (1982) 805 815.

[82LAW/MAR] Lawal(lt,> D., Marquart; R., Werner, G.D., Weigel, F., The phosphat,es al1(1 arsenates of l~exavalent actinicles. V: Americiiln~, J . Less-Colnmon Met., 85 (1982) 37 41.

[82NAI/CHA] Nair, G.M.> Chan(1er; K., Joshil J.K.> Hy(1rolysis constal~ts of plilto- 11iiln1(111) ancl arnericiiln~(III)~ Racliochirn. Act,&, 30 (1982) 37 40.

[82RAD/RYA] Raclchel~ko; V.M., Ryal~illin, M.A., Seleznev; A.G.> Shilr~l~arev, E.V.; SII- (iakov; L.V.; Kal~shukov~ I.I.> Vasil'ev; V.Ya.; Syl~thesis al1(1 st,ucly of the

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[82RAI/STR] Rai; D.> Strickert, R.G., Soli~t)ilit,ies of actinide soli(1s iln(ler oxic coll(1i- tionsl Report PNL-SA-10368, Pacific Nort,k~west Lal~oratory~ Riclllan(1, Washillgton, 1982> 181).

Silva, R.J.; The soli11)ilities of cryst,alline neo(lyn~iiln~ all(1 arnericiiln~ tri- l~y(lroxi(les; Report LBL-15055, Lawrence Berkeley Lal~oratory, Berkeley, Californial 1982; 571).

Taylor; J.R.; All irtro(111ction t,o error analysis: The st,ucly of ilncertain- ties in ~~hysical ~neasi~relnent,s~ Mill Valleyl California: University Sciel~ce Booksl 1982; 2701).

[82WAG/EVA] Wagman, D.D., Evalls; W.H., Parkerl V.B., Schumn~; R.H.> Halow, I.; Bailey, S.M., C ~ I I I ~ I I P ~ , K.L., Nuttall, R.L.> The NBS tal~les of chenlical ther~rn)~lynamic properties: Selectecl values fix im~rganic ancl Cl ancl Ca orgallie sul~stallces in S1 units, J. Pllys. Cllem. Ref. Data, 11, S~II I I I~ . No. 2 (1982) 1 392.

[82WEI/WIS] Weigell F.; Wishnevsky; V.; Giil(111er~ R.; The vapor 1111ase hy(lro1ysis of P11Br:j and AIIIB~:~: Heats of forlnatioi~ of PitOBr ancl AnlOBr; J . Less- Colr~rnon Met,., 84 (1982) 147 155.

[83ALL] Allard; B.> Actinide soli~t,iol~ equilil~ria ancl soli11)ilities in geologic sys- telrlsl Report TR-83 35, SKBFIKBS, Stockhol~n~ Swe(lenl 1983, 481).

[83BAR/SAR] Bartscher, W.; Sari, C., A ther~rn)~lynan~ic stil(ly of the uraniinn-arnerici11111 oxi(le Uo.iAlno.sOz+r, J . Nucl. Mater.> 118 (1983) 220 223.

[83BOU/GUI] Bourges, J.Y.> Gi~i l la i ln~e~ B.; Koehly, G.> Hol~art, D.E., Pet,erson, J.R.; Coexistel~ce of anlericiinn in foi~r oxi(1ation states in socliinn carl~onate- so(1iiln1 l~icarl~onate me(1iiln1; Inorg. Cheln., 22 (1983) 1179 1184.

[83CAC/CHO] Caceci, M.S.> Clloppin, G.R., The (iet,ern~inat,iol~ of t,he first lly(1rolysis constal~t of Eu(II1) ancl Aln(III), Ra(1iochiln. Acta, 33 (1983) 101 104.

[83EDE/BUC] E(lelst,einl N., Bi~cller~ J .> Silva; R., Nitsche, H., T h e r l r ~ o l y a r i : II~OII- erties of chenlical species in lli~clear waste; Report ONWI-399 all(1 LBL- 14325, Lawrence Berkeley Lal1orator3: Berkeleyl Califorllia, Jau 1983, 1151).

[83ERI/KOP] Erin> E.A.; Kopytov, V.V.> Vasil'ev; V.Y.> Rykovl A.G., Behavior of pen- tavalel~t americium ill solutions of potassium ~)hosl)hotin~gstat,e KIOP2W170~ilr Sov. Rac l iod~en~.~ 25 (1983) 49 55.

[83FER/GRE] Ferri; D.; G r e r t l ~ e ~ I., Salvat,ore, F., St,u(lies 011 inet,al carl~onate eq11ilit)ria. 7. Re(li~ction of the t,ris(carl~o~~ato)~lioxo~irar~ate(VI) ion; ~ 0 ~ ( ~ 0 : j ) : f , in cart)onat,e soli~t,iol~s; Illorg. C h e n ~ . ~ 22 (1983) 3162 3165.

F i ~ g e r ~ J.; Parker, V.B.; Hi~t)t)ar(l, W.N., Oett,il~g, F.L.; The chenlical ther~rn)~lynamics of actinide elelnent,s ancl compoiln(1s: Part 8. Tlle actinide hali(iesl Vienna: Ir~terr~ational Atolr~ic Energy Agencyl 1983, 26711.

Haire, R.G., Youngl peter sol^; J.R.; X-ray (iiffract,iol~ ancl at)sorpt,iol~ s~)ect,rol)hotolr~et,ric sti~(iies of AlnI:j and ArnOIl J . Less-Colnmon Met,., 93 (1983) 339 345.

Mikheev; N.B.> Lower oxidation stat,es of actini(iesl Racliochiln. Act,&, 32 (1983) 69 80.

Mi~sikas, C., Cuillerdier, C., Livet; J.; Forchioni; A., Chacllaty; C., Azicle int,eraction with 4f ancl 5f ions ill aqileoils solutions. 1. Trivalel~t ionsl Illorg. C h e n ~ . ~ 22 (1983) 2513 2518.

Rai, D.> St,rickert,> R.G.> Moore, D.A.> Ryarll J.L., Anl(II1) l~yclrolysis con- s t an t ,~ and solul~ility of Anl(II1) 11y(lroxi(le~ Radiochilr~. Acta; 33 (1983) 201 206.

Sln~sl~akov; V.D., Se1ez11ev~ A.G., Kos i~ l in~ N.S.> Shi~shakova; T.V., On the r u + (i tral~sit,iol~ in americium, Pllys. Met,. Metall., 55 (1983) 188 190.

Silva, R.J.; The soli~l~ilities of cryst,alline neo(lyn~iiln~ alld arnericiiln~ tri- l~y(iroxi(le; in: Mat,erials alld Molecillar Researell Divisiol~; Alllli~al Report 1982; LBL-15150, Lawrence Berkeley Lal~oratory~ Berkeley; Califi~rnia; 1983; pp.251 253.

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Allard; B., Olofsol~; U,> Torst~nfelt ,~ B.; Er~virolnnent,al Actinide Cllem- ist,ry, Illorg. Chiln. Acta, 94 (1984) 205 221.

Anant,haswarny, J . , Atkinson, G.; Therlm)~lynamics of col~cent,ratecl electrolyte n~ixt,ures. 4. Pitzer-Det)ye-Hiickel lin~it,il~g slopes fix wat,er fiom 0 to l0O0C ancl fi-on1 1 at,rn to 1 kt)ar; J. C h e n ~ . Eng. Dat,a, 29 (1984) 81 87.

Bernkopf; M.F., kin^; J.I., Hy(irolysrreakt,iol~pr~ iln(1 kart)onat,komplex- ierin~g von (lreiwertigen~ anlericiinn ir11 nat,iirlicl~er~ atli~at,ischen syst,en~; Report RCM-02884, Inst,. fiir Ra~liochelnie (ier Tech. Univ. Miincller~~ 1984; 20011.~ ill Gernlal~.

Brewer; L.> The resl~onsil~ility of l~ igh t,elnperat,ure scielltists; High Telnl). Sci.> 17 (1984) 1 30.

Buzt)eel B.L., Tlle SLATEC connm)n rnat,hen~atical lil~rary, in: Soi~rces alld ~levelopn~ert of lr~atl~ernat,ical soft,ware (Cowell> W.R.; ed.), Engle- woo(1; N.J.: Prertice-Hall Series ill Conq)i~tat,iol~al Mat,henlatics, 1984, pp.302 320.

[84FLO/HAS] Flotow; H.E., Haschke, J.M., Yan~ailchi~ S.> The cl~ernical tl~ermo(lynan~- ics of actinide elelnent,s ancl coln1)oun~ls: Part 9. The actinide hy(lri<les, Vienna: Ir~terr~ational At,omic Energy Agencyl 1984> 1151).

[84FRE] Freen~al~; R.D.> Col~versiol~ of st,anclarcl (1 at,m) tl~ermo(lynan~ic data t,o the new stal~(iar(i-stat,e pressure, 1 1)al. (10" Pa), J. Cl~em. Eng. Dat,a, 29 (1984) 1115 111.

[84FRE/LAN] Freen~al~; A.J.; Lall(ierl G.H. (rtls.), Hancll~ook on t,he pl~ysics al1(1 cheln- ist,ry of t,he actini(lesl Vol. l> Amst,er(laln: North-Hollan(1, 1984; 5151).

[84GRO/DRO] Gronvol~l~ F., Drowart; J.; Westri l~n~ E.F.; Jr., T l ~ e chelr~ical t11erlrn)- (lyl~alnics of act,il~i(le elernel~ts and cornpoiln(1s: Part 4. T l ~ e act,il~i(le chalcogenicles (rxcli~(iing oxi(1es); Vienna: Ir~terr~ational Atonlie Energy Agel~cy, 1984, 2651).

[84HOL/RAN] Holley, C.E.> Jr., Rall(1; M.H.> St,orms, E.K.> The chelr~ical tl~ermo(lynan~- ics of actinide elen~erts ancl cornpoiln(1s: Part 6. The actinide carl)i(lesl Vienna: Ir~terr~ational At,omic Energy Agencyl 1984> 1011).

[84HOS] Host,et,tler; J.D., Electro(1e elect,ronsl a(li~eoi~s electrons, and reclox pot,en- tials in i~atilral watersl Anl. J . Sci.; 284 (1984) 734 759.

[84KER] Kerrisk, J.F., Americii~n~ tl~ermo(lynalnic (lat,a for the EQ3/6 (lat,al)ase, Report LA-lI104O-MS, Los Alalm)s Nat,iol~al Lal~oratory~ Los Alan~os, New Mexico, Ji11 1984.

[84KIM/BER] Kirn, J.I., Bernkopf, M.; Lierse, Ch., Koppol~ l~ F., Hy(lro1ysis reactions of Anl(II1) al1(1 Pil(V1) ions in near-nn~tral soli~tions~ ill: Geochelnical 1)e- l~avior of (lispose(1 ra(lioact,ive waste (Barmy; G.S.> Navratill J.D.> Schulzl W.W., rds.), ACS Symp. Ser., No. 246; Washil~gton, D.C.: American Cl~ernical Society, 1984; pp.115 134.

[84MAR/MES] Marshall; W.L.> Mesn~er~ R.E., Pressure-density relat,iol~sl~ips al1(1 ioniza tion equilil~ria in aqileous soli~tions~ J . Soli~t,iol~ C h e n ~ . ~ 13 (1984) 383 391.

[84NAS/CLE2] Nash, K.L., Clevelandl J.M., Thrr~m)clynan~ics of the system: An~erici- i n r ( 1 1 1 ) - f l i i St,al)ility const,ar~ts, ent,halpies; entropies and soli11)ilit,y procluct,sl Ra(lioc11irn. Act,&, 37 (1984) 19 24.

[84SIL] Silva, R.J.> The 1)ehavior of an~ericiinn in atli~eoi~s cart)onat,e syst,en~s; Sci. Basis Nilcl. Wast,e Managen~ert V11 (McVay, G.L., d.)> hel(1 Novemt)er 1983 in Bostol~; New ~ o r k : Nort,l~ Hollal1(1 Elsevier> 1984> pp875 881.

[84SIL/NIT] Silva, R.J., Nitsche, H.; Tl~errno(lynan~ic properties of chelr~ical species of waste ra(lionucli(lesl in: NRC Nuclear waste geochen~ist,ry '83 (Alexal~(ler~ D.H.> Bircl~ar(i; G.F., eds.); Symp. hel(1 30 31 Ai~gilst 1983, ill Restol~; Virginia, Report NUREG/CP-1111521 U.S. Nilclear Rrgillat,ory Connnis- sion, Wasllingt,onl D.C., 1984> ~111.70 93.

[84VIE/TAR] Vieillard, P,, Tardy, Y.> Thernlochenlical propert,ies of phosphatesl in: Phosphat,e lrlillerals (Nriagi~, J.O.; Moore> P.B.; rtls.)> Berlin: Spril~ger- Verlag; 1984, pp.171 198.

[84VIT] Vitorgel P ,> Mesilre (ie constalltes t l~er~r~o(lynan~i( l i~es (ie compos4s trans- i i e o r o r l g e o c l i i e : conlplexation clu Np(V) et cle 13Anl(III) par les cart)onat,es, l~yclrolyse clu Pil(V1) et (le l'Aln(III), in: Sernirlar held 6 10 Fel~r. 1984 in Sofia, report IAEA-SR-104125, Vienna: Il~terl~ational At,omic Energy Agellcy, 13 l)., in Frencl~.

[84WEI/WIT] Weigell F., Wittnlaln~; F.D.> Sclli~ster~ W., Martli~art,~ R.> The Alr~ Si systelr~, J. Less-Comn~ol~ Met.; 102 (1984) 227 238.

[85DAV/FOU] David, F., Foi~rest; B.> D111)lessis~ J . , Hy(1ratior1 t,hern~o(lyl~alr~ics of 11111- tonium ancl tral~s~)li~t ,onii~ln iol~s; J. Nlicl. Mater., 130 (1985) 273 279.

[XSFERIGRE] Ferri; D., Grerlt l~e~ I.; hie tall er^^ S.; Ni.ker-Neilnla1111; E.; Salvatore> F.; Stil(1ies 011 rnetal cart)onat,e equilil~ria: 12. Zinc(I1) carl~onate colnplexes in acid soli~tion~ Acta Cheln. Scal1(1.~ A39 (1985) 347 353.

[85FRE/KEL] Freenlal~; A.J.; Kellerl C. (rtls.), Han(1t)ook 011 the pllysics and chelrlistry of the actini(lesl Vol. 3; Amst,er(lan~: North-Hollan(1, 1985, 52011.

[85FRE/LAN] Freenlal~; A.J.; Lall(ierl G.H. (rtls.), Hancll~ook on t,he pllysics all(1 cheln- ist,ry of t,he actini(lesl Vol. 2> Amst,er(laln: North-Hollan(1, 1985; 5031).

[85HAI/BEN] Haire, R.G.> Belledict; U,> Yolir~g~ J.P., peters or^^ .J.R.> Begi111; G.M., The effect of pressi~re on t,he al~sorption spectrinn and the crystal st,ruct,ure of a l~l~y( i roi~s J . Pllys. C: Soli(1 St,at,e Phys.; 18 (1985) 4595 4601.

[85HIL/GUR] Hil(ler11)ran~l~ D.L.> Gurvichl L.V., Yimgman, V.S.> The cllernical t,her- ~m)clynamics of actinide elelnent,s all(1 conq)oin~(ls: Part 13. The gaseous actinide iol~s; Vielnla: Int,ernat,iol~al At,omic Energy Agellcy, 1985, 1871).

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Kirn, J.I., Basic act,il~i(le all(1 fission pro(li1ct cl~emistry~ in: MIRAGE project,l first sumnlary report covering work perio(1 Jamlary to Decemt)er; 1983 (Ci,me; B.> d.)> report EUR-9543-EN1 Li1xrlr11)ourg: Comnlission of the European Cornnlin~it,ies~ 1985> pp.9 40.

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[85MAG/CAR] Magiriils; S., Carnall; W.T., Kilnl J.I., Ra(lio1ytic oxi(1ation of Am(II1) to Anl(V) ill NaCl soli~t,iol~s; Racliocheln. Act,&, 38 (1985) 29 32.

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Rol)ouch, P,, Cont,ril)iltion B la pri.vision clu con~portelnent (ie l'anlkrici- i l lr l l clu pli~t,oniinn et (111 neptilnium (ians la gkosp11l.r~; (1onni.e~ chirniques, P11.D. t,hesisl Ecole Ei~ropi.eln~e (les Hailtes Etil(les (ies In(li~st,ries Chirni- cliles cle St,rasl)ourgl 13 Nov. 1987> Report CEA-R-5473, Colr~rnissariat A 1'Energie Atolnicli~e~ Gif-si~r-Yvett,e, France; 1989, 2161)., partly in Frencl~.

Riisch, F., Reilrlarlr~~ T.; Bi~klanov, G.V.; Milallov; M,, Khalkin, V.A., Dreyer, R.; Elect,romigration of carrier-free ra(1iomlclicles. 13. Ion m ) - l~ilities and hy(lro1ysis of "I'Aln-Aln(II1) in aclileous inert elect,rolytes; J . Raclioallal. Nilcl. Cllem.; 134 (1989) 109 128.

Schoet)rrcllts, J.P., Gens, R., Fuger, J . , Morss, L.R.; Ther~m~che~nica l all(1 strilctilral stil(1ies of complex act,illi(le chlori(1es CsaNaA1~Clfi (An = U-Cf); ionizat,iol~ 1)otertials and l~y(lrat,iol~ ent,halpies of An3+ ionsl Tl~errnocl~in~. Acta, 139 (1989) 49 66.

S11oc.k~ E.L., Helgeson, H.C.> Correctiol~s to [88SHO/HEL], Geocl~in~. Cos~rn)chirn. Act,&, 53 (1989) 215.

Shock, E.L.; Helgesol~; H.C., Sver,jenskyl D.A., Calcillat,iol~ of the t,her- ~m)clynamic and transport propert,ies of aclileoils species at h ig l~ pressilres all(1 temperatilres: Stall(lar(1 partial nlolal properties of illorgallie nei~t,ral species, Geochiln. Cosnlochiln. Act,&, 53 (1989) 2157 2183.

Slnith, R.M.> Martell> A.E., Crit,ical st,al)ility const,arlts, Vol. 6: Secon(1 si~pplrlnent,~ New York: Plenum Pressl 1989; 64311.

Tananaev, I.G.> Forn~s of hexavalel~t p l u t o l ~ i i ~ n ~ ancl anlericiinn in basic acli~eo~is soli~tions~ Sov. Racliochen~.~ 31 (1989) 303 307.

Yilsov; A.B.> Pl~otoluminescem of alnericiiln~ (111) in aqueoils all(1 organic solutions, ill: Act,il~i(les 89; Al~stracts Illterllat. Conf.> hel(1 24 29 Sept. 1989 in Tashkellt, Moscow: Naitkal 1989; p.240.

Yilsov; A.B., Fe(ioseev, A.M., Ci~r ium all(1 americium chen~ilurninescer~c:e in redox reactions, in: Actinides 89> Al~stracts Int,ernat,. Conf.; 11eld 24 29 Sept,. 1989 ill Tashkent,> Moscow: Nauka, 1989, pp.241 242.

A r c l ~ e r ~ D.G., Wangl P.; Tlle (lielectric constal~t of water all(1 Det)ye- Hiickel lin~it,il~g law slopesl J. Pllys. Chew. Ref. Data, 19 (1990) 371 411.

Ciavatt,al L.; T l ~ e specific il~teraction t,hrory in e(lui1il)riinnanalysis: Some empirical rules for estirnat,il~g il~teractiol~ coefficient,^ of inet,al ion coln- plexesl Ann. Chirn. Ron~a , 80 (1990) 255 263.

Cor(lfunke, E.H.P.; Koningsl R.J.M., Pot,terl P.E., Prins, G., Rand, M.H., Tl~errnocl~ernical data for reactor n~aterials and fission pro(111cts (Cor(1- funke, E.H.P.> Kol~ings, R.J.M.> eds.); Alnsterclarn: Nort,h-Hollandl 1990, 69511.

David, F., Maslenniko~~ A.G.> Peretri~khil~; V.P., Electrocl~emical recluc- tion of actinide ions ill aqueoils solutior~. Applications t,o separat,iol~s and some il~terlnet,allic cornpoiln(1 syst,hesis, J . Ra(lioana1. Nucl. C h e n ~ . ~ 143 (1990) 415 426.

Fehr~y, A.R., Rai, D.; Filltol~; R.W.> The soli11)ility of A~IOHCO:~(C) and the aqueoils ther~rn)~lynamics of the syst,en~ Na+ Am3+ HCOT CO:- O H HaO, Racliochiln. Acta, 50 (1990) 193 204.

Goil(liakas, J .> Haire; R.G.> Fi~ger; J.> Thern~o(lyl~alnics of lart l~al~i(le al1(1 act,il~i(le perovskite-type oxides. IV. Molar ertl~alpies of forlnation of MM30t3 (M = Ba or Sr, M' = Ce; Tl); or Aln) compoi~n(ls, J . Cheln. Tl~ermo(lynan~ics, 22 (1990) 577 587.

Leigl~; G.J., Nome~~clatilre of inorganic chelnistry; reconnnen(Iat,iol~s 1990, IUPAC Colr~rnissiol~ on Nornel~clati~rr of Inorganic Cl~ernistry~ 0xfi)r~l: Blackwell Sci. Pi11)l.; 1990; 2891).

Monnir~~ C.> The influence of pressure 011 the activity coefficients of the soli~t,es and on the soli11)ility of n~inerals in the syst,en~ Na Ca C1 SO4 HaO t,o 200°C ancl 1 kt)ar, and t,o 11igl1 NaCl concel~trat,iol~, Geocl~in~. Cos~rn)chirn. Act,&, 54 (1990) 3265 3282.

Oelkers; E.H.> Helgesonl H.C.> Triple-ion anions and polynuclear colnplexing in si~percritical electrolyt,e soli~tions~ Geocl~in~. Cosmocl~in~. Acta, 54 (1990) 727 738.

Persl~in, A.S., Sapozln~ikova; T.V., Hy(lro1ysis of Anl(III)> J. Ra(iioana1. Nilcl. Cl~em.; 143 (1990) 455 462.

Riisch, F.> R e i l r ~ a r ~ r ~ ~ T., Buklal~ov; V.; Milarn~v~ M,, Kl~alkin~ V.A., Dreyer, R.> Electron~igrat,io~~ of carrier-fiee ra~liol~i~cli(les. XIV. Com- plex forlnation of 2'1Am Am(II1) wit11 oxalat,e ancl sillfate in aqueoils soli~t,iol~; J. Raclioal~al. Nilcl. Cl~em.; 140 (1990) 159 169.

Tananaev, I.G.; Hy(1roxicles of pent,avalel~t arnericiiln~; Sov. Racliochen~.~ 32 (1990) 305 307.

Tananaev, I.G., Forlns of Np(V) and Am(V) in 1)asic atlileoils ine(lial Sov. Racliochen~.~ 32 (1990) 476 479.

Vasil'ev; V.I., Kalevich, E.S.> Ra~lche l~ko~ V.M., Egurn~v~ V.P.> Izn~alkov, A.N.; Sl l in~l~arev~ E.V., Vasil'ev, V.Ya., Therlnal~1ecoln~)osition of Am(II1) al1(1 Cln(II1) nitrat,es, Sov. Ra(iioc11em.~ 32 (1990) 141 143.

Wanner, H., Gi~idelil~es for t,he i l~ ( l epe~~( ie r~ t peer review of TDB report,sl Report TDB-6, OECD Nilclear Energy Agencyl Dat,a Bank, Gif-si~r- Yvett,e, Frallce, March 1990, 81).

Wood1 S.A., The aqileous geocllemistry of t,he rare-earth elernellts and ytt,riinn. 1. Review of availal~le low-tem~~erat i~re (lat,a fix im'rganic colnplexes ancl t,he inorganic REE speciat,ion of natural wat,ers, Cheln. Geol.; 82 (1990) 159 186.

An(1erso11; G.M., Castet; S.; Schot,t; J .> Meslner, R.E., Tlle (lel~sit,y nlo(1el fix estirnat,iol~ of tllerrno(1ynanlic pararnet,ers of reactions a t k~ ig l~ telnper- a t i~res all(1 pressuresl Geochiln. Cosn~ochirn. Act,&, 55 (1991) 1769 1779.

Freenlal~; A.J., Kellerl C. (rtls.), Han(1t)ook 011 the pllysics and chelrlistry of the actini(lesl Vol. 6; Amst,er(lan~: North-Hollan(1, 1991, 74211.

Mart,illot, L.; Molten-salt ellemistry of act,illi(les; in: Hall(1l)ook on the pllysics and ellemistry of t,he actinides (Freemanl A.J., Kellerl C.; rds.), Vol. Anlster(1aln: Nort,h-Hollandl 1991, pp.241 279.

Meinrat,k~, G., Kiml J.I., The cart)onat,e conlplexation of t,he Am(II1) ionl Racliochiln. Acta, 52/53 (1991) 29 34.

Meinrat,k~, G., Kilrll J.I., Solul~ility ~)ro(iilcts of (iifferel~t Am(II1) and N(l(II1) cart)onat,es, Eilr. J . Solid Stat,e Illorg. C h e n ~ . ~ 28 (1991) 383 388.

Vitorgel P.; Trau The; P,> Solul~ility linlit,s of ra~liol~i~cli(les in int,erst,itial water Americium in cement,. Task 3 Characterization of ra(lioact,ive waste forlns. A series of final rel~orts (1985 89) No. 34, Report EUR 13664, 1991; Colrlrnissiol~ of t,he Ellropean Colnmi~nities; Li1xelr11)ourg~ 391'.

Wanner, H., The NEA Ther~rn~che~nical Data Base project, Report TDB- 0.2> OECD Nuclear Energy Agency, Data Bank, Gif-si~r-Yvett,e, Frallce, Nove~rll~er 1991; 1011.

Wanner, H., Gui(1elines fix the review proceclure ancl data selectionl Report TDB-1.l1 OECD Nilclear Energy Age~lcy, Dat,a Bank, Gif-si~r- Yvett,e, Frallce, Decemt)er 19911 511.

Ewart,, F.T.> Smitll-Briggs; J.L.> Tllornason, H.P., Williarns, S.J., The soli~t)ilit,y of actinides ill a celnent,itioi~s near-field e l~vironn~er~t ; Waste Manage~nent,~ 12 (1992) 241 252.

Fuger> J .> T h e r r ~ o l y ~ a i c properties of actirli(1e ~ ( I I I ~ O I I S species relevant, to geochelnical prol~lems, Ra(lioc11in1. Acta, 58/59 (1992) 81 91.

Fuger> J.; Khoclakovsky, I.L.> Sergeyeva, E.I.> Me(ive(lev, V.A., Navratil; J.D.> The chelrlical Tl~errno(lynanlics of Actinide Elelnent,~ ancl Com- poi111(1s: Part 12. The Act,illi(le A(lueo11s Im'rganic Complexes; Vienna: I l~terl~ational At,omic Energy Agellcy, 1992; 22411.

G i l ~ s o n ~ J.K., Hairel R.G., High-temperati~re fillorination sti~(iies of i l r a 11ii1n1; neptilnium, pli~t,oniinn ancl a r n r r i c i i ~ ~ n ~ J. Alloys and Conq)oin~(ls; l81 (1992) 23 32.

Grellthe; I.> Fuger, J . , Konil~gs; R.J.M.> L e ~ n i r e ~ R.J., Muller, A.B., Ngi~yel~-Trung~ C., W a l n ~ e r ~ H., Chelnical ther~m)~lynarnics of uraniinn ( W a l n ~ e r ~ H.; Forest, I.> rds.), Arnst,er(ialn: Elsevier Scierlce Pi~l~lishers B.V., 1992> 7151).

Grellthe; I., S p a l ~ i u ~ K., Eriksen, T. , Analysis of the solul~ility eqi~ilil~ria of y t , t r i i~n~ cart)onat,e ill aqileous perchlorate media using the Pitzer and Brrrnste~l-Gi1gge1111ei111-Scatcl1ar(i io11-il~teraction nlo(1els; J . Cllem. Soc. Fara(1;ty T r a l ~ s . ~ 88 (1992) 1267 1273.

Grellthe; I.; W a l n ~ e r ~ H.; Gi~idelil~es fhr the extrapolation to zero iollic strellgth, Report TDB-2.2> OECD Ni~clear Energy Agency, Data Bank, Gif-si~r-Yvet,tel Frallce, March 1992; 241).

Koyanla, T. , Jolnlsol~; T.R., F isc l~er~ D.F., Dist,ril)i~tion of act,illi(les ill ~ m ) l t e l ~ chlori(1e salt/ca(llniinn rnetal systems, J . Alloys ancl Conq)oin~(ls; l89 (1992) 37 44.

Killyukhil~, S.A.> Kalnenskaya; A.N., Mikl~eev, N.B., Behavior of micro- gram all(1 weig11at)le arnoilnt,~ of Alr~ ill THF soli~tions a t low oxidation potel~tials, Sov. Racliochen~.~ 34 (1992) 117 120.

Rai, D.> Felnly, A.R., Fi~lt ,on~ R.W., Soli~l~ility ancl iou act,ivit,y pro(111ct of AlrlPO4 .:r.H2O(aln); Racliochiln. Act,&, 56 (1992) 7 14.

Runcle, W.> Meinrat,k~, G.; Kiml J.I., A st,ucly of soli(1-liquid phase e(l11i- l i l~ria of t,rivaler~t lal~thanicle all(1 act,illi(ie ions in cart)onat,e syst,en~s; Ra- ( i iocl~in~. Act,&, 58/59 (1992) 93 100.

S11oc.k~ E.L., Oelkers, E.H., .Johnsonl J.W., Sverje~lsky~ D.A., Helgeso~~; H.C.> Calculation of the t,hem~o(iyl~alnic propert,ies of aqileous species at, l~ igh pressures ancl telnperat,ures. Efect,ive electrostat,ic radii; clissociation constallts all(1 st,anclarcl partial nlolal propert,ies t,o 1000'C ancl 5 k l~ar ; J . Cllem. Soc. Faraday Trans.; 88 (1992) 803 826.

Tl~olnason~ H.P., Willian~s; S.J., Near-field soli~l~ility stil(lies, Report NSS/R128, AEA-D&R-0068; Harwell Lal)., 0xfi)r~lshire~ U.K., 1992, 401).

Wanner, H.> Stan(lar(1s and corlvent,ions fix TDB pilt)lications, Report TDB-5.2, OECD Nilclear Energy Age~~ey , Data Bankl Gif-si~r-Yvett,e, Frallce, March 1992; 2211.

Ackerman, J.P., Sett,lel J.L.> Dist,ril)i~tion of pli~t,oniinn~ americium, and several rare earth fission pro(li1ct elernerlts 11etween li(llii(1 ca(l lr~ii~lr~ and LiCl KC1 e1itect,ic1 J. Alloys all(1 Colnpoiln(ls, 199 (1993) 77 84.

Giffailt, E., Vitorgel P.; Evi(lel~ce of ratiiolytic oxi(lat,iol~ of "'Anl ill Na+ / C 1 / HCOT / C O : media, Sci. Basis Nucl. Wast,e Mal~agernel~t XVI (Int,errant,e, C.G.> Pal~alan, R.T.> rtls.), Mat. Res. Soc. Synq). Proc.> 294 (1993) 747 751.

Giffailt, E.; Vitorge, P.; Cap(levilal H.; Correct,iol~s de tempPrat,lire silr 1es coefficients (i'act,ivit,k calculks selol~ 18 TIS, report CEA-N-2737> Centre (i'Eti~(les N~clkaires~ Fol~tel~;ty-ai~x-R,oses~ 1993, 2911.~ in Frencl~.

Lee, J.H.; Byme, R.H., Colnplexatio~~ of t,rivaler~t rare earth elelnent,s (Ce, Eul Gdl Tl); Yl)) 1)y car l~ol~ate iol~s; Geochirn. Cosn~ochiln. Acta, 57 (1993) 295 302.

Pi~ig~lornel~ech, I., Rard, J.A.> Wanner; H.; Gilidelil~es for teln~perat,lire corrections to ther~rn)~lynamic (lat,a al1(1 ent,halpy calculationsl Report TDB-4> OECD Nilclear Energy Agencx Data Bank, Issy-les-Moi~lineai~x, Fral~ce, Draft of March 1993, 531).

Giffailt, E., Inflilel~ce (ies ions chlori~re s i ~ r la chirnie (ies actini(iesl P11.D. Tl~esis; Univ. Paris-Sil(1, U.F.R. Scientifiqi~e cl'Orsay, 1994, 259p.> ill French.

Grel~the; I.; Plyasilnov, A.V.> On the ilse of the specific int,eraction theory for the im)~lelling of ther~rn)~lynamic quantit,ies in aqileous electrolyte systelr~s as a funct,iol~ of p> T and ionic strengtl~ (si~l)lnitt,e(l)~ (1994).

Jilng, B., Edelsteil~; N.M.> Seaborg, G.T., T l ~ e l~yclrolysis l~ehavior of the transilranium elelnent,sl in: Coorclil~ation chen~ist,ry a cent,ury of progress ( K a u f i ~ ~ a l ~ ; G.B., rtl.); A.C.S. Sylnl)osi~im Series 565, Washingtol~; D.C.: An~ericar~ Chen~ical Societ,y, 1994> pp.361 379.

Morss, L.R.; Willialr~s~ C.W., Syl~thesis of crystalline arnericiiln~ l~yclrox- ide; Am(OH):j, and (leterlnil~ation of its entl~alpy of fi)rmat,iol~; est,ilna- tion of t,he solul~ility-~)ro(ii~ct constal~ts of actinicle(II1) l~yclroxi(ies~ Ra- ( i iocl~in~. Act,&, 66/67 (1994) 89 93.

Wanner, H., Gui(ie1ines for the assignn~ent of in~cert,ail~ties, Report TDB- 3.3> OECD Nuclear Energy Agency, Data Bank, Issy-les-Moi~lineai~x, Fral~ce, May 1994, 141).

Parker, V.B.> Kho(1akovskii; I.L.> The ther~rn)~lynamic properties of the a(lileo~is ions ( t 2 and +3) of iron and the key com~)oi~nds of iron^^ to 1)e pi~l)lishe(l ill J . Cl~em. Phys. Ref. Dat,a, (1995).

Chapter V11

Authors list

This chapter corlt,ains an alpl1al)ctical list of t,hc alit,llors of t,hc rcfcrcrlccs cit,cd in this hook, cf. Cllapt,cr \.'I. The rcfcrcrlcc cotlcs gi\-crl nrit,h each narnc corresponds to t,hc piil)lications of ~vhich t,llc person is t,hc author or a co-aiit,llor. Xot,c t,llat, irlcorlsistcncics rnay occur tlllc to diffcrcnt int,crprct,at,ions of foreign alphahct,~. Tllcsc irlcorlsistcncics arc not corrcct,ctl in t,llis re~icw.

.A<:kerrnan, J.P.

.A<:kerrnann. R.J.

.Akrlla. J. rlkha<:hinskiy. \'.V. rlkirnoto, Y. .Aksel'r~lrI, N.\:. .All>X~(i. D.

.Alter. H.1T. rlnanthasmarny, J .An(ierson, G.M. .A11(ireic11111<, N.N. .Ansara, I. .Ar<:klrr, D.G. .Asprey, L.B.

.Atkinson, G.

.A\Tlg>L<lr(>, .A.

.Aziz, .A. Dars, C.E. , J r . D. c~&~\%-(ie, .. S.V.

Dagnall. K.TT. Bailey, S.RI. Daisrlrn. P.A. Daklankova, P.C. Dansal, B.\I.L. D. . ,Lr c L I I ~ V , .A.T;11. D>Lrk)>X~lel~> Y-ll..A. D>Lrk)rr, D.JT. Dart,scher, TT. Dat,es, J.L. Dat,es, R.G. Dayl~arz. R.D.

Dr>Xll. G.JT. Draslry. M.L. Drglm, G.\I. Dell. J.T. Drrle<li<:t, U. Denson, L.V. Drrgrnan. G..&. Drrnrlt,. U. Drrnkopf, \I. Drrnkopf, L1.F. D r s a n ~ o n , P. Drvingt,on, P.R.

Birloglio, G. Billon, ..I. Bjrrnlrn, J. Boccll~illon, G. Bornsr, \I. Borisov. R1.S. Bo~lrgrs. J.Y. Bracllry. D.J. Bran(i. J.R. Brat,sch. S.G. Brewer, L. Brillxcl, L. Brc$nstr(i. J.N. Brown. P.L. Bruno. J . B~~chanan , J.RI. B11c11rr. J . B I I C ~ I I , G. B~l(iar~tseva, N..&. B~~klanov, G.V. B~~klanov, V. Biipprlrnann, K. B~lrnrt , t , J.L. Burns. J.H. B~lzt)rr, B.L. Byrnr, R.H. Cacrci, R1.S. Cantrrll, K.J. Cap(irvila, H. Carlrson. U.G.F. c . a~na l l , . . TY.T.

Carniglia. S.C. Caro, P. Carrb, D. Castrt, S. Crlrrla, J. Chachaty, C. Chanclrr. K. Chanclratillakr, R1.R. Charvillat, J.-P.

Chateal~, C. Chiarizia, R. Cl~ilalla. T.D.

Chiott,i, P. Choporor-. D . h Choppin, G.R.

Ch~~(iinov. E.(; C h ~ ~ r n e j ~ , K.L. c i . .. ,~ratt,a. L.

Clevelanrl, J.M. C(>l)t)le, .J.\T'. Cohen, D. Colernan. C.F. Colernan. J.S. Cnnper, .J.N. Cor(ifilnke, E.H.P. Cox, J.D. Crerners, .A. Croff, A.G. Cross, J.E. C~~iller(lier, C. C~mningharn. B.B

Danesi. P.R. Dallt~en, C.H. D. ' L T I ~ , .' F. D. 'LT .' IeS, C.\Y.

De . i l l e l~~i>~, I.B. De Carr-alho, R.G. De Novinrl. C.H. De Plarlo, .A. Degischer. G. Derneshkir~, \'..A. Dbsiri., B. Dexpert, H. Drever, J.I. Dreyer, R. Drol)ichevskii, Y-11.1'. Drorrart,. J. Dllplessis. J . Dllyckaerts, G. El~erle. S.H. E(ie1stein. N.

Eclelstein, N.RI. Egllnov. \'.P. Eichler. E. Elrsir~, A..&. Ellison, R.D. Eriksen, T. Erin, E..&. Errnolrnko, V.I. Ermay, N.D. Errans, lT.H. Emart, F.T. Eyring. L. Fahey. J.A. Faircloth, R.L. Fang, D. Farrly, J . J . Fargras, M. Fray. D.C. Frk~er. R.C.

Frrneli~~s, W.C. Frrreira rle Rlirancla, C Frrri. D. Filirnonov, 17.T. Fischrr, D.F. Fitollssi, R. Flotorr. H.E. Flowers. G.C. Forchioni, A. Follrest, B. Frrcl, PI. Frrernan. .&..l.

Frrernan. R.D. Frrrno~~t-Larno~~rar~r~e, R. Frrnkel', V.Y. Frrnkel, \'.h. Frierl, S. Frierlrnan, H. '4. Frolnv, A..&. Fuger, .J.

F~lk~lshirna. E. F~llton, R.\T. Galin, RI. G. . .' a l rm, D. Gelrnan. .&.D. Gens, R. Gil~son. J.K. Giffaut, E. Ginzt)~~rg, F.L Givon, \I.

Gl~~shko . \'.P. Golclrnan. ..I. Gorl)enko-Grrrnanov. D.S. Gor(ior1, S. Gorsky, A.G. Go~lrliah~s. J . Graf. P. Grenthe. I.

Gr~mvolrl, F. Gschneirlner. K.A., Jr. G~~ggenheirn. E.A. G I I ~ ~ ~ ~ I I I ~ I ~ , B. G~~illal~rrlont, R.

Giil(ir~rr, R. GII~III, S.R. G11rvick1, L.V Hahn, R.L. Hairr, R.G.

Hale, F.V. Hall. G.R. Hall. R.0.A. Halow, I. Harnann, S.D. Hara, RI. Harrnon. H.D. Haschke. J.\I. Haskell, K.H. Hauske, H. Herlh~n(i. T. Ilk 12, -.. I . . I I . ( ' . - 1 1 1 1 . 1 . l . ' l l l l : l . I l l ] . 0 111.1.]. ' \ \ I . \ . \ I I I : I : .

l I I I I . . 1 0 111.1.2'. ' ! 1 0 1 . 1 . l l l . l . ] . p~!>llO o l . l . ]

Hrnrion. P. Herrick, C.C. Hrlnnann, F.K. Hirt,anrn. S. Hil(irnt)ran(i. D.L. Hol~art, D.E. Hc~ll t~r~~ler , .J.1'1. Hollry, C.E., Jr . Holul), J . Hornann. K. Hooker, P.J. Host,rt,tlrr, J.D. Hox3-sr. R.M. H~~l) t )>~rcl , TY.N. H ~ ~ l ~ r r t , S. H11c:llrr. I. H~~ssonnois. M. Irving, H. Irvirlg, H.1'I.N.H. h~liano, \I. Izrnalkov, .&.N. Jrnsrn, B.S. Jrnsrn, K..&. Johnson. J.TY. Johnson. K.S. Johnson. Q. Johnson. T.R. Jonrs, .&.D. Joshi. J.K. Jollniallx, B. Jovr, J. J ~ n g , U. Kalrvich, E.S. Kalltxy, N. Karnrnskaj~a, .&.N. Kapsh~~kov, 1.1. Kart,ashrvtx, N..&. Kat,z, J.J. Kaxuasuji, I. Kazanskii. K.S. Kernan, T.K.

Krllrr, C ,

Krrrisk. J .F. Krtrls, J. K h a c h k ~ ~ r ~ ~ z o v , G..&. Khalkin. \'...I. Khalt,llrin, G.\'. Khizhn!.ak, P.L. Khoclakovskii, I.L. Khoclakovsky, I.L. Khophlr. P.K. Kikindai, T. Kirn. J.I.

Kirn. J.J. Kinarcl, lT.F. Kirkharn. D.H. Kishirnoto, \I. Klrins<:hrnirIt,. P.D. Klrnzr, R. Kno<:h, TT. Koch. C.W. Kochrrgin, S.M. Korhly, G. Kohl, R. Kolokol't,sov. V.D. Konings, R.J.\I. Koppolcl, F . Kopytov, \'.V. Korot,kin, YII.S. Kosrnkov. V.\I. Koslllin, N.S. Kosyakov, V.N. Kot,lin, \'.P. Koprna , T. Krarnrr, G.F. Krrstov, G.A. Krivokhatskii, A.S. Krot,. N.N. KIIISP. F.H. Kl~chit,sl~, K. Kulyako, Y.RI. Klllyl~khin, S.A. Kllslnnaklnnari, RI. Laffittr, M.

Lagox3-ski. J . J . Lahr, H. L>~irllrr, .J.B. Larn, D.J. Larnport,. L. Lander, G.H. Larllrllr, P. Lat,irnrr. TT.M Laxualdt, D. Lazzari, G.P. Le Rlarois. G. Lr1)rrlrT~. 1.A.

Lr(irrr1, C.RI. Lee. J.A. Lee. J.H. Leggrt,t, D.J. Lrgollx, Y. Lrigh, G.J. Lrrnirr, R.J. Levy, H. Lrwis, G.N. Lirrsr, Ch. Lillry. E.M. Litvina, h1.N. Livrt,. J. Lloyrl, R1.H. Lohr, H.R. Lorirrs, C. Lorirrs, J . Lllnrlqvist,. R. Lyalylshkin. N.V. Lylr. S.J. RI. .' ' ~Lglnlls. S. Rlagon, L. Rlahajan. G.R. Rlairr, D. Rlakarorx, T.P. Rlar<:on. J.P. Rlar<:lls. Y.

Rlarin, B. Rlarkin. T.L. Rlarqllart,. R

M. a15 . ,k 1~~11, . JT.L. M , . alteall, . RI.

Martell, ..I.E. M. altlnot, . ' L.

hlaslennikov, .&.G. Mason, G.1T. hlathllr, J.N. hlayorga, G. iYIazllr, Y.F. MCCIIP. R1.C. hlcDo\%-ell, 1T.J. McElrojr, D.L. McNeilly, C.E. Mc1Thar1, D.B. iYIeclve~Irv, V.A. Meinrat,h, G. hlerini. J. hlesrnrr, R.E. hleyrr, G. hlikhailova, N.K. hlikheev. N.B. hlilanov, \I. hlillero, F.J. hlilligan. TY.O. iYIills. I. hlilyl~korx, R1.S. hlironov. N.N. iYIit<:k~rll. A.1T. hlits~~gashira, T. iYIjassoeclov, B. hlonclal, J.U. hlonnin, C. Moore. D.A. hlorgan, J.J. hlorss. L.R.

hlllller. W. hliiller. W. hll~noz. J.L. h l l~ s ih~s . C. hlyasoerlov, U.F

hlyasoerlov, \'.F. Nair. G.LI. Naqvi, S.J. N. ~ ~ r ~ ~ p n a n k l ~ t , t y , . . . P.

Nash, K.L. N. t . .. '

CL ,rl~rljar~, P.R. Narrrat,il, J.D. Nkker-Ne~nnann, E. Ne\%-ton, (;.TT..&. Ne\%-ton, T.\T'. Ng11yer1-Trung. C. Nikolaevskii, V.U. Nikolotorx, Z.I. Nitsche. H.

Norclstrorn, D.K Norling. U.K. Novotni., P. N ~ ~ g e n t , L.J. N~~tt ,a l l , R.L. Oelkers, E.H. Oett,ing. F.L. Olofson, U. Olson, \T.hl. Parker, \'.B.

Pa rkh~~r s t , D.L. Patil. S.K. Paz~~kh in , E.M. Pennernan, R. ..I

Pepparrl, D.F. Peretr~~khin, V.F. Peretr~~khin, V.P. Pererxlc~rr, S.A. Perlrnan, I. Pershin, A.S. Pet,erson, D.E. Pet,erson, J.R.

Pllillips. C.A. Phillips. S.L. Phipps, T.E. Pirozhkov. S.\'. Piskllnov, E.M. Pit,zer, K.S.

Plllrnrnrr. L.N. Plyasllnov. ..I.\'. Pol!.ashov. 1.M. Porter. R.A. Porto, R. Potter, P.E. Poznyakov. A.N. Prins, G. Prllsakov. \'.N. P~~ig(iornrnech. I. Pyt,komicz, R.M. Rat)irIra~~. S. Rarl<:hrnko. \'.M. Rai, D.

Ranclall. M. Ran. P.R.V. Ran. \'.K. Rarrl, .J.'.I. Raschrlla, D.L. Rasrrlllssrr~ J. J. Ral111, E.G. Razl)it,r~oi. \'.RI. Rrirnarln, T. Rrisfrlcl, M.J. Riglrt, C. Rinarrl, P.\I. Rot)ir~son, R.A. Rot)ir~son, 17.J. Rot)oll<:h, P. Rodrly, J.W. Roof. R.B. Rnsch. F. Rossotti. H. Rozrn. .&.RI.

Rul~rn. H. R I I I I ( ~ ~ , IT. Ryat)inin, R1.A. R p n , J.L. Rykov, A.G. S a t ~ a ~ l , C.S. Sahliri, RI. Salvatnrr, E. Sarnhoun. K. Sapozhnikova. T.V. S. all, .' C. Satoh. I. Scat,charrl, G. Schlri(i. T . Schrni(it, K.H. Schock. R.N. Scho~t)rrchts, J.P. Schott, J . Sclllllz, W.W. Sch~lrnrn, R.H. Sch~~strr , W. Schrnarzrnt)a<:h, G. Scit)ona, G. Sral~org, G.T. Sears, G.W. Srifrrt, R.L. Srkinr, T. Srlrznrv. .&.G. Srrgryrva. E.I. Srrik, \'.F. Srrnr. R.J. Srt,tlr, J.L. Shafirv, A.1. Shalinrt,~. A.U. Shalinoff. G.\'. Shannon, R.D. Sharrna, H.D. Shrstakov, D.I. Shiloh. RI. Shilov, \'.N. Shirnl~arrv, E.V. Shirlry, V.S. Shock, E.L. Shushakov, \'.D.

Sh~~shakova, T.1'. Shve(iov. \'.P. Siegel, M.D. Sillbn, L.G. Silva. R. Silva. R.J.

Silvest,er, L.F. Sirnakin. G.A. Sirnpson. O.C. Sjot)lorn. R. Sjot)lorn. R.K. Skeen, J . Srnirolls, F. Srnit,h, R.M. Srnit,h-Briggs. J.L. Soclerholrn. L. Siihnel, 0. Sokolov, \'.B. Sonnenl~rrger. D.C. Spahill, K. Spirlet, .J.C. St>Lcller, S. Stan(iifer, E.RI. Starik, I.E. Strl)l~nov, O.B. Steinfink. H. Steparlnv, ..I.\'. Stephens. D.R. Ste\%-ar~l, RI...I...I. Stokely, J.R. Stokes, R.H. Storrns, E.K. Strazik. \Y.F. Strickert, R .G. Strorr11)erg. H.D. S~IOIISP. C.E. st11111111, TT'. St11pi11. \'...I. Sllrlakov, L.V. Sllllivan, J.C. Slmclbn, N. S~lz~lki . S. Sverjensky. D.A.

Tanarnas, R. T. . . an,Lnaev, I.G. Tanet, G. Tanger I\', J.C. Tardy, Y . Tasker, P.\T'. Taylor, J.C. Taylor, J.R. Teaglle. L.S. Ternpleton, D.H. Tet,ent)a~~rn, M. Thtxyer, W. Thornason. H.P. Thorn. R.J. Thorstenson, D.C. Tirnofeev, G. A. Torstenfelt, U. Trar~ The. P. Trofirnov, T.I. Tmeecl, C.J. Unrein, P.J. \:t~nrlrvencler. TY.H. \:t~ninl)ro~~kx, R. \:txrga, L.P. \:t~sil'ev, \:.I. \:t~sil'ev, \:.P. \:t~sil'ev, 1T.Y.. \:t~sil'ev, \:.Y->L. \:rlovenko, \'.RI. \kits, I.V. \:ieillar~l, P. \:is!.ashchrva, G.I. \:itnrge, P.

I'nlkov, Y.F. \i,n Keller. C. nbcle. \T'.Z. nbgrnan, D.D. nbllrnann, J.C f i l t e r . K.H. nbl ton. E.L. nbng , P. nbnner , H.

nbrcl, E.H.

nbrcl, J.W. IT>Lrcl, 1'1. ITr1)er. Jr. ITrigrl, E.

ITr11:k1, G..&. ITrrnrr, G.D. ITrstrl~rn, E.F.. Jr. IThiffrr~, D.H. IThitr, H.J.. Jr. IThitfirl(i. RI. ITilliarns, C.\T. ITilliarns, S.J. ITishnrvsky. V. ITit,trnanr~, F.D. ITc~jako\%-ski. '4. Wolf, \I. Wolf, T. IT<I0(i. S.'&. ITcIo(is. M. Yt~l<(>vlrv, G.N.

Yt~rna~~chi, S. Ytxrlir, E. \iolmg, J.P. Y1111irl>~, K.S. Y ~ ~ r ~ g r r ~ a n , \'.S. YIISOV. .&.B. z. .k. ' . CL(. I C L ~ I ~ ~ S ~ I I , W.H Zarnorani, E. Zrl~roski, E.L. Zrnkova, R..&.

Chapter V111

Formula list

This chapter prcscnt,~. in st,arltlartl order of arrangcrncnt (cf. Scct,ion 11.1.8) a list of forrrliilac of arncricillrn corlt,aining species. Tllc rrlcarling of the phase designators, (xi), (er); etc., is cxplainctl in Scct,ion 11.1.4.

Tllc forrnlllac that arc not tlisciissctl in t,hc prcscnt review arc proritlcd ~vit,ll infor- rrlntiorl on rcfcrcnccs that rnay cont,ain t,hcrrnodynamic dat,a on tllcsc corrlpoiinds or corrlplcxcs (for complct,c cit,at,ions sec Chapt,cr \:I). Tllc forrrliilac for ~vhich sclcctcd dat,a arc prcscrlt,ctl in Chapter 111, as \ ~ ~ l l as those \vhich arc tlisciissctl but for ~vhich no data arc rccorrlmcrltlcd 1)y this review; arc marked correspondingly.

Tllc inclllsion of t,llcsc formnlac in t,llis chapt,cr is to 1)c iindcrst,ood as information on t,hc cxist,cncc of pii1)lishctl rnatcrial on t,llcsc formlllac. It in no ay implies t,llat, the prcscnt r c ~ ~ i c w gives any credit t,o cit,llcr t,hc t,hcrmotlynamic tlat,a or the cllcrrlical corrlposit,ion or cxist,crlcc of t,hcsc species.

Sorrlc arncricillrn formnlac arc rcport,cd only in [87BR0/1\:.%X]. Not,c ho~vcvcr. t,llat, tllcrc is no cxpcrirncnt,al indication for the cxist,crlcc of t,llcsc species. arltl t,hat only cstirnatcs for t,hcir cqnilibrinrn constants of forrrlat,iorl arc given in t,llc t,hcorct,ical work of [87BR(I/I\~.%N].

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Formrrla list

see 11. 87 [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [78ALL/DEA], [82SIL], [83ALL], [86KiN]. [87BRO/KiN] [87BRO/J,\N] [82SIL], [83.&LL], [86JT'.iN], [87BRO/JT'.iN] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] data selecterl in t l ~ e preser~t, review [87BRO/J,\N] [86BRA/LAG] data selecterl in t l ~ e preser~t, review [87BRO/J,\N] see 11. 101 data selecterl in t l ~ e preser~t, review data selecterl in t l ~ e preser~t, review [87BRO/J,\N] see 11. 106 data selecterl in t l ~ e preser~t, review see 11. 112 [78ALL/DEA], [87DRO/W.ilu] see 11. 114 see 11. 114 [87BRO/J,\N] [87BRO/J,\N] see 11. 114 see 11. 114 see 11. 114 [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] see 11. 115 [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N]

data select,ed ~ I I the preser~t revie~v [82JEN]. [8iBRO/\T'.&lu] see 11. 116 see 11. 104 [ainRO/W.&lu] [ainRO/W.&lu] data select,ed ~ I I the preser~t review [54KOC/CUN] [ainRO/W.&lu] [ainRO/W.&lu] [i2KRE]. [86BR,&/LA-\G] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [i2KRE] data select,ed ~ I I the preser~t review [ i6nEI/WIS] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] see 11. 105 [i6ShlI/RI.&R] see 11. 105 see 11. 105 [ainRO/W.&lu] see 11. 121 see 11. 105 [ainRO/W.&lu] [ainRO/W.&lu] data select,ed ~ I I the preser~t review [82WEI/WIS] [ainRO/W.&lu] [ainRO/W.&lu] [i2KRE]. [86BR.&/LAG] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu] [ainRO/W.&lu]

Formrrla list

[87BRO/J,\N] data selecterl in t l ~ e present review [87BRO/J,\N] see 11. 106 [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [8 iBRO/W..lK] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [73RIOS2]. [73RIOS] [87BRO/J,\N] [87BRO/J,\N] see 11. 123 [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] data selecterl in t l ~ e present review [87BRO/J,\N] [87BRO/J,\N] [72FUG]. ['i2KRE], [8GBR..l/L..lG] [87BRO/J,\N] [87BRO/J,\N] [87BRO/JY.iN] [87BRO/J,\N] [87BRO/J,\N] see 11. 124 [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/Ji\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N]

[8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] data selecte(i in t,lle prese11t review [86UR.&/L.&G] see p. 126 see p. 126 see p. 126 data selecte(i in t,lle prese11t review [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] data selecte(i in t,lle prese11t review [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] [8inRO/W.&lu] see p. 127 see p. 131 see p. 127 see p. 128 see p. 131 data selecte(i in t,lle prese11t review see p. 132 see p. 132

- H - H - - .- .- H H m m m m m .- .- m ......................... z z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z G G Z % $ $ $ 2 2 2 . . . . . . . . . . . . . . . . . . . . . . . . . t + : + s s $ s s s s s s s s s s s s s s s s s s s s s s s s s sggzggjggjz\\\g<z<"m<z\\\\\\\\\\\\\\\\\\\\\\\\\ m m QiiiiiQii ~ O O O i O i O i i O i O O O O O O O O O O O O O O O O O O O O O O O O O

. . . . . . . cZcZcZ .cZ .cZ . .cZ . c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z c Z ,: " """" , : "h,: e a a a "a "a ""a " a a p p p p p p p p p p p p p p p p p p p p p p p Z Q Q Q Q Q Z Q Q L L ,.,.L. Q , . Q , . Q Q L . Q L.,.

m m m m m ~ m Q m ~ Q m Q m m m m m m m m m m m m m m m m m m m m m m m m m z % % % % % - % %zz---*-*- *1*1111111111111111---------

Formrrla list

[87BRO/J,\N] see 11. 144 [87BRO/J,\N] [87BRO/J,\N] see 1 ~ . 141, 143 [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] see 11. 140 see 1 ~ . 141, 143 [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] see 11. 140 [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] [87BRO/J,\N] see 11. 144 see 11. 145 see 11. 146 see 11. 146 see 11. 146 see 11. 147 see 11. 146 see 11. 147 see 11. 147 see 11. 147 data selecterl in tlle present review data selecterl in tlle present review [87BRO/J,\N] [85P..lZ/KRI] [69SEK/S..lK], [R?BRO/TY..lN] [87BRO/J,\N] [87BRO/J,\N]

Q .- Q .- Q Q .- .- Q .- Q .- Q .- > m > > > m m > > > g z g g g z z g g g 3 $ 3 3 3 5 $ 3 3 3

S 5 S S : , :: , , : : : g - 0 g g g 0 0 g - g - g M cZ G G & cZ cZ M M

- M

2 - R 3 3 3 R R - 2 - 2 2 + m + + + m m + + + -

-02 - -m m- -02 -* m zz.5 zzz E-z.5 zz.5 .S E-E-zz.5 zzzzz.5 zzz z LQ .S z z - z z z LQ z 5 z $ $ = < $ $ ss<$ss,s,s~s$?tsas~ss?$sssstss~sd?$szssa $ ? $ z $ < = z $ * $ 5 $ $ = < $ $ $ $ z $ $ ? $ + = < $ z $ $ 0 W $ ? $ . $ sosrns

G ,, a ,,, a ,, G G ,\,,,, G ,\\\\ G -.Ld G \ \ \ \ \ \ G 2 2 d O O ~ O O O d O ~ O ~ O O ~ ~ O ~ O ~ O O ~ O O O O O z O O . O z O O N O O " d O . , . O

f f i f f i " f f i f f i f f i . E W E " f f i f f i " " f f i A f f i W f f i f f i " f f i f f i f f i f f i f f i " f f i f f i 3 s $ " f f i f f i < f f i f f i Z . f f i 3 s 3 s & a n m a a a % a m a m a n m ma?'a,aa m a a a a a m a n + a + m a a a a a c : " a + a + a Q,.LL 5 ,.,.L. QL.~,.~ L.,. + s L ~ & L ~ ~ L.,. 5 L ~ L L L L L L L L 5 LLLL Q L L Q % L L L L L Q L L L L ~ Q L L Q L L Q L L g zzz g o , m , k z = z z G , m , z z z z G zz g 00 g G , m , z z z z k g z g z g z

Formrrla l is t

.1rn02(HC0,), (aq) ,\rnO,(HCO,).~ .irn(OH),CO; .irr1(HC0,), (q) Arn(HC0,): .1rn0,(CH,C02)2 (cr) ,\rnOH(CO,)~- . 1 r n O , ( O ~ ) , C 0 ~ ~ .1rn02(HC0,), (aq) ,\rnO,(HCO,); ,\rnO,(HCO,); ,\rnO,(HCO,)~- .1rn(HC0,)4 (aq) Arn(HC0,); .1rn(CH,C02)4(cr) .irr1(HC0,), (q) Arn(HC0,): .1rn(C0,),0H4- ,\rnO,(HCO,)2- ,\rn(HCO,); ,\rn(HCO,);- .1rnO,(HCO,); .1rnO,(~CO,)2- .1rn(HC0,)4 (aq) Arn(HC0,); ,\rnO,(HCO,):- Arn(~C0, ) ; - .1rnO,(~CO,)2- , \ r n O , ( ~ C 0 , ) ~ - ,\rn(HCO,); Arn(~C0, ) ; - .1rr1(HC,0,), ,\rnO,(~C0,):- Arn(~C0, ) ; - ,\rn(HCO,);- (.1rn0,),(OH):3CO; Am, (C0,),.2H20(<:r) .1rn,(C,04)~4~10H20(c:r) (.1rnO2),(OH),CO: .1rnCIi2+ .1rnCF3+ .Arrl(CN); ,\rn(CN);+ i\rr~(CN), (aq) .irr~(CN): i \ r r ~ ( C N ) ~ (aq)

i\rrl(CN)T

-------------- Z Z Z Z Z Z Z Z Z Z Z Z Z Z $ $ $ $ $ $ $ $ $ $ $ $ $ $ s s s s s s s s s s s s s s ,,,,,,,,,,,,,,m 000000000000002 d d d d d d d d d d d d d d & a a a R R R R R R R R R R R Q L- L- L- m m m m m m m m m m m m m m ~ --------------

-- Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z $ 5 $ $ $ $ $ $ $ $ $ $ $ $ $ $ ss s s s s s s s s s s s s s s - ,,-,,,,,,,,,,,,,,- 00200000000000000~ d d . d d d d d d d d d d d d d d 6

O . a a ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Q R R Q ,. ,. eezeeeeeeeeeeeeeez

0 0 0 i i L. L. L. L. L. m i i i i i m & & & & & & Q Q Q Q Q Q z z z z z z

* S X"! * -.fi

-A 3 2 , L20 - - - -

0 c "0 go - - - 5 - - 5 - - - 1 1 1 1 1 - N l N l "N "N *" *" I** I* -i

l l l l l 002u c , I n 1 ,,,,*,*,,*, + 5 5 I I I 5+ -------- l l l

5+ -------- -TIC L L L L L L L L L;?lz v+ + +,"",",'+,'R22 ","","","E z z Z Z Z Z Z Z Z Z z-C,-c l ,Cm ,Cm S" S - - - - z z ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ c &^SU

z z z z y y -------- 5 ,- , , U U U U U U U U U U m m (n(n(n(n(n(n(n(nT~2~~~ 2 N N N N N N N N d V - u U,, , , , , , , , , ,-,-,-,-,-,-,-,-,-,-Y.z.~G X m % """"0 0 0 0 0 0 0 0 0 0 & L g u m m ----------- - - - - - 2 2 2 Ac2 -=q - - - - - - - - - - - - - - - - - - - - - - - - - - S E ~ m m " " " " " " " ' - - - - - - - - - - -

2 2 2 2 2 2 2 2 2 2 2 2 2 < Z < & 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

Formrrla list

.irr~.ilO, (U) Tl.irn(SO,),(s) Tl,.irr~, (SO&(s) a - . h , (\l00,):~ p-.irrI, (Moo,), . i r r ~ , (IT0,):3 (m) . i r r 1 ( P , I T ~ ~ 0 ~ ~ ) ~ ~ . ~ ~ ~ I ( P , I T ~ ~ O ~ ~ ) ~ ~ .irnVO, (cr) .irnVO, (cr) .irrll1 ,:3:3 NtlO, (er) (~-.irr~Iil~O, p-.irnNt)o4 .irrll1 ,:3:3 TaOi3 (U) .irr~TaO,(cr) . i r r~I i l~TiO~ (m) .irnTaTiO, (er) .irr~ScO:~ (U) . i r r 1 0 , I i ~ 1 0 ~ ~ Ull,5.ir~~o.s,~),(~:r) .irnO,UO;+ .irnPa04 (cr) SrrlrnO, (er) Sr:3.ir~~06 (U) Sr.irn,O,(s) UaArnO, (cr) Ua,.irnOfi (cr) UaArn,O,(s) Ua,.irr~Iil~O~(~:r) Ua,.irnTa06 (er) Ua,.irnPaO,(cr) Li.irnO,(s) Li,.irnO, (S)

Li,rlrnO4 (er) Li,.irnO, (er) Li6.irn0, (er) Li7.irn0, (er) Li,.irnO, (er) Li.irr~E, (U) Li.irn(hloO,), (er) Na,.irnO, (cr) Na,.irnO, (cr) Na,.irnO, (cr) Na,.irr~O~ (m) Na7.irr~,F:31 (m) NaArnO,CO, (S)

Na,ir11(C0,), (U)

see 11. 98 see 11. 131 see 11. 131 see 11. 98 see 11. 98 see 11. 98 see 11. 144 see 11. 144 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 173 see 11. 172 [8l<;UI/HOB] see 11. 98 data select,ed i r ~ t,he 11rese11t review see 11. 98 see 11. 98 data select,ed i r ~ t,he 11rese11t review see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 115 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 98 see 11. 115 see 11. 165 see 11. 163

Na,.irr~(CO,), (er) Na.irn(hloO,),(cr) Na,.&rr~(hIoO,), (er) K2.irnO4 (er) K2.irnC1, (er) K.irr~(SO,),(s) K,.irr~, (SO&(s) K,.irn(SO,),.H,O(s) K.irnO,PO,(s) K.irnO,.isO, (S) K.irnO,CO, (<:I) K,.irn0,(C0,)2(~) Ks . i~~~0 , (SO~3)~3 ( s ) K,.irr1,(\1~~0,),(~) KII,.irr~, (\l(>O,), (S) Rt) , r l r r~F~ (cr) Rt),.irr~Cl~ (<:I) Rt).irr~(SO,), (S) Rt).irnO,PO,(s) Rt).irnO,.isO,(s) Rt).irnO,CO,(cr) Cs.irr1C1, (S) Cs,.irnCl, (S)

Cs.irr1(SO,), (S) Cs.irr1O,PO,(s) Cs.irrlo,.iso,(s) Cs.irr~O,CO,(cr) Cs,.irnO, (CO,), (S) Cs,Iia.irr~Cl, (er)

see 11. 163 see 11. 98 see 11. 98 see 11. 98 see 11. 120 see 11. 131 see 11. 131 see 11. 131 see 11. 144 see 11. 146 see 11. 165 see 11. 165 see p. 165 see 11. 98 see 11. 98 see 11. 115 see 11. 120 see 11. 131 see 11. 144 see 11. 146 see 11. 165 see 11. 119 see 7). 119 see 11. 131 see 11. 144 see 11. 146 see 11. 165 see 11. 165 data $eleet,ed ~ I I the preser~t review

Appendix A

Discussion of selected references

[54FEA] Feay, D.C., Some chemical properties o f curium, Ph.D. thesis, Radiation Laboratory, University o f California, report UCRL-2547, Berkeley, California, 1954, 50p.

Fcny rcport,s the soliil)ilit,y of cllrillrrl and nrrlcriciiim t,rifllloridc in nqllcons soliit,ions containing cxccss fllloridc as a fimct,ion of t,crnpcratiirc (0; 23 and 47°C). .%nalysis of tllcsc solubility data [54FE.%] yicldctl

3 .%rnF; + F - .%mF:3(;tq) log,, h': = 3.11*0.07 &H; = (21.9*2.1) k J . rnol-' 1.5'; = (133*17) J . K-' . mol-l

3 .41nF:~ (S) -4mF.3 (aq) l o g I = 4.83*0.07 &H; = (14.6*2.1) k J . rnol-' &S; = (44*17) J . K-' . mol-l

Tllc cxpcrirrlcnts nrcrc pcrformctl from nndcrsat~~ration. Ho\vcvcr; cqnilibrinrn rrligllt not have hccn reached hccnllsc of inadcq~lat,c st,irring (Fcay states t,hnt the sarnl)lcs n7crc bot,h self stirred dnc t,o gas croliit,ion, nrltl rnnn~lally ~vi th n plat,iniirn wire). Only fc\v cxpcrirncnt,al dct,crrninations wcrc pcrformctl at each tcrnpcrat,~lrc, nrld t,his review considers it possil)lc t,llat the solitl rrligllt have rcdissolvcd cornplct,cly in t,hc samples rrlost diliit,cd in flnoritlc ([F-],.,,,. -- 0.001 11). Fnrt,llcrrnorc, it is not possiblc to dctcrmirlc the nnt,urc of t,llc prctlominant nrrlcriciiim species in soliition hascd only on t,hcsc few solubility rncasiircrncnt,s, and Fcny did not report any charact,crisnt,ion of t,hc solid phase cit,hcr. Bccnllsc of all t,hcsc consitlcrat,ions. the cq11ilil)riiim const,nrlt,s nrltl t,llcrrnodynnrnic data rcport,ctl by Fcay arc tlisrcgardcd in this rcvic\v.

[56WAR/WEL] Ward, M,, Welch, G.A., The chloride complexes o f trivalent plutonium, americium and curium, J. Inorg. Nucl. Chem., 2 (1956) 395-402.

Tllc authors invcst,igatcd the complex formation of sclcct,ctl t,rivalcnt actinitlcs (.%m; Cm and Pn) in hydrochloric acitl solutions by iising an ion cxchangc mct,hotl. Tllc

I I I C ~ S I I ~ C I I I C I ~ ~ , ~ ~vere prcsiimahly matlc at roorrl tcrnpcratiirc. Preliminary cxpcrirncnt,~ of actinitlc dist,rih~lt,ion bct,~vccn t,hc cat,ion cxcharlgcr and t,hc sol~lt,ion phase wcrc rrlndc at fairly high ionic st,rcngt,h, usirlg rrlixt,~lrcs of pcrclllorat,c and cllloritlc ions. Tllc rcsiilts siiggcst,ctl t,hc forrnation of t,llc first t,~vo cllloro cornplcxcs. -4s indicat,cd in Figure 1 of t,hc original paper, t,llc prclirninary arncriciiim cxpcrirrlcnts wcrc pcrformctl at [H+] = 0.5 hl . while the cllloridc ion corlccntrat,ion urns varictl hct,\~~ccn 0 and 3.5 11.

Ward and Ilklch derived t,llc tlissocint,ion constant of .krnCl'" frorn diiplicatc mca- siircrrlcnt,~ of t,llc arrlcriciiim dist,rih~lt,ion cocficicrlt,~ in 0.206 h1 arltl 0.5 h1 HC1 soliitions. The a~lt,hors claimctl t,hat of all the arncrici~lrn spccics present in t,hc sol~lt,ion. only the adsorpt,ion of .%m3+ ions on t,llc resin \!,as significant,. Carlcson and Irv- irlg [54CAkR/1R\:], Grcntllc [62GRE] and Irving ant1 Khopkar [64IR\'/KHO] have sllo\~~n that t,hc intlividnal dist,rih~lt,ion rat,ios of the ~lrlcorrlplcxctl lant,llanidc arltl actinitlc(II1) ions on strong cat,ion cxcharlgcrs arc aboiit 10 t,o 20 tirrlcs higher t,harl those calcnlat,cd for tlivalcnt corrlplcx species. Thcrcforc, t,his irltlicat,cs t,llat corrcctions for t,hc prcscrlcc of .%mC12+ in t,hc rcsirl should he rlcgligihlc at t,hc rclatircly low cllloridc conccnt,rations used by Ilkrd arltl Ilklch.

Akccordi~lg t,o the terminology adopt,ctl by t,his rcric\v, t,hc forrnation const,ant,s at, I = 0.206 h l and 0.5 11 arc log,, p, = 0.35 and 0.24, rcspcct,ivcly. \vith no iinccrtaint,y T ~ ~ ~ I I C S assig~lcd by il:artl a11d Ilklch. .%ssnrning t,llat t,hc variat,ion of aniorlic cornposition at const,ant ionic st,rcngt,h tlocs not cllangc t,llc ion intcract,ion cocficicnt,~. i .e . ; E(A&+,(:~-) = E ( . ~ ~ + , ( : ~ ~ ; ) and E(.~.~(:~W+,(:,-) = E ( . ~ , ( : ~ ~ + , ( : ~ ~ ~ ) . t,hc I I I C ~ S I I ~ C ~ d i f i r c ~ ~ c c in the dist,rih~lt,ion cocfficicnt,~ of arncrici~lrn hct,\~~ccn chloride-ficc arltl hydrochloric acitl sol~lt,ions may cnt,ircly he att,rih~lt,ctl to cornplcx forrrlat,ion effects. Ho\vcvcr, bcca~lsc of t,llc very lirrlitcd niimbcr of cxpcrirncrlt,al points, t,llis rcric\v assigrls an nnccrt,ainty of * 0.2 in t,llc val~lc of log,, .lI. The Davics cquat,ion ~lsctl by t,hc all- tllors to calcnlat,c t,hc st,arltlartl cqnilibrinrn const,ant is of do11ht,f111 application at ionic st,rcngtlls larger t,harl 0.1 h1. Tllc corrcct,ion rrladc by t,llis rcric\v nrit,h t,hc specific ion irlt,cractiorl cqiiations in .kppcndix B using AE, = ( 0 . 2 2 * 0.1) kg . rnol-l. rcsnlt,s in log,, p," = (1.13 f 0.20) and (1.18 * 0.20) from t,llc val~lcs rcport,ctl at I = 0.206 11 and 0.5 hI rcspcctircly.

Ak~ncriciiim iipt,akc by an anion cxchangcr in 8 hI HC1 soliit,ions urns taken as an cvidcrlcc for t,llc format,ion of ncgat,ivcly cllargcd cllloro cornplcxcs. H o \ ~ ~ c ~ ~ c r , no qllarlt,it,at,ivc data wcrc reported.

[56YAK/KOS] Yakovlev, G . Kosyakov, V.N., Gorbenko-Germanov, D.S., Zenkova, R.A., Korovin, A.P., Sobolev, Y.P. , Spectrophotometric studies o f the behaviour o f americium ions in solutions, Proc. International Conf. on the Peaceful Uses o f Atomic Energy, held 1955, in Geneva, Switzerland, Vol. VII, New York: United Nations, 1956, pp.363-368.

Format,ion of amcricinrn(II1) cornplcxcs in pcrchloric, hydrochloric, nitric and snl- phuric acids urns invcst,ignt,ctl by l\lakovlc~r et o,l. [56YA%K/I<OS] usirlg spcctrophotornct,ry. .%t high acid corlccntrat,ions (pH < 0). spcct,ral sllift,s arltl tlccrcascs of rrlolar cxt,inctiorl cocfficicnts of the cllaractcrist,ic peaks in the U\'. and IR regions arc at,- tribntcd to t,llc format,ion of arrlcriciiim complcxcs. Ho\vcvcr, the composit,ion of the prctlomirlant spccics in sol~lt,ion arltl the corresponding st,ahilit,y const,arlt,s car1 not i)c

cxt,rnct,cd from t,llcsc qnnlitatirc rcs~llt,s

[6OLEB/PIR] Lebedev, I .A., Pirozhkov, S.V., Yakovlev, G . Determination o f the composition and the instability constants o f oxalate, nitrate and sulphate complexes o f Am"' and Cm"' by the method o f ion exchange, Radiokhimiya, 2 ( 5 ) (1960) 549-558, in Russian; English transl.: pp.39-47.

Lcl)cdcv, Pirozllkov and I'Iakovlc~. [GOLEB/PIR] llsctl an ion cxchnrlgc t,cchniqllc to stiidy the nrncriciiim(II1) rlit,rnt,c nrltl snlphat,c syst,crns at pH = 3.5 t,o 4, nrltl I = 1 h1 and I = 0.75 h1 for t,hc rlit,rnt,c nrltl snlphatc syst,crns rcspcctircly. Tllc

17.12; rcspcct,ivcly). .$n addit,ional cxpcrirrlcnt pcrforrrlcd at high siilphnt,c conccn- tratiorl (at I = 1.5 h1) was intcrprct,cd assllrning the formation of l)oth .$mSO: nrltl .$m(S(14)~; but the scarceness of the cxpcrirncnt,al dat,n and the narro\17 conccnt,ration range invcstigat,cd do not allo\v n rclial~lc tlct,crrrlinnt,ion of cqnilibrinrn constants; nrltl tllcrcforc the val~lcs rcport,ctl by Lcl)cdcv, Pirozllko~~ nrltl Ynkovlcv for t,llc s~llphatc syst,cm at I = 1.5 hI arc disrcgartlcd by t,llis rcric\v.

[61PEN/COL] Penneman, R.A., Coleman, J.S., Keenan, T . K . , Alkaline oxidation o f americium; preparation and reactions o f Am(lV) hydroxide, J. Inorg. Nucl. Chem., 17 (1961) 138-145.

Tllc n~lt,hors rcport,cd qiialit,at,ivc ol)scrvations on t,llc st,nbilit,y of .4rn(OH)4(s) prc- pared by hypochloritc or ozonc oxidnt,ion of .4rn(OH):3(s) s~lspcrlsions in NaOH solllt,ions. .$ so1iil)lc hydrolysis species of .$rn(\'I) was clairrlcd to bc protlllccd ~vhcn using ozonc as oxitlising agent,.

[61PEP/MAS] Peppard, D.F., Mason, G.W., Hucher, I . , Stability constants o f certain lanthanide(ll1) and actinide(ll1) chloride and nitrate complexes, Report TID-14716, UAC-5777, 1961, 13p.

This report appears to l)c the sarnc stiidy as Ref. [G%PEP/II.$S].

[61STA/GIN] Starik, I.E., Ginzburg, F.L., State o f microamounts o f radioelements in dilute solution, Sov. Radiochem., 3 (1961) 49-55.

This qnnlitatirc st>udy on t,llc sorpt,ion of amcricinrn on ion cxcllangcrs contains no dat,a pcrt,irlcnt t,o this review.

[62GRE] Grenthe, I., Chloride complexes o f trivalent americium. Short communication, Acta Chem. Scand., 16 (1962) 2300.

Tllc nut,hor used a cnt,ion cxcllangc resin to st,~ltly the .$m(III) complcxation ~vit,ll C 1 ions in n 4 11 H(C104.C1) mctliiim at 20°C. .$ combination of graphical and ciirvc fitting rrlctllods was used in t,hc data analysis, as dcscril~cd in Ref. [G2GRE2]. Tllc calciilnt,ions suggest a contril)iit,ion of the complex species .$rnCl'" to t,llc t,ot,nl nrncri-

ciiirrl adsorpt,ion on t,llc resin. Grcntllc follrltl the st,al)ility constants for the form. a t ' ,ion of A%~nCl'" ant1 -4rnC1; to he log,, ill = ( 0 . 1 6 f 0.02) and log,, 'lZ = ( 0 . 7 4 f 0.1); rcspcct,ivcly. The llnccrt,aintics assignctl by t,llc ant,hor appear t,o bc equal t,o the st,andard deviation of the rncan valiics. Taking also irlt,o account the tcrrlpcrat,llrc diffcrcncc from the rcfcrcncc st,at,c; this review cst,imat,cs t,hc llnccrt,ainty in log,, p, as *0.05 and in log,, i12 as f 0.2.

Lebedev, I.A., Yakovlev, G.N., Determination o f the composition and stability constants o f thiocyanate complexes o f Am( l l l ) , Cm(l l l ) and Ce(l l l ) by ion exchange, Sov. Radiochem., 4 (1962) 273-275.

A%~ncriciiim corrlplcxat,ion by t,llc thiocyannt,c ligantl was st,udicd nsing a cat,ion cx- change t,cchniqnc at t,~vo ionic strengths (0.5 and 5.0 h1 XaSCX/NaC1(14). at pH = 4. Tllc cxpcrirncnt,al data, oht,aincd at I = 0.5 11, show that only .%rnSCN2+ is formctl at [SCN-] 5 0.36 hl. The tlist,ribntion cocficicnt at [SCX-] 2 0.4 h1 tlcviat,ctl fiorn lincarit,y. intlicat,irlg t,hat a higher complex may bc present,. -4t I = 5.0 11, t,llcrc is cvidcncc for two cornplcxcs: .%mSCN2+ ant1 . % I ~ ( S C N ) : ~ ( ~ ~ ) . Tllc allt,hors (lid not, report t,hc corresponding st,ahilit,y constants at I = 5.0 hI. only t,llc ~ ~ a l n c s corrcct,cd to zero ionic st,rcngt,h by t,llc Davics cqnat,ion wcrc given. Bccansc this crnpirical rclation is not valid at ionic strengths grcat,cr t,llan 0.1 hI (cf. .%ppcndix B); t,hc rcport,ctl const,arlt,s at I = 0 arc not considcrctl by this review. Tllc st,ahilit,y const,arlt, dct,crrrlinctl at I = 0.5 11, log,, ill = (0.66 f 0.05) (cf. Tahlc \:.17); is convcrt,cd to rrlolal iinits ant1 cxt,rapolat,ctl t,o zcro ionic st,rcngt,ll iising t,llc specific intcract,ion cqliations, cf. .%ppcndix B. ~vi th AE = ( 0 . 1 5 * 0.05) kg . mol-l. This rcsiilts in log,, p," = (1.42 f 0.2). ~vhcrc t,hc iinccrtaint,y has bccn incrcasctl t,o take into accollrlt, the ~lnkno\vn t,crnpcratiirc at ~vhich t,his st,udy as pcrforrncd.

[62PEP/MAS] Peppard, D.F., Mason, G.W., Hucher, I . , Stability constants o f certain lanthanide(ll1) and actinide(ll1) chloride and nitrate complexes, J. Inorg. Nucl. Chem., 24 (1962) 881-888.

Tllc authors tlct,crrrlinctl the forrnation const,ant,s of t,llc first chloro and nit,rat,c corrlplcxcs of .%m(III) and various lant,llanidcs in 1 h1 H(ClO;,Cl or NOT) rncdia at (22 * 1)"C. Solvcnt cxt,ract,ion ~vi th tli[~~ara-(1,1,3,3-t,cttrar~~ct,l~yll~iit,yl)pl~c~~yl] phospllonic acid in t,oliicnc urns iiscd as the cxpcrirncntal rncthod. .%lt,hoiigh the cllclat,ing agent iiscd i)clongs t,o a group of corrlpoiinds kno\vn to extract apprccial)lc conccnt,rat,ions of acids. t,llc extracted species did not contain bulk anions. This urns cst,ahlisllcd on t,hc basis of t,hc third order dcpcntlcncc of t,llc amcricinrn distril)iit,ion cocficicnt on t,hc hydrogcn ion conccntrat,ion. hlodclling of the cxpcrirncnt,al dat,a g a ~ c log,, p, = (0.05*0.01) ant1 log,, ill = (0.26*0.07) for t,llc forrnation of .4rrlClZ+ and -4rnNO;'; rcspcct,ivcly. The corrcct,ions for the srrlall tliffcrcncc in tcrrlpcrat,llrc from t,hc rcfcrcncc valllc of 25°C arc 11cgligil)lc. Thcsc st,ahilit,y const,ant,s, convcrt,cd to rrlolal nnit,s. arc cxtrapolat,cd t,o zcro ionic strcngt,h, nsing t,hc sclcct,ctl intcrac- tion cocfficicnts (cf. .%ppcndix B, Section B.1.4). to give: log,, p," = (0.95 f 0.15) and log,, p," = (1.29 * 0.1) for .%rnCl'" and .%mNO:+; rcspcctircly, ~vhcrc t,hc iinccrtaint,y for t,hc nitrat,c cornplcx has l)ccn increased to *0.1 for the reasons discnsscd

in Scctiorl 17.6.1.4.1. 11.138. Tllcsc valiics have hccn llsctl t,o calclllatc t,hc standard cqlii1il)riiim const,arlt,s in Scct,ions \'..4.1.2.1 and 17.6.1.4.1.

[64BAN/PAT] Bansal, B.M.L., Patil, S.K., Sharma, H.D., Chloride, nitrate and sulphate complexes o f europium(ll l) and americium(ll l), J. Inorg. Nucl. Chem., 26 (1964) 993-1000.

This st,udy rcport,s ion cxcharlgc rncasiircrncnt,s of cqiii1il)riiim const,ant,s for the formation of .4rn(III) and Ell(II1) corrlplcxcs nrit,h Cl-. NOT arltl S O : ions at (26 * 1)"C. The cxpcrirrlcnts n7crc pcrforrrlcd in t,hc follo~ving ionic mctlia: Na(C104;X) at pH = 3, and H(C104,X), \~rllcrc X, t,hc cornplcxing anions (Cl-. NOT or SO:-); wcrc progrcssivcly rcplaccd nrit,h pcrchlorat,c ions t,o kccp a fixctl ionic st,rcngt,h of 1.0 h1. For all ligands, slightly llighcr valiics of cqlli1il)riiim constants nrcrc rncasnrcd in Ya+-cont,aining sol~lt,ions. This may l)c ascril~cd to rrlcdillrrl tlcpcndcnt variations of the actirit,y cocficicnt,s. Bansal, Pat,il arltl Sharma rcportcd log,, fil(.lrnC1'") =

(0.05*0.05) arltl (O.15f 0.03). at pH = 0 arltl pH = 3 rcspcctircly. Tllc assiimptiorl rrladc by Bansal. Pat,il and Sharrna t,llat ion cxchangc occiirrctl only for .4rn"+ appears to bc correct. .Is discllsscd llrltlcr Ref. [56\V.4R/IVEL]; t,hc tlist,ribntion of t,hc part,ly corrlplcxctl species at the highest ligand conccnt,ration st,udicd shonltl have hccn less than one t,crlt,h of t,llat of the frcc mct,al ions. -4s also rccalc~llatcd by t,his rcric\v, no st,at,ist,ically sigrlificarlt cvidcncc for t,llc forrrlat,iorl of llighcr order corrlplcxcs is folind. Tllc rcport,ctl cqnilibrinrn const,ant,s arc corrcct,ctl to zcro ionic strength using the specific ion irlt,cract,ion cqiiations of .4ppcndix B yielding log,, i/,"(.4mC12+) =

(0.96 * 0.15) and (1.25 f 0.15). at pH = 0 and pH = 3 rcspcctircly. reanalysis of t,hc cxpcrimcrlt,al data ol)t,ainctl in nitrat,c rrlcdia by this rcric\v

yicltls log,, ill (.4rnNOi+) = (0.%7*0.02) (in H+) arltl (0.%3*0.03) (in Na+). Tllcsc rcsiilt,s arc in agrccrrlcnt nrit,h ot,hcr lit,crat,llrc valiics. Tllc rcportcd antl/or re-cxi~,lnat,ctl cqlii1il)riiim constants arc corrcct,cd t,o zcro ionic st,rcrlgtll usirlg the specific ion int,craction cqiiations of .lppcndix B. This rcs~llt,s in log,, 'l,"(.4rnNOi+) = (1.30f 0.1) arltl (1.38 * 0.10). in HC104 and NaC104 solutions rcspcct,ivcly, ~vhcrc t,hc llrlccrt,aintics have hccn incrcascd t,o *0.1 for the reasons discllssctl in Scct,ion \".6.1.4.1, p.138.

Tllc cxpcrirncnt,al tlat,a for t,hc .4m(III) S O : systcrn n7crc irlt,crprctcd by Bansal, Pat,il and Sharrna assllrning t,llc format,ion of -4rnSO: and .4m(S(14)2. Thcsc rcs~llt,s rcfcr t,o an nnpnl>lishcd work by Nair and \Vclch. and hcncc, arc not considcrctl by this revie\\,.

[64SEK] Sekine, T., Complex formation o f La(l l l ) , Eu( l l l ) , Lu( l l l ) and Am( l l l ) wi th oxalate, sulphate, chloride and thiocyanate ions, J. Inorg. Nucl. Chem., 26 (1964) 1463-1465.

h solvent cxt,ract,ion st,udy of t,llc arncricillrn chloritlc. siilphat,c and thiocyanat,c syst,cms is s~lrrlmarisctl in this papcr. Tllc cxpcrirncntal dct,ails arc given in [65SEK, 65SEK2. 65SEK31. rcspcctircly.

[64SHI/MAR] Shiloh, M,, Marcus, Y. The chemistry o f trivalent neptunium plutonium and americium in halide solutions, Report IA-924, Israel Atomic Energy Commission, Soreq Research Establ., 1964, 26p.

Tllc amcricinrn st,~ltly t1cscril)cd in t,his report is also presented in rcfcrcrlccs [69hI.%R/SHI] (chloride complcxation) and [69SHI/GII7] (brornidc cornplcxnt,ion).

[65CHO/KET] Choppin, G.R., Ketels, J., Thiocyanate complexes o f some trivalent lanthanide and actinide elements, J. Inorg. Nucl. Chem., 27 (1965) 133551339,

Tllc authors stiidictl arncricillrn cornplcxat,ion in SCN- rrlcdin nsing n solvcnt cxtract,ion t,cchniqnc (I~is-2-ct,hyl-llcxyl or t , l~o~) l~os~) l~or ic acid. ladrhp. in t,olncnc nrltl 1.0 11 NaSCN/NaC104 at pH = 2). .%t 25"C, t,hc tlat,a nrcrc int,crprct,ctl assllrning the forrrlat,ion of .%mSCN2+ and .%m(SCN): cornplcxcs. The cxt,ract,ion hchavioiir of nrrlcriciiim urns also invcst,ignt,ctl at higher tcrnpcratiircs (40 and 55°C) in ordcr to dctcrmirlc the t,hcrrnodynnrnic filrlct,ions for t,llc formnt,ion of .$rnSCN2+ (cf. Tn- ble \'..l$): A,Hm(298.15 K) = ( 1 8 . 2 5 f 1.25) k.J . rrlol-l and 1,Sm(298.15 K) =

( 5 1 . 4 9 * 4.18) J . K-' . rnol-'. &Hm nrltl &Sm sccm to have n tcrrlpcrat,llrc tlcpcn- dcrlcc opposit,~ t,o t,hnt reported in t,hc later pllhlicat,iorls [70KIN/CHO, i2H.$R/PET, i4KIN/CHO] and arc t,llcrcforc not considcrcd in t,llis review. I.'alncs of &Hm nrltl 1,Smconccming the formation of t,hc sccorltl complex wcrc not rcport,cd. dnc to the nnccrt,aintics in the dct,crrnination of t,hc corrcspondirlg formnt,ion constant.

[65CHO/STR] Choppin, G.R., Strazik, W.F., Complexes o f trivalent lanthanide and actinide ions: I. Outer-sphere ion pairs, lnorg. Chem., 4 (1965) 1250-1254.

Clloppin and Strazik pcrformctl a solvcnt cxt,rnctiorl cxpcrirrlcnt nsing dinonylnapht,halcnc snlphonic acitl; dissolrctl in ra-hcptanc. as n liqnitl cation cxchnngcr. Tllc ionic st,rcrlgt,ll urns kept const,ant (I = 1.0 hI HC104/HNO:3). Tllc dnt,n wcrc irlt,crprct,ctl assnrning t,llc formnt,ion of .%rnNOi+ wit11 log,il = (0.26 * 0.02). Tllc rcport,ctl cqiii1il)riiim constant is corrcct,cd t,o zero ionic st,rcngt,h nsing specific ion irlt,cractiorl cqllat,ions (cf. .%ppcndix B). .%n iinccrtnint,y of *0.1 is assigned to all nit,rnt,c log,, PI val~lcs in ordcr t,o t,nkc int,o account the vnriat,ion in t,llc aniorlic cornposit,ion of t,hc rncdia. This rcsiilts in log,, P," = (1.29 * 0.10).

[65SEK] Sekine, T., Solvent extraction studies o f trivalent actinide and lanthanide complexes in aqueous solutions: I. Chloride complexes o f La( l l l ) , Eu(l l l ) , Lu(l l l ) , and Am(l l l ) in 4 M NaCI04, Acta Chem. Scand., 19 (1965) 143551444,

A$ syncrgic solvcnt cxtractiorl systcrn corrlposcd of 2-t,l~c1~oylt,riflnoroi1~cct~o11c nrltl tri- b~lt,ylphosphat,c in CC14 as llsctl to stiidy corrlplcx formnt,ion of .%rn"+. La"+, Ell"+ nrld Li?+ ~vi th cllloridc ions at 25°C. Tllc rncnsnrcrncnts wcrc mntlc at a const,nrlt, ncitlit,y of loglo[H+] = 2 . Tllc cllloritlc ion conccnt,rat,ion was varied hct,\~~ccn 0.4 11 nrld 3.6 h1 by nsing NaC104 as irlcrt clcctrolytc t,o kccp t,hc ionic st,rcngt,h fixctl at, 4 11 Xn+. Tllc cxt,ract,ion rrlcchnrlisrrl as proved t,o he the snrrlc hot,ll in t,llc prcscncc

and in t,llc al)scncc of the ligand. The cxpcrimcrlt,al rrlct,llod arltl the calciilat,ion proccdnrc used by t,hc aut,hor arc satisfact,ory. Tllc st,al)ilit,y const,arlt,s of .%rnCl'" anrltl .%1nC1: nrcrc rcport,cd t,o bc log,, P, = ( 0 . 1 5 * 0.07) and log,, i/2 = ( 0 . 6 9 f 0.10). Tllc iinccrtaint,ics providctl by Sckirlc (thrcc t,imcs the st,arltlartl deviation) reflect the accuracy of the ciirvc fit,t,irlg procctl~lrc. They do not t,akc irlt,o account the large changes in the ionic rncdinrn diiring t,llc cxpcrimcnt,~. This rcvic~v t,llcrcforc assigrls larger iinccrtaint,ics as follo\~rs: *0.14 in log,, ill and *0.2 in log,, 'lZ.

Sekine, T., Solvent extraction study o f trivalent actinide and lanthanide complexes in aqueous solutions. I I . Sulphate complexes o f La(l l l ) , Eu( l l l ) , Lu(l l l ) , and Am( l l l ) in 1 M Na(CI04), Acta Chem. Scand., 19 (1965) 1469-1475.

Sckinc st,~ltlicd the snlphat,c cornplcxat,ion of amcrici~lrn(III) at 25°C by a solrcnt, cxt,ract,ion rrlct,llod (3 < pH < 4; I = 1 hI Xa2S04/XaC104 at 25°C). Tllc variation of t,llc tlist,ribntion cocficicrlt nrit,h incrcasirlg [SO:-] urns irlt,crprctcd ass~lrning the prcscncc of .%rnSO: and .%m(S(l4)2 cornplcxcs. Tllc aiit,llor iiscd an iinspccificd T ~ ~ ~ I I C frorrl [58BJE/SCH] for t,llc second dissociation const,ant of HZS04. Tllc cornplcxat,ion constants given by t,llc aiit,llor arc used in the sclcct,ion proccdiirc t1cscril)cd in Scctiorl 17.5.1.2.1. Extrapolat,ion to zero ionic st,rcngtll (cf. .%ppcndix B) yields log,, P," = (3 .87f 0.11) and log,, 9," = (5.72 f 0.10).

[65SEK3] Sekine, T., Solvent extraction study o f trivalent actinide and lanthanide complexes in aqueous solutions: IV. Thiocyanate complexes o f La(l l l ) , Eu( l l l ) , Lu(l l l ) and Am( l l l ) in 5 M NaC104 solution a t 25'C, Acta Chem. Scand., 19 (1965) 1519-1525.

Sckinc rncasnrcd t,llc tlist,ribntion coefficient of .%rn(III) bct,\~~ccn an aqllcons phase at I = 5.0 I1 XaSCX/NaC1(14 and 3 5 pH 5 4; and an orgarlic phase cont,ainirlg 2-t,l~c1~oylt,riflnoroi1~cct~o11c in CC14. at 25°C. Tllc variat,ion of t,llc tlist,ribntion cocficicrlt as a fimct,ion of [SCN-] indicated t,hc format,ion of t,hc complcxcs .%mSCN2+, . % I ~ ( S C N ) : ~ ( ~ ~ ) and .%rn(SCX):. .%l1 the at,tcrrlpt,s to incliidc t,llc sccorltl cornplcx; .%m(SCN);. in t,hc st,at,istical data analysis scllcrrlc protl~lccd a poorer fit to the dat,a. indicating t,hat this const,ant urns not st,at,ist,ically nccdcd t,o fit t,llc distril)iit,ion dat,a. i .e . ; .$rn(SCN): rlcvcr cxcccdctl 5% in t,llc irlvcst,igat,ctl cxpcrimcrlt,al corltlit,ions [65SEK]. E~rcn t,lloiigh t,llc stability const,arlt,s nrcrc obtaincd fiorn acciirat,c cxpcrirncntal data [65SEK]. no cxt,rnpolat,ion t,o zero ionic st,rcngt,h is pcrformctl l)ccaiisc of t,hc high clcctrolytc corlccntrat,ion used (I = 5 h1).

[66BOR/ELE] Borisov, M.S . , Elesin, A.A. , Lebedev, I .A., Filimonov, V.T., Yakovlev, G.N., Investigation o f the complexing o f trivalent actinides and lanthanides in phosphoric acid solutions, Sov. Radiochem., 8 (1966) 40-44.

Borisov et o,l. st,udicd t,hc complcxation of amcrici~lrn(III) in phosphoric acid soliitions iising a cat,ion cxcharlgc tcchniqiic at 0.2 I1 XH4Cl(14, (20 f 2)"C. Tllc cxpcrirrlcrlt,al rcsnlt,s wcrc int,crprct,ctl ass~lrning t,hc format,ion of .%I~H~Po:+. .% plot of logl,((ljd,O/h'~l) - 1) US. log1,[H2PO:] (~vhcrc I%'d.O is t,hc tlist,ril>i~tio~l cocficicrlt in

the al)scncc of ligantl) sho~vs t,llat the complcxing ligarltl is H2P0, arltl t,hat only the first complex is forrncd. .% rcirlt,crprct,at,iorl of t,hc data sho\~.s t,llat ijd,, (the part,it,ion cocficicrlt of the cornplcx) has t,o bc negative, but this assnrnpt,ion is not proven cxpcrirncnt,ally by Borisov et 111. Hcncc, the rcport,cd cqnilibrinrn constants arc not,

[66GIV] Givon, M . Nitrate complexing o f americium, in: Proc. XXXVl Meeting Israel Chem. Soc., held in Tel Aviv, October 1966, Israel J. Chem., 4 (la) (1966) 3p.

This al)st,ract rcport,s the amcricinrn(II1)-~~itri~,t,c st,~ltly presented in dct,ail lat,cr by Shiloh, Givon and hlarcns [69SHI/GI\-1.

[66MAR] Marcus,Y., Anion exchange o f metal complexes: XV. Anion exchange and amine extrac- t ion o f lanthanides and trivalent actinides from chloride solutions, J. Inorg. Nucl. Chem., 28 (1966) 209-219.

Tllc dist,ribllt,ion dat,a of .%m(III) l)ctn~ccn an anion cxcharlgcr and LiCl soliit,ions in t,llc conccnt,rat,ion range 8 t,o 13.5 hI wcrc interpreted by assiimirlg t,llc prcscrlcc of .%1nC1: arltl .%rnCl;. No cqnilibrinrn const,ant,s n7crc calcnlat,cd.

[66VDO/KOL] Vdovenko, V.M., Kolokol'tsov, V.B. , Stebunov, O.B., Relaxation processes in complex formation. I. Copper and americium chlorides in aqueous solutions, Sov. Radiochem., 8 (1966) 266-269.

Tllc authors calclllatcd t,hc cqllilibrillrn const,ant,s of cllloritlc corrlplcxcs of .%m(III) from mcasllrcrrlcnts of prot,on niiclcar rnagnct,ic rclaxat,ion t,irrlc as a fimct,ion of LiCl conccnt,rat,ion n.it,hin t,llc range 0.5 hI and 4.5 hI. Tllcrc is no indicat,ion aboiit the tcrnpcratiirc of the cxpcrimcnt,~. Tllc st,al)ilit,y const,ant,s rcport,ctl for .%mC12+ arltl .%1nC1: n7crc log,, 9, = 0.032 and log,, i12 = 0 . 9 7 ; rcspcctircly, n.it,hollt any iinccrtaint,y cst,irnation. Tllc cornpiit,at,ion procedure closely rcscmblcs t,hat gcncrally iiscd for t,hc intcrprct,at,ion of spcct,ropllot,omct,ric rncasnrcrncnts. Tllc cxpcrirncnt,al dat,a wcrc rcrisctl in Ref. [69\?DO/STE] by using an alt,crnatirc mct,hotl of cstirn. a t ' ,ion. .%lthongh t,hc sarnc notation as llsctl in t,hc t,wo papers, t,llc cqllilibrillrn const,arlt,s wcrc rcport,cd as st,cpnrisc dissociation const,arlt,s in Ref. [66I7DO/KOL], and as stcp- wise format,ion constants in Ref. [69\?DO/STE]. They arc rcprcscnt,cd hcrc as overall st,ability constants. Tllc reanalysis by \"dovcnko and St,cbllrlov [69\?DO/STE] of the cxpcrirncnt,al dat,a gave log,, p, = (0.26 * 0.12) arltl log,, .I2 = ( 0 . 0 4 6 f 0.29). In vic~v of t,llc large changcs in t,llc actirit,y cocfficicnts of t,hc varioiis arncricillrn species, it is not possible t,o use t,llcsc dat,a to calcnlat,c standard cqiii1il)riiim constants.

[67CAR/CHO] De Carvalho R.G., Choppin G.R., Lanthanide and actinide sulphate complexes: I. Deter- mination o f stability constants, J. Inorg. Nucl. Chem., 29 (1967) 725-735.

A%~ncriciiim(III) complcxation in s~llphiiric acid soliit,ions urns st,udicd by Dc Car- ~ralllo and Clloppirl [67C.%R/CHO] usirlg a solvent cxt,ractiorl rrlctllod at 2.0 hI Na2S04/-

NaCl(14 ionic rncdia. pH = 3; nrltl (25 f 0.1)"C. Tllc formation of .IrnSO: nrltl .I1n(SO4), cornplcxcs as snggcst,cd t,o fit t,hc cxpcrirncrlt,nl rcslllt,~. The n~lt,hors iiscd n vnliic of li = 10 for t,llc H++SO: + HSO: cqiiilil,rinrn; this vnliic urns t,nkcn as an nvcragc of t,wo litcratiirc tlat,a [3lZEB/.4LT, 54SUNI nrltl is in good agrccrrlcnt ~vit,ll the cst,imnt,c rnadc by this rcric\v. The st,al)ilit,y const,ant,s for .IrnSO: and .Im(S(l4)2 arc llsctl in t,llc sclcct,ion proccdiirc dcscribctl in Scct,ion \'..3.1.2.1. Ext,rapolation t,o I = 0 (cf. -4ppcntlix B) yields loglo 9," = (3.79 * 0.18) and log,, L/," = (4.92 * 0.20).

[67CAR/CH02] De Carvalho R.G., Choppin G.R., Lanthanide and actinide sulphate complexes: II. Deter- mination of thermodynamic parameters, J. Inorg. Nucl. Chem., 29 (1967) 737-743.

Tllc aiit,llors report n list of stability constants calcnlat,cd from solvent cxtractiorl dat,a (sirnilnr to [GiC.4R/CHO]) at 0, 25; 40 and 35°C nrltl at I = 2 11 ( ( z j Tn- blc \".12). -4 ~vcight,ctl linear regression of .'lnfi,,, us. l/T(IC1)" (for rr = 1 or 2) by this rcric\v lcntls t,o t,hc re-dctcrminat,ion of t,llc cnt,halpy and entropy changcs (&Hm nrld A,Sm), (:j Scct,ion \'.3.1.2.1.

Marcus, Y., The solubility of americium(lll) chloride in concentrated lithium chloride solutions, Radiochim. Acta, 8 (1967) 212-214.

hlarcns st,~ltlicd t,hc solubility of \\,ell-chnmct,criscd .I~nCl:~(cr) in nqllcons LiCl solllt,ions by approaching cqnilibrinrn bot,ll from over- and nndcrsatiirat,ion. Tllc LiCl conccnt,rnt,ion as varictl l)ctn~ccn 9 h1 nrltl 13.2 hI \vit,hollt, addition of an inert clcctrolyt,c to kccp a const,ant ionic st,rcngt,h. No significnrlt tliffcrcnccs n7crc ol)scrvcd bct,wccn solubility mcasllrcrrlcnts at (25 * 1)"C and (40 * 1)"C. The soliil)ilit,y ciirvc was rrlodcllcd by assnrning t,llc forrrlat,ion of .IrnCl:. Tllc niimcrical ~ralnc of the cqlii1il)riiim const,nrlt for the rcactiorl .I~nCl:~(s) + -41nCl: + C 1 as rcport,cd to i)c log,, lie,,, = ( 0 . 4 5 f 0.04). Tllc crrlpiricnl relationship iiscd t,o tlcscril)~ the variation of t,llc rrlcnrl act,ivit,y cocfficicnt of -4rnCl: nrit,h chloride conccnt,rnt,ion tlocs not, take into account properly act,ivit,y cffcct,s in the high ionic st,rcrlgt,ll rncdia. Sirlcc it is not possiblc to ol)t,ain standard cqnilibrinrn const,nrlt,s from tlat,a ol)t,ainctl in soliit,ions of ~rarying and very high ionic st,rcngt,h, the rcport,cd vnliic is not considcrctl by the prcscrlt review.

[67NAI] Nair G.M., Americium(lll) sulphate complexes, Proc. Nucl. Radiat. Chem. Symp., held 6-9 March 1967, in Poona, Chemistry Committee, Department of Atomic Energy, Goverment of India, 1ip.405-410.

Preliminary prcscrlt,nt,ion of t,hc amcricinrn(II1) snlphat,c chcrnist,ry. The cxpcrirncntal dct,nils and t,llc cxllaiist,ivc trcatmcnt of tlat,a arc prcscrlt,ctl in n later pllblica- tion [68N.II].

[67RYA] Ryan, J.L., Octahedral hexahalide complexes o f the trivalent actinides, in: Lanthanide/ actinide chemistry, Advances in Chemistry Series No 71, American Chemical Society Publications, 1967, pp.331-334.

Tllc a~lt~hor reported sl)cct,rophot,ornctricnl indicat,iorls on tllc prcscncc of -4rn~l;-

[68AZI/LYL] Aziz A., Lyle S.J., Naqvi S.J., Chemical equilibria in americium and curium sulphate and oxalate systems and an application o f a liquid scintillation counting method, J. Inorg. Nucl. Chem., 30 (1968) 1013-1018.

Tllc aiit,llors st,udicd tllc arncrici~lrn(III) s~llpllatc system combining a cat,ion cx- change and solvcnt cxt,ract,ion t,cchniq~lcs at I = 0.5 I 1 (Na2SO4/XnC1O4), pH = 3.6 and (25 * 0.5)"C. Bot,ll cxpcrirncnt,al mct,hotls irltlicat,c tllc formation of .4mSO: arltl .$m(S(l4)2 cornplcxcs. Tllc rcport,cd st,al)ilit,y const,arlt,s arc llsctl in t,llc sclcctiorl proccdnrc t1cscril)cd in Scct,ion \".5.1.%.1. Extrapolat,ion t,o I = 0 (($ .4ppcndix B) yields log,, p," = (3.91 f 0.04) and log,, 9," = (5.57 f 0.06).

[68NAI] Nair, G.M., Americium(ll l) sulphate complexes, Radiochim. Acta, 10 (1966) 116-119.

Nair st,udicd t,hc arncriciiim(II1)-s~~lpll:~,t,c syst,cm nsing a cat,ion cxchangc t,cchniqiic, at %?'C. I = 1 hl (H+. Na+)(HSOy; SO:. C10;) mctlia [GiN.41. 68X.$I]. Tllc cxpcrirncnt,al rcsiilts nrcrc irlt,crprctcd assllrning t,hc forrrlat,ion of -4rnSO:; .4m(HS04)I and .$rn(S04);. The S O : corlccntrat,ion \!,as calc~llat,ctl nsing K = 0.302 for t,hc sccorld dissociat,ion const,arlt of H2S01; rcport,ctl i11 Ref. [55EIC/R.$B].

This rcvic\v rcirlt,crprcts tllc cxpcrirncnt,al distril)iit,ion cocficicnts; h',ll. ol)t,ainctl at, pH = 0. Tllc second dissociat,ion constant of H2S04 urns calcnlat,cd for each of tllc cxpcrirncnt,al points rcport,cd by Nair, and log,, li, was fonnd t,o vary bct,~vccn 1.16 and 1.29. -4s cxpcct,cd. t,llcsc ~ ~ a l n c s arc tliffcrcnt from tllc tlissocint,ion const,arlt,s of HSO; given in Ref. [89ShII/II.$R] for XaC104 rncdia, hccallsc t,llc actirit,y cocficicrlt,~ of snlphat,c and i)isiilphat,c ions charlgc ~vhcn NaCl(14 is rcplacctl by rrlixtiircs of siilpll~lric and pcrcllloric acids. The ionic st,rcngt,h is fonnd t,o vary only slightly in tllc cxpcrirrlcnts of Nair (0.97 h1 < I < 1.04 hI); \vllich shonltl not affect considerably tllc rcslllt,ing st,ai)ilit,y const,ant,s. ~ l l c linear variat,ion of ((I<'~/K~) - I) 71s. [SO:-] irltlicat,cs t,llc prcscrlcc of .$rnSO: only, \vitll log,, L/, = (1.88 f 0.10). Tllcrc is no nccd to incliidc cit,hcr .4rn(HS04): or .$rn(S04), t,o interpret tllc cxpcrimcrlt,al dat,a.

Tllc rcsiilts obtaincd at pH = 3 arc not affected by tllc acitl const,ant,. Tllc stability corlst,ant,s rcport,ctl by Nair. log,, ill = (1.49 * 0.01) and log,, fi2 = (2.36 f 0.01); arc in agrccrrlcnt nrit,h oiir rccalcnlat,ions and arc used by this rcvic\v. Tllc iinccrtaint,y of log,, is ho\vcvcr increased t,o *0.05. -4s cxpcct,cd tllcrc is a tliffcrcncc l)ctn~ccn tllc valllc of ill in sodium and acid s~ll~)l~ato/pcrcl~lori~~t~c rncdia.

Tllcsc st,al)ilit,y const,ant,s arc llsctl in tllc sclcction procedure dcscrihcd in Scc- t o . 5 1 . 2 . 1 Tllc val~lcs ol)t,ainctl at pH = 3 arc cxtrapolat,cd t,o I = 0 (cf. .$p- pcrldix B) t,o yicltl log,, i/; = (3.79 * 0.06) and log,, p," = (5.42 f 0.10).

[69AZI/LYL] Aziz, A., Lyle, S.J., Equilibrium constants for aqueous fluoro complexes of scandium, yttrium, americium(lll) and curium(lll) by extraction into di-2-ethylhexyl phosphoric acid, J. Inorg. Nucl. Chem., 31 (1969) 3471-3480.

Tllc complcxation of Sc"+, Y3+. .%rn"+ ant1 CrrF3+ \vit,ll fl~loridc ions in 0.5 11 NaCl(14 at pH = 3.6 \!,as st,udicd by solvent cxtract,ion \!,it11 tli-2-ct,hylhcxyl phosphoric acid. hrlell,p, in t,oliicnc. The t,cmpcmt,urc was kept const,arlt at 25°C. .%ziz and Lylc proposed an cqnilibrinrn rrlodcl involving t,llc format,ion of .4rnF2+, .%rnF; and .%~nF:~(aq). The st,ahilit,y constants at zcro ionic st,rcrlgt,ll arc, rcspcctircly, log,, p," = (4.37 * 0.05). log,, L/," = (7.66 f 0.06) ant1 log,, L/: = (11.1). as rccal- c~llat,ctl by t,his revie\!, iising the ion int,cract,ion cocfficicnts given in .%ppcndix B.

Tllc tlist,ribntion coefficient. D, bct,~vccn t,hc organic and t,hc aqllcons phase urns fo~ind t,o dccrcasc rcg~llarly nrit,h increasing t,llc flnoritlc ion conccnt,ration up t,o 1.5 X 10-" h1. This urns associat,cd \vit,ll t,llc tlcprcssing role of complex forrn a t ' ,ion in the aqiicolls sol~lt,ion on the extraction of t,hc aqua ion .%rn"+. .It higher F conccntrat,ions. t,llc extraction of t,hc rlciit,ral corrlplcx A%~nF:j(aq) \!,as also clairncd t,o occur. H o \ ~ ~ c ~ ~ c r , at pH = 3.6, hrlell,p is kno\vn to bc a good cxt,ract,ing agent also for divalent ions. .%lthongh this \!,as apparcnt,ly cxcliidctl on the basis of the ol)scrvcd third ortlcr dcpcntlcncc of D on t,hc ladrh,p concentration; the extraction mcchanisrn proposed by .%ziz and Lylc is not atlcqiiatcly proven. The format,ion const,arlt,s of .%1nFW +ancl .%mF: arc at least one ortlcr of magnitiidc higher than rcport,cd in ot,hcr two-phase distril)iit,ion st,~ltlics nrhcrc t,hc partition mcchanisrn co~lld he idcntifictl rrlorc precisely [76CHO/UNR; 84YA%S/CLE2].

[69BAR/MIK] Barbanel, Yu. A., Mikhailova, N.K., Study of the complex formation of Am(ll l) with the C l ion in aqueous solutions by the method of spectrophotometry, Sov. Radiochem., 11 (1969) 576-579.

Tllc absorpt,ion spectra of .4rn(III) ions wcrc st,~ltlictl in aqllcons HC1 and LiCl solut,ions at (25* 1)"C. The ligand conccnt,rnt,ions nrcrc varied bct,~vccn zcro and 12.6 11 for HCl, and 10.75 h1 for LiCl sol~lt,ions. Tllc a~lt,hors dctcrmincd t,hc st,al)ilit,y const,ant of .%rnCl'" from t,hc change of t,llc rrlolar ahsorhanccs in t,hc ~vavclcngth region 500 t,o 510 nrn. obtaining log,, 9, = ( 2 * 0.05). This is a rrlixcd const,arlt ol)t,ainctl by using t,hc conccnt,ration of the -4rn species and t,llc act,ivit,y of t,hc cllloritlc ions. Tllc cxpcrirncnt,al approach ant1 t,hc calciilat,ion procedure ~lsctl by the a~lt,hors arc not sat,isfact,ory. The rcs~llt,s of t,llis st,~ltly arc not 11scd in the prcscnt revie\!, l)ccaiisc of t,hc considcrahlc variation of ionic st,rcrlgt,ll t,hronghont t,llc cxpcrirncnts.

[69DES] Desire, B., Determination de la premiere constante d'hydrolyse d'elements trivalents des series "4f ' e t "5 f ' , These Doctorale 3"'"' cycle, Facult6 des Sciences de Paris, 1969, 45p, in French.

Tllc content of t,his t,hcsis urns piil)lishctl in t , \~~o diRcrcnt papers. Inform. a t ' ,ion on lanthanitlcs is given in Ref. [71GUI/DES], ~vhilc hydrolysis dat,a of interest t,o t,llis rcvic~v arc rcport,cd in Ref. [69DES/HUS].

[69DES/HUS] Dbsirb, B., Hussonnois, M,, Guillaumont, R. , Dbtermination de la premiere constante d'hydrolyse de I'ambricium, du curium, du berkblium et du californium, C.R. Hebd. Acad. Sci. Paris, Ser. C, 269 (1969) 448-451, in French.

Tllc authors invcst,igatcd t,llc hytlrolysis hchavioiir of the trivalent act,i~lidcs .%m3+; Cm3+, Bk"+ and Cf"+ nsing a solrcnt cxtractiorl t,cchniq~lc (2-t,hc~~oyltrifliioroac;cto- nc, tttx, in i)cnzcnc). Tllc ionic strength was i)iiffcrcd at 0.1 I1 ~vi th (H. Li)C1(14. For arncricinrn; the pH rarlgc st,~ltlicd was 4.2 to 5.9. Tllc slope of t,hc log,, D ?IS. pH plot (\vhcrc D is the tlist,ribntion coefficient) is w r y close t,o t,llc thcorct,ical slope of 3 cxpcctcd in t,llc prcscncc of .%m3+. H o \ ~ ~ c ~ ~ c r , dcspit,c the sprcatl ol)scrvcd in the dat,a. a second-po~vcr tlcpcndcncc on pH was clairncd t,o rcs~llt above pH = 5.2. This was taken as an indication of .%rn(IHW format,ion in t,hc aqncoiis phase. Tllc first, hytlrolysis const,arlt proposed by the aiit,llors is logl,'il = (5.92*0.11) at (23*1)"C. Our re-c~i~,lnat,ion ~lsctl a nrcightcd least,-sqiiarcs procctl~lrc ~vit,ll error cst,irnatcs on cxpcrirncnt,al paramct,crs derived fiorn Di.siri.'s t,hcsis [69DES] and from a cornpan- ion paper [69GUI/FER]. 1l:ithin the accuracy of t,hc rncasiircrncnt,s t,his rcric\v can fintl no cvidcrlcc t,llat .%rnOHW as prcscrlt in any not,iccal)lc amo~lnt,, nrhich is in accortlancc ~vit,ll calciilat,ions done nsing t,llc ~ralnc for logl,',i," sclcct,cd in t,llc prcscnt review and cxtrapolat,cd t,o 0.1 I1 ionic st,rcngt,h.

[69MAR2] Marin, B., Comportement des lanthanides et transuraniens trivalents en milieu chlorhy- drique, Ph.D. Thesis, Universitb de Paris, Report CEA-R-3803, 1969.

Tllc complex formation of t,rivalcnt lant,hanidcs. .%d+ and C r d + nrit,h cllloridc ions was stiidictl by paper clcct,ropllorcsis at 15°C. Tllc st,al)ilit,y const,arlt,s of .%rnCl'" anrltl .%1nC1: n7crc dctcrmirlcd to he. rcspcct,ivcly. loglo ill = 1.0 and log,, 'lZ = 0.34. Xo const,ant ionic mctliiim as used, ~vit,ll C 1 conccnt,~.at,ions ~rarying from 10-2 h1 t,o 10 hI. Sirlcc no appropriate mct,hotls arc avai1al)lc for t,llcir corrcct,ion t,o I = 0. t,llcsc T ~ ~ ~ I I C S arc not credited by this rcvic~v.

[69MAR/KIK] Marin, B., Kikindai, T . , Etude comparbe de I'hydrolyse de I'europium et de I'ambricium en milieu chlorure par blectrophorese sur papier, C.R. Hebd. Acad. Sci. Paris, Ser. C, 268 (1969) 1-4, in French.

Tllc arncrici~lrn and ciiropinrn hydrolysis in HCl/KCl mctliiim (I = 5 X 10-" h1) was invcst,ignt,ctl l)ctn~ccn pH = 2.5 and 5 iising paper clcct,rophorcsis. The tcrnpcratiirc as fixctl at ( 1 5 f 1)'C. Two plat,canx wcrc fo~lrld in the clcct,ropllorct,ic mohilit,y curve. Tllc first as assigrlcd to t,llc aqua. ion .%rn"+ (at pH < 2.5); and the sccond to the hydroxo corrlplcx .%rnOHW (at pH > 3.5). Tllc intlividnal clcctrical mohilit,y T ~ ~ ~ I I C S ~vere t,llcn iiscd t,o calc~llatc t,hc st,al)ilit,y constant (called hydrolysis const,arlt, in t,llc original paper) for t,hc .%rnOHW sspccics. Tllc hydrolysis const,arlt log,,'"ll as defined in the prcscnt rcric\v, urns dct,crrrlincd t,o he ( 3 . 0 5 * 0.05) for .%rrlOHZ+ and ( 3 . 1 5 * 0.05) for EIIOH". Insnfficicnt cxpcrimcrlt,al details can l)c cxt,ract,cd from t,hc paper (clcct,rotlc calibration procedure, pH cont,rol on t,llc support for clcc-

trophorcsis, total .%m conccntrat,ion, cxist,crlcc of clcctro-osmot,ic flow). Calcnlat,ions of clcct,rical rnol)ilit,ics from t,llc posit,ion of l~road .%rn peaks along t,hc paper st,rip arc likely t,o he affected by largc errors. The rcport,cd const,arlt is not crctlit,cd by the

[69MAR/SHI] Marcus, Y., Shiloh, M,, A spectrophotometric study of trivalent actinide complexes in solution: IV. Americium wi th chloride ligands, Israel J. Chem., 7 (1969) 31-43.

hlarcns and Slliloll rncasnrcd t,llc spcct,ral changcs of .%m(III) in various aqllcons and non-aqncoiis sol~lt,ions at increasing corlccntrat,iorls of cllloritlc ions. In order t,o

wcrc matlc t,o cornpare t,hc solution spcct,ra ~vi th t,llosc ol)t,ainctl for charact,crisctl solid

Prono~lrlccd cllangcs wcrc observed for t,llc al)sorpt,ion hands at 235 nrrl and 503 nrrl in aqllcons LiCl rncdia at 0.5 hI acitlit,y. Both \ ~ ~ a ~ ~ c l c ~ ~ g t , l ~ s n7crc used to calcnlat,c the formation const,ant,s of .IrnCl'" anrltl .%mCl: nrit,h good int,crrlal agrccrncnt. obtaining log,, 'll = ( 2 . 2 * 0.1) arltl log,, fi2 = ( 4 . 7 * 0.06) at 22'C. The LiCl conccnt,ration was cllangctl from 0 to 13.7 hI. but no const,arlt ionic st,rcngt,h as rnaintaincd. Tllc procedure for cst,imnt,irlg cq~lilihri~lrn const,ant,s ~lsctl the act,ivity of t,hc cllloridc ions and t,llc conccnt,ration of t,llc arrlcriciiim species giving, thcrcforc, rrlixctl const,ant,s. hlarcus and Slliloll concl~ltlcd t,llat t,hc ~vcak cornplcxcs sccn by spcctrol)llotornctr;vlct,ry wcrc of t,llc inner-sphcrc t,ypc. ~vit,ll; ho\vcvcr, a mixed inner-out,cr sphcrc charact,cr for .IrnCl'".

Tllc largc variation of act,ivity cocfficicnts, and t,llc qiicst,ionahlc ass~lrnpt,ion of in- variance of t,hc cxtinct,ion cocfficicnt,~ nrit,h cllangcs in the LiCl conccnt,rat,ion rcndcr the rcport,ctl val~lcs of lirrlit,cd application for the cstirnation of cqnilibrinrn const,arlt,s at I = 0.

[69MOS] Moskvin, A.I., Complex formation o f the actinides wi th anions o f acids in aqueous solutions, Sov. Radiochem., 11 (1969) 447-449.

This piil)lication is a compilation of st,al)ilit,y const,ant,s of act,inidc complcxcs. prcscnt,ctl at t,hc hlosco~v Scrrlinar on .%nalyt,ical Chcmist,ry (1964). No cxpcrimcrlt,al dct,ails wcrc reported. Tllc t,ah~llatcd ~ ~ a l n c s for the amcrici~lrn(III) pllospllat,c syst,cm arc given at I = 1.0 11. Thcsc tlat,a arc prcscnt,cd in Tal)lc \.'.15. but arc not acccpt,cd by t,llis rc~~icw.

[69SHI/GIV] Shiloh, M,, Givon, M,, Marcus, Y., A spectrophotometric study o f trivalent actinide complexes in solutions: I l l . Americium wi th bromide, iodide, nitrate and carbonate ligands, J. Inorg. Nucl. Chem., 31 (1969) 1807-1814.

Spcct,ropllot,omct,ric st,~ltlics wcrc used t,o identify t,hc .%m(III) corrlplcxcs present in aqncoiis solutions cont,ainirlg hrornidc; ioditlc. nit,ratc or cnrbonat,c ions. Tllc rncasnrcrncnt,~ n7crc rrladc at 25°C. Xo const,arlt ionic strength mctliiim as used.

Tllc forrrlat,ion of .IrnBi" was clairrlcd t,o occiir only in conccnt,ratcd LiBr soliit,ions

nhorc 8.7 h1. Tllc ol)scrvcd spcct,ral cllangcs in t,hc visil)lc region n7crc assocint,ctl ~vit,ll inner-sphcrc int,cmct,ions. Tllc reported stability constant. log,, p, = ( 3 . 3 * 0.1); is n rrlixcd const,nrlt incorporat,ing hot,ll act,ivit,y and conccnt,rnt,ion terms. H o \ ~ ~ c ~ ~ c r , as disciissctl in this -4ppcntlix iindcr Ref. [69hI.4R/SHI]. it is tlifficnlt t,o tlcrivc rclinhlc qllant,it,at,ivc inf~rrrlat~ion on this weak cornplcx bccallsc it rcq~lircs large variations in the act,ivit,y cocfficicnts t,hro~lghont t,llc cxpcrirncnts. Sirrlilar argiimcrlt,~ apply t,o the rcport,ctl cq~lilihri~lrn const,nrlt for -4rnNO;'; log,, p, = ( 1 . 3 0 f 0.09); oht,aincd fiorn spcct,m in soliit,ions containing up t,o 15 11 HNQj [69SHI/GI\:, Fig. 31.

Spcct,rnl changcs in t,llc arncrici~lrn iotlidc syst,cm n7crc ol)scrvcd only in conccn- tratcd hlg12 solutions (4.1 hl), but no qiiantitatirc dat,a nrcrc rcport,ctl.

Shiloh, Gi~ron and 1Inrc1ls also st,udicd t,hc sol~lhilit,y of a chcrnicnlly cllaractcriscd . $ I ~ ~ ( C O : ~ ) : ~ ( S ) in 0.1 t,o 0.6 hI pot,nssinrn carhonatc mctlia [69SHI/GI\']. Tllc aiit,llors did not consider the irlfl~lcncc of t,hc ionic strength. nrhich varied fiorn 0.4 t,o 2 11, 1~1 t int,crprct,ctl t,llcir rcs~llt,s by ass~lrning t,hc formnt,ion of .4rn(CO:j):30H'-. Nc\vton nrld Siillivnrl [85NEII:/SUL] later pointed out. in t,llcir review of actinitlc carl)onnt,c cornplcxcs, t,llat t,llcsc sol~lhilit,y data did not distingiiisll bct,~vccn .4m(CO:3):j0H4- nrld .4mz(CO:3)2-. They also found t,llat,; if a rcasonnhlc ionic st,rcngt,h corrcct,ion is irlcl~ltlcd in t,hc analysis, t,llc solubility data may he dcscrihcd by the rcnct,ion

with I%'s,:j(\'.35) = (I%'s,n(\'.36) X itj) sho\~~ing that .4m(C0:~) ; is the prctlomirlant, corrlplcx up to [CO:-] = 2 h1. Follo\~.ing t,hc rcintcrprctation by Rollouch [89ROB]; the sol~lhilit,y dnt,n, digitised from Figiirc 4 in [69SHI/GI\']; arc used by this rcric\v to pcrforrrl an cxt,rnpolnt,ion using t,hc specific int,cract,ion cqiiations (cf. .4ppcndix B) rrlnkirlg the nssiimptiorl [CO:-] zz [K2C03]. The follo\ving rclation for t,hc ionic st,rcngtll corrcct,ion (cf. Figure -4.1) is ol)t,ainctl:

~vhcrc I%'s,:j(\'.35) nrltl [K2C0:j] arc cxprcsscd in rnolal nnit,s. and t,llc Dcbyc-Hiickcl tcrrn; D, is dcfinctl in Eq. (B.2) of .$ppcndix B.

carl)onnt,c conccnt,rnt,ions (specially in this work ~vhcrc t,hc solutions n7crc apparently cq~iilil)rat,cd nrit,h nt,rrlospllcric C02(g)) \~ronltl favor t,llc forrrlat,ion of .$I~CO:~OH(S) at t,llc cxpcnsc of .4rn2(CO:3):3(s), as o~lt,lincd by \:it,orgc [92\:IT] and accortling t,o Eq. (\'.3i) in p.162. In t,hc prcscncc of solid arncriciiim hydroxy-carhonatc, the soliil)ilit,y tlat,a may bc t1cscril)cd by t,hc rcactiorl

wit11 I%'s,:j(\'.32) = (KS,,(\:.33) X p:j). Sirrlilar proccdiirc and nssiimptiorls as those dcscril~cd nhovc for rcactiorl (\:.35) arc now applied to rcact,ion (\:.32). Tllc follo~ving rclation for t,hc ionic st,rcrlgt,ll corrcctiorl ( c j Figiirc -4.1) is t,hcrl ol)t,ainctl:

F l : Expcrirncntal solubility data from [69SHI/GIV] cxt,rapolat,ctl to I = 0 using t,llc specific ion irlt,cract,ion cqllat,ions (cf. -4ppcndix B). Upper diagram (a) assnrning reaction: 0.5 .4m2(C0:j):j(s) + 1.5 C O ; + .4m(C0:~);-. Lo~vcr diagram (b) assllrning rca~t~ion: .%rnCO:3OH(s) + 2 C O : + -4rn(C0:~): + OH-. The lirlcs correspond t,o Eqs. (-4.1) arltl (-4.2) rcspcctircly, and t,llc tlot,t,ctl curves rcprcscrlt tllc 95% cr~~l f ide~~ce i~lt,cr~~als.

log,, [-'rnI, o, 2 0 - 5.3 - 2 log,,[CO:-] + log,, [OH-] -5.4

Aklt,lloiigh the soliil)ilit,y dat,a of Shiloh, Givon and 1Iarciis sho~v nncqllivocally t,llat, .km(CO:3); is t,hc prctlominant corrlplcx 111) t,o [CO;-] = 2 h1; it is not possible t,o concliidc ~vit,ll confidcncc ~vhich is t,hc cqiii1il)riiim rcact,ion taking place; and the dat,a can not l)c used in t,hc sclcct,ion proccdnrcs described in Scct,ion 17.7.1.2.2.

[69VDO/STE] Vdovenko, V .M. , Stebunov, O.B., Relaxation processes during complex formation: IV. Determination o f the stability constants o f the complexes from the data o f the proton relaxation method, Sov. Radiochem., 11 (1969) 625-629.

In this paper \ 'Tdo~~c~lko and St,cbllrlov rccalciilat,ctl cqnilibrinrn constants for .krn(III) corrlplcxat,ion ~vit,ll cllloridc ions from cxpcrirncntal dat,a in Ref. [66\'DO/KOL].

[70KIN/CHO] Kinard, W.F., Choppin, G.R., The thermodynamic o f complexing o f trivalent actinide ions by thiocyanate, Report TID-25671, Florida state University, Thallahasse, Florida, 1970, 13p.

This appears t,o i)c t,hc same st,udy reported as Ref. [74KIN/CHO] \vhcrc more cxpcrirncnt,al tlct,ails arc givcn. Tllc st,al)ilit,y const,ants obt,aincd at various tcrnpcratiircs arc rcport,cd itlcnt,ically in t,llc two piil)lications, ~vhich indicates t,llat a misprint may l)c present in Table I of Ref. [70KIN/CHO] (50 irlstcatl of 55°C).

[70LAH/KNO] Lahr, H . , Knoch, W., Bestimmung von Stabilitatskonstanten einiger Aktinidenkomplexe: I I . Nitrat- und Chloridkomplexe von Uran, Neptunium, Plutonium und Americium, Ra- diochim. Acta 13 (1970) 1-5, in German.

Lahr and Knocll st,udicd t,hc forrrlat,ion of arncricillm(II1) nit,ratc corrlplcxcs in 8 11 H+ at 20°C. They llsctl an extraction mct,hotl basctl on t,ri-ra-oct,ylamin dissolrctl in

(3-n ) , xylcnc. They found for t,hc rcact,ion + n NO, + . k ~ n ( N ( l : ~ ) ~ . NO^) = 0.47; 0.17 and 0.04 for r , = 1. 2 ant1 3; rcspcct,ivcly. Tllc nit,ratc conccnt,rat,ion varictl from 0 t,o 8 11. This shonltl rcslllt in large changcs in t,llc actirit,y factors of t,hc varioiis species. The '~cqllilibri~lrn constants" givcn by t,llc allt,hors arc bct,t,cr regarded as crnpirical pararnct,crs t,han as t,rnc st,abilit,y constants. It is not possil)lc t,o cxt,rapolat,c dat,a from this high ionic strength to I = 0. This review t,llcrcforc disregards t,llcsc dat,a.

In spite of t,llc title, no rncasiircmc~lt,s of arncricillm corrlplcxat,ion in t,llc cllloridc syst,cm arc rcport,ctl.

[70MAR/BOM] Marcus, Y., Bomse, M,, Octahedral chloride complexes o f trivalent actinides and lanthanides in solution, Israel J. Chem., 8 (1970) 901-911.

Tllc ol)jcctirc of t,his paper was to invcst,igatc t,hc forrnation of hcxacoordinat,ctl species of .%m3+; C r d + and varioiis lant,llanidcs in chloride-containing soliit,ions. For t,llis purpose; hlarcns arltl Bomsc iiscd solvcnt,~ of lo\v diclcct,ric const,ant,s. -411 rncasnrcrncnt,~ wcrc matlc at 25°C by using sl)cct,ropllot,omct,ry. The stcp~visc cqni- lil~rinrn constant for the forrnation of .%mC12 from .%mCl; was calcnlat,cd t,o i)c I%'6 = (150 f 20) in a rrlixcd solrcnt acctonit,rilc/siiccinorlitrilc, and = (G0 * 20) in propane-1;2-diol carhonatc. Tllcsc arc condit,ional const,ant,s nrhich tl~lc t,o t,hc non- aqiicolls rncdia arc not considcrcd in this revie\\,,

[71HAR] Harmon, H.D., The thiocyanate and chloride complexes of some trivalent actinides, Ph.D. thesis in inorganic chemistry, University o f Tennessee, Knoxville, Tennessee, 1971, 143p.

A%t,tcrnpt,s nrcrc rnadc t,o sclcct appropriat,~ syncrgic mixt,urcs for solvcnt cxtractiorl st,~idics of .%rn"+. Bk"+ arltl Es3+ complcxation ~vit,ll chloride ions. Ho\vcvcr, only prc- liminary data nrcrc rcport,cd. Sec the disc~lssiorl in tallis .%ppcndix of [72H.%R/PET] and [72H.%R/PET%] for t,hc cxpcrirncnt,al tlct,ails on t,llc arncrici~lrn(III)-tlliocyanat,c syst,cm stiidictl by spcct,ropllot,omct,ry and solvcnt extraction.

[71KHO/NAR] Khopkar, P.K., Narayanankutty, P,, Effect o f ionic media on the stability constants o f chloride, nitrate and thiocyanate complexes o f americium(ll l) and europium(ll l), J. Inorg. Nucl. Chem., 33 (1971) 495-502.

% solvcnt cxt,ract,ion t,cchniq~lc nrit,h dino~~ylnapl~thalcnc siilphorlic acitl (lrdrans) in ra-hcxanc was used t,o invcstigat,c t,llc corrlplcxat,ion of .%rn"+ arltl Ell"+ with chloritlc. nitrat,c and t,hiocyanatc ions. The authors iiscd constant ionic st,rcngt,h rncdia (1 11) at (30 *O.l)"C. in \vhich the ratio of pcrclllorat,c to ligand ions urns varied. Tllc effect of ~rarying t,llc cat,ion of the backgro~lntl clcctrolytc (Li+; H+; Na+ or NH:) on t,hc cqiii1ii)riiim const,arlt,s was also st,udicd.

Khopkar arltl Narayananklit,t,y assiimctl t,llat only .%m3+ as cxt,ract,ctl irlt,o the aqiicolls phase. To clarify this. t,hc dcpcndcncc of the arncrici~lrn dist,rih~lt,ion m- tio ~vit,ll t,llc hrlnrrs corlccntrat,ion in t,hc organic phase at const,ant conccnt,rnt,ions of irlorgarlic ligands in t,llc aqllcons sol~lt,ion slloiild have i)ccn invcstigat,cd. .%S lrcirrras be- haves as a liquid cat,ion cxchangcr, dixi~,lcnt or rrlono~nlcnt amcricinrn cornplcxcs may also have i)ccn extracted. Ho\vcvcr; t,hc order of cxtract,ahilit,y of t,llc complex ions is cxpcct,ctl t,o dccrcasc nrit,h tlccrcasirlg t,hc chargc/sizc rat,io. .%ccording to the consitlcrat,ions rrladc in this .%ppcndix under Ref. [5GIV.%R/\VEL]. t,hc assiimptiorl matlc by Khopkar arltl N ~ ~ , r ~ ~ , y a n a ~ k t , t y appears t,o bc rcasonablc. i)ccaiisc the conccnt,ration of t,hc corrlplcxirlg anions rlcvcr cxcccdcd 1 h1.

Tllc species .%rnCl'" and .%rnCl: nrcrc clairncd t,o i)c prcscrlt in the arrlcriciiim cllloritlc syst,cm. Tllc ~ ~ a l n c s of log,, 9, ranged from ( 0 . 2 5 * 0.02) t,o +(0.1%* 0.02); depending 11pon \~,hcthcr lit,hi~lrrl or arnrnoni~lrn as used, cf. Table 17.8. .%lthongh less rcg~llarly, t,llc valiic of log,, urns also fo~lrltl to incrcasc ~vit,ll decreasing dcgrcc

of solvation of t,llc hulk cat,ion. Sirrlilar ol)scrvations wcrc rnadc by Bansal, Pat,il nrltl Sharrna [64B.%N/P.%T]. The ol)scrvcd vnriat,ions arc likely to bc dnc to changcs in the actirit,y cocficicrlt,~ ~vhich arc independent of t,llc nnt,urc of t,llc mctliiim only at, w r y lo\v ionic st,rcngt,hs. Tllc stability constants of -4rnCl'" arc slightly smaller t,hnrl those mcas~lrctl by ot,hcr nut,hors at lo\vcr tcrnpcrat,~lrcs, as cxpcct,ctl for t,llc forrrlat,ion of outer-sphcrc cornplcxcs. Ho~vcvcr. according t,o t,llc cnthalpy ~ralnc for EnC12+ rcport,ctl by Choppin and Unrcin [63CHO/UNR]; the variation of t,llc cqnilibrinrn const,ant ~vi th tcrrlpcrat,~lrc l>ct,~vccn 30 and 25°C sllo~lld he ncgligihlc. Tllc diffcrcrlcc bct,\~~ccn the various sct,s of val~lcs rnay also he ascribed t,o t,llc cnlcnlat,ion procedure.

\Vit,ll respect to t,llc single ~rariablc 9, rnodcl, the addition of is cxpcctcd t,o give n srnallcr ~ralnc for 9,. It is. ho~vcvcr. tlifficnlt to cst,irrlat,c t,hc st,nt,istical significance of t,llc rrlodcl nrit,h two prcdict,or ~rariablcs; l)ccaiisc no cxpcrirncrlt,nl m\!, data wcrc give11 in the papcr. For t,his reason, only ill is considcrctl for calc~llation of the thcrrnodynarnic vnliic, i)iit t,llc nssociatcd nnccrt,nint,y is incrcnsctl t,o *0.1 logarit,llrrlic nnit,s. The st,nhilit,y const,ant,s at zcro ionic st,rcngt,h arc log,, i/;(.%mCl2+) = (0.87 * 0.15) and (l.l%f 0.15) in acid and sodi~lrrl ionic rncdia rcspcct,ivcly, as rccnlcnlat,cd by this review usirlg the ion intcract,ion cocfficicnts give11 in -4ppcntlix B. .%pparcnt,ly, the ntltlit,ion of .%rnCl: in the data analysis urns foiind t,o l)c sigrlificnrlt only for soliit,ions at 3OoC, while no irrlprovcmcrlt of the error slim as ol)t,ainctl for prclirninnry cxpcrirncnt,al data at room t,crnpcratiirc.

A % ~ n X ~ z + and .4rn(NO:j): wcrc clairrlcd t,o he prcscnt in t,llc nrrlcriciiim nitrat,c systern. Tllc val~lcs of log,, i/l(.4rnNOi+) rangctl bct,~vccn (0.23*0.0%) nrltl (0.30*0.0%). depending 11pon \vhcthcr Li+ or XH: as iiscd. cf. Table \'.14. Thcsc val~lcs arc in fair ngrccrrlcnt ~vi th other p~lhlisllcd rcsnlt,s [62PEP/h1.4S; 64B.%N/P.%T; G5CHO/STR]. Tllc st,nhilit,y const,nrlt,s arc convcrtcd to rrlolal urlit,s nrltl cxtrapolat,cd to zcro ionic st,rcngtll using t,llc specific ion intcract,ion cqnnt,ions of .%ppcndix B; rcsiilting in log,, p,"(.4rnNOi+) = (1.32 * 0.1), (1.3% * 0.1) and (1.41 * 0.1) in acitl; lit,hi~lrrl nrltl sotliiim ionic rrlcdin rcspcct,ivcly, \vhcrc t,llc ~lrlccrt,aint,ics have bccn incrcnsctl t,o *0.1 for the rcnsorls tlisciissctl in Scct,ion \'..6.1.4.1, 11.138.

From t,llc dist,rih~lt,ion tlat,a. .%rnSCN2+ nrltl .4rn(SCX): sccm t,o he cvidcnccd in the nrrlcriciiim t,lliocyanatc systcrn. Tllc corresponding val~lcs of t,llc stability const,ants; oht,aincd in Na+ and NH: rncdin, arc rcport,cd t,o he i~~tlist,i~~giiisl~al>lc ~vit,llin the cxpcrirncntal errors. The cxpcrirncntal tlat,a nrcrc not rcport,ctl, but the rncnsnrcd dist,ribntion cocfficicnt,~ (at 30°C and I = 1.0 I1 NH:) n7crc ol)t,ainctl by digitising the available figure. T\vo diRcrcnt rrlodcls n7crc then t,cstcd by this review. First,, it was assnrncd t,hc prcscncc of t,llc first t,wo cornplcxcs ol)t,aining val~lcs of log,, 9, nrltl log,, sirrlilnr t,o those proposed by Khopknr and Nnmyanankntt,y. Then nrc fit,tcd the data by ass~lrning t,hc formnt,ion of .%mSCN2+ and .%m(SCN):j(aq). as snggcst,cd by Sckinc [65SEK3] nrltl Hnrrrlon [7%H.%R/PET]; oht,ainirlg a somc\vhat bct,tcr least, sqnnrcs fit t,o t,hc tlat,a. This indicates t,hnt cornplcxation by t,llc t,hiocynnat,c ligand is rnt,hcr weak and t,llat the tlct,crrrlinnt,ion of the corresponding stability const,nrlt,s rrlay i)c w r y scrlsit,ivc to chnrlgcs in the chemical model. Tllc prcscncc of .%mSCN2+ is ccrt,ainly cvidcrlccd in t,llc cxpcrimcrlt,~ of Khopkar et 111.; l)iit no concl~lsion on the forrnation of t,hc sccond and/or third complex car1 i)c dctl~lccd. Hcncc. t,llc reported forrnation const,ant of .%m(SCN): in [71KHO/N.4R] is not sclcct,ctl by t,llis rcric\v.

Tllc valllc of log,, 'll at 30°C rcport,cd in [71KHO/X.$R] is convcrt,cd t,o rrlolal iinits and cxt,rapolatcd to zero ionic strength usirlg t,llc specific irlt,cract,ion cqllat,ions. (:j .$p- pcndix B; ~vi th AE = (0.15*0.05) kg.rnol-'. This rcslllt,~ in log,, i/," = (1.23*0.11).

[71MOS2] Moskvin, A.I., Investigation of the complex formation of trivalent plutonium, americium and curium in phosphate solutions, Sov. Radiochem., 13 (1971) 688-693.

hloskvin st,~ltlicd the amcricinrn(II1) phosphate systcrn by an cat,ion cxcllangc t,cchniqiic in 1.0 h1; NHICl solutions at an ~lnkno\vn t,cnlpcrat,~lrc usirlg a nritlc rarlgc of tot,al pllospllat,c conccnt,mt,ion: 0.05 5 [H:3P04],,o,, < 6.8 h1. The cxpcrimcrlt,~ wcrc pcrforrrlcd l)oth at pH = 1.8 and at [H+] = 0.5 h1. The variat,ion of t,hc tlist,ribntion coefficient,; I jd nrit,h incrcasirlg [H2POT] as int,crprct,cd assnrning t,hc forrrlat,ion of four corrlplcxcs of the gcrlcral cornposition . $ ~ ( H ~ P O ~ ) ~ ~ - " ) ~vi th n = 1 t,o 4. Ho~vcvcr. 11s- irlg t,llc spcciation proposctl by hloskvin, non-rcalist,ic ncgat,ivc ~ ~ a l n c s arc calcnlat,cd for t,llc partition cocfficicnts of t,llc cat,ionic arncricilim species (.$m3+; .$~H~PO:+ and .$rn(H2PO4):). Tllc cation cxchangc t,cchniqnc appears inadcqnat,c t,o st,udy t,llis syst,cm ~vllcrc t,hcrc arc scrcml pot,cnt,ial ligands \vhich rnay for111 many cat,ionic cornplcxcs. Tllcrcforc t,hc cqllilihrillrn const,ant,s proposed by LIoskvin arc rcjcct,cd by t,llis

[72BAI/CHO] Baisden, P.A., Choppin, G.R., Kinard, W.F., Ion pairing of Am(ll l) with perchlorate, J. Inorg. Nucl. Chem., 34 (1972) 2029-2032.

Tllc allt,hors st,udicd t,llc ion pair forrrlat,ion hct,\~~ccn .$m(III) arltl C10; ions by sol- ~ ~ c n t cxtractiorl ~vit,ll dinonylnapht,halcnc snlpl~onic acitl in n-hcpt,anc at 25°C. Tllc ionic strength of t,llc aqiicolls phase as fixed at 2 hI by using HBFl as background clcct,rolyt,c. Thcrcforc, act,ivit,y cocfficicnt,~ varied ~vhcn the mctliiim was cllangctl fiorn “inert" anions t,o ligarltl anions. Tllc cqiii1il)riiim constant tlcrivcd by the aiit,hors, hoxvcvcr, refers to a "pllrc" pcrchloratc rncdinrn. .$S t1cscril)cd in an earlier report, [67CHO/KEL], act,ivity cffcct,s in the rrlixcd clcctrolyt,c solllt,ions nrcrc acconntcd for by introdiicing. as constant pamrnctcrs, t,hc act,ivit,y cocfficicnt,~ of t,llc pure hack- groiind clcct,rolyt,c and of t,llc pure ligand solution; irlstcatl of correcting each dat,a point of rrlixcd cornposition. hlorcovcr, as also st,at,cd by t,hc authors, no act,ivit,y cocfficicrlt,~ nrcrc available for HBF4. .$pparcntly, t,hcsc val~lcs nrcrc tlcrivcd indircct,ly from t,hc cxpcrirncntal rncasnrcrncnt,~ of st,al)ilit,y corlst,arlt,s for t,hc .$rn(III) cornplcx wit11 ptol~lcnc slllphonic acitl (ll,pts) in t,hc syst,cms HC1O4-ll,pts and HBF4-ll,pt,s.

It is difficiilt t,o cval~lat,c t,llc iinccrtaint,y associat,ctl ~vi th t,llc approximations rnadc by t,llc allt,hors. Hcncc. it is not clcar if the very lo\v value rcport,ctl; 9, = (0.86f 0.06). rcprcscrlt,~ an cffcctirc formation const,ant or rat,llcr reflects charlgcs of t,llc ionic rncdillrn. IIorcovcr. possil)lc irlt,crnct,ions of .$rn(III) nrit,h HBFl n7crc not consitlcrcd q~lant,it,at,ivcly. In vic\v of tllcsc consitlcrat,ions, the prcscnt rcric\v does not, irlcllltlc t,hc rcport,ctl const,ant in t,hc sclcct,ctl data set.

[72COH] Cohen, D., Americium(V1) in basic solution, Inorg. Nucl. Chem. Letters, 8 (1972) 533- 535.

This is a spcctrophotornct,ric stiidy of .%rn(\'I) in 1 11 CsOH. Rctl~lct,ion of .%m(\T) and formation of an .irn(\') prccipit,at,c urns rcportcd t,o occur in one or t,~vo (lays. Xo cqlii1il)riiirn const,nnt,s wcrc rcportcd.

[72HAR/PET] Harmon, H.D., Peterson, J.R., McDowell, W.J., Coleman, C.F., The tetrad effect: the thiocyanate complex stability constants of some trivalent actinides, J. Inorg. Nucl. Chem., 34 (1972) 1381-1397.

Tllc authors st,~ltlicd t,llc formnt,ion of amcricinrn(II1) t,lliocyanatc cornplcxcs in 1.0 11 NaSCN/NaC104 rncdia at pH = 2. Sol~~cnt cxt,ract,ion cxpcrimcnt,~ wcrc con- dllct,cd at 18, 25, 30 and 35°C t,o invcst,igatc t,hc t,crnpcrnt,urc cflcct,~. The t,rcnt,rrlcnt, of t,hc tlat,a s h o ~ ~ ~ d t,llat rnono-, di- and tri-t,lliocyannt,c cornplcxcs wcrc forrrlcd at, 0 < [SCX-] 5 1.0 h1; accortling t,o:

Tllc aiit,llors iiscd t,wo motlcls in ~vhich the prcscncc of .%rn(SCN): urns consitl-

crcd (p,, 'IZ, or orrlit,t,ctl (p,, p:j). The rcs~llt,s indicate t,llat neither of t,llc nhovc rrlodcls urns consist,cnt,ly superior, cvcn if the (p,, p:j) rrlodcl as co11sitlcral)ly more cffcct,ivc for Bk(III), Cf(II1) and Es(II1). .%S tlisciisscd in [ilKHO/N.%R] t,llc corn-

corresponding stability const,nnt,s rnay bc very scnsitirc t,o changes in the cllcrrlicnl rnodcl. Tllc prcscncc of .%mSCN2+ is ccrt,ninly cvidcncctl in t,llis work, ~vhilc no 1111- nrnbigiions critlcncc of t,hc forrrlat,ion of t,llc sccond and/or t,llc third cornplcx can bc obtained fiorn this solvent extraction dnt,n set. Thcrcforc the vnliics of 'lZ ant1

rcport,ctl by Hnrrrlon et 1x1. arc not sclcct,cd by t,llis rcvic\v. Tllc first forrrlat,ion const,ant log,, i l I ( I = 1 hI) = (0.36 * 0.05), cf. Tal)lc \:.l?'. is convcrtcd to rnolal iinits and cxt,rapolatcd to zero ionic st,rcrlgt,ll \vit,ll t,hc specific ion intcract,ion cqliations of .%ppcntlix B iising AE, = ( 0 . 1 5 * 0.05) kg . mol-l. This rcsiilts in log,, p: = (1.41 f 0.08).

Dnc t,o t,hc iinccrtai~lt,y in t,llc spcciation rrlcnt,ioncd above. t,llc ~ ~ a l n c s of itj oh- taincd at diffcrcrlt t,cmpcmt,urcs (18 t,o 45°C) arc not used by t,llis rcvic~v t,o cnlcnlat,c cnt,halpy ant1 entropy changes. Ho\vcvcr, the vnliics of ill arc llsctl to dctcrminc the reaction cnt,hnlpy and entropy at I = 1 11 by a n~cight,ctl linear regression .'11lp, 71s. 1 / T (K-')" obtaining: A,Hm(.i.3. rr = 1. I = 1 11) = (8.2 f 4.8) k J . mol-l ant1 1,Sm(.%.3; n = 1, I = 1 hl) = (34*16) .J.K-'.rnol-l. Tllcsc vnliics arc in agrccmcnt, with t,hc rcsnlt,s rcport,cd by the n~lt,hors (cf. Table lT.18).

[72HAR/PET2] Harmon, H.D., Peterson, J.R., Bell, J.T., McDowell, W.J., A spectrophotometric study of the formation of americium thiocyanate complexes, J. Inorg. Nucl. Chem., 3 4 (1974) 1711-1719.

Tllc authors pcrforrrlcd spcct,ropllot,omct,ric rncasnrcrncnt,~, in 1.0 hI NaSCN/ NaCl(14 rrlcdin to ohscrrc the spcct,rnl chnrlgcs of t,llc 503 nm nrrlcriciiim al~sorption peak, produced by SCN- cornplcxnt,ion. They dct,crrrlincd the forrnation const,ants of .%mSCN2+ nrltl .%m(SCN): and silggcstcd t,llc prcscncc of .%~n(sCN):~(aq) at [SCN-] 2 1.0 hI. In ortlcr to rcprotlilcc t,llc t,ahillnt,ctl cqnilibrinrn const,ant,s. t,llis review digit,iscd the rrlolar absorpt,ivitics at 503 rlrn as n filrlct,ion of [SCN-] in Fig- nrc 2 of t,llc original papcr. The soft,~varc SQU.%D [%LEG] is iiscd t,o cxt,rnct the st,ability const,ant,s. Tllc large scnt,tcr in the spcct,roscopic data rrlakcs it irrlpossihlc to dcrivc all tllrcc cqiii1il)riiim const,ant,s. .% valilc of log,, ill = (0.88 f 0.06) can only bc obtaincd frorn the data at [SCX-] 5 0.1 h1; hilt not frorn data at higher t,lliocya- nat,c conccnt,ration. Ilk nt,tcrrlpt,ctl (fixing log,, p,) to dctcrmirlc log,, or log,, p:3. No rclial~lc conclilsion on t,llc cxist,cncc of .%m(SCN): and/or .%m(SCN):3(nq) car1 i)c cxt,rnct,cd from t,hc dnt,n i)ccaiisc of t,hc considcrablc scatt,cr in t,llc valilcs. This rcric\v tllcrcforc disregards all tllcsc sl)cct,rophot,ornctric rcsiilts

[72MCD/COL] McDowell, W.J., Coleman, C.F., The sulphate complexes of some trivalent transplutonium actinides and europium, J. Inorg. Nucl. Chem., 3 4 (1972) 2837-2850.

h l c D o \ ~ ~ l l nrltl Colcmnrl pcrformctl a solrcnt cxt,ract,ion cxpcrirrlcnt t,o invcst,ignt,c siilpllat,c complcxcs of nrncriciiim(II1); iising n hcnzcnc solution of l-nonyltlccylami~~c nrld an aqiicoils snlphilric acitl sodium sillphatc solilt,ion. Tllc cxpcrirncrlt,nl dnt,n wcrc int,crprct,ctl assuming t,llc formnt,ion of .%rrl(~O~)::-~~,) (71, = 1,2 ,3) .

A%s lo\v conccnt,rnt,ions of H2S04 Na2S04 were 11set1; t,llc Dellye-Hiickcl rcl. a t ' ,ion was approprint,cly npplictl. Tllc st,al)ilit,y constants log,, 9," nrltl log,, p," prcscnt,cd in Tahlc \'..12; arc in good ngrccrrlcnt nrit,h t,hc ~ ~ a l n c s cxt,rapolatcd by this rcric\v, cf. Scctiorl 17.5.1.2.1. using the specific ion irlt,crnct,ion cqilat,ions of .%ppcndix B. Fnrt,hcr cxpcrirncnt,al work is ncccssnry t,o confirm t,llc prcscncc of .%rn(SO4),;-. Tllc ~ralnc of log,, p: is t,llcrcforc not sclcctcd by t,his rcvic\v.

[72SHA/STE] Shalinets, A.B., Stepanov, A.V., Investigation of complex formation of the trivalent actinide and lanthanide elements by the method of electromigration. XVII. Hydrolysis, Sov. Radiochem., 1 4 (1972) 290-293.

Tllc aiit,llors st,iltlicd t,llc hytlrolysis of .%rn(III) and Crn(II1) in 5 X 10-" hI NH4C104 at 25°C. .%n clcctromigrat,ion tcchniqiic \vithont solid slipport urns ilsctl. 10-" 11 Cc(II1) urns addctl t,o t,llc solilt,ions as a carrier, probal~ly to rcdncc .%m nrltl Cm ntl- sorptiorl on the urn11 of t,hc clcct,rorrligrat,iorl cell. Tllc tlccrcnsc of clcctricnl mohilit,ics with increasing pH from 2 to 5 as rrlodcllctl assuming t,llc forrnation of t,llc rnononil- clcar species .%rnOHW and .%rn(OH):. Tllc hydrolysis const,ant,s rccnlcnlat,cd fiorn the rcport,cd forrrlat,ion const,ant,s (ilsing log,, I%',v = 1 3 . 8 3 ~vhich had bccn dct,crrrlinctl ~ r c ~ i o i i s l y [65STE/SHIr]) arc = ( 3 . 1 3 * 0.1) and log,$/2 = 6 . 7 6 .

Tllcsc val~lcs arc ortlcrs of rnagnit,udc higher than those ol)t,ainctl in a nnrnhcr of ot,hcr, rrlorc carcfiil st,~ltlics. Tllc cxpcrirncnt,al tcchniqiic iiscd by Shalinct,~ and Stcpanov can easily give inconsistcnt rcsnlt,s i)ccaiisc of convcct,ivc fl~lxcs and t,llc difficult dc- tcrrnination of t,hc front of t,hc migrating species which move as a pl~lrrlc rather t,han as a sharp peak. Tllc rcport,ctl hydrolysis const,arlt,s arc not ~lsctl in t,hc cxi~,lnat,ion in this rcvic117.

[73CHI/DAN] Chiarizia, R., Danesi, P.R., Scibona, G., Liquid anion exchange o f thiocyanate-nitrate actinide and lanthanide complexes, J. Inorg. Nucl. Chem., 35 (1973) 3595-3604.

Tllc authors st,~ltlicd t,llc .%rn(III)-SCN--X% syst,crn iising a solvent cxtraction tcchniqnc at 25°C. Tricaprylrnct,l~ylarr~~r~oni~l~r~ chloride in o-xylcnc as cqiiilil)rat,cd with a 2.0 h1 NH4SCN-/NH4XO:+ aqiicolls phase at pH = 2. Tllc aut,hor clairrls to have dctcrmincd the stability const,ant,s of the arncrici~lrn nit,ratc ant1 t,hiocyanat,c cornplcxcs, fiorn the distril)iit,ion cocficicnt,s. Tllcrc was ho~vcvcr a consitlcr- ahlc scatt,cr in t,llc dat,a. The reported format,ion constant of the .%rnNOi+ cornplcx log,, pl(NO,) = (0.20 * 0.03) sccrrls to he in agrccrrlcnt ~vi th prcvio~ls lit,cmt,urc valncs [62PEP/hl.%S, G4B.%X/P.T. 65CHO/STR; 71KHO/N.%R]. Tllc forrrlat,ion of the thiocyanat,c corrlplcxcs .IrnSCN2+, .%m(SCN): and AI~n(SCX):3(aq) n7crc snggcst,cd. Ho~vcvcr. t,llc spcciation diagram oht,aincd by t,llis rcvic~v ~vit,ll t,llc proposctl cqni- lil~rinrn tlat,a sho\~.s t,hat .IrnSCN2+ ncrcr cxcccds 5%; while .%rn(SCN): is the prc- dominant species at 0 . G 5 log,,[SCN-] 5 0 . 2 . This is in cornplct,~ disagrccrrlcnt, with all previous ohscrxi~,t,ions. This review consitlcrs that i)cforc contl~lct,ing a stiidy on cornpctitirc complcxation (nitrat,c-t,lliocya~~atc). a bct,tcr kno\vlctlgc of t,llc simple syst,cms. . h - S C X and .%m-NO,, is necessary. Thcrcforc, t,llc st,ahilit,y const,arlt,s rcport,ctl by Chiarizia. Dancsi ant1 Scibona arc tlisrcgardctl by t,his rcvic\v.

[73HUS/HUB] Hussonnois, M,, Hubert, S., Brillard, L., Guillaumont, R. , Dbtermination de la premiere constante d'hydrolyse de I'einsteinium, Radiochem. Radioanal. Letters, 15 (1973) 47-56, in French.

Tllc a~lt,hors st,~ltlicd t,hc hydrolysis bchavio~lr of Es"+ [73HUS/HUB] using a liqiiid- liqnitl part,it,ion t,cchniq~lc (2-tl~cnoYlt,rifl~~oroacctto~~c, tttx, in bcnzcnc) in the prcscncc of arncriciiim. Tllc pH dcpcrltlcncc of t,hc arncrici~nn cxtraction rcport,cd in Ref. [GSDES/HUS] as ~lsctl to calc~llatc the cqiii1il)riiim pH of the aqiicolls phases. For the sarnc reasons as tlisciissctl in t,llis .%ppcndix ~lrltlcr Ref. [G!lDES/HUS], the first hydrolysis const,arlt oht,aincd for t,his clcrrlcnt (loglo',il = ( 5 . 3 * 0.1) at 0.1 hl (H.Li)C1(14) is not acccpt,ctl by t,llis rcric\v. Sec also the comrrlcnts under [iGHUB/HUS].

[73KOR] Korotkin, Y.S., Hydrolysis o f transuranium elements: II. Hydrolysis o f americium(ll l) and curium(l l l ) in pure nitric acid solutions, Sov. Radiochem., 15 (1973) 682-685.

This is an cxpcrirncnt,al st,udy involving tlist,ribntion chrornatogmphy. clcct,rornigration ant1 paper chrornatogmphy. sirrlilar to [74KOR%]. .%S disc~lsscd in this .Ippcndix nntlcr rcfcrcnccs [73KOR%, 74KOR21; the cxpcrirncnt,al rrlctllods arc not very rcliahlc,

nrld t,llc rcport,cd obscrvnt,ions arc not crctlit,cd by this rcvic\v

[73KOR2] Korotkin, Yu.S., Hydrolysis o f transuranium elements: Ill. Hydrolysis o f americium(ll l) in the presence o f ions wi th positive and negative hydration energies, Sov. Radiochem., 15 (1973) 776-781.

Tllc nut,hor invcst,ignt,ctl t,llc .Irn(III)-H20 system in lit,hiurn. sotliiim and pot,as- siurrl rlit,rnt,cs and pcrchlorat,cs (0.1 11 and 1 hI ionic st,rcngt,h) at 18 t,o 20°C. Tllc charge of t,hc prcdorrlinnt,irlg spccics urns dctcrmirlcd as a fimct,ion of pH usirlg pnpcr clcct,rorrligrnt,iorl and rcvcrscd phase chrornat,ography.

Tllc proposctl hytlrolysis scllcrrlc bct,~vccn pH = 1 nrltl 11 inclndcs the forrrlat,ion

chargctl colloids. Tllc cxpcrirncnt,~ nrcrc carricd out at a t,ot,nl arncrici~lrn conccnt,ration in the ortlcr of 2 X 10-" 11. Hcncc, t,llc rncasiircrncnt,~ in the rlciit,rnl t,o alkalinc pH range wcrc likcly irlfl~lcncctl by t,llc precipitation of . I I ~ ( O H ) : ~ ( ~ ) . Korot,kirl rcport,ctl t,hc follo\~.ing ~ ~ a l n c s for t,llc first nrltl t,hc sccontl hydrolysis constants in 0.1 11 LiSO:i (pH l)ctn~ccn 3 and 4) nrit,h no error cst,imat,c given: log,$/l = 2 . 5 nrltl log,,'"12 = 6 . 6 . This ~voiild imply that .Irn hydrolysis start,s already in acitlic rncdin, an ol)scrvation in cont,rast \\,it11 those rrladc by other invcst,ignt,ions. Thcrc is no irlformnt,ion nvailablc on the procedure used t,o calc~ilnt,c cqiii1il)riiim const,ant,s nrltl on the nrny pH rncasiircmcnt,s n7crc mntlc. hlorcorcr; it is not clcnr llo\~r cqnilibrinrn dat,a tlcrivcd nsing n dynnrnic cliit,ion rrlctllod nrcrc inflncnccd by sorption-tlcsorpt,ion kirlctics of intlividnnl americium spccics on t,llc stationary phase. In view of t,hc short,. corrlings of t,his st,udy, t,llc reported hydrolysis const,ant,s arc not ~lsctl by the present review.

[73MAK/STE] Makarova, T.P., Stepanov, A.V., Shestakov, B. I . , Electromigration investigation o f the comparative stability o f fluoro-complexes o f the MF" type o f certain rare-earth and actinide elements, Russ. J. Inorg. Chem., 18 (1973), 783-785.

Tllc nut,hors invcstigat,cd the formation of .$m(III) complcxcs ~vit,ll fl~loridc ions in 0.1 h1 NaC104 at (25 * 0.5)"C by usirlg an clcct,rorrligrat,ion t,cchniq~lc. Tllc cxpcrirrlcnts n7crc carricd oiit by nsing a porous hcd of carbornndnrn po\~rdcr as stationary phasc.

In t,llc invcst,igatcd conccnt,ration range (from lO-" t,o 10-qnI total flnoritlcs at, pH = 1.8); t,hc aiit,llors fo~lrltl t,hc prcscrlcc of .IrnFW only. Even after ion st,rcngt,h corrections, t,llc vnliic loglo = (3.96 f 0.06) is higher t,llan tlct,crrrlinctl in more precise stiidics. It is often difficiilt t,o oht,nin rcliablc q~lant,it,at,ivc ~ ~ a l n c s of clcctricnl mobility nrit,h the clcct,rorrligrnt,iorl mct,hotl used by t,hc aiit,hors. Tllc shnpc of the moving spot tlcpcnds on t,llc rate of cqiiilil)rat,ion bct,\~~ccn t,hc spccics prcscnt in the syst,cm, their irlt,crnct,ions nrit,h the stationary phasc, nrltl on the possiblc cxistcncc of clcctro-osmot,ic flo\~rs and nssociatcd phcnorncna of hydrodynamic dispersion. If not properly accoiint,cd for. all t,his is likcly to int,rodiicc systcrnat,ic errors into the rncnsnrcrncnt,~. For t,llis reason; t,llc rcport,cd cq~lilihriiim const,nrlt is not inclndctl in the sclcct,ctl set of tlat,a.

[74CEL/HOL] Celeda, J., Holub, J., Smirous, F., A ionophoretic study o f the association o f Pm"+ and Am3+ ions in concentrated solutions o f calcium perchlorate and nitrate, Collection Czechoslov. Chem. Commun., 39 (1974) 3599-3602.

This is a qnalitatirc stiidy on corrlplcx forrnat,iorl of .%m(III) in Ca(C104)2 arltl Ca(XO:3)a rrlcdia by usirlg paper clcct,rophorcsis. The authors clairncd that the mono- ~ralcnt corrlplcx .%rn(NO:3): was prcscnt in the nit,ratc conccnt,ration range fiorn 1 t,o 8 hr.

[74KHO/MAT] Khopkar, P.K., Mathur, J.N., Thiocyanate complexing o f some trivalent actinides and lanthanides, J. Inorg. Nucl. Chem., 36 (1974) 3819-3825. A% solrcnt cxtractiorl t,cchniq~lc (as in Ref. [ilKHO/N.%R]) urns iiscd at,

I = 1.0 hl (XH4SCX/NHIC1O4), to tlct,crrrlinc t,hc t,hcrmotlynamic paramct,crs (&G,, &Hrn, &S',) corresponding t,o the corrlplcx forrnation bct,~vccn .%rn"+ and thiocy- anatc, cf. Tahlc \".18. Tllc forrrlat,ion of .%mSCN2+ and .%rn(SCN): was snggcst,cd at 15, 30; 37 and 45°C. Tllc prcscncc of .%rnSCXW is ccrt,ainly cvidcnccd in t,his cxpcrimcrlt,al stiidy, but no conclusions on the format,ion of the second complex car1 i)c oht,ainctl. Bcca~lsc t,hc int,crprctation of the cxpcrirrlcrlt,al data is dcpcrltlcnt on the cllcrrlical rrlodcl chosen; t,llc rcport,cd forrnation constant,s for .%rn(SCN): arc not crcdit,cd by this rcric\v. Sec also t,llc corrlrrlcnts in t,his .%ppcntlix for Ref. [71KHO/X.%R]. Tllc valiic of log,, 9, intcrpolat,cd at 25°C is convcrt,ctl t,o rrlolal urlit,s and cxt,rapolat,cd t,o zero ionic strength iising the specific int,cract,ion cqiiations, cf. .%ppcndix B; with AE = ( 0 . 1 5 * 0.05) kg . rnol-'. This rcs~llt,s in log,, p," = (1.20 f 0.15).

Tllc val~lcs of 9, arc iiscd t,o dctcrmirlc the rcact,ion cnt,ropy arltl cnthalpy at I = 1 I1 by a nrcightcd linear rcgrcssion .'lnpl 'rjs. 1/T (K-')" obtaining: &Hm:, (I = l LI) = (2.7 f 4.6) kJ . rnol-' and A,S,,J (I = 1 hI) = (12 f 15) J . K-' . rnol-l. Tllcsc T ~ ~ ~ I I C S arc in agrccIrlcnt nrit,h t,llc rcs~llt,s rcportcd by t,hc aiit,llors ( c j Tahlc \'.l$).

[74KIN/CHO] Kinard, W.F., Choppin, G.R., Complexing o f trivalent actinide ions by thiocyanate, J. Inorg. Nucl. Chem. 36 (1974) 1131-1134.

Tllc authors pcrforrrlcd a solvcnt cxtractiorl st,~ltly using t l i ~ ~ o n y l ~ ~ a ~ ) l ~ t , l ~ i ~ ~ l c ~ ~ c snlphonic acid. dissolved in ra-hcptanc; as a liquid cat,ion cxchangcr. Tllc ionic st,rcngt,h was kept const,ant (I = 5.0 hI NaSCN/NaClO4) at pH = 3. Only .%mSCN2+ urns forrrlcd up t,o [SCN-] = 0.5 h1; while . % I ~ ( S C X ) : ~ ( ~ ~ ) m7as cvidcnccd at 1.5 5 [SCN-] 5 2.5 h1. Frorrl t,hc log,, PI ~~a lncs , tlct,crrrlinctl at diffcrcnt t,crnpcratiircs (10; 25; 40; 55"C), Kinard arltl Choppin calc~llatcd the cnt,ropy and cnt,halpy changcs at 25°C: &H, = (ll.76*2.05) k.J.mol-l and A,S, = (50.2f 6.6) .J.K-'.mol-l. Tllcsc val~lcs arc in satisfact,ory agrccmcnt \\,it11 t,hc valiics rcport,cd by Harmon [72H.%R/PET], hut, differ co11sitlcral)ly from those rcport,ctl earlier by Choppin arltl Kct,cls [65CHO/KET].

\VC iiscd t,llc cqiii1il)riiim constants rcport,ctl by Kinard and Clloppirl [74KIX/CHO] (cf. Tahlc I7.17) t,o verify t,llc rcportcd t,hcrrnodynarnic ~ ~ a l n c s by pcrforrrling a ~vcight,ctl linear rcgrcssion " h i / l ?is. 1 / T (K-'))". obtaining at I = 5 h'f: !,,H, = (12.36 *

3.21) k.J.mol-l. and &S, = (51.95* 10.49) . J . K 1 .rnol-l. Tllcsc valiics arc in agrccrrlcnt ~vi th the rcsiilts reported by Kirlartl and Choppin. cf. Tahlc \'..18. Even though the st,al)ilit,y const,arlt,s arc ol)t,ainctl fiorn acciirat,c cxpcrirncntal tlat,a [74KIN/CHO], no cxtrapolat,ion t,o zero ionic strength will i)c pcrforrncd, hccallsc of t,hc high clcctrolyt,c conccnt,ration llsctl (I = 5 hI).

[74KOR] Korotkin, Y.S., Hydrolysis o f transuranium elements. IV. Sorption homogeneity o f microamounts of americium(lll), Sov. Radiochem., 16 (1974) 218-222.

C21lalit,at,ivc informat,ion is given on t,llc effect of varioiis alkali rrlct,al cat,ions on .Im(III) hydrolysis bct,~vccn pH = 0 arltl 6 stiidictl by cat,ion cxchangc. Hytlrolysis was rcport,cd t,o begin at pH = 0.4 bot,h in HC104 and in aqiicolls solllt,ions cont,ainirlg K+ ions. .Iccording t,o Korot,kin, small conccnt,rat,ions of Li+ ions shollld shift, hytlrolysis t,oxvards pH = 4. This is in cont,rntlictiorl ~v i th an earlier statcrncnt by the sarnc allt,hor [73KOR]; claimirlg t,llat 50% hydrolysis in 0.1 h1 LiNO:j occiirs alrcatly at pH = 2.5. Sirlcc the reliability of t,llc cxpcrirrlcntal t,cchniqnc iiscd by Korot,kin is q~lcst,ional~lc. t,llc rcport,cd obscrvat,ions arc not crctlitcd by t,his rcvic~v

[74KOR2] Korotkin, Y.S., Hydrolysis of transuranium elements: V . Hydrolysis of americium and curium in perchloric acid solutions, Sov. Radiochem., 16 (1974) 223-226.

This is a qllalit,at,ivc stiidy of .Im(III) arltl Cm(II1) hydrolysis in the pH range fiorn 1 t,o 9 usirlg clcctromigrat,ion and rcrcrsc-phase chromnt,ography. Hydrolysis urns rcport,ctl t,o l)cgin at pH = 0.5 t,o 1. The same conclusion urns tlrn\~,n in Ref. [73KOR] dealing ~vi th .4rn"+ and C r d + hydrolysis in nit,ric acid solutions. This pH valllc is considcmhly diRcrcnt from that oht,aincd by other dct,crrninnt,ions. -4s tlisciissctl in this -4ppcntlix iindcr Rcfs. [73KOR2] arltl [74KOR], t,hcsc cxpcrirncntal mct,hotls arc not very rclial~lc, and t,llc rcport,cd obscrvnt,ions arc not credited by t,his rcvic\v.

[75KOR] Korotkin, Y.S., Study of the hydrolysis of americium and curium, Sov. Radiochem., 17 (1975) 528-533.

This paper gives rcsiilts and concliisions very sirnilar to those rcport,ctl in Ref. [73KOR%].

[75VAS/AND] Vasil'ev, V.Y., Andreichuk, N.N., Ryabinin, M.A. , Rykov, A.G., Spectrophotometric study of complex formation and solvation of actinide ions: XII. Forms of existence of americium(Vl) in nitric acid solutions, Sov. Radiochim. 17 (1975) 28-30.

Tllc aiit,llors llsctl a spcctrophotornct,ric t,cchniqllc t,o invcst,igatc t,hc arncriciiim(\~I)- nit,rat,c syst,crn. in 0 5 [HNO:j] 5 18 hl rncdia. They irlt,crprctcd their cxpcrimcrlt,al rcsult,s assiimirlg t,hc prcscrlcc of . I ~ n ( l ~ ( - U O : ~ ) ~ ( a c ~ ) at 6 5 [H-UO:3] 5 11 hI. arltl snggcst,cd t,llc formation of . I I ~ O ~ ( N ( I : ~ ) ~ at higher nitric acitl conccntrat,ions. Bccaiisc of t,llc large change in t,hc ionic rncdia (0 5 I 5 18 hl), this rcvic~v considers t,llat, no rclial~lc valiics of cqnilibrinrn const,ant,s car1 he obtaincd from t,llcsc rncasnrcrncnt,~.

[76CHO/UNR] Choppin, G . R . , Unrein, P.J., Thermodynamic study of actinide fluoride complexation, in : Transplutonium 1975 (Muller, W., Lindner, R., er l s . ) , Amsterdam: North-Holland, 1976, pp.97-107.

Pot,crlt,iomct,ric and solvcnt cxtractiorl tcchniqiics wcrc iiscd to invcstigat,c t,llc cornplcx forrnation of v+~,rions t,ri- arltl t,ct,mvalcnt act,inidcs ~vit,ll fl~loridc ions in 1 I1 N+1Cl(14 at pH = 2.7. For .Irn(III), solrcnt cxt,ract,ion cxpcrimcrlt,~ nrit,h dinonylnapht,halcnc snlphonic acitl in n-hcpt,anc wcrc matlc at 10, 25. 40 arltl 55°C. Prclimi- nary rcsnlt,s from this ~vork have bccn rcportctl by Choppin [69.JOX/CHO; 75DEGICHOI.

In t,hc invcst,igatcd range of ligand conccntrat,ion, Choppin and Unrcirl only fo~lrltl the cxist,cncc of .4rnF2+. arltl calc~llatcd a val~lc for the stability constant of log,, ill =

(2.49 f 0.02) at 25°C. Tllc cxt,rapolat,ion t,o standard conditiorls by usirlg the ion irlt,cractiorl cocfficicnt,~ reported in -4ppcntlix B gives loglo p," = (3.58 * 0.21) ~vhcrc the ~lnccrt,ainty is increased t,o rcprcscrlt t,llc 95% confidcrlcc lcvcl

Tllc cnthalpy cllangc of t,hc rcact,ion in t,hc 1 hI pcrchlorat,c rrlcdi~lrrl urns dct,crrrlinctl by Choppin and Unrcin t,o bc &H, = (27.6 f 2.1) k J . rnol-'. This rcric\v applies t,llc \;?n't Hoff rclat,ion t,o the cqnilibrinrn const,ant,s obt,aincd by Clloppirl and Unrcirl at tliffcrcnt t,cmpcmt,urcs aft,cr corrcct,iorl to irlfirlit,c tlilntion. Tllcsc cal- c~llat,ions yicltl &H: = (16.2 f 0.5) kJ . rnol-l. Hoxvcvcr; t,llis rcvic~v tlocs not fccl confidcrlt t,o rccomrrlcnd t,his ~r+~,lnc bccansc of t,hc nnccrt,aintics affecting the specific ion intcract,ion cocfficicnts in t,llc invcstigat,cd t,crnpcrnt,urc range.

[76HUB/HUS] Hubert, S., Hussonnois, M , , Brillard, L . , Guillaumont, R., Thermodynamic functions for complexing of M"+ ions (M"+ = Pu"+ 4 to Fm;:), in : Transplutonium 1975 (Muller, W., Lindner, R . , etis.), Amsterdam: North-Holland, 1976, pp.109-118.

Tllc aiit,llors rcport,cd cnt,halpy arltl entropy charlgcs for t,hc first hydrolysis rcactions of t,rivalcnt t,mnsnrani~lrn clcrrlcnt,~ from P11 t,o Fm in 0.1 I1 (H.Li)C1(14 rrlcdi~lrrl within t,llc t,crnpcratiirc range 10 t,o 50°C. They calciilat,ctl the ~ ~ + ~ , l n c s of log,,',il for .Im(III) at each tcrrlpcrat,~lrc from t,llc diffcrcncc in tlist,rib~lt,ion cocficicrlt rncasnrcd bct,\~~ccn pH = 3.2 arltl pH = 5.4 iising 2-t,hc1~oyltrifliioro+1~cct~o11c. tttx, in bcnzcnc. This diffcrcncc as at,tril)iit,cd cnt,ircly t,o the forrnation of .4rnOHW +at pH = 5.4. How- cvcr. as rrlcnt,ionctl in t,hc tlisciission of Ref. [69DES/HUS] in t,llis .Ippcndix, tllcrc is no st,at,ist,ical slipport for t,llc sclcctiorl of siich a rrlodcl fiorn t,llc dat,a ol)t,ainctl at 25°C. Tllc sign of t,llc rcport,ctl valiics for cnt,llalpy arltl entropy charlgcs is t,llat, cxpcct,ctl for t,hc forrrlat,ion of inner-sphcrc complcxcs. Ho\vcvcr, t,llc aiit,llors' claim that cnharlccrrlcnt of hytlrolysis occurs nrit,h incrcasirlg t,cmpcmt,urc is based only on two tlat,a points. Bccaiisc of t,hc scarcc cxpcrirncntal details, it is not possible t,o rrlakc a proper iinccrtaint,y cst,imat,c. It is t,hns difficiilt to obtain fiorn tllcsc dat,a nnambigiions cvidcrlcc for the proposed hydrolysis schcrnc. Sec also t,hc corrlrrlcnts nntlcr [73HUS/HUB].

[78RAO/BAG] Rao, P.R.V., Bagawde, S.V., Ramakrishna, V.V., Patil, S.K., Sulphate complexing of some trivalent actinides, J . Inorg. Nucl. Chem., 40 (1978) 123-127.

Tllc authors st,~ltlicd t,llc arncricillrn(II1) cornplcxation in snlphat,c rncdia by the t l i ~ ~ o n y l ~ ~ a ~ ) l ~ t , l ~ i ~ ~ l c ~ ~ c slllphonic acid extraction mct,hotl, at I = 1 and 2 11 H2SO4/HCl(I4, nrltl 25°C. Tllc variation of t,hc tlist,rihllt,ion coefficient nrit,h incrcasirlg [SO:-] urns intcrprct,cd by t,hc forrrlat,ion of . % m ( ~ ~ ~ ) f - " ) ( 7 , = 1; 2) cornplcxcs, cf. Tnhlc \".12. Tllc aiit,llors used 0.066 and 0.084 (at I = 1 nrltl 2 11, rcspcct,ivcly) as t,hc tlissocint,ion constants of HSO;; taken from [51ZEB/.%LT, 76F.%R/BUC].

This review rcint,crprct,s the cxpcrirncrlt,nl rcsnlt,s of Rno et o,l. to st,udy t,llc inflncncc of t,hc ionic rncdia on t,hc tlat,a t,rcnt,rncnt,. In order t,o calclllatc t,hc stability const,nrlt,s of the amcricinrn cornplcxcs, val~lcs of [SO:-] have t,o he computed fiorn t,llc reported tot,nl siilphnric and pcrchloric acitl conccnt,ratio~~s. Using t,hc specific ion intcract,ion cqliations (cf. .%ppcndix B) nrc compute t,hc cq~lilil-~riiim const,ant for the rcactiorl H+ + S O : + HSOT (log,, li" = (1.98 * 0.05); cf. Table I\:.2) as a filrlct,ion of ionic st,rcngth: loglo K ( I ) = (1.98 - 4 0 - &I,), ~vllcrc in H2S04/HC104 mctlia,

W .%ssnrning t,hnt E(,+ ,,,, :-) W E ( ~ ~ + , , ~ , : - ) = ( 0 . 0 3 f 0.04) kg - ~rlol-', nrltl E(,+;,

zz E ( ~ ~ + , ~ ~ ~ , ; ) = ( 0 . 0 1 f 0.02) k g . rnol-l, ~ v c cnlcnlatc t,hc prot,orlat,ion const,nrlt of siilpllat,c for each of the cxpcrirncnt,al points given 1)y Rao et o,l. [78R.%O/B.%G, Tn- blc 31 (t,his gives log,, h', vnliics in the range 1.17 t , ~ 1.30 at I = 1 hI. and l)ctn~ccn 1.20 t,o 1.3% at I = 2 h1). .%S cxpcct,ctl; t,hcsc vnliics arc tliffcrcnt from t,llc dissociation const,ant,s of HSOT given in Ref. [89ShII/II.%R] for NaC1(14 rncdin, l)ccaiisc the nctirit,y cocfficicnts of snlphat,c nrltl i)isiilphnt,c ions change nrhcn NaC104 is rcplnccd by mixt,urcs of snlph~lric and pcrchloric acids.

Our calciilnt~ions lcntl to: log,, ill = (1.97 f 0.02); log,, i12 = (2.89 f 0.04) at, [H+] zz 1 hl. and log,, ill = (1.97 f 0.02), log,, 'l2 = (2.96 * 0.04) at [H+] -- 2 11. Ho~vcvcr. as the nssiimptiorl E ( ~ + , ~ , ~ , ; ) S= E(N. a+,HSo;) ,, = ( 0 . 0 1 * 0.0%) kg . rrlol-l is quit,c doubtfill, ~ v c incrcasc the llrlccrt,aintics of t,hc cnlcnlat,cd cqiii1il)riiim const,nrlt,s for the nrrlcriciiim cornplcxcs t,o *0.3 logarithmic ilnits.

[79LEB/FRE] Lebedev, I.A., Frenkel, V.Y., Kulyako, Y.M., Myasoedov, B.F., Complex formation by americium(Vl) in phosphoric acid solutions, Sov. Radiochem., 21 (1979) 699-705.

Spcct,ropllot,omct,ry and pot,cnt,iomct,ry wcrc iiscd to invcst,ignt,c t,llc .%m(\:I)-phosphat,c syst,cm in 0 5 [H:3P04] 5 12 h1 rncdin. Tllc ionic strength as not kept const,ant,. Tllc cxpcrirncntal data indicat,c t,llc prcscncc of t,hc . % ~ n ( l ~ ( H ~ P O ~ ) ~ ( a q ) cornplcx. Tllc diffcrcrlcc in the st,al)ilit,y constants dct,crrrlincd by t,llc t,wo cxpcrimcn- tal tcchniqiics (log,, i12(sp) = 3.3; loglo p2(pot,) = 4.6) arc cxplaincd by t,hc aiit,llor as being dnc to t,hc formnt,ion of ,'first,- or second-sphcrc" cornplcxcs. This rcric\v bclicvcs t,llat rrlorc cxpcrirncntal work is ncctlcd to ol)t,ain a rclial~lc vnliic for t,llis

[79LEB/FRE2] Lebedev, I.A., Frenkel, V.Y., Kulyako, Y.M., Myasoedov, B.F., lnvestigation of complex formation of americium(lll) and americium(lV) in phosphoric acid solutions., Sov. Radiochem., 21 (1979) 692-698.

Lcl)cdcv et o,l. stiidictl the arncrici~lrn-~)l~os~)l~atc syst,cm in 0.01 t,o 13 hI H:3P(I4 rncdia usirlg sl)cct,rophot,ornctry. Tllc ionic st,rcngt,ll urns not kcpt const,ant,. Tllc dccrcnsc in absorpt,ivity of t,llc 506 rlrn peak a t 0.1 5 [H:3P04] 5 5 h1 as att,rih~lt,ctl to the formnt,ion of .%mH2PO:+, \vhilc the fiirt,hcr dccrcasc a t [H:3P04] 2 5 hI urns credited t,o t,hc prcscncc of .%rn(H2P04):. This rcr ic~v corlsitlcrs t,llat t,hc dccrcasc of rrlolnr cxtinct,ion dnt,n (or scnt,tcring) a t t,llc high phosphoric acid conccnt,rations rrlay l)c an ionic st,rcrlgt,ll artifact in quasi "non-nq~~co~ls" rrlcdin (I zz (0.35 + 0.10) 11 for 4 h1 5 [H:3P04] 5 13 hl. fiorn calc~llatcd [H2PO;]), and not to t,llc forrnation of the sccorltl complex as s~lggcstcd by the aiit,llors. Hcncc, the forrnation cqnilibrinrn const,ant for .%m(H2P04): reported by Lcbctlcv et al. [79LEB/FRE2] is tlisrcgardcd.

Tllc nut,hors also rncnsnrcd t,hc oxitlat,ion potcntinls of t,llc coilplc .%m(III)/.%rn(I\~) in 10 to 15 h1 H:3P(I4 mctlia. Tllc ionic strength \!,as not kcpt constant. nrltl it is cstirnatcd to he I zz (0.3 t,o 1.6) hI. fiorn calciilnt,ctl [H2POy] vnliics. Tllc dccrcasc of ElI2 urns nssigrlcd t,o t,llc prcscncc of .%m(H2P04):. .%S ~ r c ~ i o i i s l y stated, t,llis review does not rely on tlat,a oht,aincd a t such high conccnt,mt,ions; nrltl thcrcforc, the corrcsponding stability const,nrlt will not he considered.

[80KHO/MAT] Khopkar, P.K., Mathur, J.N., Complexing of californium(lll) and other trivalent actinides by inorganic ligands, J . Inorg. Nucl. Chem., 42 (1980) 109-113.

Khopknr nrltl hIat,llur stiidictl t,llc nrncriciiim(II1)-s1111)11atc corrlplcxcs ilsirlg a sol- ~ ~ c n t cxtractiorl t,cchniqnc at 30°C; pH = 3 and I = 1 hI (NH4)2S04/-UH4C104. Tllc linear vnriat,ion of I%';' 71s. [SO:-] indicates t,hc forrnnt,ion of t,hc .%mSO: cornplcx. Tllc corrcsponding st,al)ilit,y const,ant is ~lsctl in t,hc sclcct,ion proccdiirc t1cscril)cd in Scct,ion \".5.1.2.1. Extrapolat,ion t,o I = 0 (cf. .%ppcntlix B) yields log,,fi," =

(4.04 + 0.07).

[81LEB/MAZ] Lebedev, I.A., Mazur, Y.F., lnvestigation of the complex formation of americium(lll), curium(lll), and californium(lll) with perchlorate ions in aqueous solution, Sov. Ra- diochem., 23 (1981) 291-299.

Tllc nut,hors rncasiircd the distril)iit,ion cocfficicnt,~ of .%rn(III), Crn(II1) nrltl Cf(II1) bct,\~~ccn tli-2-ct,hylhcxyl phosphoric acid in tlccnrlc and aqiicolls (Na,H)C1(I4 soliit,ions with pcrclllornt,c conccnt,rations varictl l)ctn~ccn 0.1 ant1 8 11 at pH = 1. Int,crprctation of the dnt,n l)clo\v 2 11 corlsitlcrcd t,llc prcscrlcc of .%m(C104)" +vit,h 9," = (4 + 0.9); ~vhilc t,hc oiit,cr-sphcrc cornplcx .%rn(C104); as clnimctl t,o he prcscnt a t higher conccnt,mt,ions. The formnt,ion constant for .%rn(C104); urns rncnsnrcd a t 25. 35, 45 nrltl 55°C obtaining, rcspcct,ivcly, p," = (2.0 + 0.1); (2.3 f 0.2); (2.6 f 0.3); nrltl (2.9 + 0.4). Tllc positjive val~lcs of &H: = (9.8 + 1.8) kJ . rrlol-l and 4,s: =

(38.8 * G.7) J . K-' . mol-l dcrirctl from t,hcsc rrlcasllrcrrlcnts appear to indicat,~. ho\vcvcr, an inner-sphcrc charact,cr of t,llc cornplcx.

Tllc motlcl cqiiation used by Lcl)cdcv and hlazur inclndctl two tliffcrcnt t,crrrls accoiint,ing for the forrrlat,ion of oiit,cr-sphcrc and inner-sphere complex species. Bot,ll the lat,t,cr rcactiorl and t,hc cxt,ract,ion process wcrc formally ~vrit,tcn as a displaccrncnt, of nrat,cr rnolccnlcs irlt,o the first hydrat,ion sphere of nct,inidc ions. Thiis, t,hc nrat,cr actirit,y appeared as a varial~lc raisctl t,o a pourer index. :I;. rcprcscrlt,irlg t,hc hydration nurnl)cr of t,hc trivalent actinitlcs. .%lt,hoiigh postiilat,cd t,o bc al\~rays equal t,o 8 in the conccnt,rat,ion range fiorn 2 11 to 8 hI. possil)lc nndct,cctcd variat,ions of the hydration nurnl)cr ~vit,ll ionic st,rcrlgt,ll co~lld lla~rc inflncnccd t,llc dat,a analysis. Tllc 10-fold lo\vcr T ~ ~ ~ I I C of /I; calciilat,cd in the case of Cf(II1) rcsiiltcd from t,hc assignrncnt of a lo\vcr hytlmt,ion niimbcr to californi~lrrl ions

hlorcovcr, actirit,y corrcctiorls on i)chalf of t,hc rncan actirit,y cocfficicnts of (Ya.H)C104 only. appear t,o be t,oo crude t,aking into acco~lrlt t,hc large charlgcs in the ionic strength. In view of t,llc iinccrtaint,ics of t,llc ionic st,rcngt,h corrections, the rcport,ctl cqiii1il)riiim const,arlt,s arc not used in the prcscrlt rcvicv

[82BID] Bidoglio, G., Characterisation o f Am( l l l ) complexes wi th bicarbonate and carbonate ions a t groundwater concentration levels, Radiochem. Radioanal. Letters, 53 (1982) 45-60.

Bitloglio stiidictl t,llc cxt,ract,ion of arncrici~lrn fiorn aqllcons carl)onat,c-bicarborlat,c soliit,ions t,o an organic phase (a solution of 1;s-diphcnyl 1,3-propanctlionc; hrlbnr; in bcnzcnc) at I = 0.2 11 (YaC104) and 25°C. The cxpcrimcrlt,al dat,a wcrc irlt,crprctcd assnrning t,llc forrrlat,ion of t,hc corrlplcxcs .%mHCOi+. .4rn(HC0:3):; .%m(COt3)2 arltl .%I~(CO:~)~OH". Liindqvist [82LUN] and Nit,schc. St,arlclifc and Silva [89NIT/ST.4] s h o \ ~ ~ d usirlg two diRcrcnt part,ial prcssiircs of C02(g) t,hat t,hc bicarl)onat,c cornplcxcs rrliist bc rrliich ~vcakcr, Bidoglio. and t,llcrcforc Bidoglio's int,crprct,at,ion of his cxt,ract,ion data sccms t,o bc in error. Tllc author did not measure the distril)iit,ion cocficicrlt in t,llc abscncc of cnrbonat,c ligantl, and t,hcrcforc no rclial~lc st,abilit,y const,ants car1 be tlct,crrrlinctl fiorn the cxpcrimcrlt,al tlat,a.

Follo~ving t,llc rcint,crprctation matlc by Robo~lch [89ROB], the distril)iit,ion cocficicrlt,s arc plot,t,ctl in Figure -4.2 as a fiinctiorl of [C(I:-]. Tllc fact t,hat t,llc point,s at, different pH val~lcs fall on t,hc same ciirvc indicat,cs t,llc forrrlat,ion of only carl)onat,c corrlplcxcs in t,hc aqncoiis solutions, and from t,llc slope of the curve; it can bc dcdnccd that if the cxt,ract,ctl spccics is .%m(OH):3(ladl~rra):3~ the11 t,hc prctlomirlant spccics in the aqncoiis phase is .%m(COt3); at 8.3 5 pH 5 9 and 4 . 4 5 log1,[CO~-] 5 3 , ~vhich is in agrccmcnt ~vit,ll t,hc rcs~llt,s of Liindqvist [82LUN]. Robo~lch [89ROB] arltl hlcinrat,ll and Kirn [911IEI/KIhI].

No cxpcrimcrlt,al cvidcncc for t,llc formation of hydroxy-carbonate complcxcs is present,, arltl t,llcrcforc t,hc stability const,ant,s init,ially rcport,ctl by Bitloglio [82BID] arc not credited by t,his rcvic\v.

Tllc sccorltl hydrolysis constant (logl,'"12 = 1 4 . 7 ) was calciilat,ctl from t,llc pH dcpcndcncc of t,hc distril)iit,ion cocfficicnt,~, D. in the al)scncc of carbonate ligands. Tllcsc D valiics co~lld only be obtaincd by cxt,rapolat,ion from cxpcrimcrlt,al curves at variable cnrbonat,c conccnt,rations t,o [C(Ii-] = 0. Bccansc of the prctlomirlant,

Figure -4.2: Distril)iit,ion cocficicnts of .$rn(III), D; co1nl)inctl ~vit,ll pH-~~alncs in 0.2 11 NaCl(14 at 25°C [82BID]. Tllc continno~ls line is tlra\vn ass~lrning t,hc format,ion of only .4rn(CO:3), in the aqllcons phase.

26

3 pH - log,, D

25

corrlplcxat,ion ~vit,ll carl)onat,cs, idcntifi~at~ion of t,hc rnirlor .4rn(OH): spccics appears to bc tlifficnlt,. and tllcrcforc t,his constant is not consitlcrcd in t,llis rcric\v.

Fukasawa, T., Kawasuji, I . , Mitsugashira, T., Investigation on the complex formation o f some lanthanoids(lll) and actinoids(lll) wi th chloride and bromide, Bull. Chem. Soc. Japan, 55 (1982) 726-729.

Tllc a~lt,hors invcst,igatcd t,hc complcxation of varioiis t,rixi~,lcnt larlt,harlidcs arltl actinitlcs (Srn. Ell, Gd, Tb, .$c. .$m; Cm, Bk and Cf) nrit,h chloride arltl bromide ions by usirlg a solrcnt cxtractiorl tcchniqiic (his(2-ct,l~yll~cxfl)pllosplloric acid. ladrhp. in octane) at 20°C. The ionic st,rcrlgt,ll as kept at 3.0 11 using appropriat,~ rrlixtiircs of LiC104, LiCl and LiBr. The cxpcrimcrlt,~ Ivcrc carrictl oiit at constant acidit,y of 0.15 11 pcrchloric acid. Invcst,igation of the extraction mcchanisrn sho\~~ctl that the same spccics as cxt,ract,ctl int,o t,hc organic phase i-10th in the prcscncc arltl in the ahscncc in t,llc aqncoiis phase of chloride and i)romitlc ions. This allo\~~cd a simplified trcat,rrlcnt of t,llc cxpcrirncnt,al dat,a for the dctcrmination of cq~lilihri~lrn const,ant,s. Fiikasa\~ra et 111. rcport,ctl loglo ill = ( 0 . 2 6 * 0.02) and log,, 'l2 = ( 0 . 6 6 * 0.04) for t,llc chloro complcxcs of americium arltl log,, ill = ( 0 . 5 2 f 0.04) and log,, fi2 =

( 0 . 5 5 * 0.03) for t,hc hrorrlo corrlplcxcs of arncriciiirn. A$ rcanalysis of t,llc dat,a matlc by t,his rcric\v confirrrls t,hc proposed motlcl. .$l-

tllo~lgll sligllt,ly diffcrcrlt val~lcs for 9, arltl 'I2 arc obtained. t,hc ~ ~ a l n c s rcport,ctl by

Fiikasa\~~a et 111. arc preferred l)ccaiisc of t,hc tlifficnlt digit,alisat,ion of t,hc cxpcrimcn- tal dat,a from the original papcr. Ext,rapolat,ion t,o zero ionic st,rcrlgt,ll usirlg the specific ion intcract,ion cocficicrlt,~ of .%ppcndix B and ncglcct,irlg t,crnpcratiirc cffcct,s on AE val~lcs ~voiild give log,, p," = (0.46 * 0.18) and log,, 9," = (0.09 f 0.19) for the first cllloridc and hrorrlidc corrlplcxcs of .%m3+; rcspcct,ivcly. E~rcn considcrirlg a very large iinccrtaint,y, t,hc log,, p," ~ralnc of -4rnCl" +nro~lld bc out,sidc the range of val~lcs sclcct,ctl by t,his review [56\V.4R/IVEL, 62PEP/hI.%S, 64B.4N/PA%T, 71KHO/X.%R]. This rnay i)c diic t,o the effect of cllangcs in t,llc anionic cornposition at constant ionic st,rcngtll on t,llc ~ ~ a l n c s of AE. For t,his reasons t,llc valiics proposed by Fiikasa\~~a et d. have not hccn rctaincd for t,llc calcnlat,ion of rccornrrlcndcd cqnilibrinrn const,ant,s.

[82LUN] Lundqvist, R . , Hydrophilic complexes of the actinides: I . Carbonates of trivalent americium and europium, Acta Chem. Scand., A36 (1982) 741-750.

L~lntlqvist invcst,ignt,ctl .%rn(III) arltl Eii(II1) corrlplcxat,ion nrit,h carhonatc and hydroxide in 1 hI NaC104 soliit,ions at 25°C by stiidying t,hc distril)iit,ion of .%m(III) bct,\~~ccn the aqllcons phase and t,rihut,yl phosphate.

Hytlrolysis st,udics of 2'1.%m(III) n7crc condiictcd bot,l1 at tracer conccnt,rat,ion lcrcls and in t,hc prcscncc of non-mtlioact,ivc Ell carricr (5 X 10-Qto 2 X 10-A hI) in order to rcdiicc arrlcriciiim sorptiorl on glass snrfaccs. Tllc cxt,ract,ion ciirvcs tliffcrcd in the t,wo cases. -4ss1lrning a solubility const,arlt 'I%'s.o for E~( ( lH) :~(nrn) itlcnt,ical t,o that sclcct,ctl by this rcvic~v for .4rn(OH):3(a~n); precipitation rrlight lla~rc occnrrcd for the test soliit,ions ahovc pH = 8 t,o 8.5. Ho~vcvcr. this sho~lld not lla~rc inflncnccd the relative distril)iit,ion of arrlcriciiim bct,~vccn t,llc organic and the aqncoiis phases. as long as cqiii1il)riiim as achieved in t,hc two phases. L~lntlqvist obtaincd more rcprotl~lciblc rcsnlt,s ~vi th t,hc carrier-cont,aining soliitions. Xcvcrt,hclcss; t,hc aiit,llor calciilat,ctl loglo'~ll = -(7.5*0.3) fiorn t,hc pH valiic of 50% dccrcasc of .%rn cxtractiorl in t,hc al)scncc of Ell carricr.

This rcvic~v t,rics t,o re-cst,irnatc hytlrolysis corlstarlt,~ from the t,~vo sct,s of dat,a. Tllc cxpcrimcrlt,al point,s at t,raccr conccnt,rations of arncrici~lrn can only he fit,tcd with a sirlglc varial~lc motlcl "II up to pH = 9.7. a rcsiilt ~vhich is in disagrccrrlcnt, with a 111lrnl)cr of ot,llcr st,~ltlics. -4 sat,isfactory regression cquat,ion of t,hc sccond set of cxpcrimcrlt,al data was oht,aincd by iising a (v,. '"l,) rnodcl. In t,his case, the addition of v2 rrlcct,~ t,llc 1% i)iit not the 5% significance lcvcl of the F-t,cst t,o cnt,cr. It is not possible. ho~vcvcr. t,o sclcct alt,crnat,ivc hytlrolysis scllcmcs including polynnclcar species, as snggcst,cd by the rclat,ivcly high conccnt,ration of En carricr. Tllc calc~llatcd cqnilibrinrn const,arlt,s logl$Il = -7.3 arltl log1$12 = 1 5 . 0 , arc close to those sclcctcd by t,his rcric\v ~vhcn corrcct,ctl t,o t,llc corrlmorl rcfcrcncc st,at,c 1=0 with AE, = (0.04 f 0.05) and AE, = ( 0 . 0 4 f 0.07) kg . rnol-' (cf. .%ppcndix B).

i',, 0 This rcsnlt,s in log,,'"l," = ( 6 . 4 * 0.4) and log,, I , = ( 1 3 . 8 * 0.2). Tllc reported nnccrt,aintics reflect t,hc tlifficnlt,ics in selecting a rnodcl.

Tllc format,ion constants of -4rnCO: and .4rn(CO:3), wcrc oht,aincd from stiidics of the solrcnt cxtractiorl of .%rn(III) as a filrlct,ion of [C(l;-]. It as assnrncd for the analysis of t,llc distril)iit,ion data that the amcrici~lrrl carhonatc complcxcs ditl not cxt,ract int,o the organic phase. This was confirrrlcd by clcctromigrat,ion cxpcr-

irncnt,~. .%lthongh HCO, was the prcdorrlinnnt ion of the cnrbonat,c syst,cm under the cxpcrimcnt,nl conditions (pc:o, = 0.1 and 1.0 at,rn), tllcrc urns no critlcncc for .%I~(HCO:~)~~- ' " ) cornplcxcs. Tllc tlct,crrrlinctl stabilit,y constants; convcrt,ctl to rnolal ilnit,s, arc cxtrapolat,cd to zero ionic st,rcrlgt,ll using t,hc sclcctcd ion intcract,ion cocfficicrlt,~ (cf. .%ppcndix B; Section B.1.4). to give log,, 9," = (8.00 * 0.10) ant1 log,, p," = (12.57 * 0.21). Thcsc val~lcs arc iiscd in the sclcction procctl~lrc t1cscril)cd in Section 17.7.1.2.1.

[82NAI/CHA] Nair, G.M., Chander K . , Joshi, J.K. , Hydrolysis constants o f plutonium(lll) and americium(l l l ) , Radiochim. Acta, 30 (1982) 37-40.

Tllc nut,hors iiscd n pot,cnt,iorrlct,ric rrlct,llod t,o mcasiirc t,llc hydrolysis const,nnt,s of .%m(III); Pii(III), Sm(II1) and Eii(II1) in 1 I1 YaC1O4 at 25°C. Tllc nrrlcriciiim titration was carried oiit in t,hc pH range from 4 to 7.2 until t,hc precipitation of the hydroxide was ohscrrctl. The nut,hors cstirrlat,cd the val~lc of t,hc first hydrolysis

cxpcrirncnt,al forrrlat,ion ciirvc ( C 'OS. pH). Tllc nrcight of each point urns iteratively calciilnt,ctl tl~lrirlg the rcgrcssion proccdiirc rnt,hcr t,han cxt,crnally supplied as t,llc in- verse of t,hc varinncc of intlividnnl rncasiircmcnt,s. This let1 t,o an ~lntlcrcst,irnation of the nnccrt,nint,y assigned to t,hc "II ~ralnc. For different [.%m],,,,, conccnt,rations, the cxpcrirncnt,al point,s (lid not coincide int,o a single curre l)clo\v pH = 6.5. Tit,rnt,ctl conccnt,rnt,ions \!,ere so loxv t,llat scnt,tcring in the dnt,a rnay i)c ascribctl t,o systcrnat,ic errors in the mcasllrcrrlcnt of small changes of ligand nnrnhcr (a). .% rccalc~llation of the best fit,ting curve using a rrlodcl incliiding .%m(OH): as addit,ional species provides n statist,icnlly significant tlccrcnsc of t,hc rcsidiial snrn of sqllarcs. .%lthongh the hytlrolysis const,ant,s tlcrivcd from t,llcsc calc~llations arc of t,llc correct order of mng- nit,~ltlc. t,hc choice of s~lcll a motlcl is q~lcst,ionablc. hccaiisc the highest axrcmgc ligand nurnl)cr achic~~ctl is only 0.6; and t,llc addit,ion of ':l2 appears t,o he scnsit,ivc to only n fc\v point,s of the formnt,ion ciirvc. Ho~vcvcr. t,his tlocs not sccm t,o bc n s~lfficicrlt rcn- son t,o discard the t,~vo-vnrial~lc rnodcl. This rcvic\v calciilnt,cs log,$, = ( 7 . 2 * 0.2) and log1,:i2 = ( 1 5 . 0 * 0.3). Tllc assocint,ctl ~lnccrtaint,ics reflect t,hc diffic~llt,ics in sclcct,ing a rnodcl. Conversion t,o I = 0 using t,llc specific ion intcract,ion cocfficicrlt,~ rcport,cd in Scct,ions 17.3.2.4 ant1 B.1.4 yields log,,'"l," = ( 6 . 3 * 0.2) ant1 log,,'~l," = ( 1 3 . 8 * 0.3).

[82RAI/STR] Rai, D., Strickert, R.G., Solubilities o f actinide solids under oxic conditions, Report PNL- SA-10368, Pacific Northwest Laboratory, Richland, Washington, 1982, 18p.

This rcfcrcncc inclndcs t,llc snrrlc solubility rcs~llt,s for .%m(OH):j(cr) as rcfcrcncc [83R.%I/STR] l)iit \vithont giving any tlct,ails.

[a251 L] Silva, R.J., Thermodynamic properties o f chemical species in nuclear waste. Topical report: The solubilities o f crystalline neodymium and americium trihydroxides, LBL-15055, Lawrence Berkeley Laboratory, Berkeley, California, 1982, 57p.

Soliil)ilit,y rncnsnrcrncnt,~ of ":3.4~n(OH):3(cr) and N c ~ ( O H ) : ~ ( C ~ ) n7crc rnadc in 0.1 I1 NaCl(14 solutions at (25 * 1)"C n.it,hin t,llc pH range G to 10.

This is t,hc only soliil)ilit,y st,udy nrit,h nrrlcriciiim hydroxide iising an X-ray charac- tcrisctl cryst,nllinc solitl. Tllc solitl phnsc was prcpnrcd by rigoroilsly corlt,rollcd high- tcrnpcratiirc transformation of .4rn(OH):3(n~n). Optical vic~ving by Scanning Elcct,rorl hlicroscopy of Ntl(OH):3(cr) samples at t,hc crltl of t,hc soliil)ilit,y cxpcrirncnt,~ sllo~vcd no cllangcs in t,llc cryst,als. By analogy. t,his was taken as a proof that no secondary solid phases n7crc forrrlcd tlllrirlg the cq~lilihmt,ion pcriotl of ":3.4~n(OH):3(cr) (contact, tirrlcs of 17. 28 and 48 days). Tllc o.-radint,ion tlamagc of t,hc crystal st,rnct,urc ohscrrctl by Hairc et al. [77HA41/LLO] for "1.4rn(OH):3(cr) can rcasonnhly bc considcrcd negligible in Silva's cxpcrirncnt,~, i)ccaiisc of t,llc rrlllcll lower specific nct,ivity of ":3.4rn (6.8 IIBq/rng) corrlparcd nrit,h 2'1.4m (120 hlBq/rng).

brat,ctl for 48 days. Each rncnsnrcd amcricinrn conccntrat,ion as then given cqiial ~vcight nrltl corlsitlcrcd as an indiritl~lal data point,, inst,cad of iising average val~lcs. This improperly incrcnsctl the dcgrccs of frcctlom from (18 - p) t,o (30 - p); ~vhcrc the integer rcfcrs t,o t,hc 111lrnl)cr of ol)scrvations nrld p is the 111lrnl)cr of nnkno\~rn rcgrcssion cocfficicnt,~ in t,hc rnodcl. Silvn iiscd n least,-sqiiarcs procctlllrc keeping logl,;"ll = ( 7 . 7 f 0.3) const,ant and solving sirniilt,nnconsly for 'Rli,;o, '"IZ, 7ti nrltl I . Tllc log1$ll vnliic urns t,nkcn from a prcviolls work ~vhcrc the first hydrolysis const,ant of Cm(II1) was rncnsnrcd by pot,cnt,iomct,ry [83EDE/BUC]. Tllcrc is. llo\~r- cvcr. n t,yping error in Tal)lc 9 of Ref. [82SIL]. The list,cd vnliic of logl,:il rcfcrs t,o an ionic st,rcngt,h of 0.1 I1 KC1. Silva rcport,ctl t,hcrrnodynnrnic const,nrlt,s aft,cr ionic st,rcngtll corrcct,ions ~vi th t,hc Davics cqllat,ion. Tllc same cq~lat,ion was llsctl in t,llis review t,o rccnlcnlat,c cqnilibrinrn const,ant,s at 0.1 I1 XnC104, obtaining loglo'Rli,;o =

(16.6Hl.4). log1,'i2 = -(16.7*0.7). log,,:i:+ = -(25.0*0.3); and log1,',i4 -34.9. \cry sirrlilar ~ ~ a l n c s of hydrolysis constants for Nd(II1) nrcrc derived from t,hc Nd(OH):3(cr) soliil)ilit,y rncnsnrcrncnt,~.

This rcvic~v pcrforrrls a rcintcrprct,at,ion of t,llc amcricillrrl soliil)ilit,y dnt,n of Silva using only 18 cxpcrirncntal points. Tllc lack of mcasiircmcrlt,s in the pH rnrlgc fiorn 8 to 8.8. and the scarcc data point,s in t,hc platen11 region make t,hcsc data iins~lit,al)lc for an int,crprctation llsirlg t,llc fill1 rnodcl. The rcsiilts of t,hc least,-squares rcfirlcmcrlt,~ irltlicat,c that the t,~~~o-xi~,rial>lc motlcl incliiding 'I%'s.o and v2 yields the greatest init,ial dccrcnsc of t,hc residual mean sqnnrc (RhIS). The st,cp\visc ntltlit,ions of :ll and ;:I:3 filrthcr dccrcasc t,llc RhIS, i)iit t,hc achic~~ctl rcdnct,ion is not siifficicnt t,o jiist,ify the incliision of 7:3 in t,hc rcgrcssion cqiiation. Figure -4.3 sho\~rs t,hnt Silvn's dnt,n compare nrcll ~vit,ll t,hosc oht,nincd by St,ntllcr and Kirn [88ST.4/KIII] \17ho ol)scrvcd the solubility curve t,o lcvcl do~vn at higher pH vnliics, cf. Figure -4.9. The st,nt,istical F-rat,io t,cst,s indicat,c t,llat adding ':ll t,o t,llc rrlodcl is sigrlificnrlt at 5%' but not at 1%. Examirlat,ion of t,llc rcsidiials sho~vs t,llat t,hc rrlodcl does not pcrforrrl snt,isfnct,orily l>clo\~r pH = 8 if :ll is iiscd. instcntl, as a fixed pararnct,cr. .4 st,nt,istically significant,

Figure -4.3: Soliil)ilit,y rncasiircmcnt,s of .Irn(III) hydroxide in 0.1 hI NaC1(14 fiorn Silva [82SIL] (A) ancl fiorn Ref. [88STAI/KIhI] ( U ) . Tllc continno~ls curre represents the valiics calc~llatcd ~vit,ll t,hc set of cqiiili1)riiim constants re-cstirnat,cd 1)y t,his rcric\v from cxpcrimcrlt,al dat,a in Ref. [82SIL]; arltl the dot,tcd curves sho~v t,hc associat,ctl nnccrt,aintics.

dcscript,ion of t,llc cxpcrirncntal dat,a is t,llcn provided 1)y

l o g l o s = 15.9 * 0.6 loglo~~ll = -6.9 * 0.6 loglo'~12 = -15.1 * 0.6

Con~~crsion t,o t,llc rnolalit,y scale and cxtrapolat,ion t,o I = 0 ~vit,ll t,llc sclcctcd specific ion intcract,ion cocficicnts (cf. Scct,ion B.1.4) gives

l o g l o o = 15.2 * 0.6 loglo;~l," = -6.5 * 0.6

i R l 0 p loglo 1 - -14.4 * 0.6

[83BOU/GUI] Bourges, J.Y., Guillaume, B., Koehly, G., Hobart, D.E., Peterson, J.R. , Coexistence of americium in four oxidation states in sodium carbonate - sodium bicarbonate medium, Inorg. Chem., 22 (1983) 1179-1184.

Bourgcs et 111. corrlhincd sl)cct,rophot,ornctry and cyclic voltarnrnctry to st,~ltly the spcciat,ion of arrlcriciiim in carl>o1~at,c/l>icar1)onat~c rnctlia at 25°C. Tllcsc rcs~llt,s clearly dcmorlstrat,c the cocxist,cncc of t,llc four oxidat,ion st,at,cs of amcricinrn (111. I\?,I7;\'I) in corlccntrat,cd carl)onat,c mctlia. Tllc aiit,llors rncasnrcd t,llc apparent normal potcnt,ial of the .4m(\?I)/.4rn(I7) and .4m(I\')/.4rn(III) co~lplcs in [HCOT] = 1.15 11,

[CCIi-] = 0.85 11 soliit,ions. ol)t,aining: E0(\?I/\') = 0.971 1' 71s. SHE and Eo(I\'/III) =

0.925 1' ?IS. SHE rcspcctircly. Bonrgcs et (11. also invcst,igatcd t,llc infliicncc of the carl)onat,c conccnt,ration on tllcsc forrrlal potcntials in aqncoiis soliit,ions cont,ainirlg rrlixtiircs of NaHC0:j and Xn2C(I:3 ([HCOT] + [CO:-] = 2 M). Tllc apparent norrrlal pot,cnt,ial of t,hc -4rn(\'I)/.11n(\') conplc urns found to i)c pmct,ically indcpcrltlcnt of [CCIi-]: ( I / ) = (0.975 f 0.01) 1: as. SHE. Tllc ~ralnc of Eo(I\'/III). irlstcatl dccrcasctl rnonot,onically ~vit,ll incrcasirlg [CO:-]. Corrcct,ions for t,llc liquid jiinctiorl pot,cnt,ial wcrc apparently not pcrforrrlcd by Bonrgcs et d., arltl cst,imat,ions ~vit,ll the Hcntlcrson's cq~lat,ion [73B.T. p1i.36 441 sho\v t,llat an additiorlal ~lnccrt,ainty of *0.015 1' sho~lld he addctl t,o t,hcir rncasiircmcnt,s.

Scvcral aiit,llors [83FER/GRE, 86GRE/ROB, 89ROB] have rcintcrprct,cd tllcsc cx-

Tllcsc rcintcrl)rct,at,ions indicat,c t,hat . 1 1 n ( ~ ( I : j ) ~ , . 4 r n 0 ~ ( ~ 0 : j ) ~ and .4rn02(~(I:j):f arc t,llc 1imit)irlg complcxcs for the I\",\' and 1'1 oxidat,ion states (as cxpcct,cd by analogy ~vi th U(I\?); NI)(\') arltl U(\?I)-P11(\'1). rcspcct,ivcly). F~lrthcrmorc; the measure- rrlcnts of Bourgcs et al. sho~v t,llat . 4 r n ( ~ ( I : ~ ) ~ ~ is the Arn(II1) lirrliting cornplcx, ~vhich is in agrccmcnt ~vi th the rcint,crprct,ctl ohscrvat,ions of Shiloh. Givon and 1Iarc1ls (cf. the tlisciission of Ref. [69SHI/GI\'] in t,his -4ppcntlix).

Follo~ving t,llc rcirlt,crprct,at,iorls in Rcfs. [83FER/GRE. 89ROB, 8GGRE/ROB]; t,llis review assiimcs t,llat t,hc apparent normal pot,cnt,ials rncasnrcd by Bourgcs e t (11. [83BOU/GUI]. rcfcr t,o rcact,ions (.1.4) and (-4.5). From t,hc formal rcdox potential of the .4rn(\'I)/.11n(\') conplc it is possil)lc t,o ol)t,ain loglo li(.4.4, [CO:-]y,oy, = 2 11) =

(16.48 *0.42). The cxt,rapolation of t,his cq~lilihri~lrn const,ant from [NaHCO:j] = 2 11 to standard corltlit,ions ~vi th the specific ion int,craction cqiiations of -4ppcntlix B is quit,c ~lrlccrt,ain diic t,o t,hc nnccrt,aint,y in the valiics of t,llc ion int,cractiorl cocficicrlt,~ for t,llc amcricinrn cornplcxcs. Nc~~crtllclcss, ass~lrning t,llat AE is similar to t,hat of the sarnc rcact,ion involving iiraninrn corrlplcxcs in NaC104 mctliiim but \vitll incrcascd nnccrt,ainty, AE = (-0.61 f 0.3) kg.rno1-' [92GRE/FUG, p.3221. and usirlg Az2 = 9; ~ v c ol)t,ain E" (-4.4) = (0.775 * 0.038) 1' 'OS. SHE. i .e . ; log,, h'" (-4.4) = (13.1 * 0.6).

Tllc forrrlal rctlox pot,cnt,ial of t,hc .4rn(I\?)/.11n(III) coiiplc, ~vhich tlccrcascs ~vit,ll the rat,io [Xa2CO:3]/[N:~,HCO:j]. cf. [83BOU/GUI, Fignrc 91. can l)c intcrprct,cd according to rcact,ion (.1.5):

RTln(10) E"' = E0(.1.5) +

P-

~vhcrc E"' st,arltls for t,llc formal rctlox pot,crlt,ial of the .4rn(I\?)/.11n(III) co~lplc. Tllc specific ion int,cractiorl cqnat,ions in .1ppcndix B arc used to calcnlat,c the act,ivit,y cocfficicnts ~vi th E(,,( -,,, +)) zz E(,;( ); -,,, +)) = ( 0 . 2 7 f 0.15) kg . rnol-'; cf. Tal~lc B.4, ol)t,aining E"(.4.5) = (1.19 f 0.05) 1: 71s. SHE, i.e.. log1,Ko(.1.5) =

(20.1 * 0.9).

[83CAC/CHO] Caceci, M.S., Choppin, G.R., The determination o f the first hydrolysis constant o f Eu(l l l ) and Am(l l l ) , Radiochim. Acta, 33 (1983) 101-104.

This is a solrcnt cxt,ract,ion st,udy of .krn(III) ant1 En(II1) hytlrolysis in 0.7 11 NaC1 at 21°C usirlg n cornpctitirc mct,hotl of corrlplcx formnt,ion nrit,h oxalat,c ions. Expcrimcrlt,~ wcrc pcrforrrlcd only at pH zz 6 and pH zz 8. Stability const,nrlt,s of

(:3-an) .krn(C2O4),,, ( r r = 1 nrltl 2) \ ~ ~ c r c first dctcrmirlcd at pH = 5.9 ~vhcrc hytlrolysis is negligible. Tllc set of tlat,a at pH = 8.05 urns t,hcrl modcllcd ass~lrning the cxist,cncc of .krn(OH)" only. .k calc~llation of the relative nrrlourlt,~ of hytlrolysis spccics sho\~.s. ho\vcvcr, t,hnt t,hc forrrlat,ion of .krn(OH): cnrlrlot hc ncglcct,ctl in t,hc dnt,n annly- sis. This calc~llation was rnadc using t,llc vnliic for logl,'7/," sclcct,ctl in t,hc present review and t,llc specific ion intcract,ion cq~lat,ions in -4ppcntlix B assnrning t,llat AE for t,hc hydrolysis rcnct,ion ~voiild bc t,llc sarnc in cllloritlc as in pcrclllornt,c rncdia

= 0 . 0 4 kg . mol-l). It is not possil)lc fkorn t,llcsc data to obt,nin a hydrolysis const,ant for .4rn(OH):. This \~ronltl have rcqnirctl ntlditiorlal cxpcrirrlcnts at vnrioiis pH val~lcs. Tllc val~lc has t,o bc dcrirctl from t,hc best fit pararnct,crs of t,hc cxpcrimcrlt,nl curre at pH = 8.05. Thcsc arc ol)t,ainctl as a combinat,ion of cqnilibrinrn const,ant,s for all corrlpct,it,ivc rcnct,ions in the systcrn (sccontl hydrolysis, cornplcx forrnation ~vit,ll cllloritlc and oxalat,c). Taking irlt,o account t,hc lirrlitcd 111lrnl)cr of rncnsnrcrncnt,~, t,hc single pH ~ralnc st,udicd. and the various corrcctiorls that have t,o bc mntlc. t,hc rcport,ctl val~lc for is rlot ncccpt,cd by t,his revie\\,.

[83EDE/BUC] Edelstein, N., Bucher, J., Silva, R., Nitsche, H., Thermodynamic properties o f chemical species in nuclear waste, Report ONWI-399, LBL-14325, Lawrence Berkley Laboratory, Berkley, California, 1983, 115p.

111lrnl)cr of t,cchniq~lcs wcrc ~lsctl by t,llc nut,hors t,o invcst,ignt,c act,inidc cornplcx forrnation in rlciit,rnl and l~asic sol~lt,ions.

Tllc only qnnnt,it,at,ivc informnt,ion of irlt,crcst t,o t,llis rcric\v refers t,o t,hc first hydrolysis const,ant,s of Crn(II1) and Nd(II1). Tllcsc n7crc dct,crrrlincd by pot,cnt,iorrlct,ric rncnsnrcrncnt,~ of [H+] in 0.1 I1 KC1 soliit,ions. Dnt,n analysis was lirrlit,cd t,o t,llc por- tion of the titrat,ion CII~T'C I)cforc prccipit,at,ion of mct,al hytlroxidcs occurred. Tllc forrnation of polymeric hydrolysis spccics urns cxnrnirlcd and tliscardcd diiring the rcgrcssion analysis. .klt,hoiigh t,llis \~ronltl have rcq~iircd rrlorc syst,cmnt,ic pH titra- tions oxrcr n range of rnctal conccnt,mt,ions; t,hc sirlglc vnrial~lc motlcl proposctl by the n~lt,llors provides a l o g l a l ~ralnc for Crrl and Ntl of the correct order of rnagnit,~ltlc ( ? . i f 0.3).

Tllc nut,hors rncasiircd also t,hc solubility in 0.1 LI NaC104 of ":3.4rn(OH):3(s) at, 25°C. Tllc hytlroxidc as clairncd t,o be arnorphoiis. but no characterisation of the solid phase urns mntlc. It is difficult t,o rnakc an intcrprct,at,ion of t,hc few cxpcrirncntal tlat,a reported [83EDE/BUC, -4ppcntlix D]. H o \ ~ ~ c ~ ~ c r , t,hc ~ralnc proposed for logl,'Rli,;o = (li.5*0.3) at 0.1 I1 ionic st,rcrlgt,ll is in agrccrncnt \\,it11 t,llat foiind by Rni et al. [83R.%I/STR], for t,hc soliil)ilit,y prodiict of \\,ell-charactcriscdrctcrisc .k~n(OH):~(am).

[83RAI/STR] Rai, D . , Strickert, R.G., Moore, D.A., Ryan, J.L., Am( l l l ) hydrolysis constants and solubility o f Am( l l l ) hydroxide, Radiochim. Acta, 33 (1983) 201-206.

Tllc nut,hors rncasiircd .4m(III) conccnt,rnt,ions in t,hc prcscncc of arncrici~lrn(III) hytlroxidc at (22 f %)"C. Tllc cxpcrirrlcnts n7crc conduct,cd using bot,h 2'1.4m in 1.5 X

10-" h1 CnClz soliit,ions. nrltl 2'".4m in pH-acljjnst,cd dcionizcd nrnt,cr. Bccn~lsc of radiolysis cffcct,s in 2'1.4m sol~lt,ions; t,llc thcrmotlynarnic hydrolysis const,nrlt,s wcrc cstirnatcd from t,hc i)cst fit,t,irlg curve of the 2'".4m soliil)ilit,y data. The follo~ving T ~ ~ ~ I I C S ere ol)t,ainctl by Rni et al.: log,^'^, = (17.5 +0.3); log1$," = -(17.1* 0.5); l o g l n R 5 -27. The authors proposctl an iippcr limit of log,,"i/," 5 -8.2, alt,ho~lgh no st,nt,istical irnprovcrncnt was found by ntltling .4rnOH2+ in t,hc rnodcl.

No hackgro~lrltl salt urns ntltlcd to kccp the nct,ivity cocfficicnts constant. Ho\vcvcr, the st,~ltly was rrladc at such low ionic st,rcngt,h t,hat iinccrtaint,ics in t,hc act,ivit,y cocficicrlt corrcct,ions t,o I = 0, iterated during t,llc calc~llations by means of the Dxics cquat,ion, slloiild have only affected tlat,a at higher arncrici~lrn solnbilitics.

This is one of t,llc fc\v sol~lhilit,y stiidics of arncriciiim t,rihydroxitlc reporting the charact,crisnt,ion of t,hc solid phase. X-ray cliffi-nc;t,io~l analysis of t,llc prccipit,nt,c at, pH = 7.5 and 9.6 indicat,c the prcscncc of .4m(OH):3(arn), ~vhilc a rrlixctl phase of n higher dcgrcc of cryst,allinity was tlct,cctcd above pH = 9.6. This fact urns not, ntldrcssctl in t,llc calc~llation of t,hc cq~lilihri~lrn const,ant,s. Tllc iisc of t,ct,mpropyl nrn- rrloni~lrrl hytlroxidc as hasic t,it,rant may lla~rc infliicnccd t,llc siirfacc properties of the prccipit,nt,c. Rcanalysis of t,llc cxpcrirncrlt,nl dnt,n hclo\v pH = 9.6 does not provide n st,atist,icnl support for sclcct,ing a particular hydrolysis scheme. Tllc solubility ciirvc rccalciilnt,ctl iising t,hc hydrolysis constants (cf. Tahlc 111.2) and the solubility protl- nct for t,hc crystalline hydroxitlc. loglo "K:,, = (15.2 * 0.6) sclcctcd by t,his rcric\v, is in fair agrccmcnt (n.it,hin f 0.5 log,,-unit,s) ~vit,ll t,hc cxpcrirncnt,al tlat,a l)ctn~ccn pH zz 7.5 and pH = 13. Ho~vcvcr. this is in cont,radict,ion ~vit,ll the X-my difinc- tion mcasllrcrrlcnts sho~ving t,hc prcscncc of n cryst,nllinc phnsc only above pH = 9.6. Kccping t,hc hydrolysis const,nrlt,s fixed t,o t,hc vnliics sclcct,ctl by t,his rcric\v and ntl- jnsting the soliil)ilit,y protl~lct t,o the cxpcrirncnt,al poirlt,~ l)clo\v pH = 7.5, a ~ralnc of log,, 'h':;, = (17.0 * 0.6) has bccn obtained. This is very close t,o the ~ralnc reported by Rai et al. Together nrit,h our st,nt,istical analysis; this might indicate t,llat the points at pH 5 7.5 lla~rc t,hc highest ~vcight in t,hc rcgrcssion procctl~lrc. Figure -4.4 sho\\~s t,hc sol~lhilit,y data for chnrnct,criscd .4m(OH):3(n~n) ol)t,ainctl by Rai et d., nrltl by Nitscllc and Edclstcirl [85XIT/EDE2] in 0.1 hl NnC10'. Tllc Figiirc also sllo\~rs calciilnt,ctl solnbilitics at the ionic st,rcrlgt,lls used by Rni et al.. dctcrmirlcd on the basis of t,llc tlissolvcd arncrici~lrn conccnt,mt,ions; the nrnonnt of acid or i)asc iiscd to kccp soliit,ions clcct,rically ncut,ral; and t,llc hytlrolysis const,nrlt,s sclcct,cd hcrc (cf. Tahlc 111.2).

[a351 L] Silva, R.J., The solubilities o f crystalline neodymium and americium trihydroxide, in: Materials and Molecular Research Division, Annual Report 1982, LBL-15150, Lawrence Berkeley Laboratory, Berkeley, California, 1983, lip 251-253.

This is n siimrnarv of Ref. [82SIL].

Figure .%.4: Sol~lhilit,y rncasnrcrncnt,~ of amorphoiis .%m(III) hydroxitlc fiorn [83R.%I/STR] in pH-acl,j~lstcd dcionizcd wat,cr (U); and fiorn [85NIT/EDE2] in 0.1 I1 NaCl(14 (a). Tllc cont,iniions ciirvcs represents t,llc val~lcs calciilat,ctl \\,it11 t,llc sclcct,ctl set of hytlrolysis const,arlt,s (cf. Tal)lc 111.2) at lo\v ionic st,rcngt,hs. The upper corlt,irl~loiis CII~T'C C O ~ ~ C S ~ O I ~ ~ S to logl~h'~,n = (17.0 * 0.6); and t,hc lo\vcr one t,o log,,"^, = (15.2 * 0.6). The dott,cd cnrvcs show t,llc associated iinccrtaint,ics.

[84BER/KIM] Bernkopf, M.F., K im, J.I., Hydrolysereaktionen und Karbonatkomplexierung von drei- wertigem Americium i m naturlichen aquatischen System, Report RCM-02884, Inst. fur Radiochemie, Technische Universitat Munchen, 1984, 200p., in German.

Tllc aiit,llors mcas~lrctl the solubility of "I'.%m(OH):j(s). 2'1.%m02(s) arltl EII(OH):~(S) in 0.1 h1 XaC104 soliit,ions at roorrl tcrnpcratiirc (25°C '!). Rcsnlt,s arc also given on t,llc sol~lhilit,y of 2'1.%mCO:jOH(s) and EI~CO:~OH(S) in XaHCOt3 arltl Na2CO:j sol~lt,ions.

Sirrlilar cxpcrimcrlt,~ rcport,cd by t,llc same a~lt,hors in a cornparlion puhlicat,ion [84KIhI/BER] rcsnlt,ctl in diRcrcnt solubility 71s. pH cnrvcs (cf. Figure .%.5). .%pparcnt,ly the sarrlc solid phases wcrc ~lsctl in t,hc t,wo stiidics. Tllc cxpcrirncntal rrlat,rix in Tahlc .%.l sho\~.s. llo\vcvcr, t,hat ageing condit,ions tliffcrctl not only from orlc cxpcrirrlcnt t,o t,llc ot,llcr, i~ i i t cvcn n.it,hin a sirlglc tlat,a set,. Scvcral invcst,igators lla~rc sho\~rn that changcs of solitl phase in aqllcons snspcnsions of .$rn(III) hydroxitlcs tl~lc to agc- irlg corltlit,ions i)ccomc cvidcrlt in hours and cont,im~c for nrccks (cf. Scct,ion 17.3). Figure -4.5 indicat,cs a fairly good agrccmcnt i)ctnrccn sol~lhilit,y mcasllrcrrlcnts of .%~n((lH):~(s) iising t,hc bat,ch-t,ypc procedure. hI:~,,jor tlisagrccrrlcnt hct,\~~ccn t,llc solii-

Tahlc .$.l: Expcrirncntal matrix t1cscril)ing t,hc diffcrcnt procctl~lrcs iiscd t,o rncnsnrc "lAk~n(III) solubility in 0.1 hI XnC104 by Kirn et o,l. [84BER/KIhI. 84KIII/BER].

Solid Proccdiirc .kct,ivity Corlt,nct Rcfcrcrlcc (hIBq.ml-') t,imc

.k~n(OH):~(s) bnt,ch; pH < 8 20 (a) [84BER/KIhI] titrat,ion, pH > 8 5.9 (1))

.krnOz (S) bnt,ch, pH < 8 35 (c,) titrat,ion, pH > 8 1 (1))

. ~ I ~ ( O H ) : ~ (S) bnt,ch 23.7 (d) [84KIII/BER]

.krnOz (S) bnt,ch 63 (pH < 4) (d) 1 2 . 6 ( p H > 4 ) (d)

(a) several days

(1) ) orle titratior~ point per drxy (c) trro rrlorltl~s

(11) frorr~ orle meek tn sever>~l I ~ I O I I ~ ~ I S

bilit,ics rcport,ctl in [84BER/KIII] nrltl in [84KIhI/BER] cxist,s allore pH zz 8 ~vllcrc the cxpcrirncrlt,nl procctl~lrc chnrlgcd from "hat,ch" t,o "t,it,ration". This indicat,cs t,llat, in sorrlc of t,hc cxpcrirncnt,~ cit,hcr cqnilibrinrn is not reached or t,hcrc is n corlvcrsion of t,hc solid t,o a tliffcrcnt phase.

This review re-cstirnat,cs t,hc hydrolysis const,nrlt,s from t,llc sol~lhilit,y data bclo~v pH = 8 of t,hc .4rn(OH):3(s) cxpcrirncnt,~ in Ref. [84BER/KIhI]. The rcport,cd vnl- ncs of log,,[OH-] arc corrected for liquid jiinctiorl effects by cxpcrirncntal measure- rrlcnts usirlg t,hc sarnc sct,up as Bcrnkopf and Kirn [84BER/KIhI]. Tllc rclat,ionsllip bct,\~~ccn corrcct,ctl and cxpcrirncnt,al val~lcs for t,hc hytlroxidc ion conccnt,ration be- comes: log,,[OH-] ,,,,. = (log,, [OH-] ,,,. - 0.07). \:al~lcs of log,,[H+] arc cnlcnlat,cd from t,llc corrcct,cd hytlroxidc ion conccnt,rnt,ions nrld the ionic protl~lct of ~ ~ ~ a t c r in 0.1 h1 NaC1(14, ~vhich is rccnlcnlat,cd (using t,hc specific ion irlt,crnct,ion cqiiations in -4ppcntlix B) t,o log,, I%'t,: = -13.798. Tllc least, sqiiarcs adjiist,rrlcnt of t,llc hydrolysis const,nrlt,s from t,llc solubility data is fiilly irlscrlsit,ivc t,o the ~ralnc of ':ll ~vhich cnrlrlot he dcrirctl from t,his set of cxpcrimcnt,al data. This rcric\v firltls log,,;Rli,;o = (13.7 * 0.2) nrltl logl;',lz = ( 1 4 . 7 f 0.2).

Tllc rccalc~llatcd sol~lhilit,y const,nrlt differs considcmhly from t,llosc fo~lrltl for ~vcll-chnmct,criscd .k~n(OH):~(am) and .km(OH):3(cr) [83R.$I/STR; 82SILl. No char- nctcrisation of t,llc solitl urns reported by Bcrnkopf ant1 Kirn. Hcncc, it is not clcar if the diffcrcrlcc is at,t,ribntablc t,o part,iclc size cficts or to n hydroxide phase of diffcrcrlt, soliil)ilit,y. For t,llis reason; only log,,:i2 is incl~ltlcd in t,llc set of sclcct,ctl cqnilibrinrn const,ant,s. Tllc st,andard ~ralnc is calc~llatcd nrit,h t,llc specific ion intcract,ion cqiiations of .kppcndix B t,o bc log,,;"l," = ( 1 4 . 0 * 0.2).

F 4 . : Cornparison of soliil)ilit,y dat,a of .4m(III) hydroxide in 0.1 I1 XaC104 rcport,ctl by Bcrnkopf and Kirn [84BER/KIII] ( A at pH < 8, and X at pH 2 8) arltl by Kirn e t 111. [84KIhI/BER] (0 at pH < 8; and ?i at pH 2 8). Tllc dat,a points in Ref. [84KIhI/BER] above pH = 10 arc not incliidcd hcca~isc t,llcy carlrlot bc dist,ingnishctl nncqiiirocally fiorn t,hosc referring t,o the dissol~lt,iorl cxpcrirncnt of .4mOa(s). Only the dat,a point,s at pH < 8 ( A [84BER/KIhI] and 0 [84KIII/BER]) lla~rc hccn consitlcrcd in the least sqllarcs re-cvaliiations. Tllc cont,in~ions ciirvc represents t,llc val~lcs calciilat,ctl nrit,h the cqnilibrinrn const,arlt,s log,o'Rli,;o ant1 log,$2 re-cstirnat,cd by t,llis review fiorn dat,a in Ref. [84BER/KIlI], and the dot,t,ctl ciirvcs sho\v t,hc associat,ctl nnccrt,aintics.

Tllc rcart,ion

was proposed t,o control .4m(III) solubility in the prcscncc of .4rr102(s). These solnbilit,y dat,a arc in complct,c disagrccmcnt nrit,h similar rncasiircmcnt,s rcport,ctl by Kirn et d. [84KIhI/BER]. This rcric\v tlocs not corlsidcr the post,~llatcd dissol~lt,ion rrlccllanism of .4mOa(s) as proven. Tllc cqiii1il)riiim const,ant,s obtaincd from t,llcsc sets of dat,a arc t,hcrcforc not acccpt,cd in the present review.

Bcrnkopf and Kirn also rcport,cd a solubility product const,arlt for t,llc rrlixctl hydroxy-carl)onat,c solid .41nC0:~OH(s) [84BER/KIhI]. Tllc ~ralnc urns oht,aincd fiorn the rcsiilts of soliil)ilit,y rncasiircmcnt,s condnct,ctl nndcr ovcrsat,uratcd conditiorls ~vit,ll respect t,o .4rn(III) in dilut,c hi carbon at,^ rrlcdia (at I = 0.1 t,o 0.3 11 XaC104). start,. irlg ~vit,ll a solid .4rn(OH):3(s). Tllc carl)onat,c conccnt,ration urns varied by changing t,llc pH of the sol~lt,ion nndcr const,ant C02(g) partial pressure (pc:o, = 10-"."

Figure .k.6: Sol~lhilit,y dnt,n of amcricinrn(II1) rcport,ctl by Bcrnkopf and Kirn [84BER/KIII] in t,llc nhscrlcc of C02(g) in 0.1 hl NaCl(14 (A at pH < 8. ancl X

at pH 2 8) and at pc:(), = lO-".%t,rrl (e) in 0.1 t,o 0.3 11 NaC104.

5

nt,rn). Tllc solid phase urns not cllaractcriscd i)iit was nssiimctl to he .k1nC0:~OH(s). Bcrnkopf nrltl Kim int,crprct,ctl t,hcir sol~lhilit,y rcsiilt,~ ass~lrning the prcscncc of hy-

(:3-$), droxidc (.4rn(OH), ; i = 1. 2.3); carl)onnt,c ( .4rn(~(l :~)?-~'") ; n = 1, 2, 3) nrltl rrlixctl llytlroxy-carl~onnt~c (.km(OH)i(CO:j)~~-"2'"). ; ,' r = 1.2 and r , = l ,%) cornplcxcs. Ho~vcvcr. it is not possiblc to dist,ingnish hct,\~~ccn Ak~nCO:3(OH), and . k ~ n ( C ( l : ~ ) ~ from sol~lhilit,y tlat,a ol)t,ainctl at a constant pc:(),. Tllc fact that .km(OH):j(s) nrltl .k~nCO:~(lH(s) have cxnct,ly the same solubility in the pH range 6 t,o 8 (cf. Figure -4.6 nrld Figiirc 6.23 in [84BER/KI11]). mnkcs it tlifficnlt to disting~lisll l)ctn~ccn t,hc t,wo solids. It is possil)lc t,hnt the t,ransformnt,ion of t,llc initial solitl; .k~n(OH):~(s) i ~'.4rnC0:jOH(s)", may have occiirrctl slo117ly during t,llc cxpcrirncnt,~. Thcsc sol~lhilit,y dnt,n, ~vhich rnay i)c i)ascd on n ,'varying" solid. arc qncstio11al)lc; t,llc proposed cq~iilil)riiim const,nrlt,s arc tllcrcforc not t,nkcn into acco~lnt in the present review.

[84KIM/BER] K im, J.I., Bernkopf, M , , Lierse, Ch., Koppold, F., Hydrolysis reactions o f Am(l l l ) and Pu(VI) ions in near neutral solutions, in: Geochemical Behaviour o f Disposed Radioactive Waste (Barney, G.S., Navratil, J .D. , Schulz, W.W. , eds.) , ACS Symp. Ser., No. 246, Washington, D.C.: American Chemical Society, 1984, pp.115-134.

Kim et al. rncnsnrcd t,llc soliil)ilit,y of .4rn(III) nrltl Pn(\T) in 0.1 hI NaC1(l4 soliitions as n fiinctiorl of pH, cf. Table .k.1. Two sets of cxpcrimcrlt,~ \17crc pcrformctl using diffcrcrlt .krn(III) solitl phases: 2'1.km(OH):j.:r;H20(s) and "1.4rn02(s). The tlis-

soliit,ion process of .4rn02(s) coiild not bc idcntifictl. It was post,ulat,cd t,o involvc a rrlccllanism t,nrning t,llc soliit,ion phase int,o a rrlorc rctl~lcing rncdinrn \vith increasing pH. Since no rncaningfiil soliil)ilit,y constant conltl i)c ol)t,ainctl, t,his set of cxpcrirncntal tlat,a is not consitlcrcd in the prcscnt analysis. Tllc forrrlat,ion const,ant,s of .41n((l~)f-") sl)ccics and the soliil)ilit,y product of A~n(( lH):~(s) rcportcd by Kim et d. arc log,, 'll = (7.44 f 0.83); log,, 'l2 = (13.9% * 0.63); log,, it3 = (18.47 f 0.52); log,, li,;, = (%7.16*0.47). Tllcrc is prohal~ly a typing error in Tahlc I of t,llc original paper hcca~lsc the calcnlat,cd ~ralnc of log,,(li,;o X = 8 . 6 9 tlocs not correspond to t,hc ordinat,c val~lc of t,hc plat,caii region of the soliibility curre for t,hc .$rn(OH):3(s) cxpcrirncnt (log,, [.4m],,oy, = 9 . 4 . cf. Figure .4.5). Tllcsc format,ion constants arc one or t , \~~o orders of magnitiidc higher t,llan t,llosc rcportcd by Bcrnkopf and Kirn [84BER/KIII] in a companion papcr. This discrepancy rrligllt \ ~ ~ l l bc dnc to an cr- roncons proccdiirc used t,o int,crprct t,llc sol~lhilit,y rncasnrcrncnt,~. Rcanalysis of the dat,a matlc by t,llis rcvic~v over t,hc cnt,irc pH range intlicat,ctl only log,, as t,llc main

Tllc cqnilibrinrn const,ant,s arc re-cst,imat,ctl from cxpcrimcnt,al tlat,a in Figure 1 of [84KIhI/BER]. The val~lcs of log,,[OH-] arc corrcct,cd for t,hc liquid jnnct,ion pot,cn- tial, and log,,[H+] is tlcrivcd as dcscribctl in t,hc disc~lssiorl of Ref. [84BER/KIhI] in t,llis .4ppcndix. The dat,a arc displayed in Figure -4.5. Only cxpcrimcnt,al points l>clo\~r pH = 8 nrcrc inclndctl in the least-sq~larcs calciilat,ions. Tllc reason for t,llis sclcct,ion is also given in t,hc disc~lssiorl of Ref. [84BER/KIII] in t,his .$ppcntlix. Xo irnprorcrncnt of statist,ics was ol)t,ainctl by nsing as addit,ional prcdict,or ~rariablc. Tllc corrlp~lt,at,ion gives l~g,,'l%'~,~ = (13.9 * 0.2) ant1 log,o',i, = ( 1 4 . 3 * 0.3). Only the loglo'"12 ~ralnc has bccn sclcct,cd by this rcvic\v bccansc t,hc exact nat,urc of the hytlroxidc is iinclcar. Ext,rapolation t,o I = 0 \vith the specific ion int,craction cqiiations of .4ppcndix B yields log,,'",," = ( 1 3 . 6 * 0.3).

[84NAS/CLE2] Nash, K.L., Cleveland, J.M., Thermodynamics of the system: Americium(lll)-fluoride. Stability constants, enthalpies, entropies and solubility product, Radiochim. Acta, 37 (1984) 19-24.

Tllc a~lt,hors invcstigat,cd the forrrlat,ion of .$rn(III) fliioridc corrlplcxcs by iising a cation cxchangc t,cchniq~lc. Tllc ionic strength of t,hc aqllcons phases urns i)iiffcrcd at 0.1 h1 \vith XaC104 ant1 t,hc pH was fixed at 3.5. The conccnt,rat,ion of frcc F- ions in t,hc t,cst soliit,ions urns mcas~lrctl dircct,ly \vith ion sclcctirc clcctrodcs carcfi~lly calil)rat,cd.

Nash and Clc~~cland rcportcd t,hc st,cp\~risc cqnilibri~lrn constants for t,llc forrrlat,ion of A4~nF"(KI = 386*20) ant1 .$rnF:(I& = 147*24) at 25°C. Con~~crsion t,o molalit,y nnit,s ant1 corrcct,ion t,o I = 0 by nsing !,cI = ( 0 . 1 2 f 0.1) and !,c2 = ( 0 . 3 6 * 0.1) k g . rrlol-l (cf. .4ppcndix B; Scct,ion B.1.4) rcsiilt in log,, L/," = (3.23 * 0.05) ant1 log,, 'l," = (5.80 f 0.15). \vhcrc i/i rcfcr to t,llc orcmll forrrlat,ion rcact,ion

and the ~lnccrt,aintics assigncd by t,llc a~lt,hors arc doubled t,o rcprcscnt t,hc 95% confidcncc lcvcl.

Tllc cxpcrirncnt,~ n7crc also pcrforrrlcd at 5" nrltl 45°C. Frorn t,hc tcrrlpcrat,llrc ~rarint,ion of t,hc cqllilibrillrn const,ant,s, t,llc aiit,llors calclllatcd t,hc cnt,hnlpy chnrlgc nccompn~lying the rcnct,ions. Xo at,t,crnpt,s car1 i)c rnadc hcrc t,o correct the rcport,ctl ~ralnc of &H, t,o I = 0, bccnllsc only cqlli1il)riiim constants at 25°C wcrc give11 by Nash and Clc~~cland. IInking the approximation t,llat ionic strength cf- fccts can be ncglcctcd, t,llis n~ollld give A,Hg(.%.6. n = 1) = (23 * 4) kJ . mol-l nrltl l,H;(.4.6; r , = 2) = (24 * 10) k.J . mol-l (nnccrt,nint,ics rcprcscnt t,llc 95% confidcncc lcl-cl). Tllc vnliic for rr = 1 is close t,o t,llat obt,aincd in Ref. [iGCHOIUNR]. Ho\vcvcr, this approximation is not rccomrrlcndcd by t,his revie\\,.

Tllc 2'1.%m actirit,y in t,hc nqllcons phase was foiind t,o tlccrcnsc syst,cmnt,ically ~vit,ll irlcrcnsirlg F corlccntrat,ions nbovc 8 X 10-" hI. This was ascribctl t,o t,llc forrrlat,ion of t,hc sparingly sol~lblc .4rnF:j(s) ~vit,ll n sol~lbilit,y protlllct I%'s.o = (5.1 f 1.6) X 10-16. This cqllilibrillrn const,nrlt car1 i)c cxt,rnpolnt,ctl t,o I = 0 \\,it11 t,llc specific ion int,craction cqnnt,ions of -4ppcntlix B; yicltling logln lie, = ( 1 6 . 5 * 0.3). a valllc ~vhich is co11sitlcral)ly lo\~rcr than t,llat cnlcnlat,cd by iisirlg the cst,imnt,ctl Gil)l)s cncrgy of forrnation of .%mF:3(cr) sclcct,ctl by t,his revie\\,. Sirlcc ficshly precipitated arnorphoiis solids iisllally exhibit higher sol~lbilit,ics t,llan cryst,allinc forms; the ol)scrvcd loss of "lA%rn act,ivit,y fiorn t,hc aqncoiis phase may possibly rcfcr to the forrnation of n tliffcrcnt solid corrlpoiind or; as also s~lggcstcd by Xnsh nrltl Clcvclnntl, t,o sorptiorl of colloitlal part,iclcs on the walls of t,llc rcact,ion vcsscl.

[84S 1 L] Silva, R.J., The behaviour of americium in aqueous carbonate systems, Sci. Basis Nucl. Waste Management V11 (McVay, G.L., eci.), held November 1983 in Boston, New York: North Holland Elsevier, 1984, 1ip.875-881.

This rcfcrcrlcc siimrnarizcs t,hc rcsnlt,s fiorn the sol~lbilit,y st,udics on .%m(OH):j(cr) nrld .4rnC0:jOH(cr) in Rcfs. [82SIL. 85SILl.

[84SIL/NIT] Silva, R.J., Nitsche, H., Thermodynamic properties of chemical species of waste radionuclides, in: NRC Nuclear waste geochemistry '83 (Alexander, D.H., Birchard, G.F., eds.), Symp. held 30-31 August 1983, in Reston, Virginia, Report NUREGICP-0052, U.S. Nu- clear Regulatory Commission, Washington, D.C., 1984, pp.70-93.

This report corlt,nins the sarnc cxpcrirncntal data as Ref. [85SIL].

[85MAG/CAR] Magirius, S., Carnall, W.T. , Kim, J.I., Radiolytic oxidation of Am(l l l ) t o Am(V) in NaCl solutions, Radiochim. Acta, 38 (1985) 29-32.

A%~n(OH):j(s) urns ficshly prccipit,at,cd by ntltlit,ion of NaOH t,o a 5 hI NaC1 soliition containing 10-" h1 .4rn(III). Radiolysis re nr .t' ,ions occnrrcd bccn~lsc of the rclnt,ivcly high tlosc rnt,c of cl-mtliation (40 IIBq/rnl). leaving only .%m(\:) species in the aqncoiis phase. The solubility tlat,a nrcrc int,crprct,cd ~vit,ll a rrlodcl considering .%m020H(s) as the soliil)ilit,y lirrlit,ing solitl phase, and .%rnO; and .%rnOZOH(ncl) as the prcdorrlinnt,irlg aqiicolls species. The reported vnh~cs of the solubility protlllct nrltl the formnt,ion const,nrlt of .%rnOZOH(ncl) arc rcspcctivcly, loglo I%'s.o = ( 9 . 3 * 0.5)

and log,, ill = (1.5*0.5). For t,llc sarnc reasons as tliscnsscd ~lrltlcr Ref. [88ST.4/KIII] in t,his -4ppcntlix. t,llcsc dat,a arc not inclndctl in the sclcct,ctl data set,.

[85NIT/EDE] Nitsche, H . , Edelstein, N.M. , Solubilities and speciation o f actinides ions in near- neutral solution, Report LBL-18900, Lawrence Berkeley Laboratory, Berkeley, California, 1985, 75p.

This appears t,o he t,hc sarrlc st,~ltly as Ref. [85NIT/EDE2].

[85NIT/EDE2] Nitsche, H., Edelstein, N.M. , Solubilities and speciation o f selected transuranium ions. A comparison o f a non-complexing solution wi th a groundwater from the Nevada tuf f site, Radiochim. Acta, 39 (1985) 23-33.

Akct,inidc sol~lhilit,ics (Xp'', NI)"'; Pnl", Pii"; Pn"'. .4rn1") in a rlat,~lral groiindn~at,cr and in 0.1 hI NaC1(14 soliit,ions wcrc mcas~lrctl by monitoring ~vit,ll t,imc t,llc actinitlc prccipit,at,ion fiorn s~lpcrsat,uratcd solutions at pH = (7.0 * 0.1) arltl at (25 * 1)"C. No tllcrmotlynamic dat,a wcrc rcportcd.

For "".krn(III), cq~lilihri~lrn corlccntrat,ions in 0.1 I 1 NaC1(14 at pH = (7.0 * 0.1) wcrc foiind t,o he in agrccrrlcnt nrit,h t,llosc mcas~lrctl by Rai et 111. [83R.4I/STR]; cf. Figure .k.4. .kccordingly; X-ray diffi.ar,t,ion analysis of t,llc prccipit,at,c. .4rn(OH):3(s), irltlicat,cd t,hat it rnainly cont,ainctl t,hc amorphous hydroxitlc. Tllc forrrlat,ion of hydrolysis species as clairncd t,o tlccrcasc the rrlolar ah~orptir i t~y ~ralnc of .4rn(III) at, 503 nrrl in 0.1 I1 NaC104.

[85SAT/M IT ] Satoh, I . , Mitsugashira, T., Hara, M , , Kishimoto, M,, Suzuki, S., A study o f the production o f transuranium elements and i t s application t o the solution chemistry in To- hoku University, in: Americium and curium chemistry and technology (Edelstein, N .M. , Navratil, J.D., Schulz, W.W., eds.), Dordrecht: D.Reidel Publ. Co., 1985, p1i.261-273.

This is the sarnc stiidy as rcportcd iindcr Ref. [82FUK/K.414:].

[a551 L] Silva, R.J., Preparation, characterisation and solubility constant o f AmOHCO:j, in: Am- ericium and curium chemistry and technology (Edelstein, N.M. , Navratil, J.D., Schulz, W.W. eds.), Dordrecht: D. Reidel Publ. Co., 1985, 1ip.225-238.

Tllc sol~lhilit,y of .k1nC0:~OH(cr) in dilut,c carl)onat,c solutions was rncasiircd by Silva [85SIL]. Tllc solitl urns idcrlt,ificd fiorn the similarit,y of it,s X-ray pou~dcr difiac- tion patt,crn ~vit,ll t,hat rcport,ctl for NtlC(I:jOH(cr) type .k [74DEX/C.%R]. Tllc solnbilit,y product was oht,aincd from rncasnrcrncnt,~ made iindcr l)oth nndcrsatiirat,cd and ovcrsat,uratcd sol~lt,ion corltlit,ions ( i . e.; by dissol~lt,ion of t,hc charact,criscd solitl in a soliit,ion init,ially frcc of arncrici~lrn and by prccipitat,ion of t,hc solid from a sol~lt,ion initially s~lpcrsat,uratcd ~vi th respect to arncriciiim). The cxpcrirrlcnts nrcrc pcrformctl at const,arlt ionic st,rcrlgt,ll (I = 0.1 h1 NaC1(I4); constant pH (pH = (6.12 f 0.03)) and ~lrltlcr controllcd C02 part,ial prcssiirc (pc:o, = 0.00792 at,rn) at (25 * 1)"C. Tllc st,ability of t,hc precipitate was rrlonit,orctl 'OS. tirrlc (mcas~lrctl sol~lhilit,y: log,, S =

(5.60 * 0.06)). l)iit t,hc varint,ion of t,llc solubility nrit,h pH and/or p,:,), as not invcstigatcd. For reaction:

Silva obtaincd log,, 'li,;, = (2.77 * 0.15) at I = 0.1 h1; ~vhich hc cxt,rapolatcd t,o (2.53 f 0.16) at I = 0. Tllcsc val~lcs arc cq~livnlcnt t,o log,, hrs., = ( 2 0 . 9 4 * 0.16) at, I = 0.1 11, nrltl log,, lie, = ( 2 1 . 8 0 * 0.16) at I = 0 for rcnct,ion:

.%I~CO:~OH(S) + .%rn"+ + O H + CO:- (\?.33) Tllc cxpcrirncnt,al tlat,a rcportcd by Silva nrcrc rcirlt,crprct,ctl as follo\~rs. \;?liics of

[H+] wcrc obt,airlcd fiorn the rcportcd pH-~~alncs ant1 single ion actirit,y cocficicrlt,~ calciilnt,ctl ~vit,ll Eq.(B.4). \?alncs of pc:o, n7crc convcrt,ctl from atm t,o bar nnit,s (cf. Scctiorl 11.3.2); nrltl n7crc iiscd t,ogctllcr ~vit,ll t,hc cnlculatcd [H+]-~~alncs nrltl t,llc kno\vn cq~iilil)riiim constant of the C O ~ ( ~ ) / C O : syst,crn (Tal)lc I\'.% and .%ppcndix B) t,o dct,crrrlinc the frcc cnrbonat,c conccnt,mt,ions: log,, [C(I;-] = (-17.53 + log,, p,:o, - 2 log,,[H+]). at I = 0.1 11 XnC104. Tllc sclcct,cd vnliic for the st,nbilit,y const,nrlt, of .%mCO: (cf. Table 111.2) as cxtrapolat,cd t,o 0.1 11 NaC104 ~vi th t,llc specific ion irlt,cractiorl cqiiations of .%ppcntlix B, log,, p, = (6.51 f 0.20), and ~lsctl to calc~l- lat,c t,llc frcc amcricinrn corlccntrat,ions that correspond t,o t,hc [.%rn],.,,. vnliics mca- siircd by Silvn [85SIL]. This procctl~lrc rcsnlt,ctl in log,, li,;,(I7.33) = ( 2 0 . 8 f 0.3) at I = 0.1 h1. This solubility protl~lct is convcrt,cd to rrlolal iinits and cxt,rnpolnt,ctl to zero ionic st,rcngt,h, usirlg the sclcctcd irlt,crnct,iorl cocfficicnt,~ (cf. .%ppcndix B; Scctiorl B.1.4); t,o give: log,, h':,, = ( 2 2 . 3 * 0.3). While t,hc rcintcrprct,cd vnliic at, 0.1 11 NaC1(14 ngrccs ~vi th t,llc ~ralnc obtaincd by Silva [85SIL], t,hc diffcrcncc in the T ~ ~ ~ I I C S a t I = 0 is diic t,o the dissirrlilnr mct,hotls used for ionic strength cxtrapolat,ions.

[86EWA/HOW] Ewart, F.T., Howse, R.M., Thomason, H.P., Williams, S.J., Cross, J.E., The solubility of actinides in the near-field, Sci. Basis Nucl. Waste Management IX (Werme, L.O., ed.), Mat. Res. Soc. Symp. Proc., 50 (1986) 701-708.

E~vart et 111. dct,crrrlincd the sol~lbilit,y of pl~lt,oniiirn, arncrici~lrn and ncptiininrn in "concrct,c cq~lilibmt,ctl ~vat,cr" (dcrnincraliscd ~vat,cr cq~lilibmt,ctl for some ~ ~ ~ c k s ~vit,ll ngctl concrct,c). The analysis of t,llc ~vat,cr gave as main comporlcnt,~ [Ca"] = 0.01 11, [Cl-] = 0.002 h1 and [SO:-] = 0.003 hl . ~vitll pH = 12 nrltl [CO;-]i,oi, = 3 X 1 0 - q I . This ~ ~ ~ a t c r urns filt,crctl and t,hc pH adjiist,ctl ~vi th XnOH or HC1 i)cforc actinitlc cllloritlcs nrcrc ntltlcd t,o reach a t,ot,nl conccnt,rnt,ion of zz 1 0 - q I . Tllc solutions wcrc rnixctl, and nft,cr an cq~lilibmt,ion t,irrlc (30 mirl~lt,cs in the case of .%rn [86E\V.%/HO\V]) they n7crc filt,crcd. acidified. and the nct,inidc conccnt,rations rncasiircd by liquid scint,illat,ion. In another report ~vit,llin t,hc sarnc project,, Tllorrlason nrltl il'illiams [92TH(I/IVIL. Figure l] sho~v that the .%m(III) conccnt,rations rncnsnrcd aftcr 3 hours ditl not differ from t,llc rncasiircmcnt,s aftcr 30 rnins. of cqiiilil)rat,ion tirnc. Tllc tcrnpcratiirc of t,hc cxpcrirrlcnts urns not rcport,cd 1)y Enrnrt et al. [86E\\'.%/H0\\']. Tllc actinitlc solid phases cont,rollirlg t,llc rncasiircd sol~lbilit,ics n7crc not tlct,crrrlinctl cxpcrirncnt,ally. and t,llcrcforc t,hcsc conccnt,rations arc not ntlcqiiatc t,o tlct,crrrlinc cq1ii1il)riiim const,ant,s.

Figures corrlparing t,llc cxpcrimcrlt,al soliil)ilit,ics arltl t,llosc calc~llatcd nrit,h the PHREEQE cotlc [80P.$R/THO] wcrc prcscrlt,ctl hy E~vart et al. in this paper [86E\V.4/HO\V]; as nrcll as in latcr pnblicat,ions [87CRO/EII'.$; 87E1\:.$/T.4S, 92E\V.4/SIII] \vhcrc a fcxv rrlorc cxpcrimcrlt,al data n7crc incliidcd in t,llc gmphs. .$lthongh the spread in t,llc data is allout one logarit,llrrlic iinit. the arncrici~lrn(III) soliil)ilit,ics mcas~lrctl at pH = 10.5 s~lggcst a tliscont,in~lit,y in t,hc shape of the solnbilit,y curve. Fignrc .$.7 displays t,hc cxpcrirncntal data cxt,ract,ctl frorn Fignrc 6 in [92E1\:.$/ShII]. In t,llc initial puhlicat,ion [86EI\'.$/H01\'], E~vart et al. t1cscril)cd their amcricinrn corlccntrat,ions assiimirlg t,llat t,llc soliil)ilit,y lirrliting solid phase changed fiorn .4mC0:jOH(s) to .$1n(0H):~(s) at pH zz 9.2 and that arncrici~lrn(III) rrlixctl l~ytlroxo-cnrbo~~:~,t,c complcxcs nrcrc present in t,llc aqllcons sol~lt,ion. as snggcst,cd by Kim et d. [84BER/KIhI; 86.$l.'O/BIL]. In a latcr pnblicat,ion. E~vart et d. [92E1\:.$/ShII] st,at,cd t,llat t,llc amcricinrn conccrlt,rat,ions coiild equally \ ~ ~ l l bc dcscrihcd ~vi th a rrlodcl corlt,aining inst,cad t,llc i)icarhonat,c cornplcxcs .$I~HCO;+ arltl .$I~(HCO:~): siiggcst,ctl by Bidoglio [82BID] and adopted by Phillips et 111.

[88PHI/H.4L]. Fignrc -4.7 corrlparcs t,hc arncrici~lrn conccnt,rations rcport,ctl by E~vart et 111.

[92E\V.4/SIII. Figure 61 ~vit,ll t,llc calciilat,ctl so1iil)ility ciirvc for .41n(OH):~(cr) nsing the cq~lilihri~lrn const,arlt,s sclcct,ctl in t,llis rcvic~v (cf. Tal~lc 111.2). Tllc calc~llations illustrat,cd in Figiirc -4.7 sho\v t,hat \vitll a fcxv cxccpt,ions. specially at pH = 10.5. the arncricinrn(II1) lcvcls can he dcscrihcd by the so1iil)ility of .41n(OH):~(cr). and t,hat hydrolysis corrlplcxcs of .$m(III) arc predominant. Tllc discrepancy aroiind pH = 10.5 rrligllt he tl~lc t,o an nnkno\~,n cxpcrimcrlt,al artifact,, or t,o sorrlc process like a charlgc in the solitl phase prcscnt in t,hc cxpcrimcrlt,~ (change in cllcrrlical composit,ion or ~rystal l ini t ,~) . or to a cllangc in t,hc kinetics of the solid-sol~lt,ion processes ~vhich rcg- nlatc t,llc conccnt,ration of arncrici~lrn(III). Dnc t,o t,hc lack of charact,crisat,ion of the solid phase and the short cqnilibration t,imcs in tllcsc cxpcrimcnt,~. is not possible t,o reach any dcfinit,~ concliision from t,hc tlat,a rcport,ctl by E~vart et 111.

[86RAO/MAH] Rao, V.K., Mahajan, G.R., Natarajan, P.R., Phosphate complexation o f americium(lll), Radiochim. Acta, 40 (1986) 145-149.

Tllc authors st,~ltlicd the cornplcxat,ion of arncricinrn(II1) by phosphate nsing a solvent cxt,ract,ion tcchniqiic ( t l i ~ ~ o n y l ~ ~ a ~ ~ l ~ t , l ~ : ~ ~ l c ~ ~ c s~llphorlic acid in hcnzcnc. and an aqlicolls phase corlt,aining 0.5 I1 NH:/H2PO~/C10~) at 30°C and pH = 2. 3, 7 and 8. Tllc dat,a was intcrprct,cd ass~lrning t,llc format,ion of .$I~H~Po:+ and .4m(HP04)+. This review calciilat,cs [H,PO(;-")] frorn t,hc t,ah~llatcd [H:jP04],.,,,.; usirlg the sclcctcd dissociat,ion constants of phosphoric acid cxt,rapolatctl t,o 0.5 I1 YH4C1O4 ~vi th the specific ion irlt,cract,ion cqnat,ions of -4ppcntlix B (log,, h', = -11.28; -6.53 arltl -1.81, at 30°C and I = 0.5 hl). The distril)iit,ion coefficient tlat,a at pH = 2 and 3 sho\17 t,llat H2POT is t,hc complcxing ligand. arltl rcanalysis of tllcsc dat,a according

gives log,, pl(.4.7) = (1.97 * 0.43) nrhich is in agrccrncnt ~vi th t,hc rcs~llt,s of Rao et

01. ( l 1 This ~ralnc; cxt,rapolat,ctl t,o I = 0, is sclcctcd in t,his rcric\v as dcscril~cd in Scct,ion 17.6.%.1.1.

Tllc cxpcrimcrlt,al data oht,aincd at pH = 7 and 8 rrligllt l)c inacciirat,c l)ccaiisc the actirit,y of t,hc aqllcons phase as obtaincd from the diffcrcrlcc of act,ivitics in the orgarlic phase before and aft,cr cqnilibration. Sincc .%rn"+ is kno\~rn t,o he ah- sorbet1 on glass n~alls at ncut,ral pH val~lcs [83CAIC/CHO]; t,llc arncrici~lrn act,ivit,y in t,llc aqiicolls phase obtaincd in t,his ~vay rnay he incorrect,, rcs~llt,ing in erroneous dist,ribntion cocfficicnts. Tllc available cxpcrirncntal tlat,a irltlicnt,c the prcscrlcc of a nc~v cornplcx (-4mHPO: or .%mP04(aq)) but arc ins~lficicrlt to dct,crrrlinc cit,llcr it,s st,oichiornct,ry or its st,al)ilit,y const,ant,. Thiis, the valiic of log,, ~,(.%rnHPO:) rcport,ctl by Rao, hlahajan arltl Natarajan (cf. Tahlc 17.15) is tlisrcgardcd by t,his rcric\v.

[87CRO/EWA] Cross, J.E., Ewart, F.T , Tweed, C J., Thermochemical modelling with application t o nuclear waste processing and disposal, Report AERE-R12324, UK Atomic Energy Authority, Harwell, UK, 1987, 45p.

Sec cornmcnt~ iindcl [86EI\-.I/HOI\-].

[87PER/LEB] Perevalov, S.A., Lebedev, I.A., Myasoedov, B.F., Complex formation of Am(ll l) and Am(lV) with phosphate ions in acetonitrile solutions, Sov. Radiochem., 29 (1987) 572- 577.

Pcrcvalov et 111. [87PER/LEB] invcstigat,cd t,llc corrlplcx forrrlat,ion of .%m(III) in acct,orlit,rilc solutions cont,ainirlg 0.05 to 2.0 hI H:3P04 using a spcct,ropllot,omct,ric tcchniqnc. Tllc spcct,ral shift and t,llc broatlcning of the 503 rlrn peak was irlt,crprctcd by t,hc forrrlat,ion of .%mH2PO:+ arltl .Irn(H2P04): in the orgarlic solvent. Tllc corrcspontling st,al)ilit,y constants arc: log,, fil = 12.0 and log,, i12 = 24.6. The stability const,ant,s arc many orders of rnagnit,~ltlc larger t,harl t,hc orlcs ol)t,ainctl in aqllcons soliit,ions.

Tllc a~lt,hors invcstigat,cd also the complex format,ion of .%m(I\') in t,hc sarrlc non- aqiicolls media. Tllc tlccrcasc of the formal pot,cnt,ial for the co~lplc .%m(I\')/.%rn(III) with incrcasirlg H:3P04 corlccntrat,ion urns int,crprctcd by t,hc prcscncc of the cornplcx .I1n(I\')(H2PO4):, for ~vhich the st,al)ilit,y constant was calcnlat,cd to l ~ c :

.%m4+ + 3 H2POT + .%~II(H~PO~): log,, 9:3 = 46.4 * 0.2

Tllcsc rcs~llt,s ol)t,ainctl in acct,orlit,rilc soliit,ions have an inforrnat,ivc ~ralnc; l)iit will not he incl~ltlcd in t,his rcric\v.

[87RAO/MAH] Rao, V.K., Mahajan, G.R., Natarajan, P.R., Hydrolysis and carboxylate complexation of trivalent americium, lnorg. Chim. Acta, 128 (1987) 131-134.

Tllc a~lt,hors invcstigat,cd t,llc complcxation of .Irn(III) \\,it11 acct,at,c and tart,mt,c ions in 0.5 I1 NaC104 soliit,ions at pH = 4 arltl pH = 8. Solvcnt cxtractiorl nrit,h tli- nonylnapht,halcnc snlpl~onic acid in bcnzcnc i as iiscd as the cxpcrirncntal t,cchniq~lc.

2 . Tllc t,art,ratc (L ) ions wcrc considcrcd to i)c t,llc only complcxing agcnt,s in t,llc systern. cvcn tllongll almost equal conccnt,rations of H L and L" arc prcscnt at pH = 4; as calciilat,ctl \vit,ll t,hc val~lcs of t,hc tlissocint,ion const,ant,s of t,art,aric acid, H2L, iiscd by t,hc aut,hors. Ilorcovcr. a disagrccmcnt exists bc t ,~~~ccn ficc ligand conccnt,rations cstirnatcd from t,ot,al t,artrat,c conccnt,mt,ions; and t,llosc used in t,hc rcgrcssion analysis of t,hc cxpcrirncnt,al data (sec Table 1 and Figiirc 2 of t,llc original paper).

Tllc valiic of the first hydrolysis const,ant,, log,$, = ( 6 . 8 0 f 0.30) urns tlcrivcd from the dat,a for t,llc t,art,ratc systcrn at pH = 8. H o \ ~ ~ c ~ ~ c r , by usirlg t,hc val~lcs of the corrlplcxat,ion constants rcport,ctl by Rao, hlahajan arltl Natarajan, t,llc .%m(III) spcciat,ion is calciilat,ctl to bc largely dorrlinat,ctl by .%rnL2+ arltl .%mL, at pH = 8 arltl at t,llc rclatircly high corlccntrat,ions of tart,mt,c ions llsctl t,hronghoiit t,llc cxpcrirncnt,~ (fiorn 5 X 10-" hI t,o 8 X 10-"I). Tllcrcforc, t,llc derived val~lc of ':ll may only he an art,ifact of the curre fitt,ing procedure.

[88KIM/BUC] K im, J.I., Buckau, G., Buppelmann, K., Klenze, R., Lierse, Ch., Stadler, S. Chemis- ches verhalten von Np, Pu und A m unter naturlichen aquatischen bedingungen. Hy- drolyse, carbonat-komplexierung, a-radiolyse, kolloidbildung, huminstofF-charakterisierung und speziation, Report RCM-00988, Inst. fur Radiochemie, Techn. Univers. Munchen, 1988, 134p., in German.

Tllc informat,ion in t,his rcport on the hytlrolysis of arncrici~lrn is also given in Rcfs. [88ST.%/KIII, 88STA%/KIh12]. sec t,hc comrrlcnt,~ in t,llis .%ppcndix on t,hc corresponding rcfcrcnccs. Tllc rcsnlt,s of Bcrnkopf and Kim on t,hc cnrbonat,c complcxation of .%m(III) arc also snrnrnariscd in this report. cf. t,hc tlisciission of [84BER/KIhI] in this .%ppcntlix.

[88RAO/MAH] Rao, V.K., Mahajan, G.R., Natarajan, P.R., The thermodynamics o f complexation o f trivalent americium by phosphate and carbonate in neutral aqueous solutions, Lanthanide and Actinide Research, 2 (1988) 347-361.

Rao. hlahajan and Yat,amjan carried out solvcnt cxt,ract,ion cxpcrirrlcnts as a fimc- tion of t,cmpcmt,urc t,o invcst,igat,c t,llc .%rn(III) carl)onat,c syst,crn at I = 0.5 I1 NaCl(14, pH = 6 and 7. The rcsiilts prcscnt,cd in Figures 3 and 4 of Ref. [88R.%O/II.%H] wcrc intcrprct,cd by Rao, hlahajan and Nat,ar:~,,jjan ass~lrning t,hc format,ion of the

2+ , .%I~HCO:~ c.omplcx. This rcric\v iiscs t,llc cxpcrirrlcnt,al dat,a at 25°C. \vhich consist,^

of t,hc total carbonat,c conccnt,mt,ions; pH and tlist,ribllt,ion cocfficicnt,~ [88R.%O/hI.%H, Tahlc 31. t,o check t,hc chemical rnodcl. The follo\ving ~ ~ a l n c s \!,ere iiscd for t,llc first, and sccorltl acidity const,arlt,s in the carhonatc syst,cm,

C ( l i + H+ +HCO, log,, K I ( I = 0.5 hl) = 6.074*0.027 C O : + 2H++C02(aq) + H20(1) log,, Ar2(I = 0.5 M)= 15.731*0.035

Figure .%.8 sho\vs t,llat t,hc distril)iit,ion cocficicrlt,~ rncasnrcd at diffcrcrlt pH ~ ~ a l n c s fall on the sarrlc ciirvc (log,, D ~ i e ~ s ~ r s log,,[C~:-]) in cont,radict,ion \vit,ll t,hc calc~llations and \vith the concl~lsions of Rao, hlahajan and Yat,ar:~,,jjan [88R.%O/hI.%H, Figiirc 31.

Figure -4.8: Dist,rih~lt,ion cocficicrlt,~ of .4m(III); D. mcas~lrctl by Rao, hlahajan arltl Natarajan [88RAIO/hI.4H] in aqllcons solutions cont,aining carl)onat,c at I = 0.5 I1 NaCl(14, pH = 6 and 7, and at 25°C.

Tllc points in Figure -4.8 irltlicnt,c the forrrlat,ion of arncrici~lrn cnrbonat,c corrlplcxcs (rather t,llan i)icarhonatc). -4s no solvcnt cxtractiorl urns rncasnrcd in t,hc al)scncc of ligand in order t,o asccrt,ain t,hc cxt,ract,ion rncchanism, it is not possil)lc t,o tlct,crrrlinc the stoichiornctry of t,hc prctlomirlant arncrici~lrn cornplcx in the aqncoiis phase. or it,s st,al)ilit,y constant. This review rcjccts t,llc cllcrrlical rrlodcl proposctl by Rao, hlah~~,.jjan and Yat,amjan and corlsitlcrs that t,hc hicarhonatc cornplcx, .4rnHCOz+. is not cvidcrlccd by t,his cxpcrirncntal work.

Rao. hlahajan and Yat,amjan also st,~ltlicd t,llc tcrnpcratiirc dcpcndcncc of .4m(III) corrlplcxat,ion by pllospllat,c ions using a solrcnt cxtract,ion tcchniqiic at I = 0.5 I1 NH:/H2PO~/C10~, pH = 2 and 7. and at tcrnpcratiircs of 10, 20 and 41°C. Tllc cxpcrirncnt,al rcsnlt,s wcrc intcrprct,cd assnrning t,hc formation of .4rnH2PO:+ arltl .ImHPO:. Tllcsc species n7crc ~ r c ~ i o i i s l y siiggcst,cd by Rao, IIah~~,,jan and Nat,ara- jar1 in a prcvio~ls stiidy [86R.4O/hI.4H]. Tllc rcportctl cqiii1il)riiim const,arlt,s arc rcprotl~lccd in Tal)lc \'.l5. The a~lt,hors calcnlat,cd cnt,halpy charlgcs from t,hc variat,ion of the cq~lilihri~lrn const,arlt,s ~vit,ll t,crnpcratiirc, arltl rcport,cd &H, = 2.37 and 1.34 kJ . rrlol-l for the forrrlat,ion of . 4 r n ~ ~ ~ ( l : + and .IrnHPO: rcspcctircly. Ho~vcvcr. from the valiics of log,, ill given in Tal)lc 2 of [88R.40/IIAIH]. the val~lcs &H, = (40 f 18) and (24 * 4) k.J . mol-l arc inst,catl ol)t,ainctl for .IrnH2PO:+ arltl .ImHPO: rcspcct,ivcly. Tllcrc is no apparent reason for siich a large discrepancy.

Tllc cxpcrirncnt,al tlat,a ol)t,ainctl at pH = 7 arc not considcrctl sufficient for the dct,crrrlinat,ion of citllcr t,hc st,oichiomct,ry or the stahilit,y const,ant of t,llc prcdorn- irlant arncrici~lrn species at ncut,ral pH (cf. tlisciission of Ref. [86R.4O/hI.4H] in this .4ppcndix), arltl t,hcrcforc, the corresponding log,, pl(.4rnHPO:) valiics (at 10 and 20°C; Tahlc \".15) arc not acccpt,cd by this rcvic\v. This rcric\v calcnlat,cs

[H2PO;], from t,llc tabnlat,cd [H:3P04],,,,,, a t pH =2 iising the sclcctcd dissoci a t ' ,ion const,ant of phosphoric acitl cxt,rapolat,ctl t,o I = 0.5 hI NH4Cl(14 ~vit,ll t,llc specific ion irlt,cract,ion cq~lat,ions in .4ppcndix B (loglo 1~':~ = -1.71; 1 . 7 6 arltl -1.86, at, 10, 20 arltl 41°C. rcspcct,ivcly). Tllc variation of t,hc dist,rih~lt,ion cocfficicnt 71s. [H2PO;] indicat,cs the formation of . ~ I ~ H ~ P o : + (pH = 2 and 3). Rcanalysis of tllcsc dat,a gi~rcs loglO /Il(.4.7) = (1.74 * 0.30), (1.80 * 0.16), arltl (1.97 * 0.28) at, 10, 20 arltl 41°C; rcspcctircly. Thcsc cq~lilihri~lrn const,arlt,s and t,llat ol)t,ainctl fiorn the rccvaliiation of Ref. [86R.4O/hI.4H] rnay l)c iiscd t,o tlct,crrrlinc the cnt,halpy arltl cnt,ropy charlgcs from a nrcightcd linear rcgrcssiorl "In /II(.4.7) ?IS. 1 / T (K-')", yicld- I H I = (14 * 6) kJ . rrlol-l and A,S,;, = (8% f 19) J . K-' . rrlol-l at 25" and I = 0.5 h1. Ext,rapolat,ion of t,hc cqiii1il)riiim constants t,o I = 0 \vitll t,llc aim of obtai~ling t,llc rcact,ion cnthalpy in st,andard condit,ions is not at,t,crnpt,cd i)ccaiisc it ~voiild rcqiiirc the cxt,ra assnrnpt,ion t,hat AE is const,arlt ~vit,ll tcrnpcrat,~lrc, intro- ducing an error of nnkno\~rn rnagnit,~ltlc. F~lrthcrmorc. t,llc srnall variat,ion of log,, /Il with tcrrlpcrat,~lrc is sirrlilar in val~lc to t,hc nnccrt,ainty in the individiial ~ ~ a l n c s of the cq~iilil)riiim const,ant,s.

[88STA/KIM] Stadler, S., Kim, J.I., Chemisches Verhalten von Americium in naturlichen wassrigen Losungen: Hydrolyse, Radiolyse und Redox-Reaktionen, Report RCM-01188, Institute fur Radiochemie der Technischen Universitat, Munchen, 1988, 141p., in German.

Tllc aiit,llors invcst,igatcd t,llc pH tlcpcndcncc of .41n(OH):~(s) sol~lhilit,y in t,hc following solutions at (%5*0.5)"C: 0.1 h1 NaC1(14 (cf. Figures .4.9 and -4.3). 0.1 hI NaC1; 0.6 11 NaC1. 3 h1 NaC1 and 5 hl NaClO,. Tllc effect of (>-induced radiolysis on solii- bilit,y urns st,udicd using diffcrcrlt t,ot,al conccnt,rnt,ions of 241.4m. This is a reasonably carefill ~vork. but no at,t,crnpt,s n7crc matlc t,o charactcrisc t,llc solid phase. Prccipi- tat,ion of trivalent lant,llanidcs nrit,h O H from soliit,iorls containing Cl-. SO:-, NO, was found t,o form hasic salt,s of composit,ion tlcpcnding l)oth on the i)iilk aniorl con- ccrltrat,ion and on the age of t,hc syst,crn [61.4KS/ERII, 7OhIIR/POL]. It is possil)lc that format,ion of rnixctl-anion prccipit,at,cs might occur also in t,hc .4m/H20/NaC1 syst,cm stiidictl by St,atllcr and Kirn.

Tllc rcport,ctl sol~lhilit,y prodiicts arc concordarlt with the valiic rncasnrcd by Silva [82SIL] for ":3.4rn(OH):3(cr). It is ~lnclcar; ho\~~crcr, if the sarrlc phasc corlt,rols the arncricinrn soliil)ilit,y in the two cases. hcca~lsc of t,hc markctlly tliffcrcnt corltlit,ions of preparation of t,hc start,ing solitls. Parallel shift of sol~lhilit,y ciirvcs occnrrcd by irlcrcasirlg t,ot,al arncricinrn actirit,y, ~vi th no fi~rt,llcr charlgc allore 44 hlBq/rnl. .Is siiggcst,cd by t,llc aiit,hors, t,hc higher ~ ~ a l n c s dctcrmincd for t,llc soliil)ilit,y product, prohal~ly rcs~llt,s from an incrcasc of available siirfacc area of t,hc solid phasc tl~lc t,o radiation tlamagc.

This rcric\v rccalc~llatcs hytlrolysis const,ant,s fiorn t,hc cxpcrirncnt,al tlat,a (plot,t,ctl in Figiircs -4.9 arltl -4.3) in 0.1 hI NaC104 nrit,h loxv ratliation cffcct (5 3.7 IIBq/rnl). Tllc cxpcrimcrlt,al pH-~~alncs rcport,cd in [88STA4/KIhI. Tahlc 7.31 arc convcrtcd t,o log,,[H+] val~lcs by int,rodncing a corrcct,ion fact,or accoiint,ing for the liqnitl jiinctiorl pot,cnt,ial (rncasnrcd by t,llis rcric\v usirlg t,llc same cxpcrirncntal sctiip as Stadlcr and Kirn) arltl the ~ralnc of t,llc actirit,y cocfficicnt of H+ rccalc~llatcd for irlt,crnnl

Figure -4.9: Solubility rncasnrcrncnt,~ of Arn(II1) hydroxide in 0.1 I1 XaC104 arltl 25°C fiorn St,atllcr and Kirn [88STAk/KIhI]. Tllc contirl~loiis ciirvc rcprcscrlt,~ t,hc solnbilit,y valiics calcnlat,cd \\,it11 t,hc set of cqnilibrinrn constants re-cstirnat,cd by t,llis review fiorn cxpcrimcrlt,al tlat,a in Ref. [88ST.4/KIII] arltl t,hc tlot,t,ctl curves sho\v tllc nssocint,ctl ~mcctt~aintics.

consist,cncy ~vit,h t,llc cqiiations given in .4ppcntlix B. Tllc corrcct,ion fo~lrltl by t,llis review is: - logl,[H+] = (pH,,,.-0.05'22). Tllc least,-squares hlarq~lartlt corrlp~lt,at,ion gives

This rcric\v incrcascs tllc cst,imat,ctl nnccrt,aint,ics l)ccansc of tllc scarcc information availahlc on t,hc cornposition of t,hc solid phase. Tllc thcrmotlynamic const,ant,s arc calciilat,ctl using tllc A E , valiics rcport,ctl in Scct,iorl \'..3.2.4 ol)t,aining log,$," =

( 6 . 6 f 0.4); log,>/," = ( 1 4 . 4 * 0.4). logl,'"l: = ( 2 5 . 7 f 0.5). The soliil)ilit,y mcasiircmcnt,s in 5 11 'JxC104 arc t,oo few t,o dcrixrc reliable infor-

rrlntiorl on cqnilibrinrn const,ant,s. Soliil)ilit,v cxpcrimcrlt,~ of .k~n(OH):~(s) in 3 hI NaC1 at 74 Bq/rnl rcsiiltcd in rrliich

higher arrlcriciiim conccnt,mt,ions; l)ccaiisc of radiolyt,ic oxidation of .4m(III) t,o .4rn(I7). Statllcr and Kirn fit,t,ctl t,hcsc cxpcrirncnt,al data nrit,h a rrlodcl assnrning -4rnO: arltl .kmOaOH(aq) as main sol~lhlc species, and .4mOaOH(s) as solubility-cont,rolling solid

phase. .klt,hoiigh no characterisation urns rrladc of the .k~n(OH):~(s) solid/liqiiid int,cr- facc nrhcrc .krn(III) oxidat,ion t,o .$m(\') shonltl occiir, spcct,ropllot,omct,ric critlcncc of .km(\:) species in solllt,ion urns reported. .kccortling t,o the calcnlat,cd forrrlat,ion const,ant. log,, ill = (1 .7 f 0.6); only 2% of .4rn020H(aq) slloiild be prcscnt in solution at, pH = 13. t,hc highest pH ~ralnc invcst,igatcd. This review considers t,llc cxpcrimcnt,al procedure not precise cnollgll t,o obtain a rclial~lc 1-alnc of the hydrolysis const,arlt, for .km020H(aq). Tllc order of magnitiidc of the solubility product of .4rn020H(s) is in agrccmcnt ~vi th ot,hcr stiidics on diRcrcnt pcntavalcnt act,inidcs. Tllc aiit,llors rcport,ctl t,hc valllc of log,, li,;, = ( 9 . 3 f 0.5) for t,llc rcact,ion

.krnOLOH(s) + .kmO: + OH-. (.l. 8)

Stadlcr ant1 Kim rrlcntioncd an ionic st,rcrlgt,ll effect on pH rncasiircmcnt,s. It is not clear, ho\vcvcr, if t,hcsc n7crc corrcct,cd for the liqiiid jnnct,ion pot,cnt,ial. If t,his is not t,hc case, a tlisplaccmcnt of t,llc .$m(\') solubility ciirvc along t,llc X-axis of aboiit, +0.i pH nnit,s (as cxpcrirncntally rncasiircd by t,llis review) n~ollld occiir at 3 h1 NaC1. Least-sq~larcs fit of the corrcct,cd dat,a nrit,h a motlcl ncglcct,ing .km020H(aq) \~ronltl then give log,, h's,n(.4.8) = ( 9 . 8 f 0.5), i.e.. logl,'R1ji.O = (4.2 * 0.5). Bcc;ansc of the high conccntrat,ion of C 1 ions. forrrlat,ion of rrlixctl prccipit,at,cs ant1 so1iil)lc arncri- ciiirrl cllloro complcxcs may not be disrcgartlcd. Honrcvcr, no charact,crisat,ion of the solid phase as rcport,cd. and t,hcrcforc t,his solnbilit,y constant for .krnOzOH(s) is not rccorrlrrlcndctl by t,his rcvic\v.

[88STA/KIM2] Stadler, S., Kim, J.I., Hydrolysis reactions of Am(ll l) and Am(V), Radiochim. Acta, 44/45 (1988) 39-44.

This appears to l)c the same st,~ltly rcport,ctl as Ref. [88ST.4/KIII] ~vhcrc more cxpcrirncnt,al details arc given

[89NIT/STA] Nitsche, H. , Standifer, E.M., Silva, R.J., Americium(lll) carbonate complexation in aqueous perchlorate solution, Radiochim. Acta, 46 (1989) 185-189.

Tllc authors tlct,crrrlinctl the forrrlat,ion const,arlt of .kmCO: in 0.1 I1 NaC104 solllt,ions by absorpt,ion spcctrol)llotornctr;vctry [89NIT/ST.4]. Tllc shift in the absorption band at 502.8 nrrl (t,o longer \~~avclcngt,h ~vi th increasing [CO:-]) was analysed by a non-linear least-sq~larcs rrlct,llod to cst,irnatc t,hc first st,al)ilit,y const,arlt (p,). By condnct,ing the rncasnrcrncnt,~ at t,wo diffcrcrlt COz(g) part,ial pressures (0.1 ant1 1.0 at,rn); it as possible t,o diRcrcnt,iatc i)ctn~ccn carbonnt,c ant1 bicarl)onat,c cornplcxation. No cvidcncc urns follrltl for t,hc cxist,cncc of arncriciiim i)icarbonatc cornplcxcs. Tllc allt,hors applied the specific ion intcract,ion cqllations (cf. .kppcndix B) on the available lit,cmt,urc dat,a [82LUN. 84BER/KIhI. 89ROB. 89XIT/ST.k] and cxt,rapolat,ctl t,hc valiic of t,hc cqnilibrinrn constant to zero ionic strength. The rcs~llt,s log,, p," = (8.16 * 0.10) and AE = ( 0 . 1 1 f 0.07) kg . rnol-' arc in agrccrrlcnt ~vit,ll sclcct,ctl valiics in t,hc prcscnt review.

[89PAZ/KOC] Pazukhin, E.M., Kochergin, S.M. Stability constants of hydrolysed forms of americium(lII) and solubility product o f its hydroxide, Sov. Radiochem., 31 (1989) 430-436.

Pnziikllirrl nrltl Kochcrgin rcport,ctl nrrlcriciiim sol~il)ilit,ics as n fimct,ion of [H+] in 3 h1 XnC104 at (20 * 0.5)"C. Most of t,hc rncasiircmcnt,~ wcrc pcrforrrlcd ~vit,ll "l-4rn; bi1t sorrlc cxpcrirrlcnts nrcrc dnplicnt,ctl ~vit,ll "".%rn. Corlt,nrrlinnt,ion by at,rnosphcric C02(g) as prcvcnt,cd. The nut,hors reported vnliics for t,hc forrrlat,ion constants of nrncricinrn hydroxo species iising a val~lc for t,hc ionic prodiict of ~vat,cr log,, h',,, =

1 4 . 0 . On this l~asis nrc cnlcnlat,c t,hc follo\~.ing ~ ~ a l n c s for t,hc soliil)ilit,y and hydrolysis const,ant,s at I = 3 hI: logl,',il = (6.40*0.11). log,,'"12 = (13.40*0.16). =

( 2 0 . 3 0 * 0.17) and logl,'Rli,;o = (14.60 * 0.11). Ext,rnpolnt,ion to I = 0 using the specific ion int,cractiorl cqiiations of .4ppcndix B gives: log,>/," = ( 5 . 1 * 0.2); log,,'~,l," = ( 1 2 . 1 * 0.2), log,,'i; = ( 1 9 . 2 f 0.2) nrld loglol;Iii;R, = (13.1 * 0.2).

Tllc rrlost st,rikirlg diffcrcrlcc i)ctn~ccn the soliil)ilit,y ciirvcs rcport,cd by ot,hcr aiit,llors [83R.%I/STR. 82SIL, 84BER/KIII, 84KIII/BER, 88ST.%/KIhI] and t,llc cxpcrimcrlt,al rcsult,s of [89P.4Z/KOC] is the rrliich higher so1iil)ility val~lcs rcport,cd in t,llis work. This rcsiilts in a w r y high ~ralnc for logl,(xh's,O X 7tj). suggesting t,hc prcscncc of n highly solnblc .4rn(OH):3(s). Ho\vcvcr, this is in cont,radict,ion ~vit,ll t,hc vnliic of logl,'Rli,;o obtaincd in t,llc rcgrcssiorl analysis ~vhich point,s t,o a solid of high crystal- linit,y. Indccd. t,hc logl,'l%'s,o is t,wo orders of rrlagnit,iltlc lower t,llan t,llat rcport,cd by ot,hcr aiit,llors ~vho cnrcfillly charact,crisctl t,llc solitl phase.

Tllc rrlct,llod iiscd by Paz~lkhin and Kocllcrgirl for t,llc prcpnrnt,ion of solid .%~n((lH):~(s) changcd ~vi th the pH-range. Ilorcovcr. no chnrnct,crisat,ion of t,llc solid was mntlc. t,hc cqiiilil)rat,ion t,imc as very short (1 to 2 lloiirs). and t,llc ccntrifiign- tion procedure ~lsctl (10000 rprn tl~lrirlg 20 rnin) may lla~rc not diffcrcrlt,iat,cd l)ctn~ccn smaller amcricinrn colloitls and true tlissolvcd arncriciiim species. Tllc conscq~lcncc of this last consideration \~ronltl i)c a rrliich higher appnrcnt solubility. Bnsctl on t,llcsc factors; the rncasiircmcnt,s rcport,cd by Pnziikllin and Kocllcrgirl arc tlisrcgardcd in this rcvic\v.

[89ROB] Robouch, P,, Contribution 2 la prgvision du comportement de I'am6ricium, du plutonium e t du neptunium dans la ggosphhre; donnges chimiques, Ph.D. thesis, presented in Strasbourg, 13 Nov. 1987, Report CEA-R-5473, Commissariat 2 I'Energie Atomique, Gif-sur-Yvette, France, 1989, 216p., partly in French.

Tllc solubility of .4m2(CO:3):3(s) as n fimct,ion of t,hc conccnt,rnt,ion of carl)onnt,c in soliit,ion urns stiidictl at 3 hI XnC104 ionic strength and (20 f 1)"C; cf. Figiirc .4.lO. X-ray tliflraction st,~ltlics n7crc rrladc of t,llc solid phnsc. and t,hc solid urns idcrlt,ificd as the norrnal carl)onnt,c of nrncriciiim(II1) by analogy of t,hc X-ray tliflraction pat,t,crn with that of lant,hanidcs. T\vo sct,s of cxpcrirrlcnts wcrc pcrforrncd: t,hc first one ~vit,ll known total cnrbonat,c conccnt,rnt,ion (3x 10-' 5 [c(I~-],.,,,. 5 1.0 h1 nrltl 7 5 pH 5 10.5); t,hc second one iindcr cont,rollctl COa(g) partial prcssiirc (pc:o, = 0.1,0.3 nrltl 1.0 nt,rrl nrltl 5.1 5 pH 5 7.8). Tllc soliil)ilit,y data wcrc analysctl in t,crrrls of carl)onnt,c corrlplcxcs ( . 4 r r l ( ~ ( l : ~ ) ~ ~ - ~ ~ ~ ) r , = 1; 2; 3) and a sol~lbilit,y protl~lct for .%~n~(C( l :~ ) :~ (s ) . No cvidcrlcc of . % r n ( C ~ : ~ ) : formnt,ion was fo~lrltl by spcctro~)l~otornctr;vctry in the 0.1 t,o

Figure .%.10: Soliil)ilit,y mcas~lrcrrlcnts of .%rn(III) at 3 hI NaC104 arltl 20°C fiorn Rollouch [89ROB]. The tliagmrn sho\~rs cxpcrirncntal point,s ( 0 ) ol)t,ainctl iindcr controlled C02(g) part,ial pressure (0.1, 0.3 arltl 1.0 a t ,~n) arltl dat,a frorn hat,cll cxpcri- mcnts s;mlplc(l aft,cr 10 ancl 20 ~vccks of ccl1lilil)ration t,imc (0 and. U rcspcct,ivcly). Tllc continno~ls ciirvc rcprcscntt; the soliil)ilit,y of .%rr12(C03)3(cr) ~al~ii lat ,ct l ~vit~ll the set of cqiii1il)riiim const,ant,s re-cst,imat,ctl by t,his rcvic\v frorn tlat,a in Ref. [89ROB]; and t,llc dott,cd curves sho~v t,llc associat,cd ~lnccrt,aint,y.

log,, [.%m] ,.,,,, -6

3.0 hI Xa2C0:j mngc, ~vhich is in agrccrrlcnt nrit,h t,llc ohscrvat,ions of Shilob et d. arltl Boiirgcs et al. (cf. discussion of Rcfs. [69SHI/GI\-. 83BOU/GUI] in t,llis .ll)l)cndix). Tllc rcport,ctl t,hcrrnodynarnic const,ant,s arc prcscrlt,cd in Tahlc \".16.

This review re-cval~lat,cs t,hc cxpcrirncntal dat,a as follo\~rs. Tllc acid cqnilibrinrn const,ant,s for t,hc carhonatc systcrn given in Tahlc I\'.% arc cxtral)olat,cd first t,o 20°C and then to 3.49 rn NaC1(14 (iising ho\~~crcr ~ - ~ ~ a l n c s valid at 25") and convcrt,cd t,o rrlolar iinits:

C O : + 2 H++C02(g) + H20(1) log,, li,,z(I = 3 hl. 20°C) = l i . 8 1 f 0.05 C O : + 2 H++COa(aq) + H20(1) log,, hrz(I = 3 hl. 20°C) = 16.21f 0.05 C O : + H+ +HCO, log,, h',(I = 3 hl. 20°C) = 9.62f 0.04

Thcsc cqi1ilil)riiim const,a,nt,s cliffcr sligl~t,ly from t,hc val~lcs llsccl by Rohollch. Thcrc- fore t,hc .'pH'' (= log,,[H+]) rncaslircmcnt,~ rcl)ort,cd in Tahlcs 2a and 21) of [89ROB] wcrc acljjnst,cd to the tliffcrcnt loglo[H+] ~ ~ a l n c s of t,llc solutions used t,o calil)rat,c his glass clcct,rodc. Thcsc corrcct,ctl valiics. n7crc nsctl nrit,h p(:o, (in l ~ a r ilnit,s) or [c(I~-],.,,,, tlat,a t,o ol)t,ain revised val~lcs of l o g , , [ ~ O ~ ~ ] ~vhich arc sho~vn in Fig-

nrc .%.10. .%n ~ln\~~cight,cd least sqllarcs fit,ting of t,hc tlat,a yicldctl the follo~ving cqni- lil~rinrn const,ant,s (at I = 3.0 11): log,, ill = (5.73 * 0.24); log,, 'lZ = (9.09 f 0.25); l ~ g , , p : ~ = (11.50* 0.18), and log,,h's,O = ( 1 5 . 2 i f 0.14) for rcact,ion:

Tllcsc val~lcs; corlvcrt,ctl to rrlolal nnit,s. arc cxt,rapolat,cd t,o zero ionic st,rcngt,h (iising ho\~~crcr t,hc ion irlt,cract,ion cocfficicnts in .%ppcndix B ~vhich arc valid at 25°C). This yicltls: log,, L/," = (7.80*0.32). log,, 9," = (11.60+0.38). log,, ill = (12.88*0.42) and log,, h';,, (1'36) = - (1 7.54 * 0.24).

Tllcrc is ho\vcvcr an alt,crrlat,ivc intcrprct,at,ion for the dat,a oht,aincd nrit,h t,llc l~atch cxpcrirncnt,~. Tllc calcnlat,cd part,ial prcssiircs of C02(g) in t,llcsc solllt,ions is in general rrliich lo\vcr (8 X 10-" bar in axwagc) t,llan in t,llc cxpcrimcrlt,~ at constant pc:(,, . This ~voiild f x o r the t,ransformat,ion of .%mZ(CO:3):3(s) irlt,o .%mCO:jOH(s) according to:

as ollt,lincd by \'.itorgc [92\'IT]. Under t,llc condit,ions st,~ltlicd by Robo~lch t,hc solii- bilit,ics of tllcsc t,wo solids arc of t,llc sarnc order of rnagnitiidc, arltl hccallsc Rohoiich only tlct,crrrlinctl t,llc rlat,llrc of t,llc solid phase by X-ray analysis on cxpcrimcrlt,~ at, controlled p,:,,,. it is possible t,hat t,llc l~ytlroxy-carl)o~~i~~t~c was prcscrlt in the l~atch cxpcrirncnt,~. If t,llat is the case; the solubility of arncricinrn at high x~alncs of [CO:-] sllo~lld i)c dcscribctl nrit,h t,llc follo~ving rcact,ions:

(sec also Ref. [94GIF]). Figure -4.11 sho\~rs t,llat indeed t,llc data obtaincd in t,llc l~atch cxpcrirncnt,~ can he cxplaincd \\,it11 t,hc solllhilit,y of .41nC0:~OH(s). Tllc valiics of the cqlii1il)riiim const,ant,s, = (hrS,,(\'.33) X X ili), iiscd t,o dra\v t,llc continno~ls curve in Figiirc .%.l1 corrcsporltl t,o 3.33 and 6.23 at I = 0 for rcact,ions (-4.9) arltl (-4.10). Thcsc valiics arc sirrlilar to t,llc cqiii1il)riiim const,arlt,s oht,aincd from the dat,a in Rcfs. [85SIL, 9OFEL/R.%I]; but differ from t,hc x~a111es given in Rcfs. [84BER/KIhI, 92RUN/hlEI].

As t,hc data oht,aincd by Rollouch [89ROB] in bat,ch cxpcrimcrlt,~ ( l o g , , [ C ~ ~ - ] 2 -3.5) car1 cqiially nrcll bc dcscribctl nrit,h the so1iil)ility of l)oth .4rn2(CO:j):3(s) arltl .%I~CO:~OH(S); only t,llc cqnilibrinrn const,arlt,s nncq~lirocally rcsnlt,ing from t,llc mca- siircrrlcnt,~ at constant p,:o,. i .e. log,, p," and log,, h7:,,(\:.36). arc used in t,llc sclcctiorl procedure t1cscril)cd in Scct,ions \~' . i . l .%.l.a and \'..7.1.2.2.h.

Rohoiich rrlcnt,ionctl [89ROB; pp.57 581 t,hat the solitl arrlcriciiim carl)onat,c in contact for rrlorc t,harl 8 rrlontlls \\,it11 soliit,ions containing [Ya2C(I3]2 1 h1 as convcrt,cd to N:1,.4rn(CO:~)~(cr). Ho\vcvcr, it is not clcar for ~vhich cxpcrirncnt,al point,s [89ROB; Tahlc 2h; page 601 t,llc X-my tliflraction pat,tcrn was oht,aincd. Fnrt,hcrrnorc, the rcport,ctl sol~lhilit,ics arc t,oo fc\v t,o permit an acciirat,c dctcrmirlat,ion of t,hc solllhilit,y

Figure -4.11: -4rncrici1lrn(III) solubility rncasiircmcnt,~ at 3 11 XnC104 and 20°C from Rohoiich [89ROB]. The tliagmrn sho~vs only cxpcrirncntal dnt,n from l~atch cxpcrirncnt,~ snrnplctl nft,cr 10 and 20 ~ ~ ~ c k s of cqiiilil)rat,ion tirrlc (0 nrltl rcspcct,ivcly). Tllc ciirvc sho~vs t,llc ~ ~ a l n c s calc~llat,ctl nssiimirlg cqiii1il)riiim ~vit,ll .41nCO:~(lH(s) nrltl t,llc follo\~.ing cq~lilihri~lrn const,ant,s: log,, 11,;2(.k.9) = 2.79 nrltl log,, 11,.:3(.4.10) = 6.82.

log,, [.4rn] ,.,,. 4 - log,,[H+]

3

log,, [CO:-]

protl~lct for this rnixctl-carl)onnt,c compo~lrltl

[89ROS/REI] Rosch, F., Reimann, T., Buklanov, G.V., Milanov, M,, Khalkin, V.A., Dreyer, R. , Electro- migration o f carrier-free radionuclides. 13. Ion mobilities and hydrolysis o f "I'.4rn-Am(lII) in aqueous inert electrolytes, J. Radioanal. Nucl. Chem., 134 (1989) 109-128.

Riiscll et o,l. prcscrlt an clcct,rornigration stiidy of "l-4rn at [ClO;] = 0.1 hI nrltl 25°C. The clcct,rornigration rrlctllod iiscd tlocs not s~~f fc r from t,llc possiblc art,ifact,s of ot,hcr clcctromigrat,ion rrlctllods usirlg solid st,nt,ionnry phases (sec considcrnt,ions nntlcr Rcfs. [6911.4R/KIK, 72SH.$/STE. 73KOR21 in t,his -4ppcntlix). Tllc ion rno- bilit,ics of t,hc amcricinrn(II1) aqua ion \17crc foiind t,o he pH-dcpcndcnt cvcn in the ncitlic pH region nrhcrc .4m(III) hydrolysis tlocs not occur. Tllc aiit,llors proposctl n change in the hydrat,ion sphcrc to cxplnin tllcsc obscr~i~,t,ions. On t,llc ot,llcr hand, they nssiimctl that this effect 11,as 11cgligil)lc in the pH range 5.5 7.9; and ascribctl only t,o hydrolysis t,llc observed vnriat,ions in the ovcrall amcricinrn mohilit,y. Tllcsc dat,a nrcrc fit,t,ctl nrit,h a rrlodcl ass~lrning the prcscrlcc of .41n"+ nrltl .4mOH2+ only, oh- taining a ~ralnc of log,$/l = ( 6 . 9 * 0.2). No at,t,crnpts \17crc rnadc to test altcrnatirc hytlrolysis schemes. -4 clramnt,ic drop of t,hc ovcrall arncriciiim mohilit,y was ol)scrvcd nhorc pH = 9. This 11,as int,crprct,ctl as the formnt,ion of t,llc hytlroxidc .4m(OH):j. nrltl

n vnliic of logl,'~l:j = ( 2 3 . 8 * 0.9) was reported. It is not clcnr ho\v this cnlcnlat,ion was mntlc. Xo irltlicnt,ion as given on the natiirc of t,his hytlroxidc, cit,llcr solid or n so1iil)lc species. Irltlccd the cxpcrirncnt,~ nrcrc rnadc by injcct,irlg 1 2 lrl of an nrn- crici~lrrl st,ock sol~lt,ion irlt,o the st,nrting posit,ion of t,llc migration t,nbc, hut no dnt,n arc given on t,llc t,ot,al amcricinrn conccnt,rnt,ion involrctl. \VC cxpcct that t,o cope with dct,cct,ion lirnit,~, quit,c high arncrici~lrn conccrlt,rnt,ions nrcrc ilsctl; nrltl t,llcrcforc local prccipit,at,ion may have occ~lrrcd. Rijsch et (XI. also proposctl an iippcr lirrlit, logl,"h'4 5 -12.9 for t,hc fourth hydrolysis cornplcx. c ~ ~ c n t,ho~lgll no cxpcrirncrlt,nl cvidcrlcc for this corrlplcx urns foiind.

Bnsctl on t,llc nhovc corlsitlcrat,ions the data of Rijscll et o,l. [89ROS/REI] have not, bccn crctlit,cd by this review.

[9OFEL/RAI] Felmy, A.R., Rai, D., Fulton, R.W., The solubility of AmOHCO:j(c) and the aqueous thermodynamics of the system N ~ + - A ~ " + - H C O , - C O ~ - - O H - H ~ ~ , Radiochim. Acta, 50 (1990) 193-204.

Fclrny, Rni nrltl Fnlt,on invcst,igatcd the sol~lhilit,y of 2'".4m in cnrbonat,c mctlia orer wide rnrlgcs of CO~-/HCO: corlccntrat,ions and pH vnliics:

at = 0.001 atm and 5.2 < pH < 9.3

at 10.6 < pH < 11.3 and 0.03 <[NaLCO,j] < 0.1 I1

at 11.7 < pH < 13.0 and [Na2C03] = 0.07 11

Tllc ionic strength of the sol~lt,ions urns not kept constant. .4lt,ho1lgll the tcrnpcr- nt,urc at nrhich t,llc cxpcrirncnt,~ wcrc pcrformctl was not rrlcnt,ionctl by Fclrny, Rni nrld Fnlt,on; t,his rcvic~v assnrncs it t,o l)c close t,o 25°C. The aiit,llors prcscnt,cd X-my pat,t,crn sirrlilnr t,o t,hc one presented by Silva and Xit,schc [84SIL/XIT] nrltl idcntifictl the prccipit,at,c as .4rnCO:jOH(s). The sol~lhilit,y tlat,a wcrc then int,crprct,ctl ass~lrning

(3-2s) the forrrlat,ion of .41n(C(l:~), (i = 1, 2. 3) cornplcxcs, ~vhich is in agrccrrlcnt ~vit,ll ot,hcr cxpcrirncntal ol)scrvations (cf. Scctiorl \'.7.1.2.1). Fclrny. Rai and Fiilton iiscd the Pit,zcr virial cocficicrlt approach [79PIT] togct,llcr ~vit,ll n nonlincnr least,-squares tcchniqnc t,o calciilnt,c st,nrltlartl cqiii1il)riiim constants (cf. Tnhlc \:.16). The aiit,llors did not incl~ltlc t,llcir sol~lhilit,y rcs~llt,s at pH 5 6.5 in the least,-sqiiarcs fit,, l)ccaiisc they s~lspcct,cd t,hnt the soliit,ions n7crc ~l~~tlcrsnt,nrat,ctl. Thcsc cxpcrirncrlt,nl points wcrc inst,cad rcplnccd ~vi th t,hc solubility rcs~llt,s of Silva and Xit,schc [84SIL/XIT, 85SILl. If only solubility rncasiircmcnt,s at pH > 6.5 arc consitlcrcd. it is only possil)lc to obtain vnliics for t,llc cqiii1il)riiim const,ant,s irlvolving t,hc prcdorrlinnrlt nqllcons nrncricinrn corrlplcxcs in this pH range. .4ssnrning, as Fclrny. Rni and F~llt,on did;

(3-2s) that .41n(C(l:~), (i = 1, 2, 3) arc t,llc prcdorrlinnrlt complcxcs. it is possil)lc to nsc

etc., to fit t,hc dnt,n at pH > 6.5. This rcvic~v digitises the solnbilitics at fixed p(:(), (convcrt,cd from nt,rrl t,o bar nnit,s) [9OFEL/R.%I; Fignrc 81 and at ~rarying conccnt,rations of N;I,~CO:~ for 78 day cq~lilihmt,ion [9OFEL/R.%I. Figure 9 and Table l]. nrltl pcrforrrls a least,-squares fit of t,llcsc soliil)ilit,ics. all of tllcrrl rncasiircd at 6.5 < pH < 11. Tllc mcasllrcrrlcnts on 0.07 I1 Na2C0:3 soliit,ions nrit,h added XnOH [90FEL/R.41. Fig- nrc 51 at 11.7 < pH < 13.0 wcrc not incliidcd in oiir re-cvnliiation hccn~lsc not crloiigh cxpcrirncnt,al details arc provided in t,hc piil)lication. Tllc fitt,ing procctl~lrc involvcd the calciilnt,ion of [H+] from reported pH-val~lcs, ant1 of t,hc ionic strength and the nctirit,y cocfficicnts (using t,hc specific ion irlt,crnct,ion cqiiations in -4ppcntlix B) by an it,crat,ion proccdiirc. (I~ving t,o t,llc low ionic strcngtlls of t,hcsc soliit,ions. the rcs~llt,s of t,llc cnlcnlat,ions arc not sensitive t,o t,llc mct,hotl usctl t,o obtain single ion act,ivit,y cocficicnt,~. Tllc calciilnt,ions sho~v that n systcrnat,ic error of *0.05 in t,hc pH-val~lcs; for example from ,j~lrlct,ion potcntinls, \~ronltl rcsiilt in errors hct,\~~ccn *0.05 and *0.1 in t,hc fit,tcd cq~lilihri~lrn constants.

Our cnlcnlat,ions yield val~lcs for log,~h':,i(.4.11) of ( 0 . 8 * 0.2), (3.7 * 0.4) nrltl (6.4 * 0.5) for I = 1, 2 nrltl 3 rcspcct,ivcly. Thcsc val~lcs car1 l)c corrlparcd ~vit,ll those cnlcnlat,cd fiorn t,hc cqiii1il)riiim const,nrlt,s rcport,cd by Fclrny, Rni and F~llt,on [90FEL/R.%I]: -0.9, 3.8 nrltl 6.7 rcspcct,ivcly. Tllc cxpcrirncnt,al tlat,a at const,nrlt, p(:(), for pH > 6.5 arc cornpared in Fignrc -4.12 \vit,h t,llc computed sol~lhilit,ics. Corrlhining t,llc rccalc~llatcd vnliics nrit,h log,, h7:,,(\'.33) = ( 2 2 . 3 * 0.3). fiorn the rcirlt,crprct,nt,iorl of the cxpcrirncnt,~ rcport,ctl by Silva [85SIL], and t,llc ionic product,

- of nrnt,cr rcs~llt,s in log,, [l," = (1.3 * 0.4). log,, il," = (12.0 * 0.5) nrltl log,, [l; =

( 1 4 . * 0.5). It sho~lld he noted t,llat \vllilc the corlst,ant,s for the first nrltl sccond corrlplcx agrcc nrit,h t,hc ~ ~ a l n c s rcport,ctl by Fclrny. Rni and F~llt,on: 7.6 and 12.3 rcspcct,ivcly. t,llcrc is sorrlc tliscrcpancy hct,\~~ccn t,llc vnliic of 9; given by Fclrny. Rni nrld F~llt,on (15.2) and our rcs~ll t ,~. This tliffcrcncc arises fiorn the fact t,hnt the rncnsnrcrncnt,~ in 0.07 11 Xn2C(I:3 at 11.7 < pH < 13.0 coiild not he incl~ltlcd in our cval~lat,ion. Thcrcforc. t,hc cqiii1il)riiim constants at I = 0 for t,hc forrrlat,ion of .%mCO:; .%rn(COt3); and . % I ~ ( c ( I : ~ ) ~ rcport,cd by Fclrny, Rni and Fnlt,on arc inclndctl in t,hc sclcct,ion procctl~lrc of Scct,ion \'..7.1.2.l.n with t,llc iinccrtaint,ics ol)t,ainctl in our rccalciilnt,ion.

On the basis of the solubility dnt,n nhovc pH = 12.5. Rai et o,l. revised the upper - -

limit proposed in a forrrlcr pnpcr [83R.$I/STR] for t,llc .4rn(OH):3(aq) cornplcx, cf. Tahlc \.;.4.

[9OPER/SAP] Pershin, A S . , Sapozhnikova, T.V., Hydrolysis of Am(lII), J . Radioanal. Nucl. Chem., 143 (1990) 455-462.

Tllc aiit,llors pcrformctl t,wo potcntiornctric titrat,ions. No informnt,ion was given on ionic st,rcrlgt,ll or t,crnpcratiirc for t,hc pH mcas~lrcrncnt,~. The soliil)ilit,y prodiict urns

Figure .%.l%: Sol~lhilit,y rncnsnrcrncnt,~ of .%mCO:30H(cr) frorn Fclrny, Rai and Fu1- ton [9OFEL/R.41] at pc:o, = 0.001 atm. Tllc cont,iniio~ls curre rcprcscnt,~ t,hc val~lcs calciilnt,ctl \\,it11 t,llc set of cqiii1il)riiim const,ant,s re-cval~lat,cd by this rcric\v fiorn cxpcrirncnt,al tlat,a in [9OFEL/R.%I]; and t,llc tlot,t,ctl ciirvcs sho\v the associat,cd 1111- ccrt,ainty.

derived frorn a jump on t,hc t,it,ration curves assocint,cd by t,hc aiit,llors t,o t,hc orlsct of prccipit,nt,ion. Pcrshirl nrltl Snpozhnikovn report t,llc follo~ving vnliic for t,hc sol~lhilit,y protluct,: = 2 7 . 3 . For lack of information on ho\v t,llc cxpcrirrlcnts Ivcrc condnct,ctl t,llis const,nrlt is disrcgartlcd in t,llis rcric\v

[9OROS/REI] Rosch, F., Reimann, T., Buklanov, V., Milanov, M,, Khalkin, V.A. , Dreyer, R., Electro- migration of carrier-free radionuclides. XIV. Complex formation of "1.4n-Am(lll) with oxalate and sulphate in aqueous solution, J . Radioanl. Nucl. Chem., 140 (1990) 159-169.

Rijscll et o,l. [90ROS/REI] invcst,igatcd t,hc forrnation of americium snlphat,o cornplcxcs usirlg an clcctromigrat,ion tcchniqiic at 298.15 K nrltl I = 0.1 hI. in HCl(14/- NaZS04 (pH = 2.8) and NaC104/Na2S04 (pH = 5.5) mctlia. The dccrcasc of t,llc nrn- crici~lrrl rnol)ilit,y nrit,h increasing [SO:-] urns int,crprct,cd by t,hc forrnation of -4rnSO: as t,hc predominant species. Tllc corresponding stahilit,y constant was found to i)c log,, 'll = (%.S* 0.3), nrltl t,llis vnliic is ~lsctl in t,llc sclcct,ion procedure dcscribctl in Scc- tion \~'.5.1.%.1. Ext,rapolation to I = 0 (cf. .%ppcndix B) yields log,, 'l," = (3.8 * 0.6). This review considers t,hnt t,llc cxpcrirncnt,al tlat,a prcscrlt,ctl by Rijsch et o,l. arc ins~lfficicrlt t,o prove t,llc cxist,crlcc of .%m(S(l4)2, and t,hcrcforc rcjcct,s t,hc rcport,cd ~ralnc of log,, I%'2.

[SOTAN] Tananaev, I.G., Hydroxides o f pentavalent americium, Sov. Radiochem., 32 (1990) 305- 307.

Tllc proccdiirc for t,hc synt,hcsis ant1 t,llc X-my characterisation of scrcml doll- blc hytlroxidcs of nrncriciiim(\:) (121.%r1102(0H)2 . .xH20(cr) .\I = Li; Na, K; ant1 ~l~f2.1~n02(OH):j . .xH20(cr); ~l'f = Xa; K) wcrc reported in t,llis paper. Tllc cxistcncc of tllcsc solid phases was taken as an cvidcncc for the prcscncc in l~asic rrlcdia of the corresponding aqncoiis .%m(\:) hydroxo cornplcxcs. Xo valiics for cqiii1il)riiim const,ants nrcrc rcport,cd.

[90TAN2] Tananaev, I.G., Forms o f Np(V) and Am(V) in basic aqueous media, Sov. Radiochem., 32 (1990) 476-479.

From spcct,ropllot,omct,ric rncasiircmcnt,s Tananac~. concl~ltlcd t,llat in alkaline solut,ions of .%m(\:). t,llc dorninant llytlroxo complcxcs arc .%m02(OH)!,-'", nrit,h r , =

1 . . . 4. Xo ~ ~ a l n c s for t,llc cqnilibrinrn const,arlt,s arc rcport,cd in t,llis work.

[91MEI/KIM] Meinrath, G., Kim, J.I., The carbonate complexation o f the Am( l l l ) ion, Radiochim. Acta, 52/53 (1991) 29-34.

Tllc aiit,llors invcstigat,cd the arncrici~lrn corrlplcxat,ion in carbon at,^ rncdia, pcrforrrling soliil)ilit,y ant1 spcct,roscopic cxpcrimcnt,~. Tllc dat,a nrcrc collcct,cd in a ionic rncdia of 0.1 hI XaC104 (at G 5 pH < 8) and 0.3 hI KaCl(l4 (at 8 < pH < 9); iindcr a controllcd C02(g) part,ial pressure (pc:o, = 0.01 at,rn). and at 25°C [9lhIEI/KIII, Ta- ble 41; cf. Figure .1.13. Tllc rcsiilts nrcrc int,crprct,ctl by t,llc forrrlat,ion of .%rnCO: ant1 .11n(C0:~);. Tllc prccipit,at,c, analysed by X-ray diffraction, t,hcrrnogravirnctry ant1 diffcrcntial t,hcrrrlal analysis, as cllaractcriscd as . % I ~ ~ ~ ( C O : ~ ) : ~ ( C ~ ) . The cquilibri~nrl const,ant,. for t,hc reaction

was cxpcrirncnt,ally tlct,crrrlinctl in 0.1 I1 NaC1(14 as log,, li = ( 1 7 . 6 % f 0.10). For this very simple cq~lilihri~lrn t,hc nnccrt,aint,y at the 95%' l c ~ ~ l (*0.2 log,,-iinits) sccrrls to bc considcmhlc, and rnay indicat,c t,hat t,llc clcctrodc rncasnrcrncnt,~ perhaps wcrc not very acciirat,c.

Tllc spcctrophotornct,ric and photoaconst,ic rcsiilts arc csscntially i)ascd on four spcct,m rncasnrcd in carbon at,^ rncdia. Tllc sccorltl forrrlat,ion constant. tlct,crrrlinctl only fiorn one spcctrllrrl at pH = 8.7 in cornhination ~vi th t,llc soliil)ilit,y rcsiilts, is to he disrcgardctl diic t,o insnfficicnt accuracy of the collcct,cd tlat,a. The valiic of log,, pl(O.l hl) = (6.48 * 0.03) dct,crrrlincd spcct,ropllotorrlct,ric;tlly is in good agrccrrlcnt ~vi th ~ r e ~ i o i i s rcsiilts by Xit,schc; St,andifcr and Silva [89NIT/ST.%] ant1 is sclcct,ctl by t,his rcric\v.

Tllc sol~lhilit,ics prcscnt,ctl in Figure 3 or Ref. [9lhIEI/KIhI] nrcrc digit,iscd by t,llis review; ant1 the data n7crc re-analyscd as follo\~rs. A1ct,ivity coefficient corrections,

Figure -4.13: Sol~lhilit,y mcasllrcrrlcnts of .4m2(CO:3):3(cr) from lIcinrat,ll and Kirn [91hIEI/KIhI] at 0.1 l 1 NaC1(14 and pH < 8 (0) and 0.3 hI NaC104 ant1 pH 2 8 (0), ant1 at pc:(), = 0.01 at,rn and 25°C. Tllc cont,inno~ls curre rcprcscnt,~ t,hc val~lcs calciilat,ctl ~vi th t,llc set of cqnilibrinrn constants dct,crrrlinctl by hlcinrat,h and Kirn [91hIEI/KIhI]~ and t,llc dott,cd curves sho~v the associat,ctl nnccrt,aint,y.

'3 + log,, [.4"1, ] ,,,,.

-6

log,, n"i

using t,hc specific ion intcract,ion cq~lat,ions of .kppcndix B; wcrc iiscd t,o ol)t,ain [H+] from t,hc rcport,cd pH-~~alncs ant1 t,o calciilat,c arncricinrn(II1)-carborlat,c cqnilibrinrn const,ant,s at I = 0.3 h1 (for t,llc point,s at pH > 8) from t,llc fit,t,ctl cqnilibrinrn const,ant,s at I = 0.1 h1. Tllc rcport,cd valiic of pc:(), was convcrtcd fiorn at,rrl t,o bar nnit,s, ant1 t,hcrl ~lsctl t,o calcnlat,c ~ ~ a l n c s of [CO:-] using log,, K(.4.12) = 1 7 . 5 3 ant1 -17.28 at I = 0.1 and 0.3 h1 rcspcctircly (cxpcrirncnt,al points at pH < 8 ant1 > 8). Tllc calc~llations sho\v that a syst,crnatic error o f f 0.05 in t,llc pH-valiics. for cxarnplc from ,j~lrlct,ion potcntials, ~voiild rcsiilt in errors bct,~vccn *0.1 and *0.2 in t,hc fit,tcd cq~iilil)riiim const,ant,s.

Our least,-squares fit,t,irlg yields t,hc follo~ving val~lcs at I = 0.1 h1 XaC104: log,, ill =

(6.1 * 0.3); log,, fi2 = (9.5 * 0.3); and log,, = ( 1 5 . 0 * 0.2). ~vhcrc the sol~lhilit,y const,ant rcfcrs t,o the rcact,ion:

Tllcsc valiics arc in agrccrrlcnt ~vi th t,llc ones rcport,cd by hlcinrat,h ant1 Kirn (cf. Tahlc \".16) ~vhich arc conscqiicntly incliidcd in t,hc sclcct,ion procctl~lrc t1cscril)cd in Section \'..7.1.2. The complcxation constants (solnbilit,y rnct,llod) and t,llc sol~lhilit,y protl~lct,~ (sol~lhilit ,~ ant1 spcct,ropllot,omct,ric rnct,hods) given by hlcinrath and Kirn

arc corlvcrt,ctl t,o rrlolal iinits and cxt,rapolat,ctl to I = 0 nrit,h t,llc specific ion intcrac- tion rrlodcl of -4ppcntlix B t,o yield: log,, 9," = (7.26+0.30) log,, p," = (11.29* 0.47); log,, l ~ , ( 1 7 . 3 6 ) = ( 1 6 . 5 4 * 0.18) and ( 1 6 . 4 5 f 0.10) (soliil)ilit,y arltl spcct,rornct,ry

[91MEI/KIM2] Meinrath, G., Kim, J.I., Solubility products o f different Am( l l l ) and Nd( l l l ) carbonates, Eur. J. Solid State Inorg. Chem., 28 (1991) 383-388.

hlcirlrat,h arltl Kirn invcst,ignt,ctl t,hc format,ion of .41n~(CO:~):~(s), XdCO:30H(s) arltl Nt12(CO:3):3(~) iindcr tliffcrcnt COz(g) partial prcssiircs in t,hc pH range of 4.1 to 6.2 at, (22*1)"C. The cllcrrlical cornposition of the Xd(II1) prccipit,at,cs n7crc cllaractcriscd by X-ray tliffraction mcasllrcrncnts, FTIR spcct,roscopy and t,hcrrnogmvimct,ry t,ogct,hcr with tliffcrcntial thermal analysis.

Nt12(CO:3):3(s) as foiind to be forrrlcd at p(:o, 2 0.01 at,rn. ~vhilc at pc:(), = 0.031% ( i .e . at,rnosphcric condit,ions) the Nd prccipit,at,c appears t,o i)c at first a mixt,urc of Nt12(CO:3):3(~) and NC~CO:~(IH(S); ~vi th a stcatly irlcrcasc of t,hc arnoiint of the hydroxy carl)onat,c solid ~vi th t,irnc.

Tllc solubility of "'.4rn(III). ol)t,ainctl for pc:o, = 1% and 100%'. n7crc irlt,crprctcd assnrning by analogy the format,ion of . k ~ n ~ ( C O : ~ ) : ~ ( s ) . Tllc cqiii1il)riiim const,ant for t,hc rcact,ion COa(g) + H20(1) + 2 H+ + C O ; . as cxpcrirncnt,ally dct,crrrlinctl in 0.1 11 NaC1(14 as log,, K = ( 1 7 . 6 2 * 0.07); arltl llsctl by hlcinrath arltl Kirn for t,llc data t,rcat,rncnt. Thcrc arc no graphs or t,ablcs in t,llc paper prcscnt- irlg t,llc cxpcrirncnt,al mcasllrcrrlcnts on amcricinrn; and t,llcrcforc it is not possil)lc to judge t,llc iinccrtaint,y in the rcsiilts. Tllc solnl>ilit,y product reported by hlcinrat,h arltl Kirn (cf. Table \?.16) convcrt,cd t,o rrlolal ilnit,s, is cxtrapolat,cd t,o zero ionic st,rcngt,h using t,llc specific ion irlt,cract,ion cqiiat,ions (cf. .kppcndix B) yielding log,, lq,(IT.36) = ( 1 6 . 3 8 f 0.10) (cf. Scct,ion \.'.7.1.2.2).

[91VIT/TRA] Vitorge, P,, Tran The, P,, Solubility l imits o f radionuclides in interstitial water- Americium in cement. Task 3 - Characterization o f radioactive waste forms. A series o f final reports (1985-89) - No. 34, Report EUR 13664, 1991, Commission o f the European Communities, Luxembourg, 39p.

I7it,orgc arltl Tran Tllc invcst,igatcd t,llc soliil)ilit,y of "I'.krn in ccmcrlt lcachat,cs arltl in KOH soliit,ions of variable conccnt,rat,ion (0 < [KOH] < 10 11) in t,llc prcscncc of 0.04 h1 Ca(OH)2(s). Xo prcca~lt,ions wcrc t,akcn to avoid contact nrit,h at,rnosphcric COz(g), c ~ ~ c n though t,hc addit,ion of Ca(OH)z(s) was contril)iit,ing to t,llc rcrrloval of tlissolvcd CO2 by prccipit,at,ion of solid calcillrrl carl)onat,c. Tllc rncasiircmcnt of arncricinrn corlccntrat,ions in the snpcmat,ant sho\~~ctl t,hat cqllilibrillrn urns att,ainctl in about 100 davs. Xo charact,crisat,ion of the sol~lbilit,y lirrlit,ing solid phase was rnadc. Incorporat,ion of arncriciiim(II1) in prccipit,at,ing CaCO:3(s) might have also occllrrcd Tllc t,crn1)cratiirc of t,hc soliil)ilit,v cxl>crirncnts is not rrlcnt,ionctl in [91I.'IT/TR.41. .. -

Tllc sol~lbilit,y of arrlcriciiim in alkalinc soliit,ions in t,hc prcscncc of cxccss Ca(OH)2(s) was foiind to bc in agrccrrlcnt nrit,h the val~lcs given by Bcrnkopf and Kirn [84BER/KIhI]. E~irart et o,l. [86E1\:.4/H01\'] and St,atllcr and Kirn [88ST.4/KIII]. 1'itorgc and Tran The

rcport,ctl log,, li,.:3 = 1 1 . 1 for reaction:

This is in agrccrrlcnt ~vit,ll t,hc cqnilibrinrn constant sclcct,ctl in t,his rcric\v (cf. Ta- ble 111.2) for cryst,allinc arrlcriciiim hydroxitlc. i .e. log,, lie, = ( 1 0 . 5 * 0.8) (ionic st,rcngtll cflcct,s arc rlcgligihlc for rcact,ion (-4.13) \vhich does not involrc cllargcd aqlicolls species).

Tllc ol)scrvcd increase in arrlcriciiim conccnt,rat,ion nrit,h incrcasirlg conccnt,ration of KOH as intcrprct,cd assiimirlg the forrrlat,ion of .4rn(OH),:

with log,, I%'4 = 0 . 2 . This valiic, ho\vcvcr, is tlisrcgardctl hcca~lsc of variations in ionic st,rcrlgt,ll and t,llc lack of charact,crisat,ion of t,llc solid phase.

[92EWA/SMI] Ewart, F T., Smith-Briggs, J L., Thomason, H.P., Williams, S.J., The solubility o f actinides in a cementitious near-f~eld environment, Waste Management, 12 (1992) 241-252.

Scc cornmcnt~ iindcl [86E11-.i/H011-].

[92RAI/FEL] Rai, D., Felmy, A.R., Fulton, R.W., Solubility and ion activity product of A m P 0 4 . .'r;H20(am), Radiochim. Acta, 56 (1992) 7-14.

Rai. Fclrny arltl Fiilton invcst,igatcd t,llc amcricinrn soliil)ilit,y in phosphat,~ rncdia. from over- and iindcr-sat,~lmt,ion. for phosphate conccntrat,ions rangirlg from 1 0 " t,o 1 o F 2 11.

pink arncrici~lrn pllospllat,c solitl as prepared by atltling 5 rrlg 2'".4m in a st,ock soliit,ion to 30 m1 of 0.1 hI NaH2P04 (pH = 4.5). .4ft,cr a fc\v days of cqiiilil)rat,ion, the precipitate as filtered, n~ashctl, siispcndcd in dcacmt,ctl ~vat,cr sarnplcs (the pH was varied in t,hc range 3 to 1 by atltling HC1). and shaken cont,iniionsly for 50 days. ":3Ak1n was then added t,o half of the i)atchcs t,o irlcrcasc the amcricinrn conccnt,ration in t,llc sol~lt,ion ( i .e . orcrsatiirat,ion). Tllc sarnplcs wcrc shaken again and analyscd aft,cr diRcrcnt cqiiilil)rat,ion times.

Chcmical and X-my tliflraction analysis sho~v the prcscncc of an amorphous arncrici~lrrl pllospllat,c solid: .4rnP04 .:rrH20(am). Tllc soluhilit,y data rnay bc siimrrlariscd as follo\~rs:

at pH 2 3, the amcricinrn conccnt,ration is w r y low ( W 1 0 - q I ) and close t,o the analyt,ical tlct,cctiorl limit of the cqniprncnt 11scd by t,hc aut,hors. No rcliahlc inf~rrrlat~ion on t,llc cornplcx forrrlat,ion car1 hc t,llcrcforc oht,aincd in t,his pH region.

at 2 < pH 5 3 t,hc arncrici~lrn corlccntrat,ion dccrcascs by two orders of magni- t,~ltlc ~vit,ll one pH ~lnit,. This is in disagrccmcnt nrit,h the cxpcct,ctl t,rcnd. -4n inspcct,ion of Table 5 in [92R.%I/FEL] sho~vs that phosphate conccnt,rations arc systcrnat,ically larger t,harl t,llc corresponding arrlcriciiim soliil)ilit,ics in t,hc pH range 2 t,o 3. There is no clcar reason for t,llis i~rll)alancc.

Figure .4.14: Solubility mcasllrcrrlcnts of .$rnP04 .:r;H20(am) from Rni. Fclrny ant1 Fiilt,on [92R.$I/FEL] (at 21 days, 0; and 86 (lays; 0 ; cqnilibration t,irnc). The con- tin~loiis ciirvc rcprcscnt,~ t,hc vnliics calciilnt,ctl ~vit,ll t,llc solubility product reported in [92R.$I/FEL] ( i .e . log,, I%':,, = -24.79) in corrlhinnt,ion nrit,h t,llc sclcct,ctl acitlit,y const,ant,s for phosphoric acid given in Tal)lc I\'..% ant1 the specific ion intcract,ion cq~iations in .4ppcndix B. The dot,tcd ciirvcs sho\v t,llc calciilnt,ctl ~lnccrt,ainty on the soliil)ilit,y \vhcn t,hc ~lnccrt,ainty in t,llc vnliic of log,, IC7t,, is set t,o *0.6.

Tllc authors used bot,h Davics cqnnt,ion [62D.4\.'] and t,llc Pitzcr virinl cocficicnt, approach [73PIT, 79PITI to cnlcnlat,c the st,andard sol~lhilit,y protluct,:

.4mP04 .rc;H20(nrn) + .$rn3+ + PO:-+.x H20(1)

log,, lie, = -24.79 * 0.18.

Tllc t,crnpcratiirc urns not rrlcntioncd by Rni. Fclrny and F~llt,on. l)iit t,his rcric\v nssnrncs it to l)c close to 2S°C.

plot of the prodiict of t,hc arncrici~lrn ant1 phosphnt,c solnbilitics rncnsnrcd by Rni. Fclmy ant1 Fiilton [92R.$I/FEL. Table S] ?IS. t,hc corrcspontling acitlit,ics [92R.%I/FEL; Tahlc l], is cornpared in Figiirc -4.14 ~vit,ll the corresponding calciilnt,ctl vnliics.

[92RUN/MEI] Runde, W., Meinrath, G., Kim, J.I., A study o f solid-liquid phase equilibria o f trivalent lanthanide and actinide ions in carbonate &terns, ~ a d i o c h i m . Acta, 58/59 (1992) 93- 100.

Rnndc; lIcinrat,ll ant1 Kim invcst,igatcd t,llc so1iil)ility of "I'.41n in cnrbonat,c rncdia at 0.1 l 1 NaC1(14 ant1 (25.0*0.2)"C using t,llc rnct,hodology dcscrihcd in [91RIEI/KIRI].

Tllc rcsiilts arc irlt,crprctcd assllrning t,llc formation of .%mZ(CO:3):3(s) (at p c : ~ , > 0.01 at,rn), arltl .%I~CO:~OH(S) (at pc:o, = 3 X 10-' at,rn). Thcrc arc no graphs or tables in the paper prcscnt,ing t,hc cxpcrirncntal rncasnrcrncnt,~ on arncricillrn. arltl tllcrcforc it is not possible to jlltlgc t,hc iinccrtaint,y in t,hc rcslllt,~. The sol~lbilit,y protlllct,~ rcport,ctl by R~lntlc. hlcirlrat,h arltl Kirn, prcscrlt,ctl in Talllc \'..16; arc con- ~rcrt,ctl t,o molal nnit,s arltl cxt,rapolatcd t,o zero ionic st,rcngt,h iising t,hc specific ion irlt,cractiorl cqllat,ions (cf. .%ppcndix B) yicltling loglo h7:,,(\:.33) = ( 2 0 . 1 8 * 0.24) and log,, 1%';,,(\'.36) = ( 1 6 . 3 2 * 0.18) (cf. Scct,ion i7.7.1.2.2).

[92VIT] Vitorge, P, , Am(OH):3(,9), AmOHCO:j(s) and Am2(C0:j):3(,9) stabilities in environmental conditions, Radiochim. Acta, 58/59 (1992) 105-107.

Tllc aiit,llor dcscribcs t,llc cqllilibria. bct,\~~ccn t,hc arrlcriciiim solitls present in the ~vatcr-l~icarbonatc-ci~~rbo~~atc systcrn; as follo\~rs:

By corrlbining t,llc acid const,arlt,s of HZCO:j(a(l) and the soliil~ilit,y ~~rodi ic ts of the different solitls, \'.itorgc concl~ltlcs t,llat .%mZ(CO:3):3(s) is st,ablc at pc:o, > 0.1 at,rn. ~vhilc at pc:o, 5 lO-'" atm t,llc solid t,hat prccipit,at,cs is . % I ~ ( O H ) : ~ ( ~ ) . and the rrlixctl solitl .%mCO:jOH(s) shonltl bc prcdorrlinarlt llrltlcr at,rnosl~hcric corltlit,ions (pc:o, zz 0.001 at,rn). Thcsc t,llcrrnodynnrnic considcrat,ions arc in gootl agrccmcnt, with cxpcrimcrlt,al cvidcncc as ~vcll as ~vit,ll t,llc calciilat,ions pcrforrrlcd in this rcric\v (cf. Scct,ion \:.7.1.2.2).

[93GIF/VIT]+ Giffaut, E . , Vitorge, P. Evidence of radiolytic oxidation of "'Am in Na+ / C l / HCO: / C O ; media, Sci. Basis Nucl. Waste Management XVI (Interrante, C.G. , Pabalan, R.T., etis.), Mat. Res. Soc. Symp. Proc., 294 (1993) 747-751.

Giffillt and i7it,orgc mcasllrctl arncricillrn conccrlt,rat,ions in 0.1 and 4 11 NaC1 soliit,ions nrit,h added .%rn2(CO:j):3(cr). Tllc soliit,ions cont,ainctl kno\~rn amollrlt,~ of

t .Arl~lit,ional experimental cletails ancl data are giver1 in a (ioct,oral tllesis [94GIF] pl~l~lishr(i aft,er t,l~is vollnne had l~een sent fnr in(bpenr1ent ~~eer-revie\%-ing.

In his thesis. Giffaut <:lr%i~r~s illat t,lle .AI~I(III) solid phase in his experiments, perforrnerl a t pc,o, < 10-' atrn, was in fact .Arr1C030H(s) inst,ea<l of .Arr1a(C03)3(s) as stat,ecl in [93GIF/\'IT]. Owing to t,his. the reslllts a t 21°C for the .Arrl(III) syst,e~r~ reporte~l in Giffaut's t,l~esis (log,, ( jy = 8.9. log,, p; = 13.5, log,, -i; = 14.8 ancl log,, I(,,,(V.33) = -22.5) [94GIF, pp. l55 ancl 1591 rliffer consi(ieral11y frorr~ the eql~ilil~rillrn cor~st,ar~ts giver1 in [93GIF/\'IT]. Uut t l ~ e V ~ L ~ I I ~ S reported f ~ r .Arr~(\') [94GIF, p.1471 (in riot rliffer significantly frorr~ the t,lle eql~ilit)rillrr~ cor~st,ar~ts in [93GIF/\'IT]. Gifft~l~t extrapolat,ecl t,lle eql~ilit)rillrr~ cor~st,ar~ts for .Am(\') t,o I = 0, ot)t,aining: log,, = 4.7, 7.0 and 5.6 for . A r n 0 ~ ( ~ 0 : ~ ) ~ , , ~ " ' with rr = 1 to 3, ancl log,, IC,o,(Na.Arn02C03(s)) = -11.4 [94GIF, p.1481.

This work also presents arrlericillrr~ soh~l~ili ty i:llrves in 4 \I NaCl ancl recll~cing con(lit,ions in the ternperatllre range 20 to '70°C. Gifft~l~t interpret,e(l t,llese experimental data assllrr~ing the forrr~atior~ of eitller .ArnCO:~OH(s) or Nar l r r~(CO:~)~(s ) .

tot,al sotliiim carl>o~~at,c/l>icarl)onat~c. Frcc carbon at,^ conccnt,rations \!,ere calcnlat,cd from glass clcctrodc rncasiircrncnt,s of log,, [H+]. -411 mcasllrcrrlcnts nrcrc pcrformctl at 2loC, cxccpt for a fc\v 4 h1 NaC1 soliit,ions \vhich nrcrc cqnilibratcd at 70°C.

Higher sol~lhilit,ics in conccnt,rat,ctl cllloritlc mctlia were irlt,crprctcd as the radiolyt,ic oxidat,ion of .4rn(III) to .$m(\'). This urns corlsistcnt \vit,ll the fact t,llat atltlit,ion of rnctallic iron. nrhich irrlposcd reducing conditions, rcs~~lt,ctl in soliil)ilit,ics at 4 11 NaC1 sirrlilar t,o t,llc solnbilitics in 0.1 11 NaCl rncdia. This also sho~vcd t,llat,; in 4 hI NaC1; cllloritlc cornplcx forrnation urns ncg1igil)lc corrlparcd ~v i th cnrbonat,c cornplcxing. Tllc rcsl~lt,s in 4 hI XaC1 mctlia nrcrc intcrprct,cd nrit,h the forrnation of .4rn02C0, arltl . ~ I ~ O ~ ( C O : ~ ) $ in cqllilihrillrn nrit,h Xa.4m02C0:j(s); ~vhilc in diliit,c cllloritlc rncdia the format,ion of .k rn (~( I :~ ) f -~ ' " ) (n = 1 t,o 3) and . ~ I ~ ~ ~ ( C O : ~ ) : ~ ( S ) was assiimcd; cf. Tahlc \".l6 and Scct,ion \".i.l.%.l.tl.

Tllc cqiii1il)riiim const,ant,s arc cxtrapolat,cd hcrc t,o I = 0 \vit,ll t,llc specific ion irlt,cractiorl cqnat,ions of .kppcndix B, and t,hc llrlccrt,airlt,ics arc ac1,jllstcd to a 95% lcvcl assnrning that the rcport,cd nnccrt,aint,ics arc f o. The rcsnlt,s for t,hc arncricillrn(II1) syst,cm in 0.1 h1 XaC1 give (assiiming t,llat chloride corrlplcx forrrlat,ion is ncg1igil)lc and t,hat E(.~&+,, :~-) N c(.4m3+ ), etc.): log,, /I? = (9.0*0.4); log,, p," = (12.9*0.4); log,, p: = (14.1 * 0.5) arltl log,, lq,(IT.36) = ( 8 . 7 * 0.3). The cxt,rapolat,ion of the arncriciiim(\:) rcsiilts in 4 hI NaC1 t,o I = 0 is pcrforrrlcd iising t,hc h,,, val~lcs for the analogous ncpt,unillrn(\') syst,crn [86GRE/ROB], again assnrning t,llat the corrlplcx forrnation hct,\~~ccn .4mO: and C 1 is ncgligiblc. cvcn in t,llcsc corlccntrat,cd cllloritlc soliit,ions. Thcsc assiimptiorls yield: log,, p,"(.4rnO2COT) = (4.6 * 0.7); log,, p,"(.4rn02(~(I:j);-) = (7.3 * 0.8); arltl log,, I<;,, = ( 1 1 . 0 * 0.6); ~vhcrc the soliil)ilit,y const,ant refers t,o rcact,ion:

Ho\vcvcr, no solitl phase charact,crisat,ion is rcport,cd in [93GIF/\'IT]. arltl no cxpcrimcrlt,al tlct,ails arc given nrhich ~voiild allo\v t,hc cstirrlat,ion of p,:,,,. Dllc t,o lack of informat,ion. t,hc cqllilihrillrn const,ant,s reported in [93GIF/\:IT] can not he credited in t,his rcvic\v.

Appendix B

Ionic strength correctionst

Thcrmotlynamic dat,a al\~rays rcfcr t,o a sclcct,ctl stantlartl st,at,c. Tllc dcfinit,ion given by IUP.kC [82L.kF] is adopted in this rcvic~v as ontlincd in Scct,ion 11.3.1. -4ccording to t,llis dcfinit,ion. t,hc st,andard st,at,c for a solllt,c B in a solution is a hypot,hct,ical soliit,ion, at t,hc standard st,at,c pressure, in nrhich r r a ~ = rrro = l mol . kg-'. ant1 in ~vhich t,hc act,ivity cocficicnt ;!B is nnit,y. Ho\vcvcr, for rnany rcactions, rncasnrcrncnt,~ cannot bc rnadc accnratcly (or at all) in dilllt,c solut,ions from ~vhich the necessary cxt,rapolat,ion t,o the st,antlartl st,at,c ~voiild i)c sirnplc. This is invariably t,hc case for rcactions involving ions of high charge. Prccisc t,hcrrnodynarnic information for t,llcsc syst,cms can only bc oht,aincd in the prcscncc of an inert clcct,rolyt,c of sufficiently high conccnt,mt,ion. cnsiiring t,llat act,ivity fact,ors arc rcasonahly const,ant t,hronghoiit, the rncasiircmcnt,s. This appendix t1cscril)cs and illiist,rat,cs the rrlct,llod used in t,llis review for t,llc cxt,rapolat,ion of cxpcrirncnt,al cqllilihriiim data t,o zero ionic st,rcngt,h.

Tllc actirit,y factors of all t,llc spccics part,icipating in rcact,ions in high ionic st,rcngtll rrlcdia must he cst,imat,ctl in order t,o rcdiicc the thcrmotlynamic dat,a oh- taincd from t,llc cxpcrirrlcnt t,o t,llc st,antlartl st,at,c (I = 0). T\vo altcrnatirc rrlct,llods can bc llsctl t,o tlcscril)~ the ionic mctliiim tlcpcndcncc of cqllilihrillrn constants:

One mct,hotl takes into account the indiritl~lal charact,crist,ics of t,llc ionic rncdin by using a rncdinrn dependent cxprcssion for t,hc act,ivit,y cocfficicnt,~ of the spccics involvcd in the cqnilibrinrn rcact,ions. The rncdinrn tlcpcndcncc is dcscril~cd by virial or ion int,craction cocfficicnts as used in the Pit,zcr cqiiations and in t,llc specific ion int,cract,ion t,hcory.

The other mct,hotl llscs an cxt,cntlcd Dcl~yc-Hiickcl cxprcssion in ~vhich t,hc ac- t,ivity cocficicnt,~ of rcact,ant,s ant1 prodnct,~ depend only on t,hc ionic cllarge and the ionic st,rcngt,h, hut it accounts for the rrlcdillrrl specific properties by introdiicing ionic pairing hct,\~~ccn the mctliiim ions and t,hc spccics involrctl in

t This rlppenclix cor~tair~s essentially t,lle t,ext written 1137 Grer~t,lle ancl \Tanner [92GRE/IT.&rllU] ~v11ic:h was also printed in t,lle llrar~illrr~ NE.&-TDU review as .&ppen(iix U [92GRE/FUG]. T l ~ e e(l~~ations presenter1 here are an esserltial part t,o t,lle review proce(illre ancl are reql~ired t,n use t,lle selecterl t l~errr~orl~~r~arr~ic V~L~IIPS. 1'1t~i11 rlifferer~ces 11et,sveer1 t,llis .&pper~rIix t~rlrl t , l~e orLe in Grerltl~e et (],l. [92GRE/FUG] are: Tat~le 0.1. Eq. (U.11) ancl Sections 0.1.2 arlrl 0.1.4. T l ~ e <:ontents of Tt~l~les 0 .3 and U.4 llas also 11een revised.

t,llc cqnilibrinrn rcactions. Earlier. t,his approach has hccn ~lsctl cxtcnsircly in marirlc chemistry. cf. Rcfs. [79JOH/PYT; 7911IL; iSPYT; 79\VHI].

Tllc act,ivity fact,or cst,imat,cs arc t,hns i)ascd on t,llc iisc of Dcl~yc-Hiickcl t,ypc cqiiations. The ~'cxt,cndcd" Dchyc-Hiickcl cq~lat,ions arc cit,hcr in t,llc forrrl of spccific ion irlt,cractiorl rrlctllods or t,hc Davics cquat,ion [6%D.I\.']. Ho\vcvcr, t,llc Davics cqiiation sllo~lld in gcncral not he ~lsctl at ionic st,rcrlgt,lls larger t,llan 0.1 rrlol.kg-l. Tllc mct,hotl prcfcrrctl in the NE.$ Tllcrmocllcrrlical Dat,a Base rcric\v is a mctliiim-dcpcndcnt cx- prcssiorl for the act,ivit,y cocfficicnt,~, \vhich is t,hc specific ion int,cractiorl t,llcory in the forrrl of t,llc Br~~~s tcd-Gi iggcn l~c i~~~-Sca t~r l~ i~~r t l approach. Ot,hcr forrrls of specific ion int,cractiorl mct,hotls (t,hc Pit,zcr and Brc\vcr ,'B-~nct,hotl" [GlLE\V/R.$N] arltl the Pit,zcr virial cocficicrlt mct,hotl [iSPIT]) arc t1cscril)ctl in the YE.$ Gnitlclincs for the cxt,rapolat,ion to zero ionic st,rcrlgt,ll [S%GRE/\V.$N].

Tllc spccific ion int,cractiorl rrlctllods arc rclial~lc for int,crcorrlparison of cxpcrimcn- tal tlat,a in a given conccnt,ration mngc. In many cascs t,llis incl~ltlcs tlat,a at rat,llcr low ionic st,rcngt,hs. I = 0.01 t,o 0.1 11, cf. Figure B.1. \vhilc in ot,hcr cases; notably for cations of high charge (2 +4 and 5 4 ) , t,llc lo~vcst available ionic st,rcngt,h is oft,cn 0.2 hI or higher, sec for cxarnplc Figures \'..l2 and \".l3 in [92GRE/FUG]. It is rcasonablc t,o assnrnc t,hat the cxt,rapolatcd cqiiilil)ri~nn const,ant,s at I = 0 arc more precise in t,llc forrrlcr than in t,hc lat,t,cr cascs. Tllc cxt,rapolation crror is composctl of two parts, one tl~lc to cxpcrimcrlt,al crrors. the ot,hcr tl~lc to rrlodcl crrors. Tllc rrlodcl crrors sccm t,o bc rather small for rnany syst,cms. lcss t,llan 0.1 nnit,s in log,, h'". For rcactions involving ions of high charge; nrhich arc cxt,cnsivcly hydrolysctl, one cannot, pcrforrn cxpcrirncnt,~ at loxv ionic st,rcngt,hs. Hcncc. it is impossible t,o cst,imat,c the cxt,rapolat,ion crror. This is true for all rrlct,llods used t,o cstirrlat,c actirit,y corrections. Systcrnat,ic motlcl crrors of this type arc not incl~ltlcd in t,hc nnccrt,aint,ics assigned to the sclcctcd tlat,a in t,his rcvic\v.

It slloiild i)c crrlpllasiscd t,hat t,hc specific ion intcract,ion rrlodcl is approzinrcxte. hlotlifying it. for cxarnplc by int,rodncing t,hc cqiiations snggcst,cd by Ciavatt,a [90CI.$, Eqs. (8 10)] (cf. Scct,ion B.1.4). nro~lld result in slight,ly diRcrcnt ion int,cractiorl coefficient,~ and cqnilibrinrn const,ant,s. Both rrlctllods proritlc an internally consist,crlt, set of ~~a lncs . H o \ ~ ~ c ~ ~ c r , t,llcir ahsoliit,c valiics rnay differ somc\vhat. Grcrlt,hc et (11.

[92GRE/FUG] cst,irnatc t,hat t,hcsc tliffcrcnccs in gcncral arc lcss t,harl 0.2 nnit,s in log,, K", i.e., approxirnatcly l k.J . rnol-' in derived &G: ~~a lncs .

B.1. The specific ion interaction equations

Tllc Dcbyc-Hiickcl tcrm, n~hicll is t,llc dorrlinarlt tcrm in t,hc cxprcssion for t,hc act,ivit,y cocficicrlt,~ in tlilntc solution; accounts for clcctrost,at,ic, non-specific long-range in- tcmct,ions. .It higher conccnt,rations short range. non-clcctrost,at,ic int,cractiorls have to i)c t,akcn into accoiint,. This is nsiially done by adding ionic st,rcrlgt,ll dependent tcrrrls to t,llc Dcbyc-Hiickcl cxprcssion. This rrlct,llod was first ontlincd by Br~ns tcd [22BRO, 22BR021; and clahorat,cd by Scat,chard [36SC.I] and Gnggcnhcim [66GUG]. Tllc two hasic ass~lrnpt,ions in the specific ion intcract,ion t,hcory arc t1cscril)cd bclo~v.

Assumption 1: Tllc actirit,y coefficient :, of an ion j of charge 2, in t,llc sol~lt,ion of ionic st,rcngt,h I,,, may bc tlcscribctl by Eq. (B. l ) .

loglo % = -2;D + X ~ ( j , k , z , , , ) l l l k (B.1)

D is t,llc Dcbyc-Hiickcl tcrm:

1 I,,, = - X rra,z:

2 ,

-4 and B arc const,ant,s nrhich arc tcrrlpcrat,~lrc and pressure dependent. and (I,,? is an ion size pararnct,cr ("dist,ancc of closest approach) for the hytlmt,ctl ion j . Tllc Dci)yc-Hiickcl lirrlit,ing slope; A. has a valiic of (0.509 * 0.001) kg1/" mol-'/%t, 25°C and 1 imr. (cf. Scct,ion B.1.2).

Tllc tcrm Brrj in t,hc dcnorrlinat,or of t,hc Dcbyc-Hiickcl tcrm has bccn assigned a val~lc of Bnj = 1.5 kg1/" ~rnol-'/%at 25°C and 1 bar, as proposctl by Scatchard [76SC.%] arltl accepted by Ciavatt,a [80CI.%]. This vah~c has i)ccn fo~lrltl t,o minimise; for scvcral species. t,hc ionic strength tlcpcndcncc of E ( ~ , ~ , I , , , , ) I)C~U~CCII I,, = 0.5 111

and I , = 3.5 m. It sho~lld bc mcrlt,ioncd t,hat sorrlc aiit,llors have proposctl diffcrcrlt, T ~ ~ ~ I I C S for Bnj. ranging from B(],,? = 1.0 [35GUG] to Bnj = 1.6 [6%\Y%S]. Ho\vcvcr, the pararrlctcr Bnj is crnpirical and as such corrclat,cd t,o t,llc val~lc of E ( , , ~ , ~ , , , ) . Hcncc. this variety of valiics for B(],,? does not rc~)rcscnt a11 ii~~ccrtai~lt,y range, i~ i i t rat,llcr irltlicat,cs t,llat scvcral diRcrcnt sct,s of Brrj and E ( ~ . ~ , I , , , ) may describe cq~lally ~ ~ ~ 1 1 the cxpcrirncnt,al mean act,ivit,y cocficicrlt,~ of a given clcct,rolyt,c. Tllc ion intcract,ion cocficicrlt,~ at 25°C listed in Tables B.3 t,hrongh B.5 have t,ll~ls t,o i)c ~lsctl ~vit,ll Bnj = 1.5 kg1/"

Tllc snrnrnation in Eq. (B.l) cxt,crltls over all ions k prcscrlt in soliit,ion. Their rnolalit,y is tlcnotcd ribii. arltl t,hc specific ion int,cractiorl pamrnctcrs, E ( ~ , ~ , ~ , , , ) . in general depend only slight,ly on the ionic st,rcngt,h. Tllc conccntrat,ions of tllc ions of t,hc ionic rrlcdi~lrrl is oft,cn \'cry much larger than t,hosc of tllc rcact,ing spccics. Hcncc, the ionic rrlcdi~lrrl ions will make t,llc main cont,rib~lt,ion to the val~lc of log,, ;!, for t,hc reacting ions. This fact oft,crl rrlakcs it possii)lc t,o simplify the siimrrlat,ion C , ~ ( ~ . ~ , ~ , , , , ) i r ~ ~ SO

that only ion irlt,cract,ion cocfficicnts i)ctn~ccn t,hc participating ionic spccics and the ionic rncdinrn ions arc inclndctl, as sho~vn in Eqs. (B.4) t,o (B.8).

Assumption 2: Tllc ion intcract,ion cocfficicnts E ( , , ~ , ~ , , , ) arc zero for ions of t,llc same cllarge sign and for iinchargcd spccics. Tllc mt,ionalc i)chintl t,llis is that E . \vhich t1cscril)cs specific short,-range intcract,ions; rrliist, bc small for ions of the sarnc charge sirlcc t,llcy arc iis~lally far fiorn orlc anot,hcr diic to clcctrost,at,ic rcpiilsion. This holds t,o a lcsscr cxt,crlt also for ~lnchargctl spccics.

Eq. (B.l) will allo\v fairly acciirat,c cstirrlat,cs of t,hc act,ivity cocficicrlt,~ in rrlixtiircs of clcct,rolyt,cs if the ion intcract,ion cocfficicnt,~ arc kno\~rn. Ion int,craction cocficicnt,~ for simple ions can bc oht,aincd from tabnlat,cd tlat,a of rncan act,ivit,y cocfficicnt,~ of st,rong clcct,rolyt,cs or from the corresponding osmot,ic cocfficicnt,~. Ion intcract,ion cocficicrlt,~ for cornplcxcs can cit,llcr bc cst,irnatcd from t,llc cllarge ant1 size of the ion or tlct,crrrlinctl cxpcrirncnt,ally from the variat,ion of the cqnilibrinrn const,ant nrit,h the ionic st,rcngt,h.

Ion intcract,ion cocficicrlt,~ arc not st,rict,ly const,ant l)iit rnay vary slight,ly ~vit,ll the ionic st,rcngt,h. The cxt,cnt of t,llis variation tlcpcntls on t,hc charge type and is small for 1:l; 1:2 ant1 2:l clcct,rolyt,cs for rrlolalitics less than 3.5 m. Tllc conccnt,ration tlcpcndcncc of the ion intcract,ion cocficicnt,~ can t,hns oft,cn he ncglcct,cd. This point urns crrlpllasiscd by Gllggcrlllcirrl [66GUG], \17ho has presented a co11sitlcral)lc arrlollrlt of cxpcrirncnt,al mat,crial siipport,ing this approach. Tllc conccnt,rat,ion dcpcndcncc is larger for clcct,rolyt,cs of higher charge. In ortlcr to accllmt,cly rcprotlllcc their act,ivity cocficicnt dat,a, conccnt,ration tlcpcndcnt ion int,cract,ion cocficicnt,~ have t,o l)e 11setl; cf. Lc\vis, Randall. Pit,zcr and Brc~vcr [61LEIV/R.%N]. Bacs ant1 hlcsrrlcr [76B.%E/hIES]. or Ciavat,t,a [80CI.%]. By iising a more claborat,~ virial expansion. Pit,zcr and co-~~wrkcrs [73PIT. 73PIT/hl.$Y. 74PITIKII1, 74PIT/IIAlY, %PIT, 76PITISIL; 78PIT/PET. 79PITI have rnanagcd t,o dcscril~c rncasiircd act,ivity cocficicnt,s of a largc 111lrnl)cr of clcct,rolyt,cs ~vit,ll high precision over a largc conccnt,ration range. Pit,zcr's motlcl gcncrally cont,ains tllrcc paramct,crs as corrlparcd to one in the specific ion int,craction t,hcory. Tllc nsc of the tl1col.y requires the kno\vlctlgc of all tllcsc pamrnctcrs. Tllc dcrivat,ion of Pit,zcr cocfficicnts for Inany corrlplcxcs such as those of t,llc actinitlcs n~ollld rcqnirc a very largc amount of addit,ional cxpcrimcnt,al work. sincc no data of t,llis t,ypc arc cnrrcnt,ly availahlc.

Tllc in ~vhich t,llc actirit,y cocficicnt corrections arc pcrformctl in this rcric\v accortling t,o t,hc specific ion int,craction t,hcory is illustrat,cd hclo\~r for a general case of a cornplcx forrrlat,ion rcact,ion. Charges arc omit,tctl for hrcvit,y.

Tllc format,ion const,ant of II,,L,(OH),,,, ';i/,,,,,,,. dct,crrrlinctl in an ionic rncdinrn (1:l salt NX) of t,hc ionic strength I , ; is rclat,cd t,o t,hc corrcspontling valiic a t zero ionic st,rcngth. 'v," ;,,; , ; by Eq. (B.3).

*, * 0 log,, 1.1, ,,,,,, = log,, 1.1, ,,,,,, + nr log,, ;!M + 11 log,, :L + n log,, (IH~o

- log,, s.,,,,,, - log,, ;!H+ 03.3)

Tllc subscript (q,n,rra) dcnot,cs t,llc cornplcx ion II,,L,(OH),. If the conccnt,rations of N ant1 X arc rrlllcll greater t,han the conccntrat,ions of h1; L; hI,,,L,(OH)n, and H+; only t,llc rrlolalit,ics r r r ~ and rrrx have t,o he t,akcn into account for the calc~llation of the term 1,. ~ ( ~ , ~ , ~ , , ) r r ~ ~ in Eq. (B.1). For cxarrlplc, for t,hc act,ivity ~ocff i~ icnt of the rnctal cat,ion 11, T ~ ~ . Eq. (B.4) is oht,aincd at 25°C and 1 bar.

Urldcr thcsc contlit,ions. I,, % rrrX = r r k ~ . Sllhstitiit,ing the log,, ;tj ~ ~ a l n c s in Eq. (B.3) with t,hc corresponding forrrls of Eq. (B.4) and rearranging lcntls to

2 g I q m - ~z D - n log,, (Ixn() = - A E I , ~ 03.5)

(B.6)

(B. 7)

Hcrc (rrazhl - q t ~ - X) , 2x4 and z~ arc the cllargcs of the corrlplcx RI,,,Lq(OH)n,. the rnctal ion RI and t,llc ligand L. rcspcct,ivcly.

Eqnilibrin i~lvolri~lg H20(1) as n rcnct,ant or product rcqnirc a correction for t,llc actirit,y of at at cr. OH,(). The act,ivit,y of ~ ~ ~ a t c r in an clcct,rolyt,c rrlixtiirc can he cnlcnlat,cd as

soli it,^ species k nrit,h rnolnlity r r a k present in t,llc soliition. In the prcscncc of an ionic rrlcdillrrl NX in dorrlinnrlt conccnt,mt,ion. Eq. (B.9) can bc sirnplificd by ncglccting the contril)iit,ions of all rrlinor spccics, i .e.; the rcact,ing ions. Hcncc, for n 1:l clcct,rolyt,c of ionic st,rcrlgt,ll I,, zz rnsx; Eg. (B.9) bccorncs

-2rnNx'D log,, OH,^ = i11(ln) X 55.51'

I'aliics of osrrlotic cocfficicnts for single clcctrolytcs have l)ccn cornpilcd by vnrioiis n~lt,llors, e.g.. Rollinson and St,okcs [59ROB/STO]. Tllc act,ivit,y of ~ ~ ~ a t c r can also i)c calciilnt,ctl frorn t,llc kno~vn act,ivit,y cocfficicnts of t,llc dissolved spccics.

In the prcscncc of an ionic rncdinrn N,,+X,, of a conccnt,rnt,ion rrliich larger t,hnrl those of t,llc reacting ions, t,llc osrrlotic cocficicrlt can he calclllatcd accortling t,o Eq. (B . l l ) (cf. Eqs. (23-39); (23-40) and (-44-2) in [GlLE\V/R.4N]).

wcrc U+ and 1 1 arc t,hc nnrnhcr of cations and anions in the salt forrrliiln (a+z+ =

a-z-). and in t,llis case

Tllc actirit,y of nrat,cr is obtaincd by inscrt,ing Eq. ( B . l l ) int,o Eq. (B.lO). It shonltl bc rrlcntiorlcd t,hat in rrlixctl clcct,rolyt,cs nrit,h several corrlponcnts at high conccnt,rations; it is ncccssary t,o nsc Pit,zcr's cqnat,ion t,o calc~~lat,c t,hc act,ivit,y of \~~a tc r . On the ot,hcr hand. is 11car C O I I S ~ , ~ I ~ ~ , (and equal t,o 1) in most cxpcrimcrlt,al st,udics of cq11ilil)ria in diliit,c aqiicolls soliit,ions. \vhcrc an ionic mctliiim is used in large cxccss ~vitll respect t,o the rcact,ant,s. Tllc rncdinrn clcctrolyt,c tlliis tlct,crrrlincs t,llc osmot,ic cocficicrlt of the solvent,.

In rlat,~lral ~vatcrs t,hc sit,nat,ion is similar; t,llc ionic strength of most surface nrat,crs is so loxv t,llat the act,ivit,y of H20(1) can i)c set equal t,o nnit,y. -4 corrcct,ion may bc ncccssary in t,llc case of sca\vat,cr, ~vhcrc a s~lficicnt,ly good approximat,ion for the osrrlotic coefficient may he obtaincd by corlsitlcring KaC1 as t,hc tlomirlant clcct,rolyt,c.

In rrlorc cornplcx sol~lt,ions of high ionic st,rcngt,hs \vith rrlorc t,llan one clcct,rolyt,c at sigrlificarlt conccntrat,ions. e.g., (Na+. hIg2+, C2+)(Cl- , SO:-); Pit,zcr's cqiiation (cf. [92GRE/1\:.4X]) may he iiscd to cstirrlat,c t,hc osmot,ic cocficicrlt,; the ncccssary irlt,cractiorl cocfficicnts arc kno~vn for rrlost syst,crns of gcochcmical interest,.

Kot,c t,llat in all ion irlt,cract,ion approaches. t,llc cqiiation for rncan act,ivity cocfficicrlt,~ can he split up to give cqnat,ions for convcnt,ional sirlglc ion act,ivity cocficicrlt,s in mixt,urcs. e.g., Eq. ( 1 ) The lat,t,cr arc st,rict,ly valid only \vhcn ~lsctl in cornhinations nrhich yield clcct,ronc~lt,ralit,y. Th~ls, while cstirrlat,ing rrlcdi~lrrl cffcct,s on st,andard pot,cnt,ials, a cornl)inat,ion of rcdox cqnilihria \vith H+ + c + 4 H2(g) is ncccssary (cf. Exarnplc B.3).

I'aliics of t,llc Dcl~yc-Hiickcl pararnct,crs A and B in Eqs. (B.2) and (B. l l ) arc listed in Tahlc B.l for a fc\v t,cmpcmt,urcs at a pressure of 1 bar hclo\~r 100°C and at the st,carn sat,uratcd pressure for t 2 100°C. The val~lcs in Table B. l rnay i)c calc~llatcd fiorn the st,at,ic diclcct,ric const,arlt and the tlcnsit,y of \vater as a fi~nct,ion of tcrrlpcrat,~lrc and prcssiirc. arltl arc also foiind for cxarnplc in Rcfs. [74HEL/KIR%, 79BR.%/PIT, 81HEL/KIR, 84.4XA1/.4TK, 90.4RC/I\:.4X].

Tllc t,crrrl B(],,? in the dcrlomirlat,or of the Dchyc-Hiickcl term D. cf. Eq. (B.2); has bccn assignctl in t,llis rcvic\v a val~lc of 1.5 kg1/" ~rnol-'/~ at 25°C arltl 1 bar, cf. Scctiorl B.1.1. -4t t,crnpcratiircs and pressures other t,llan the rcfcrcncc and standard st,atc, the follo\ving possihilit,ics exist,:

The ~ralnc of B(],,? is calcnlat,cd at each tcrrlpcratiirc assiimirlg t,llat ion sizcs arc independent of tcrrlpcrat,~lrc arltl usirlg t,hc val~ics of B list,ctl in Tal)lc B.1.

The ~ralnc of Brrj is kept constant at 1.5 kg1/" rrn~l-'/~. Diic t,hc variation of B nrit,h t,crnpcratiirc. cf. Tal)lc B. l , t,llis irrlplics a t,cmpcmt,urc tlcpcndcncc for ion size pamrnctcrs. .4ssnrning t,hat ion sizcs arc in reality const,ant,, t,llcn it is sccn t,hat this simplification int,rotl~lccs an crror in D ~vhich incrcascs \vit,ll t,cmpcmt,urc and ionic st,rcrlgt,ll (t,llis crror is lcss t,llan *0.01 at t 5 100°C arltl I < 6 rn. and lcss t,llan f 0.006 at t 5 50°C and I 5 4 rn).

Table B.l: Dcbyc-Hiickcl constants as a fiinctiorl of t,crrlpcrat,~lrc at a prcssiirc of 1 bar l>clo\~r 100°C and a t the stcarrl sat,~lrat,ctl pressure for t 2 100°C. Tllc ~lnccrt,ainty in the A pararnct,cr is cstirrlat,cd by t,his rcric\v to bc f 0.001 a t 25"C, and f 0.006 at, 300°C. \vhilc for t,hc B pararrlctcr the cst,imat,ctl iinccrt,aint,y ranges fiorn f 0.0003 at, 25°C t,o *0.001 a t 300°C.

The ~ralnc of Brrj is calcnlat,cd at each t,cmpcrat,~lrc assiimirlg a given tcrnpcra- t,urc variation for (I,,? and iising t,llc valiics of B list,cd in Table B.1. For cxarnplc, in t,llc aqncoiis ionic rrlodcl of Hclgcson e t 111. [88T.%X/HEL, 88SHO/HEL, 89SHO/HEL, 89SHO/HEL%] ionic sizes follow the relation: c],,?(T) = nj(298.15 K. 1 bar) + z j lg(T,p) [SOOEL/HEL], ~vllcrc y(T,p) is a tcrnpcratiirc arltl pressure fiinctiorl nrhich is tabnlat,cd in [88T.%N/HEL. 92SHO/OEL];

t

("C)

0 5

10 15 20 25 30 35 40 50 75

100 125 150 175 200 250 300

and is approxirnatcly zero a t tcrrlpcrat,~lrcs l>clo\~r 175°C

Tllc valiics of E ( ~ , ~ , ~ , , , ) ol)t,ainctl ~vit,ll the rrlct,llods t1cscril)cd in Scct,ion B.1.3 at, tcrnpcratiircs other than 25°C will dcpcrltl on t,llc ~ n l ~ l c adopt,ctl for B(],,?. .%S long as a consist,cnt approach is follo\~~ctl, ~ ~ a l n c s of E ( ~ , ~ , ~ , , , ) absorb the clloicc of B(],,?:,, and for rnodcratc tcrrlpcrat,~lrc intervals (bct,~vccn 0 arltl 200°C) t,llc choice Brrj =

1.5 kg1I2 . 11101-~/~ is the sirrlplcst one and is rccorrlrrlcrltlcd by t,llis rcric\v. Tllc variat,ion of E ( ~ , ~ , ~ , , , ) ~vit,ll t ,cmpcrat,~~rc is disc~~sscd by Lc~vis. Randall. Pit,zcr

and Brc~vcr [61LE\V/R.%N]; LIillcro [iSLIIL], Hclgcson et 111. [81HEL/KIR, 90OEL/HEL]. Giffiut et al. [93GIF/\TT2] and Grcnt,llc and Plyas~lnov [94GRE/PLY] Tllc al)solntc ~ ~ a l n c s for t,llc reported ion int,cractiorl paramct,crs diffcr in tllcsc stiidics due t,o t,hc fact that t,hc Dcbyc-Hiickcl t,crrrl used by t,hcsc authors is not cxact,ly the

P (bar)

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.013 2.32 4.76 8.92

15.5 29.7 85.8

A (kg. rnol-'14

0.491 0.494 0.498 0.501 0.505 0.509 0.513 0.518 0.525 0.534 0.564 0.600 0.642 0.690 0.746 0.810 0.980 1.252

B X l()-'" (kg; . rnol-4 . rn-l)

0.3246 0.3254 0.3261 0.3268 0.3277 0.3284 0.3292 0.3300 0.3312 0.3326 0.3371 0.3422 0.3476 0.3533 0.3593 0.365 0.379 0.396

sarnc. Nc~~crthclcss, corrlrrlon to all t,hcsc stiidics is the fact t,llat valiics of (ac/dT), arc iis~lally 5 0.005 kg.rnol-'.E;-' for t,crnpcratiircs hclo\v 200°C. Tllcrcforc, if val~lcs of E ( ~ , ~ , Z , , , ) ol)t,ainctl at 25°C arc iiscd in the t,cmpcrat,~lrc range 0 to 50°C t,o pcrforrn ionic st,rcrlgt,ll corrections, t,hc error in (log,, ;tj)/I,, will bc 5 0.13. It is clcar t,llat in order to rctl~lcc the iinccrtaint,ics on solubility calciilat,ions at t # 25"; st,udics on the \p ,niat,ion , of ~ ( ~ ; ~ , ~ , , , ) - v a l i i c s 1vit11 t,cmpcrat,~?rc shoiild he il~ltlcrt,akc~~.

B. l . 7. I Estirraation fmrn rnecxrr actiuity c o ~ ~ f i c i e r r t data

Example B. l :

Tllc ion irlt,cract,ion coefficient E(H+,(:~-) can bc obtaincd from pnblishcd ~ ~ a l n c s of ( 1 l . irLH(:l.

By plot>ting 1ogI0:+;H(:1 + D 11,s. i i ~ ~ ( : l a st,raigllt line ~vit,ll t,hc slope E(H+.(:~-) is oht,ainctl. Tllc dcgrcc of 1incarit)y shonltl in it,sclf indicate the range of validity of the specific ion intcract,ion approach. Osmot,ic cocfficicrlt dat,a can i)c treated in an analogo~ls \!,ay.

Example B.2:

Eq~lilihri~lrn constants arc given in Tal)lc B.2 for the rcactiorl

Tllc follo~ving formula is dctl~lccd fiorn Eq. (B.5) for t,llc cxtrapolat,ion t,o I = 0:

log,, 'l1 + 4D = log,, ,l," - AEI, (B.13)

Tllc linear regression is done as dcscribctl in -4ppcndix C. The follo\ving rcsiilts arc oht,ainctl:

log,, 9," = 0.170 lt 0.021 Ac(B.12) = ( 0 . 2 4 8 lt 0.022) kg . rrlol-l

Tllc cxpcrirncntal data arc depicted in Figiirc B.1.11rllcrc t,hc dashctl area represents the ~lnccrt,ainty range t,llat is obtaincd by iising the rcsnlt,s in log,, 9," and AE arltl correcting back to I # 0.

Example B.3:

TVhcn iising t,hc specific ion irlt,cract,ion theory, t,hc relationship bct,~vccn the rcdox pot,cnt,ial of t,hc coilplc UO$+/U4+ in a mctliiim of ionic strength I,,, arltl t,llc corrcspontling q~lant,it,y at I = 0 shonltl i)c calcnlat,cd in t,llc follo\~.ing \!,ay. Tllc rcactiorl

Tahlc B.2: Tllc prcparat,ion of t,hc cxpcrirncntal cq~lilil)riiim const,arlt,s for the cxt,rapolat,ion t,o I = 0 ~vi th the specific iorl int,cractiorl mct,hod at 25°C arltl 1 bar. according to Rcactiorl (B.12). Tllc linear regression of this set of tlat,a is sho117n in Figiirc B.1.

0.1 -0.17 f 0.10 -0.174 0.264 i 0.100 0.2 -0.25 f 0.10 -0.254 0.292 i 0.100 0.26 -0.35 f 0.04 -0.357 0.230 i 0.040 0.31 -0.39 f 0.04 -0.397 0.220 i 0.040 0.41 -0.41 f 0.04 -0.420 0.246 i 0.040 0.51 -0.32 f 0.10 -0.331 0.371 1 0 . 1 0 0 0.57 -0.42 f 0.04 -0.432 0.288 i 0.040 0.67 -0.34 f 0.04 -0.354 0.395 i 0.040 0.89 -0.42 f 0.04 -0.438 0.357 i 0.040 1.05 -0.31 f 0.10 -0.331 0.491 1 0 . 1 0 0 1.05 -0.277 i 0.260 -0.298 0.525 i 0.260 1.61 -0.24 f 0.10 -0.272 0.618 i 0.100 2.21 -0.15 f 0.10 -0.193 0.744 i 0.100 2.21 -0.12 f 0.10 -0.163 0.774 i 0.100 2.82 -0.06 f 0.10 -0.021 0.860 i 0.100 3.5 0.04 f 0.10 -0.021 0.974 i 0.100

(a) Eq~~il i t ) r i l~rr~ corlstarlts for React,ior~ (0.12) with assigned ~m<:ertaintirs, <:orrect,ecl t,o 25°C \%-here ne<:- essary.

(1)) Eq~~il i t ) r i l~rr~ corlstarlts corre<:te(i frorr~ rnolarity t,o rr~olarit,y ilnit,s. as rlrscri1)erl in Se<:tion 11.2.

Figure B.l : Plot of log,, i11+4D ~ J S . I , for Rcact,ion (B.12); U O $ + + C l + U02C1+ at, 25°C and 1 bar. Tllc st,raight line sho\vs t,llc result of the ~vcight,ctl linear regression, and the tlot,t,ctl lirlcs rcprcscrlt the ~lnccrt,ainty rarlgc ol)t,ainctl hy propagating the rcs~~lt, ing ~lrlccrt,aintics at I = 0 hack t,o I = 4 m.

I I I I I I I - -

- -

-

-

-

- log,, p," = 0.17 * 0.0%

_1c = -0.25 * 0.02 -

I I I I I I I

in t,hc galvanic cell

P t H2(g) H+ U();+, U'+ I Pt,

is

U()$+ + H2 (g) + 2 H+ + U'+ + 2 H20(1). (B.14)

For t,llis rcact,ion

2 (IT;" +X OH2()

log,, K" = log,, ) > fl,JO;+ X OH+ X !H2 ( 2

f H 2 N 1 ) ~ ~ at, reasonably 10117 part,ial pressure of H2(g); ( IH~o N 1. and

Hcnrc.

log,, K" = log,, h' - 10D

+ ('(TJ4+.(:10;) '(TJo:+.(:~o;) 2 ' ( ~ + , ( : ~ ~ ~ ; ) ) nL(:l~); . (B.15)

Tllc relationship hct,\~~ccn the cqllilihrillrn constant ant1 t,hc rctlox potential is

E is t,llc rctlox potential in a rrlcdillrrl of ionic strcngt,h I. E" is t,hc corresponding st,andard pot,cnt,ial at I = 0. and rr is the nnrnhcr of t,ransfcrrcd clcctrons in the reaction consitlcrcd. Co1nl)ining Eqs. (B.15); (B.16) and (B.17) ant1 rearranging tllcrrl lcatls to Eq. (B.18).

For rr = 2 in t,llc prcscnt example and T = 298.15 K, Eq. (B.18) bccorncs

In general ho\~~crcr, formal pot,cnt,ials arc rcport,ctl \vith rcfcrcncc t,o t,llc standard hydrogen clcct,rodc, cf. Scct,ion 11.1.6.5, as cxcrnplificd in Tahlcs l'..% and \".3 of the nraniiim NE.$ rcvic\v [92GRE/FUG]. In t,hat case, t,llc H+ appearing in t,llc rcdiiction reaction might already bc in standard conditions. For cxarnplc, cxpcrirncntal dat,a arc avai1al)lc on t,hc forrnal pot,cnt,ials for reactions

Tllc cations in rcact,ion (B.14) rcprcscnt aqiicolls species in t,hc ionic rncdia iiscd during the cxpcrimcnt,~. H o \ ~ ~ c ~ ~ c r , in reaction (B.21) H+ rcprcscnt,~ the cat,ion in the st,andard hydrogcn clcct,rotlc. and t,llcrcforc it is already in st,andard condit,ions, and its act,ivity cocfficicnt rrliist not bc incllltlcd in any cxt,rapolat,ion to I = 0 of cxpcrirncnt,al valiics for rcact,ion (B.20).

B.1.4. On tlae rno,gnit?rrle of iorr i n t e m c t i o n coc?fici(?nt,s

Ciavatt,a [80CI.l] rrladc a cornpilat,ion of ion irlt,cract,iorl cocficicrlt,~ for a large niiml~cr of clcct,rolyt,cs. Sirrlilar dat,a for cornplcxat,ions of varioiis kirltls wcrc reported by Spahin [83SP.4] and Fcrri, Grcrlt,hc arltl Sal~rat,orc [83FER/GRE]. Thcsc and some othcr tlntn for 25°C ant1 1 hnr have 11ccn collcctcd ant1 arc listed in Scction B.3.

It is 011~~ioiis from t,llc tlat,a in tllcsc t,ahlcs t,hat the chargc of an ion is of great, irnportancc for the rnagnit,~ltlc of t,hc ion intcract,ion cocficicnt. Ions of the same chargc t,ypc have sirrlilar ion int,cractiorl cocficicnts ~vit,ll a given co~lnt,cr-ion. Based on t,hc t,ah~llatcd tlat,a. Grcrlt,hc et (11. [92GRE/FUG] proposed that it is possiblc t,o cstirnatc, nrit,h an crror of at rrlost *0.1 in E ; ion i~lt,cract,ion cocfficicnt,~ for cases ~vhcrc t,llcrc arc insnficicnt cxpcrirncnt,al dat,a for an cxtrapolat,ion t,o I = 0. Tllc crror t,llat is matlc by t,his approximation is cstirrlat,cd t,o *0.1 in 1' in most cases. based on comparisorl ~vit,ll 1' ~ ~ a l n c s of various rcact,ions of the same chargc t,ypc.

Sirlcc t,hcrc arc no int,cractiorl cocficicrlt tlat,a for arncricillrn species. usirlg the argiimcrlt,~ presented in the previous paragraph. t,llis rcvic\v cstirrlat,cs t,llc follo~ving irlt,cractiorl cocfficicnts at 25°C arltl 1 bar,

Estimatcs of ion interaction cocficicrlts for othcr arncrici~lrn romplcxcs ~vcrc also rrlndc frorn ions of the same charge, i.e.

etc. Similarly. for negatively chargctl aqllcons corrlplcxcs of americium this rcric\v cstirnatcs:

Ciavat)t>a [90CI.I] has proposed an altcrnatirc rrlct,hotl t,o cstirrlat,c valiics of E for a first or sccond complex, AIL or ML2, in an ionic rncdia NX; accordirlg t,o the follo\~.ing rclat,ionships,

Ciavatt,a obtained [9OCI.4] an axrcmgc dcriat,ion of *0.05 kg.rno1-l i)ctn~ccn E-cstirnat,cs accortling t,o Eqs. (B.22) and (B.23) and t,hc E-va111es at 25'6 obtained frorn ionic st,rcngtll dcpcntlcncy of cqllilihrillrn const,ant,s.

B.2. Ion interaction coefficients ~ i e ~ s ~ r s equilibrium constants for ion pairs

It can be sllo1v11 t,hat t,hc virial t,ypc of act,ivit,y cocfficicnt cqllat,ions ant1 the ionic pairing rrlodcl arc cqiii~i~,lcnt provided t,llat t,llc ionic pairing is weak. In tllcsc cascs the dist,inct,ion bct,\~~ccn complcx forrnation and act,ivit,y cocfficicnt variations is difficiilt or c ~ ~ c n arbit,mry unless independent cxpcrirncnt,al cvidcncc for complcx forrrlat,ion is available. e.g.; fiorn spcct,roscopic tlat,a. as is t,llc case for t,hc \vcak iiraninrn(\'I) cllloritlc cornplcxcs. It slloiild i)c not,ctl t,hat the ion intcract,ion cocfficicnts cxi~,lnat,ctl and tabnlat,cd by Ciavatt,a [80CI.%] wcrc ol)t,ainctl from cxpcrimcnt,al mean act,ivit,y cocfficicnt data \vithont taking irlt,o account corrlplcx format,ion. H o \ ~ ~ c ~ ~ c r , it is kno\vn that many of the rrlct,al ions list,ctl by Ciavat,ta form weak cornplcxcs \vitll cllloridc and nit,ratc ion. This fact is rcflcctcd by ion intcract,ion cocfficicnt,~ t,llat arc smaller than t,llosc for t,llc non-cornplcxing pcrclllorat,c ion, (:f. Tablc B.3. This rcvic~v t,akcs cllloritlc and nit,rat,c complcx forrnation int,o accollrlt nrhcn t,hcsc ions arc part of the ionic rncdinrn and llscs the ~ralnc of t,hc ion int,cract,ion coefficient E ( ~ ~ , , + , ( : ~ ~ ~ ) as a siibst,it,~lt,c for E(\,.,+.(:~-) and E( ,,,, + ,,,,; ) . In t,his nray, t,hc rncdinrn dcpcrltlcncc of the actirit,y cocfficicrlt,~ is t1cscril)cd nrit,h a cornl)inat,ion of a specific ion intcract,ion rrlodcl and an ion pairing rnodcl. It is evident t,hat t,hc nsc of NE.% rccorrlmcrltlcd dat,a wit11 ionic st,rcrlgt,ll corrcct,ion rrlodcls that tliffcr from t,hosc iiscd in t,llc cxi~,lnat,ion procedure can lead t,o inconsistcncics in t,hc rcsnlt,s of t,hc spcciat,ion calc~llations.

It slloiild be rrlcntioncd that complcx forrrlat,ion may also occur bct,\~~ccn ncga- tircly cllargcd corrlplcxcs and t,llc cat,ion of t,llc ionic rncdillrn. .%n cxarnplc is the st,abilisation of t,hc corrlplcx ion U O a ( ~ 0 : 3 ) ' j at high ionic st,rcngt,h, sec for cxarnplc Section \'..7.1.2.l.d (page 322) in t,hc llrarliiim rcvic~v [92GRE/FUG].

B.3. Tables of ion interaction coefficients

Tablcs B.3 tllroiigh B.5 contain the sclcct,ctl specific ion intcract,ion cocfficicnts iiscd in t,his rcvic\v. according t,o the spccific ion int,craction theory dcscribcd. Tal)lc B.3 contains cation intcract,ion cocfficicnt,~ nrit,h Cl-; ClO; and NO,, Table B.4 anion int,cractiorl cocfficicrlt,~ \vith Li+. nrit,h Na+ or XH: and \vith K+. Tllc cocfficicrlt,~ have t,llc iinits of kg . rrlol-l (m) and arc ~ralitl for 298.15 K and 1 bar. Tllc species arc ortlcrcd by charge and appear, \vithin each charge class. in st,andard ortlcr of arrangcrncnt,, cf. Scct,ion 11.1.8.

In sorrlc cases; the ionic intcract,ion can l)c l)ctt,cr tlcscribctl by assnrning ion intcrac- tion cocfficicnt,~ as fimct,ions of t,hc ionic st,rcngt,h rat,llcr than as constants. Ciavatt,a [80CI.%] proposctl t,llc use of Eq. (B.24) for cascs \vhcrc t,hc iinccrtaint,ics in Tablcs B.3 and B.4 arc *0.03 kg . rrlol-l or greater.

For t,llcsc cases; ant1 ~vhcn the nnccrt,aint,y can be irnprovcd nrit,h respect to the nsc of a constant valiic of E, t,llc valiics cl and ca gi~7c11 i11 Tablc B.5 sllonltl bc llsctl.

It shollld bc rlot,cd that ion int,craction cocfficicnts t,ablllatcd in Tablcs B.3 t,hrongh B.5 rnay also involve ion pairing cffcct,~, as dcscribcd in Section B.3. In direct corn-

parisons of ion int,cractiorl cocficicnt,s. or ~vhcn cst,irrlat,cs arc rnadc 1)y analogy, t,llis aspect must he t,akcn irlt,o acco~lnt,.

Tahlc B.3: Ion intcract,ion cocficicnts (k;y. rnol-l) at 25°C nrltl 1 bar for cnt,ions j wit,ll k = Cl-; ClOl and NO,. taken frorn Cinvatta [80CI.4] ~lrllcss irltlicnt,ctl ot,llcr~~risc. Tllc llrlccrt,aintics rcprcscnt t,hc 95% confidcrlcc lcvcl, rrlost of tllcrrl wcrc cstirnatcd by Ciavnt,ta [88CI.4]. The ion intcract,ion cocfficicnt,~ mnrkctl ~vit,ll t can bc dcscrihcd rrlorc acciirat,cly ~vit,ll an ionic st,rcrlgt,ll dependent filnct,ion, list,ctl in Tahlc B.5. .Is discnsscd in Scctiorl B.2, care shollld he t,nkcn \vllcn using t,llc cocficicrlt,s ~(\472+;(:1-) nrltl E ( ~ ~ ~ , , + , ~ ( ~ ? ) reported hy Ciavat,t,a [80CI.4], nrhich wcrc cxi~,lnnt,ctl ~vithont t,nking chloride and nlt,ratc corrlplcxnt,ion irlt,o accoiint,.

j k i -1

H+

YH: H2glY+ T1+ ZnHCO: CdCl+ CdI+ CdSCN+ HgCl+ Cn+ .$g+ YCO:

UO: UOaOH+ (U(12):3(OH): UF: UOaF+ UOaCl+ UOaC10: UOaBr+ UOaBrO: UOaIO: UOaN: UOaNO: UOaSCY+ YI,O: P i i O ~ .4rrl(OH): -4rnF:

Cl-

0.12 f 0.01

-0.01 * 0.01 -0.06 f 0.0%

o . % ( ~ )

0.81 f 0.17(':) 0.1 * 0.1(~) 0.04 f 0 . 0 7 ( ~ )

ClOT

0.14 f 0.0%

-0.08 * 0 . d

0 . 2 1 f 0.06t

0.25 f 0.0% 0.27 f 0.0% 0.31 f 0.0% 0.19 f 0.0% 0.11 f 0.01

0.00 f 0.01 0.17 f 0.04(") 0.26 f 0.03(':)

-0.06 f 3.7(') 0.45 f 0.15(") 0.1 * o . I (~ ) 0.29 f 0.05(") 0.33 f 0.04(':) 0.33 f 0.04(~) 0.24 f 0.04(~) 0.33 f 0.04(~) 0.33 f 0.04(~) 0.3 * 0.1(~) 0.33 f 0.04(~) 0.22 f 0.04(~) 0.25 f 0.05(') 0.17 f 0.05(') 0.17 f 0.04(j) 0.17 f 0.04(j)

NO,

0.07 * 0.01

-0.06 * 0.03t

-0.12 * 0.05t

0.51 * 1.4(') 0.41 * 0.2%(")

Tahlc B.3 (cont,in~lcd)

Foot,not,cs: (a) Taken frorr~ He(i11mcl [&SHED].

(1)) Taken frorr~ Riglet, Rot)oll<:h and I'itorge [89RIG/ROB], \%-here the folio\%-ing assl~rnptions mere made : c ( ~ ~ + , + , ~ ~ ~ , ; , X = 0.49 kg . rr~ol-l as

for ot,l~er (M"+, C10,) interactions, and c ( ~ ~ , ~ ; + , ~ ~ ~ , ) X E (p, , b ; + , ( , , m

2+ ,-, = 0.46 kg. 11101-'. c ( l , c ) 2 ,<,l( , (c) Evall~aterl in 1UE.4-TDB review on llrar~illrr~ tl~errnorlj~r~arr~ics

[92GRE/FUG], l~s i r~g c(,,(,;+,.u, = (0.46 f 0.03) kg. rr~ol-l. \%-here X = Cl-,

C104 ancl NO;, cf. Section 0.2. (11) Taken frorr~ Spa11i11 [83SP.4].

(e) Taken frorr~ Urllr~o [86BRU], rrl~ere t,lx following assl~rr~ptions \%-ere rnarle: E ~ ~ ~ ~ + , ~ ~ ~ , ; , = 0.30kg.rnol-' as for otl~er qjni+.clo,). C ( ~ ~ X + . ~ ~ - ) = 0.17kg.

rnol-' as for otl~er E ~ ~ , ~ ~ + , ( ~ ~ ) , ,Uo;) = 0.17 kg .rr~nl-' as f ~ r other

E j n j ~ + , u o ; ) .

(f) Estirr~at,ecl in NE.4-TDU review on llrar~illrr~ tl~errr~orlj~r~arr~ics [92GRE/FUG].

(g) Evall~aterl in 1UE.4-TDB review on l~rar~illrr~ t,herrno(iynarnics [92GRE/FUG] using c ( , ~ , + , ~ , ~ ~ - ) = (0.76 & 0.06) kg. 11101-'.

(h) Taken frorr~ Ferri e t al. [85FER/GRE]. (i) It is re<:allecl t l ~ a t tl~ese coefIi<:ients \%-ere r~ot llserl in the 1UE.4-TDB review

on l l r a r ~ i ~ ~ r r ~ t,herrnoclynarni<:s [92GRE/FUG] l~ecallse t,hey \%-ere evall~aterl t)y Ciarxtt,a [80CI.4] \%-it,hollt t,akir~g chloricle a1111 r~itrat,e corr~plexat,ion into ac<:olmt. Inst,eacl, Grer~t l~e e t 111. llserl - c ( , ~ ~ , ; + , . ~ ) = (0.46 f 0.03) kg . rr101-l,

for X = Cl-, C10; ar~rl NO;.

(j) Estirr~at,ecl in t l~ is review (p.322).

(k) Evall~aterl in t,l~is review (p.130).

+ X

+

f, ell

t t - m - N - m * * - - N

9 9 9 00 0

9 9 0 0

9 9 9 9 9 000 0 0

9 0

++I +I +I +I + I + + +I +I +I m m 0 4 m * A * 4 m X2 c c c C C C

c c C C

c 1 1 c c 000 0 C

c 0

I l l l l

- - - - - - - - - C C S S - -

U U t t & z e t e e . % t t ~ m ~ 2 ~ m ~ ~ m m X m - m m a m ~ ~ ~ m a ) o ) o ) o - ) o ) o ) o 10 ~2 c c c c c c c c c c c e c c c c c c c c c c c c e c c c o o o o o o o o o o o v 0 0 0000000 o o o v o o o

c c 0 0

a m d m d d m m m a d o a m o m m m m m r-ao+IomiQ m N 9 9 1 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 1 C C O C O C C O C O O C C 0 O O C C C 0 0 0 0 C C C 0 0 0 0

l l l l l l l 1 l 1 l 1 l l l l

t t t m h - + m h a h h a 9 C

9 99 9 C C C C

9 9 C C

9 C

9 C

+I +I ++I +I + I+ +I +I N C m m 13 13 m m m 9 0

v -!v v 0 00 0

9 9 0 0

9 0

9 0

l l

l C - z S

l

-4 l U

j k i -1

~ 2 0 : -

HPO:- CO:- SiO,(OH)S- Si,o:3(0~):- CrOj- UOaFj- U02 (SO4);- U02 (N,):- U02 (C0:3)$-

P(]:- S i , O t i ( ~ H ) ~ ~ - S~:~O.,(OH),:- Si4O./(OH).:- .4rri(C03)~-

r20$- Fc(C?J)g- u(CO:3)i- UOa ( ~ 0 : 3 ) : -

U02 ( ~ 0 : 3 ) 5 -

u(CO:3)E- (u(12)3(~~:3)ii-

(a) E l in [92GRE/FUG].

(1) ) Estirr~aterl in NE.i-TDU review on llrar~illrr~ t,herrno<lyr~arni<:s [92GRE/FUG].

(c) Frorr~ [80CI.i]. These vallles differ frorr~ tllose reporte(i in t l ~ e NE.&-TDD llrar~il~rr~ review [92GRE/FUG]. See the (lis<:~~ssion in Section D.4.

(cl) See the dis(:~issi~n in Section D.4. (e) Estirr~aterl in this review (p.322).

Li+

NE.&-TDD

Xn+

-0.08 f 0.05t -0.15 f 0.06t -0.08 f 0.03(") -0.10 f 0.07(") -0.15 f 0 . 0 6 ( ~ )

-0.06 f 0.04t -0.08 f 0 . 0 6 ( ~ ) -0.12 f 0.06(~) -0.1 * 0.1(~) -0.02 f 0 . 0 9 ( ~ )

-0.25 f 0.03t -0.25 f 0 . 0 3 ( ~ ) -0.25 f 0 . 0 3 ( ~ ) -0.25 f 0 . 0 3 ( ~ ) -0.15 f 0.05(')

-0.26 f 0.05

-0.09 f 0.10(~.") -0.01 f 0.11(~)

-0.62 f 0 . 1 5 ( ~ )

-0.30 f 0 . 1 5 ( ~ ) 0.37 f 0.11(~)

review on nranillrr~

K+

-0.10 f 0 . d 0.02 f 0.01

-0.08 f 0.04t

-0.09 f 0.02

-0.15 f 0.05 -0.17 f 0.03

t,herrno<lyr~arni<:s

Tahlc B.5: 1011 irlt,cract,ion cocficicrlt,~ c(l.j,k) and c(2 .. : k ) (in ~lrlit,s of kg . rnol-') for cations j nrit,h k = Cl-. ClOT and NOT (first part), and for aniorls j ~vi th k =

Li+; Na+ arltl K+ (sccontl part,). accortling t,o t,llc relationship E = E L + c2 loglO Im. Tllc tlat,a arc fiorn Ciavatt,a [80CI.4] arltl valid at 25°C arltl 1 bar. The ~lrlccrt,aintics rcprcscrlt t,llc 95% ~ o n f i d c n ~ c level; and rrlost of t,llcrrl wcrc cst,imat,ctl by Ciavatt,a [88CI.k].

Appendix C

Assigned uncertaintiest

Orlc of t,llc objcct,ivcs of t,hc NE.$ Thcrrrlochcrrlical Data Base (TDB) project is t,o provide an itlca of t,hc ~lrlccrt,aintics associat,cd nrit,h the data sclcct,cd in t,llis rcric\v. .Is a riilc, t,llc nnccrt,aint,ics dcfinc the range ~vit,llin \vhich the corrcsporltling dat,a can bc rcprodnccd \vit,ll a prol)ability of 95% at any place and by any appropriate mct,hotl. In many cascs. st,at,ist,ical t,rcnt,rrlcnt is lirrlitcd or impossihlc dnc t,o the availability of only orlc or fcxv tlat,a points. .I part,iciilar prohlcrrl has t,o he solrctl \vhcn significant, discrcpancics occur l>ct,~vccn diffcrcrlt sourcc dat,a. This appendix oiit,lincs the st,at,istical proccdnrcs ~vhich nrcrc ~lsctl for fimdarncntally tliffcrcnt prohlcrrls and cxplains the philosophy ~lsctl in t,his rcvic~v ~vhcn statist,ics wcrc inapp1ical)lc. Tllcsc rules arc follo\~~ctl consist,cnt,ly t,hronglloiit t,llc scrics of rcvic~vs \vithin the TDB Project,. Foiir fi~ntlamcnt,ally tliffcrcnt cascs arc consitlcrcd:

1. Onc sourre datinrl avai1al)lc

2. Two or more intlc1)cndcnt sonrcc data avai1al)lc

3. S c ~ w a l data avai1al)lc at diRcrcnt ionic st,rcrlgt,lls

4. Data at non-st,antlartl conditions: Proccdnrcs for dat,a corrcct,ion and rccalc~l- lat,ion.

C.1. One source datum

Tllc assignrncnt of an iinccrtaint,y t,o a sclcctcd valiic t,hat is hascd on only one cxpcrirrlcrlt,al sonrcc is a highly snbjcct,ivc procedure. In sorrlc cases; t,hc 111lrnl)cr of dat,a points t,hc sclcct,ctl ~ralnc is basctl on allo\~rs the nsc of the "root rrlcarl sqiiarc" [82T.lY] dcviat,ion of t,llc data point,s X , t,o dcscrihc the st,andard tlcviat,ion sx associated \vit,ll

t This rlppenclix cor~tair~s esserltially t,lle text rrritt,er~ t)y nkrlrler [94\T'.iIi] r%-llic:h rras rxlsc~ printer1 in t l ~ e ~lrarli~lrr~ NE.i-TDB review as .ippenrlix C [92GRE/FUG]. Becallse of its importance in t,lle srle<:tion of data arlrl to guide the users of t l ~ e val~les in Chapters I11 rxrlrl IJT, t , l~e text, is repro(il~<:erl here aft,er sorrle rrlirlor revision.

Tllc st,arltlartl dcriat,ion s,\- is tlliis calc~llatcd from t,hc dispersion of t,llc cq~lally ~vcight,cd dat,a point,s Xi aroiind t,llc axrcmgc X. arltl t,llc prol)ability is 95% t,hat an Xi is n.it,hin X* 1.96 sx; sec Taylor [82T.%I-; pp.344-2451. Tllc standard tlcviat,ion sx is a rncasnrc of t,hc prccisiorl of the cxpcrirncnt and does not incl~ltlc any systcrnat,ic crrors.

hlany aiit,llors report st,arltlartl tlcviat,ions s,\- calc~ilat,ctl ~vit,ll Eq. (C.l) (but oft,crl not rrliiltiplicd by 1.96). but tllcsc tlo not rcprcscrlt t,llc quality of t,hc rcport,ctl val~lcs in absoliit,c t,crrns. It is t,hns irrlport,arlt not t,o confi~sc the st,andard tlcviat,ion s with t,hc ~lnccrt,ainty o. Tllc lat,tcr reflects t,llc reliability and rcprotl~lcibility of an cxpcrirncnt,al x~alnc and also incl~ltlcs all kirltls of syst,cmat,ic crrors s j t,hat may i)c involved. The iinccrtaint,y o can i)c calc~llatcd nrit,h Eq. (C.2); assiimirlg t,llat the syst,cmat,ic crrors arc intlcpcndcnt,.

Tllc cst,irnation of the syst,crnatic crrors sj (~vhich, of coiirsc; have to rclat,c t,o X anrltl bc cxprcsscd in the sarrlc unit,) can only bc rnadc by a person who is familiar nrit,h the cxpcrirncnt,al rncthod. Tllc nnccrt,aint,y o has t,o correspond to t,llc 95% confidcncc lcx-cl preferred in this rcric\v. It shonltl i)c rlot,cd t,hat for all t,hc corrcct,ions arltl rccalciilat,ions rnadc (e.g.. t,crnpcratiirc or ionic strcngt,h corrcct,ions) t,llc rules of the propagat,ion of crrors have t,o bc follo\~~ctl; as o~lt,linctl in Scct,ion C.4.2.

hlorc oft,cn; t,llc dct,crrnination of sx is not possible bccansc cit,hcr only one or t,wo dat,a points arc ax7ailal)lc; or the a~lt,hors (lid not report t,hc intlividnal val~lcs. Tllc nnccrt,ainty o in t,llc rcsiilting val~lc car1 st,ill i)c cst,irnat,ctl usirlg Eq. (C.2) ass~lrning that ,S$ is rrl~lcll smaller than Cj(s:), ~vhich is iis~lally t,hc case any\\7ay.

C.2. Two or more independent source data

Frcqncnt,ly. two or more cxpcrirncntal tlat,a sources arc available, rcport,irlg cxpcri- mental dctcrmirlat,ions of the dcsirctl t,hcrrnodynarnic data. In general, the qiialit,y of tllcsc dct,crrninations varies widely. arltl t,hc data have t,o be ~vcigllt,ctl accordingly for the calciilat,ion of t,hc rncan. Inst,cad of assigning nrcight fact,ors, the intlividnal soiircc dat,a Xi arc providctl ~vit,ll an iinccrtaint,y o, t,hat also incliidcs all syst,crnatic crrors and rcprcscnt,~ t,hc 95% c o ~ ~ f i d e ~ ~ c e level; as described i11 Scrt,ion C.1. The weighted rrlcarl 7 and it,s ~lnccrt,ainty o, arc t,llcn calciilat,cd according t,o Eqs. (C.3) arltl (C.4).

T u ~ o or. rrtmrrr irrdrprrrdrat sorrr.cr rlnta

Eqs. (C .3) and (C .4) may only i)c used if all t,hc X, belong to t,llc same parent tlis- tribntion. If t,llcrc arc scrioiis discrcparlcics arrlong the X,, one proceeds as t1cscril)cd bclo\17 under Scctiorl C.2.1. It can bc sccn from Eq. (C .4) that o , is tlircctly dc- pendent on t,hc al)solntc magnitiidc of t,llc oi val~lcs; and not on the dispcrsiorl of the dat,a point,s aro~lrltl t,hc mean. This is rcasonahlc hccaiisc tllcrc arc no discrcparlcics arrlorlg t,llc X i ; and hcca~lsc t,hc oi valiics already rcprcscrlt the 95% confidcrlcc lcvcl. Tllc sclcct,ctl ~lnccrt,ainty o , will t,hcrcforc also rcprcscrlt t,llc 95% confidcncc lcvcl.

In cases nrhcrc all the ~lrlccrt,aintics arc equal o, = o, Eqs. (C .3) and (C.4) rcdncc to Eqs. (C.5) arltl (C .6) .

Example C . l :

Five dat,a soiirccs report ~ ~ a l n c s for the thcrmotlynarnic qnant,it,y X . Tllc rcvic\~rcr has assignctl iinccrtaint,ics t,llat rcprcscnt the 95% corlfitlcncc l c ~ ~ l as dcscrihcd in Scctiorl C.1.

.kccortling t,o Eqs. (C .3) and (C .4) . t,llc follo~ving result is ol)t,ainctl:

Tllc calcnlat,cd iinccrtaint,y o , = 0.2 appears relatively srnall but is statist,ically correct. for t,hc valiics arc ass~lrncd t,o follo117 a Ga~lssian dist,rih~lt,ion. .Is a consc- q~lcncc of Eq. (C .4) , o y will al117ays corrlc out srrlallcr t,harl the srnallcst o,. -4ss1lrning ol = 0.10 inst,cad of 0.25 ~voiild yield X = (25.0 * 0.1). and o 4 = 0.60 nro~lld result, in 7 = (25.6 f 0.2) . In fact. the ~ ~ a l n c s (X, f o,) in t,his example arc at the limit of consist,cncy, t,llat is, the range ( X 4 f 04) does rlot overlap ~vi th t,hc rarlgcs ( X 2 f 02)

arld * Q ) . Tllcrc might bc a l)ctt,cr way to solve this prol)lcrn. Thrcc possil)lc alt,crnatircs sccrrl rrlorc rcasonahlc:

i. The iinccrtaint,ics o, arc reassigned bccansc t,llcy appear t,oo opt,imistic aft,cr fiirt,hcr considcmt,ion. Some asscssrncnt,~ rnay have t,o bc rccorlsitlcrcd and tllc iinccrtaint,ics rcnssigncd. For cxnrnplc, rniiltiplying all t,llc oi by 2 ~voiild yicltl X = (25.3 * 0.3).

ii. If rccorlsitlcrat,ion of t,llc previous nsscssrrlcnts gives no cvidcncc for reassigning t,llc X, and o, (90% confidc~lcc l cx~ l ) vnliics listed a l ~ o x ~ ; t,llc statist,icnl COII- cl~lsion \!rill i)c that all t,llc X , do not belong t,o t,hc snrrlc parent distrii)iit,ion and cnrlrlot t,hcrcforc be t,rcat,cd in tllc sarnc group (cf. it,crrl iii i)clo\v for n non- st,nt,istical cxplannt,ion). Tllc val~lcs for I = 1, 4 and 0 might i)c considcrcd as I)clonging t,o Group .l nrltl tllc val~lcs for I = 2 and 3 t,o Groiip B. Tllc nrcightcd axrcmgc of t,hc val~lcs in Groiip .l is .ZT.4(i = 1,4 ,0) = (24.90 * 0.21) and of t,llosc in Group B XB(I = 2,3) = (26.06 * 0.31); t,hc sccond tligit after tllc tlcc- irrlal point bcing carried orer t,o avoitl loss of information. The sclcct,cd x~alnc is 11ox~~ tlct,crrrlinctl as t1cscril)cd bclo\~r ~lrltlcr "Discrcpancics" (Scct,ion C.2.1), Cnsc I. X.4 nrltl XB arc averaged (straight, average, tllcrc is no rcnsorl for giving X.4 n larger ~vcight t,hnrl XB); nrltl o x is clloscn in siich a \!,ay t,llat it corers t,llc complct,c rnrlgcs of expectancy of X.4 and XB. Tllc sclcct,cd x~alnc is then X = (25.5 * 0.9).

iii .lnot,hcr cxplannt,ion coiild be t,llat iinidcrlt,ificd syst,crnatic crrors arc assocint,ctl nrit,h sorrlc vnliics. If t,llis sccms likely to bc tllc case, tllcrc is no rcason for splitt,ing t,hc val~lcs up int,o t,~vo groups. The correct \!,ay of proceeding \~ronltl i)c t,o calciilnt,c t,llc ~ln\~~cigllt,cd nvcragc of all t,hc fire points nrltl assign an iinccrtaint,y t,hnt covers t,hc \~rllolc rnrlgc of cxpcct,nncy of t,hc five vnliics. Tllc rcs~llt,ing vnliic is t,hcrl = (25.40 * 1.05); \~rllicll is roiindcd nccordirlg t,o tllc rules in Scctiorl C.4.3 t,o X = (25.4 * 1.1).

T\vo data arc called tliscrcpant if t,llcy diffcr significnnt,ly, i.e., t,hcir nnccrt,nint,y ranges do not overlap. In this cont,cxt,, two cnscs of discrcpancics arc considcrctl. Case I: T\vo significant,ly diffcrcnt sourcc data arc ax7ailal)lc. Cnsc 11: Scxwal. rnost,ly consist,crlt, sourcc data arc nvailablc. one of t,hcrrl bcing significantly tliffcrcnt. i.e.; an "o~lt,licr".

Case I. TUI~I ciiscrepcxrrt cio,tcx: This is a pnrtic~ilnrly tlifficnlt case i)ccaiisc tllc nurnl)cr of dnt,n point,s is obx~ioiisly insiifficicnt t,o nllon~ t,llc ~)rcfcrcn~c of one of the two x~alncs. If tllcrc is nbsoliit,cly no \!,ay of discartling orlc of tllc two vnliics nrltl sclcct,irlg t,hc other. tllc only solution is t,o average tllc two soiircc tlat,a in ortlcr t,o obt,ain t,llc sclcct,cd x~alnc; bccn~lsc t,llc iindcrlying rcason for t,llc discrcpnncy rrliist i)c nnrccognizctl syst,cmnt,ic errors. Tllcrc is no point in calc~llating n ~vcight,ctl axrcmgc, cvcn if t,llc t,~vo sourcc data have been given different ~lnccrt,aintics, i)ccaiisc t,llcrc is obvio~lsly t,oo lit,tlc inf~rrrlat~ion to give cvcn only lirrlitcd prcfcrcrlcc t,o orlc of tllc - x~a111es. The nnccrt,aint,y oy nssigrlcd to t,hc sclcctcd rncan .ZT has to corer tllc range

T u ~ o or. rrtmrrr irrdrprrrdrat sorrr.cr rlnta

of cxpcct,at,ion of imth sourcc dat,a XI; X 2 , as sho\vn in Eq. (C.?).

OF = (C.7)

~vllcrc i = 1; 2, arltl U,, is the larger of t,llc t , ~ ~ ~ o ~lnccrtaint,ics U,; sec Exarnplc C.l.ii and Example C.2.

Example C.%:

Tllc follo\~.ing crcdihlc soiircc dat,a arc given:

XI = 4.5 * 0.3

Ji2 = 5.9 * 0.5.

Tllc iinccrtaint,ics have hccn assignctl by t,hc rcric\vcr. Both cxpcrirncnt,al rrlct,llods arc satisfact,ory, and tllcrc is no jiist,ification to discard one of the tlat,a. The sclcctcd T ~ ~ ~ I I C is then:

X = 5.2 f 1.2.

Ill~ist,ration for Exarnplc C.2:

Ccrse II. 0'11,tliel:s: This prol)lcrn can oft,cn i)c solrctl by cit,llcr tliscarding the o~lt~lying data point,, or by providing it nrit,h a large iinccrtaint,y to lo\vcr its ~vcigllt,. If. ho~vcvcr. the outlying ~ralnc is corlsitlcrcd t,o he of high quality arltl t,hcrc is no reason to discard all t,hc other data, t,his case is t,rcatcd in a way similar t,o Case I. Example C.3 illnst,mt,cs t,hc procedure.

Example C.3:

Tllc follo\~.ing tlat,a points arc available. The rcvic~vcr has assigrlcd t,llc ~lrlccrt,aintics and secs no jnst,ificat,ion for any change.

Tllcrc arc t,wo sets of data t,llat,; st,at,istically. hclorlg t,o tliffcrcnt parent dist,rihllt,ions .l and B. .lccording t,o Eqs. (C.3) and (C.4), t,hc following average val~lcs arc follrltl for tllc t,\1'0 gr0lll)S: .Y.4(i = 1) = (4.45*0.35) a1ltl XB( j = 2, 3,4, 5) = (5.62*0.23). Tllc sclcct,ctl valiic ~vill i)c the st,raight average of X.4 arltl XB. analogoiis to Example C.l :

C.3. Several data at different ionic strengths

Tllc cxtrapolat,ion procctl~lrc llsctl in t,his review is t,hc specific ion int,cractiorl rrlodcl ollt,linctl in -4ppcntlix B. Tllc objcct,ivc of t,llis rcvicw is t,o provide sclcct,ctl dat,a sct,s at standard contlit,ions. i .e . , among others, at in fin it,^ tlilntion for aqllcons spccics. Eqllilihrillrrl const,arlt,s tlct,crrrlinctl at diRcrcnt ionic st,rcrlgt,lls can; accordirlg to the specific ion irlt,cract,ion cqnat,ions, bc cxt,rapolat,ctl t,o I = 0 nrit,h a lincar rcgrcssion model. yielding as t,hc intcrccpt t,hc desired cqiii1il)rinrn constant at I = 0, and as the slopc t,llc st,oiclliorrlct,ric sum of the ion irlt,cractiorl cocficicnt,~. AE. The ion irlt,cractiorl cocfficicnt of the t,argct spccics car1 llsnally l)c extracted from AE and is list,cd in t,hc corresponding table of .lppcndix B.

Tllc avai1al)lc soiircc dat,a rnay somct,irrlcs he sparse or may not corer a sufficient range of ionic strengths to allo\v a proper linear rcgrcssion. In t,llis case, the corrcctiorl to I = 0 shollld bc carried out according t,o the proccdiirc dcscribctl in Scct,ion C.4.1.

If sufficient dat,a arc available at diRcrcnt ionic strengths and in t,llc same inert, salt rncdinrn, a ~vcight,ctl lincar rcgrcssion will i)c t,llc appropriate ay t,o oht,ain hot,ll the constant at I = 0, 7. and AE. Tllc first st,cp is t,llc conversion of the ionic st,rcngtll from t,llc frcqiicntly used rrlolar (rnol . tlrn-"; h1) to t,llc molal (m01 . kg-', m) scale, as dcscrihcd in Scct,ion 11.2. The sccorld st,cp is t,hc assignmcrlt of an nnccrt,ainty U,, to each data point Xi at t,llc rnolalit,y r r a k , i ; accortling to the rules dcscril~cd in Scct,ion C.1. .l large niimbcr of corrlmcrcial and piil)lic dornain cornpiit,cr programs and roiit,incs exist for \~,cight,cd linear rcgrcssions. The sllhrollt,irlc piil)lishctl by Bcvingt,on [69BE\'. 1ip.104-1051 has been used for t,hc calciilat,ions in t,llc cxamplcs of this appendix. Eqs. (C.8) tllroiigh (C.12) prcscrlt the cqnat,ions that arc iiscd for the calciilat,ion of t,llc intcrccpt 7 and the slopc -LE:

In t,his t,hc nnccrt,aint,ics o, arc not only ~lsctl for the weighting of t,llc tlat,a in Eqs. (C.8) and (C.9), hut also for t,llc calcnlat,ion of the nnccrt,aint,ics o y and o ~ ~

in Eqs. (C.lO) and (C . l l ) . If the o, rcprcscnt t,llc 95%' corlfitlcncc l c ~ ~ l . o y and o ~ ~

will also tlo so. In ot,llcr ~vortls, t,hc nnccrt,aint,ics of t,hc int,crccpt and the slope do not depend on t,llc dispersion of t,hc dat,a point,s aro~lntl the st,raight line but rat,llcr directly on their absol~lt,c nnccrt,aint,ics oi.

Example C.4:

Tcrl independent dctcrmirlat,ions of t,hc cqiii1il)riiim const,arlt log,,':/ for t,hc rcactiorl

arc avai1al)lc in HC104/NaC104 rncdia at diRcrcnt ionic strengths. Unccrt,aint,ics t,llat, rcprcscrlt t,llc 95% confidcrlcc lcvcl lla~rc l)ccn assigncd by the rcric\vcr. .% nrcightcd linear rcgrcssion; (logl,:i+2D) 'OS. rnk, according t,o t,llc formula loglo',i(C.13)+%D =

log,,'~lo(C.13) - AE rnk, will yield t,hc correct valiics for t,llc intercept log,,'~,lo(C.13) and t,hc slope AE. In t,his case; r r a k corresponds t,o t,hc rnolalit,y of C10;. D is the Dcl~yc-Hiickcl term, cf. .%ppcndix B.

Tllc rcsnlt,s of t,llc linear rcgrcssiorl arc:

int,crccpt = 1.837 f 0.054 = log,,'~lo(C.13) slope = 0.029 f 0.036 = -h.

Calciilat~ion of t>llc ion intcract,ion coefficient E( +,c:lOq) = - 1 ~ + E( ;+,c:lOq) -

E ( ~ + , ~ : ~ ~ ) , ) : Fro111 E(~,( ) ;+ ,c:l o;) = (0.46 f 0.03) kg . mol-l. = (0.14 * 0.02) kg . rnol-' (sec .%ppcndix B) arltl t,llc slope of t,hc linear regression, E =

( 0 . 0 3 * 0.04) kg . mol-l, it follo~vs that E ~ ~ ; ~ ) , ~ + ,c:l = (0.29 * 0.05) kg . rnol-'. , - * ,

Note t,llat the iinccrtaint,y (f 0.05) kg . rnol-' is ol)t,aincd basctl on t,hc riilcs of error propagat,ion as dcscrihcd in Scct,ion C.4.2:

Tllc rcsnlt,ing sclcctcd val~lcs arc t,hns

Discrcpancics arc principally t,rcat,ctl as dcscribctl in Scct,ion C.%. .%gain. t,~vo cases can bc defined. Casc I: Only two tlat,a arc avai1al)lc. Casc 11: .%n "oiit,licr" cannot, bc discartled. If only one tlat,a point is availal)lc; t,llc procedure for corrcctiorl t,o zero ionic st,rcrlgt,ll oiit,linctl in Scct,ion C.4 sho~lld he f o l l o ~ ~ ~ d .

Ccxse I. Too fe'iri rraolalities: If only t,~vo soiircc dat,a arc availal)lc; tllcrc will i)c no st,raight,for\~~ard way to dccidc \vhcthcr or not t,hcsc two data point,s belong to the sarnc parent dist,rih~lt,ion unless cit,llcr the slopc of the straight line is kno~vn or the two dat,a rcfcr t,o t,hc samc ionic st,rcngt,h. Dra\ving a st,raight line right tllroiigh the two data point,s is an inappropriat,~ procctl~lrc hcca~lsc all the errors associat,ctl ~vit,ll the t,wo sourcc dat,a \~ronltl acc~lrrliilnt,c and may lead t,o highly erroneous ~ ~ a l n c s of log,, Ii" and AE. In t,llis casc. an ion irlt,cract,ion cocfficicnt for t,hc key species in the rcact,ion in qiicst,ion may l)c sclcct,cd by analogy (charge is t,llc rrlost irrlport,arlt, paramct,cr). and a straight linc nrit,h t,hc slopc AE as calciilat,ctl may t,llcn l)c draxvn through each dat,a point. If tllcrc is no reason t,o discard one of t,llc t,~vo dat,a points based on t,llc qualit,y of t,hc underlying cxpcrirncnt,, t,hc sclcctcd ~ralnc will bc the nn~~,cight,cd average of the two st,andard st,at,c dat,a ol)t,ainctl by t,llis proccdiirc. arltl it,s iinccrtaint,y rrlllst corer the cntirc range of cxpcctancy of the t,wo ~~a lncs , analogous to Casc I in Scct,ion C.%. It shonltl bc rrlcnt,ionctl that t,llc ranges of cxpcct,ancy of the corrected ~ ~ a l n c s at I = 0 arc given by their ilrlccrt,aint,ics ~vhich arc hascd on the iinccrtaint,ics of t,hc soiircc tlat,a at I # 0 and the iinccrtaint,y in t,hc slope of the st,raigllt linc. Tllc lat,tcr nnccrt,aint,y is not an cst,imat,c but is calciilat,ctl from the nnccrt,aintics in the ion irlt,cract,ion cocfficicnt,~ involved, according to t,llc rules of error propagat,ion ontlincd in Scctiorl C.4.2. Tllc ion int,cract,ion cocfficicnt,~ cstirrlat,cd by analogy arc listed in t,llc t,al)lc of sclcctcd ion int,cract,ion cocfficicrlt,~ (-4ppcntlix B); bi1t they arc flagged as cst,irnatcs.

Ccxse II. 0'11,tliel:s cxrrci i ncorr s i s t en t rlato, s e t s : This casc inclndcs sit,uat,ions ~vhcrc it is difficiilt t,o dccidc ~vhct,hcr or not a large nnrnhcr of points hclorlg t,o t,hc samc parent tlist,ribntion. Tllcrc is no general rule on ho~v to solve t,his prol)lcrn. and dc- cisiorls arc left t,o the jiidgcrrlcnt of the rcvic\~rcr. For cxarnplc, if cigllt data points follo\v a st,raight linc rcasonahly nrcll arltl t,~vo lie \!,ay out. it rnay bc j~lstifictl t,o tlis- card t,llc "oiit,licrs". If, ho\vcvcr, the cigllt point,s arc scat,t,crctl considerably and t,wo points arc jiist a hit fi~rt,llcr oiit,, one can probably not corlsitlcr t,hcrrl as "o~lt,licrs". It depends on t,llc particular casc and on t,llc j~ltlgcrrlcnt of t,hc rcvic\~rcr \vhcthcr it is rcasonablc t,o increase t,llc iinccrtaint,ics of t,llc data t,o reach consist,cncy, or \vhcthcr the slope AE of the st,raight linc slloiild i)c cstirrlat,cd by analogy.

Example C.5:

Six rclinhlc tlct,crrrlinnt,ions of t,llc cqnilibrinrn const,ant log,, 9 of t,hc rcactior~

arc avai1al)lc in tliffcrcnt clcct,rolyt,c mctlia:

I , = 0.1 h1 (KN0:3): log,, fi(C.14) = 1.19 * 0.03 I , = 0.33 hl (KY0:3): log,, fi(C.14) = 0.90 * 0.10 I , = 1.0 h1 (NaC104): log,, fi(C.14) = 0.75 * 0.03 I , = 1.0 h1 (NaC104): log,, fi(C.14) = 0.76 * 0.03 I , = 1.0 h1 (NaC104): log,, fi(C.14) = 0.93 * 0.03 I , = 2.5 h1 (N:I ,~O:~): log,, fi(C.14) = 0.7% * 0.03

Tllc nnccrt,nint,ics arc nssiimctl t,o rcprcscnt t,llc 95% corlfitlcncc lcvcl. Frorrl t,llc val~lcs at I , = 1 11, it can he sec11 t,hnt t,hcrc is a lack of consist,cncy in the data, and t,llat, n linear rcgrcssiorl like in Example C.4 \~ronltl not bc approprint,c. Inst,cad, t,llc iisc of AE vnliics from rcact,ions of t,llc samc charge t,ypc is cnconragcd. .Inalogics nrit,h AE arc rrlorc rclial~lc t,llan nrlalogics nrit,h singlc E ~ ~ a l n c s diic t,o cancelling cffcct,~. For the sarnc reason. t,hc dcpcntlcncy of AE on t,hc t,ypc of clcctrolytc is oft,crl srnallcr t,hnrl for singlc E vnliics.

AI rcnct,ion of t,llc samc charge t,ypc as Rcact,ion C.14. and for \vhich AE is ~vcll known, is

Tllc ~ralnc of Ll~(C.15) = ( 0 . 2 0 * 0.02) was ol)t,aincd from a linear rcgrcssiorl using 16 cxpcrirncnt,al tlat,a hct,\~~ccn I, = 0.1 11 and I , = 3 11 xn(C1.C104) [92GRE/FUG]. It is t,hns ass~lrncd t,hnt,

Tllc corrcct,ion of log,, p(C.14) to I, = 0 is done usirlg the specific ion intcract,ion cqliation, cf. TDB-2; nrhich uses rrlolnl ilnit,s:

log,, p + 4D = log,,i" - AEI, (C.16)

D is the Dcl~yc-Hiickcl term in rrlolnl iinits and I, t,hc ionic strength convcrt,cd t,o rrlolal nnit,s by usirlg t,llc conversion fact,ors listed in [76B.IE/hIES. p.4391. Tllc following list gives t,hc dct,nils of this calciilnt,ion. Tllc rcs~llt,ing llrlccrt,aintics in log,, 9 arc obtaincd hascd on the riilcs of error propagnt,ion as t1cscril)cd in Scct,ion C.4.2.

(a) These vah~es \%-ere <:orrect,ecl for the fc~rr~~r~t ior~ of t,lle rlitrr~te <:ornplex UOaNO: 1137 using logl, I l (UOnNO:) = (0.30 & 0.15) [92GRE/FUG] .

I,

0.101 0.335 1.050 1.050 1.050 2.714

Aks urns expected, t,hc rcsiilting valiics logl, Do arc irlconsist,cnt ant1 have t,llcrcforc to he t,rcat,cd as dcscribctl in Case I of Scct,ion C.2. That is, t,hc sclcct,ctl valiic will bc the iinn~cightcd average of log,, p; and its ~lnccrt,aint,y will cover t,hc cntirc range of cxpcct,ancy of t,hc six ~~a lncs . .k nrcightcd axrcmgc ~voiild only i)c j~lstifictl if the six T ~ ~ ~ I I C S of logl, Do ~vere consistent. The rcs~llt is

log,, ,lo = 1.56 * 0.39

electrolyte

KN03 KN0:j NaClOl NaClOl NaClOl NaN0:j

C.4. Procedures for data handling

Tllc corrcction of cxpcrimcnt,al tlat,a t,o zero ionic st,rcrlgt,ll is necessary in all cases ~vhcrc a linear rcgrcssion is i1npossii)lc or appears inappropriat,c. The rrlct,llod iiscd thronghoiit the rcvic\v is the specific ion intcract,ion cq~lat,ions t1cscril)cd in detail in Akppcndix B. T\vo ~rariablcs arc ncctlcd for t,his corrcct,ion. and bot,h have t,o i)c provided nrit,h an iinccrtaint,y at t,hc 95%' confidcncc lcvcl: t,llc cxpcrirncntal soiircc ~ral11e. logl, li or logl, '/; and the st,oiclliorrlct,ric slim of t,hc ion int,cract,ion cocficicnt,~. A . Tllc ion int,cract,ion cocfficicnts (sec Tahlcs B.3, B.4 and B.5 of -4ppcntlix B) required to calciilat,c AE may not all bc kno~vn. lIissing valiics t,llcrcforc nccd t,o i)c cstirnatcd. It is rccallcd that the clcct,ric charge has the rrlost significant inflncncc on t,llc magnitiidc of t,llc ion int,craction cocfficicnt,~, and t,llat it is in general more rcliahlc t,o cstirrlat,c AE from kno\vn reactions of the same cllarge t,ypc. rat,llcr than t,o cstirnatc single E ~~a lncs . Tllc nnccrt,aint,y of t,hc corrcct,cd ~ralnc at I = 0 is calcnlat,cd by t,aking into accoiint t,hc propagat,ion of errors, as dcscribctl hclo\~r. It slloiild i)c not,cd t,llat the ionic strength is frcqncnt,ly given in rrlolcs per tlrn" of soliit,ion (molar, hl) and has t,o bc convcrtcd to moles per kg H 2 0 (rnolal; rn); as the rrlodcl requires. Con~~crsion fact,ors for t,hc rrlost comrrlon inert salts arc given in Tahlc 11.5.

loglo (i

1.19 + 0.03 0.90 + 0.10 0.75 + 0.03 0.76 + 0.03 0.93 + 0.03 0.72 + 0.03

440

0.438 0.617 0.822 0.822 0.822 0.968

AEI,

0 . 0 2 5 0 . 0 8 4 0 . 2 6 3 0 . 2 6 3 0 . 2 6 3 0 . 6 7 9

loglo

1.68 + 0.113(") 1.65 + 0.111(") 1.31 + 0.04 1.32 + 0.04 1.49 + 0.04 1.82 + 0.13(")

P r r ~ r r d r w r s f o r . d a t a 1rtrr1,rllirr.y

Example C.6:

For t,llc cqnilibrinrn const,arlt of t,hc rcactiori

only one credible tlct,crrrlinat,ion in 3 hI NaC1(l4 soh~tion is kno~vn; log,,'i(C.li) =

-6.31, t,o ~vhich an iinccrtaint,y of *0.12 has l)ccn assigned. Tllc ion intcract,ion cocficicrlt,~ arc as follo~~rs:

E ~ + , , ~ , , = (0.56 f 0.03) kg . l l l O 1 r l

E ~ , ~ , , ~ , , = (0.26 f 0.11) kg . 11101-l

E ( ~ + , , : ~ ~ ; ) = (0.14 f 0.02) kg . 11101-l

Tllc val~lcs of AE and 04E car1 be ol)t,ainctl readily (cf. Eq. C.19):

Tllc t,~vo varial)lcs arc t,ll~ls:

.~ccortling t,o the specific ion int,cractiorl rrlodcl t,llc follo~ving cqnat,ion is llsctl t,o correct for ionic st,rcrlgt,ll for t,hc rcactiorl considcrcd hcrc:

D is the Dcbyc-Hiickcl t,crrn: D = 0.509&/(1 + l.5\/%;;). Tllc ionic st,rcngt,h I,, and t,llc rnolalit,y r r a ,:l,,; (I,,, -- rn,:,,,;) have t,o be cxprcsscd in molal nnit,s. 3 11 NaCl(14 corresponding t,o 3.5 m NaC104 (sec Scct,ion 11.2). giving D = 0.25. This rcsult,s in

Tllc iinccrtaint,y in log,,"i" is calclllatcd from t,hc nnccrt,aintics in logl,*p arltl AE (cf. Eq. C.19):

2

* = , + ) = J(0.12)2 + (3.5 X 0 . 1 2 ) ~ = 0.14.

Tllc sclcct,ctl, rollrltlcd ~ralnc is

- - - - c - m m @ ? @ ? @ ? C ' ! c i c i c i c i - - - U

P r r ~ r r d r w r s f o r . d a t a 1rtrr1,rllirr.y 345

Eq. (C.23) : &G$ = R T l n K " : K" = (8.2 + 1.2) X 1 0 ~ R = 8.3145 .J . K-' . mol-l T = 298.15K

&G$ = ( 3 9 . 4 6 + 0.36) kJ . rnol-l l n l i " = 15.92 + 0.15

log,, l<" = 111 K"/ ln(10) = 6.91 + 0.06

.$gain. it can he sec11 that t,llc nnccrt,aint,y in log,, K" cannot he t,llc same as in l n K 0 . Tllc const,arlt conversion fact,or of ln(10) = 2.303 is also to i)c applied t,o the nnccrt,ainty.

Tllc standard riilcs t,o he iiscd for roiinding arc:

1. Il'hcn t,llc digit follo\~.ing t,llc last digit to he rctaincd is less than 5. t,hc last, digit rct,ainctl is kcpt nnchangctl.

2. Il'hcn t,hc tligit follo\~.ing t,llc last digit to i)c rctaincd is greater t,harl 5. t,llc last, digit rct,ainctl is incrcascd by 1.

3. Il'hcn t,hc tligit follo\~.ing t,llc last tligit to bc rct,aincd is 5 and

a) t,hcrc arc no tligit,~ (or only zeroes) beyond t,llc 5, an odd digit in t,hc last, place t,o bc rct,aincd is incrcascd by l ~vhilc an cvcn tligit is kcpt ~lnchangcd.

h) ot,llcr non-zero digit,s follo\~r, t,llc last digit to i)c rctaincd is incrcascd by 1; \vhcthcr otltl or c ~ ~ c n .

This procctlllrc avoids int,rodncing a systcrnat,ic error from al\~rays tlropping or not, dropping a 5 aft,cr t,llc last tligit retained.

IVhcn atltling or subtracting, the result is rollrltlcd t,o t,llc 111lrnl)cr of tlccirnal placcs (not sigrlificarlt digit,^) in t,hc t,crrrl \vit,ll t,hc lcast niimhcr of places. In rrliiltiplicat,ion and division, t,hc rcs~llt,s arc rollrltlcd t,o t,llc nnrnhcr of sigrlificarlt digits in the t,crrrl wit11 t,hc lcast 111lrnl)cr of sigrlificarlt tligit,~.

In gcncral; all opcrat,ions arc carricd oiit in fiill, and only the final rcsiilts arc rountlcd. in ortlcr to avoitl t,llc loss of inf~rrrlat~ion from rcpcatcd roiinding. For t,llis reason. several additiorlal digit,s arc carried in all calciilat,ions llrlt,il the final sclcctcd set of tlat,a is dcvclopcd. and only t,hcrl arc data roiindctl.

Tllc ~lnccrt,ainty of a ~ralnc basically dcfirlcs t,llc niimhcr of significant tligit,~ a ~ralnc sllo~lld i)c given.

Examples: 3.478 + 0.008 3.48 + 0.01 2.8 + 0.4

In t,llc case of auxiliary dnt,n or ~ ~ a l n c s t,hnt arc used for later cnlcnlat,ions. it is often not, convcnicnt t,o round t,o t,llc last significant digit,. In the vnliic (4.85*0.36), for cxnrnplc, the "5" is close to i~cing sigrlificnrlt and slloiild i)c carried along n rccalc~llation pat,ll in ortlcr t,o avoitl loss of information. In part,icnlar cases; ~vhcrc the rounding t,o significant tligit,~ conltl lcntl t,o slight internal inconsistcncics. digit,s nrit,h no significant, rrlcnrling in absol~lt,c t,crrrls arc rlcvcrt,llclcss retained. Tllc ~lnccrt,ainty of a sclcctcd ~ra111c nlu~nys rontai~ls t,hc same niimbcr of digits nft,cr t,llc tlccirnal point as t,llc ~ralnc it,sclf.

Appendix D

Corrections to the Uranium NEA-TDB reviewt

Ingnlar GRENTHE Ignasi PUIGDOMENECH Departnlert of Illorgallic Cllemistry OECD Ni~clear Energy Agerlry Royal Illstiti~te of Technology Le Seine Saint Gerrnair~ S-100 44 St,ockholm (Swe(1e11) 12, t)oi~levar~l (les Iles

F 92130 Issy les Moulineai~x (France)

M. C. Alr~aia SANDINO Malcohn H. RAND D-76137 Karlsri111e (Gern~a l~y) Wir~tersHill Consi~ltal~cy

Dry San(lforcll Al)ing(lon Oxon OX13 6JP (United Kingdom)

D.1. Introduction

Rcadcrs of t,llc nraniurn rcvic\v [92GRE/FUG] have point,ctl oiit t,o iis scrcml rrlinor prohlcrrls and rnisprint,~.

The labcls ',U(OH)4(nq)" and "UOaCO:~(nq)" sho~lld he intcrchnrlgcd in Fig- lire I".19. p.325.

In Scct,ion 17.3.3.1.4. p.136, the rcfcrcncc in the first line sho~lld bc '~Cortlfilnkc [66COR]"; ~vhilc in t,hc sccorltl line aft,cr Eq. (\:.22); the rcfcrcncc [66COR] slloiild read [63COR/.$LI].

The valnc of AfHk(UOI . 4H20. cr; 298.15 K) shonltl i)c ( 2 3 8 4 . 7 f 2.1) kJ . mol-l (inst,cad of 2 3 9 4 . 8 k J . rnol-l). I)oth in Tal)lc 111.1, p.32; and in Scc- t,ion \".3.3.1.4, p.136.

t . i l t l ~ o ~ ~ g h t,l~is t,ext llas txen prepared 1)~. t l ~ e al~tllors listerl, rrlost of t l ~ e corre(:tions mentioned in it have 11ee11 pointed out variol~s o1)servant readers: D. C~~t)ic(:iot,ti, J . Fuger, R.J. Lernire. P. I'itorge and ot,hers. It rrlllst t)e stresserl illat illis ,ippen(iix h(~,s not her,rr sr1,hrrrittr~rl to intlrpr!nderrt pf!f?r-muir~rl~. Jl~clgernent sllolllri be used rrklerl applying tlle corrlrrlerlt,s ancl ~~a,;r%llles giver1 ill t,klis and follorrir~g pages.

348 Covrctf oas to t11,r Ur(~rrrrrrn NEA- TDB rrrirrru

The t,it,lc and t,hc last page niimbcr for Ref. [63COR/.kLI]; ~vhich nrcrc orrlitt,cd in t,llc iiraninrn l~ook can i)c fo~lrltl in the Rcfcrcncc list of t,llis .kppcndix.

In Figures \'..7, l'..$, \'.l9 and \".20. the variable "pc", ~vllich dcrlot,cs t,hc Y- axis, is not tlcfincd any\vhcrc in t,llc ~lrarliiim rcvic\v. Tllc dcfinit,ion of t,llis varial~lc is given in Scct,ion 11.1.6.5 of this volurnc.

S c ~ w a l crrors in .kppcndiccs B arltl C of [92GRE/FUG] have been corrcct,cd and rcprirlt,ctl in this vol~lrnc, for cxarnplc, Eqs. 1 ) I ( C . ) . Likc\visc, foot,not,cs "(c)" arltl "(i)" in Tal)lc B.3 of [92GRE/FUG] have bccn rcviscd.

In t,llc first line of Scct,ion 17.9.5.2.3. p.347, t,llc cornpound shonltl l)c Ba2SrU06(cr) and not BaZCaUOfi(cr).

Tllc authors of the nraniurn ~~ol i imc agrccd t,llat ~ipdatcs of t,llc review t,o inclndc lat,cr pnblicat,ions ~voiild not bc rnadc, hut t,llat t,llc sclcct,cd valiics coiild he rcviscd if crrors n7crc discovered. Prol)lcrns i)roiight to oiir at,tcrlt,ion ~vit,ll t,llc sclcctcd nraniurn thcrrnodynarnic tlat,a in Chapt,cr I11 arltl ~vit,ll the specific ion irlt,cract,ion cocficicrlt,~ in .kppcndix B of Ref. [92GRE/FUG] arc dealt ~vi th in t,llc follo~ving Scct,ions.

D.2. Uranium trichloride

Tllc valiic of C,",,(UCl:j; cr, 298.15K) in Table 111.1 of t,hc nraniurn XE.k-TDB rcric\v [92GRE/FUG; p.361 is crroncoiis. Grcntllc et al. [92GRE/FUG; pp.200 2021 adopted the valiics rcport,ctl by Cortlfilnkc. Konings and TVcstr~lrn [89COR/KON]; hut the nurnl)crs nrcrc rnist,ypctl. Tllc correct ~ralnc is C,",,(UC1:j. cr; 298.15 K) = (102.5 * 0.5) .J . K-' . rnol-', irlstcatl of 95.1 .J . K-' . rnol-'; and t,hc t,hcrrrlal filrlct,ion qiiotcd in Tahlc 111.3 [92GRE/FUG, p.611 sho~lld read

\VC note ho\vcvcr t,llat t,his filrlct,ion has a rrlinirrl~lrrl at 315 K. In ortlcr t,o rcrrlovc this art,ifact t,hc original dat,a [47GIN/COR] shonltl he rcfit,t,ctl.

D.3. Aqueous uranium hydroxide complexes

Conccrrls ha~rc IICCII ex~)res~ed allout t,hc inadcq~lacy of t,llc sclcct,cd ~ ~ a l n c s for t,llis species, namely:

UOS+ + 2 H,O(l) + U02(OH)2(aq) + 2 H+ log,, '1'1,"(298.15 K) 5 1 0 . 3

~vhich corrcsporltls t,o -lfGk(U02(OH)2. aq. 298.15 K) 2 1 3 6 8 kJ . mol-l. This upper stability limit \~ronltl suggest t,hat t,llis corrlplcx is not a prctlomirlat,ing hydrolysis species in the iiraninrn(I'1) syst,crn. Ho~vcvcr. Figiircs 17.4 t,o 17.5. 17.7 and \'.l8 in pages 115, 116, 128 and 322 of Ref. [92GRE/FUG] sho\v t,hat t,llis species prcdorni- nat,cs over a large range of contlit,ions. hlost of tllcsc Figures rrligllt bc rnislcatling,

bccn~lsc for t,llc sake of clarit,y they n7crc const,rnct,ctl snpprcssing t,hc prccipit,nt,ion of solid phases. Xcvcrt,hclcss; Figiirc 17.5 in [92GRE/FUG] sllo\~rs that U02(0H)2(aq) can reach conccnt,rations approaching 10-" h1 in cq~lilihri~lrrl nrit,h schocpitc if the sclcct,ctl iippcr lirrlit for log,, v," is used. It appears thcrcforc; t,llat sorrlc addit,ional corrlrrlcnts arc rcq~lircd for t,his complex.

Tllc sclcctcd vnliics cxprcsscd t,llc kno\vlctlgc on this syst,crn by t,llc dnt,c t,hc draft, was scrlt for peer-rcric\v. Lnt,cr pnblicnt,ions (for cxnrnplc [9lCHO/hI.4T. 92BIS/I<R.k; 92SIL, 94TOR/C.%S]) 11ax.c sho\~rn t,hnt t,hc nct,ual val~lc of &Gm for t,llis cornplcx is prohal~ly larger t,hnrl t,llc lo\vcr limit set by Grcrlt,llc e t al. by nhoiit 8 k.J . rnol-'; cf. tthc footnote in 11.113 of Ref. [92GRE/FUG]. Ncvcrthclcss, n revised vnliic for t,llis corrlplcx is not offered bccansc of t,hc tlccision t,nkcrl t,hnt t,llc iiraninrn i~ook \~ronltl not he ~lptlat,cd in t,llc near fi~tiirc t,o t,nkc ncco~lrlt of snbscqncnt pnblicnt,ions,

Users of the sclcct,cd data set for t,llis syst,crn slloiild he n\17arc of t,llc caxrcat,s cxprcssctl in scct,ion ".4 pot,cnt,ial inconsist,cncy" in [92GRE/FUG, p11.129 1311. -4lt,ho1lgh it np- pears t,llat the stability of U(OH)4(aq) has i)ccn ovcrcstirrlat,cd by ortlcrs of rnagnit,~ltlc in [92GRE/FUG], t,hc irlconsist,cncics rrlcntiorlcd by Grcntllc e t (11. st,ill rcrn. a n ' nnrc- solved, and a re-cxnrninnt,ion of t,his syst,cm is hcing ~indcrt,akcn sirn~llt,anco~lsly ~vit,ll the ncpt,~lniiim and pl~lt,orliiim NE.4-rcvic\1rs.

D.4. Uranium carbonate complexes and compounds

.klthongh no rcrrlarks have bccn mntlc on t,hc sclcct,cd thcrmotlynarnic vnliics con- cerning t,his chcrrlical syst,cm, a re-acljust,rncnt of t,llc rrlct,llod for ionic st,rcngt,h corrcct,ions has t,nkcn place n.it,hin the XE.1-TDB project as discnsscd i)clo\v. This has insignificant consequences on t,hc sclcct,cd thcrmotlynarnic vnliics. but might have non-11cgligil)lc cffcct,s on t,hc ionic st,rcrlgt,ll cxt,rapolat,ions in cnrbonat,~ sol~lt,ions for users of the specific ion int,cractiorl cqnnt,ions tlisciisscd in .kppcndix B.

hlorc irrlport,arlt is t,hc fact that t,hc thcrmotlynarnic tlat,a sclcctcd by Grcnt,llc et o,l. [92GRE/FUG] arc not likely t,o reflect t,hc bc11~1,vioiir of U(I\') at pH < 7, i)ccaiisc rrlixctl hydroxitlc carhonatc/hicnrbo~~i~~t~c complcxcs of U(I\:) arc prol)ably forrrlcd in those aqncoiis solutions (cf. [92GRE/FUG, p.3231). Expcrimcrlt,nl informnt,ion on the corrlplcxcs formctl and their stability is st,ill i~adly nccdcd 3 ycnrs aft,cr t,llc public a t ' ,ion of t,hc NE.4 rrcric\v.

Tllc grounds for the chnrlgc in t,llc pararnct,crs of t,llc ionic st,rcrlgt,ll corrcctiorl rrlctllod for carhonatc solutions, nrltl it,s effects on t,llc sclcct,cd iiraninrn vnliics. arc prcscrlt,ctl in the follo\ving tlisciissions.

For consistency. the auxiliary data prcscrlt,ctl in Chnpt,cr I \ ' have to he used ~vit,ll the x~alncs sclcct,cd in the XE.1-TDB rcvic~vs. For t,hr aqiicolls cnrbonat,~ syst,cm, the cq~iilil)riiim constants arc calc~llatcd fiorn the COD.4T.4 Key \;?liics [89COX/II:.kG] with t,hc nnccrt,nint,ics re-cxi~,lnnt,ctl in Chnpt,cr 1'1 of [92GRE/FUG]. For cxarnplc for the rcactiorl

C O : + 2 H+ + COL (g) + H,0(1) (D.1)


log,, lc = (18.15 0.04) is oht,nincd cornl)ining the val~lcs given in Table I17.2

Tllc sclcct,cd dnt,n in the NE.%-TDB project sllo~lld he iiscd in combinat,ion ~vit,ll the spccific ion intcract,ion cqiiations (cf. .%ppcndix B). This ~vill cnsiirc consist,cncy bct,\~~ccn t,hc ionic st,rcngt,h corrcct,ions iiscd in t,llc rrlodclling calc~llations and during the NE.% rcric\v proccdiirc.

Ho\vcvcr, n rncmbcr of t,llc t,carn for t,llc yp/P11 rcvic\v (Dr. \?it,orgc. CE.4, France) has point,ctl oiit t,hnt for the aqiicolls carl)onnt,c syst,crn the cxpcrimcnt,nl cqnilibrinrn const,ant,s in NaC104 mctlia arc poorly rcprcscnt,cd by t,llc combinat,ion of COD.4T.A Kcy \;?liics and t,hc spccific ion int,cractiorl cq~lat,ions (iising the val~lcs of E(,,+,,:(,:-)

and E(~~+,,,:(,;) ntlopt,cd in [92GRE/FUG]). Nc~~crthclcss, it rrlllst bc stated t,hnt the calciilnt,ctl ant1 cxpcrirncnt,al vnliics do ngrcc ~vit,llin t,llc iinccrtaint,y of t,llc cxtrapola- tions. .% bct,tcr agrccrrlcnt hct,\~~ccn t,llc COD.%T.% Key \;?liics ant1 the cxpcrimcnt,nl rncnsnrcrncnt,~ is oht,aincd using the ~-~ra lncs rcport,cd by Ciavat,t,n [80CI.%]. .%pparcnt,ly t,hc vnliics of E(,,+ ,,:( ,:-) and E(,,+,, ,:,,;) adopt,cd in [92GRE/FUG] nrcrc oh- taincd from a fitt,ing of nct,ivity (or osrnot,ic) cocfficicnt tlat,a for Na2CO:j ant1 NaHC(13 soliit,ions. H o \ ~ ~ c ~ ~ c r , Dr. \"it,orgc point,cd out t,hnt t,his procctl~lrc is inntlcqiiatc, be- ca lm hydrolysis will take place in tllcsc soliit,ions of the "p~lrc" snlt,s, introdiicing n syst,cmnt,ic error in t,hc ~ - ~ ~ a l n c s obtaincd by t,llc fit,t,irlg procctl~lrc. Thcsc argnrncnt,~ ~vcight,cd against the policy of keeping t,hc ~ ~ a l n c s of t,hc spccific ion int,crnct,ion pn- rarnctcrs constant t,hronglloiit t,llc NE.%-TDB rcvic~vs; and it was finally decided t,llat, it ~~ronltl i)c rcasonablc to change t,hc vnliics of t,llc two key ~ - ~ ~ a l n c s to those given in [80CI.%]:

,,:( ,:-) = ( 0 . 0 8 f 0.03) k g . rnol-l. ( D 4 -

- (0.00 f 0.02) k g . rnol-l. L(sa+,~(:o;) (D.3)

In order t,o kccp internal consist,c~~cy nrrlong the NE.%-TDB rcvic~vs, this change of ~ - ~ ~ a l n c s requires a re-c~i~,lnnt,ion of t,llc ~ ~ a l n c s sclcct,ctl in t,hc YE.% rcvic~v on nraniiim thcrmotlynamics [S%GRE/FUG]. Grcntllc at al. sclcctcd data for 10 aqiic- 011s carl)onnt,c/l)icarho~~atc cornplcxcs of iiraninrn; incliiding mixed corrlplcxcs ~vit,ll hytlroxo or oxo groups. Fnrt,hcrrnorc, t,hc nraniurn review cont,ains sclcct,ctl val~lcs for t,wo cornplcxcs cont,aining l)oth dioxonrani~lrn(\'I) ant1 cit,llcr dioxol)lntoni~lrn(\'I) or dioxoncptiiniurr~(\'I). T\vo solid phascs lla~rc sclcct,cd val~lcs: U02CO:j(cr) ant1 N:14U02(CO:3):3(~r).

In addition t,o formation ant1 rcactiorl data 7 spccific ion int,crnct,ion cocficicrlt,~ wcrc sclcct,cd by Grcntllc et al. [92GRE/FUG. Table B.41 for nqllcons corrlplcxcs of nraniiim and cnrbonat,c (incl~ltling n rrlixcd cnrbonat,c-hydroxo cornplcx).

Tllc sclcctiorl proccdiirc f o l l o ~ ~ ~ d by Grcnt,llc et (11. is rcpcatcd hcrc using the ncx~~ E-vnliics as dcscribctl in the follo\~.ing Scct,ions. .%S cxpcct,cd. t,hc effect of the ncx~~ E-vnliics (cf. Eqs. (D.2) and (D.3)) in t,llc sclcct,cd thcrrnodynarnic tlat,a for nraniurn corrlplcxcs and compo~lrltls is quit,c small, hut t,hc cllnngcs arc larger on t,hc ~ ~ a l n c s of the spccific ion intcract,ion cocfficicnts of iiraninrn carhonatc cornplcxcs. Tllc rcs~llt,s of t,hcsc re-c~i~,lnnt,ions arc siimrnarizctl in Tal)lcs D.1. D.2 and D.3.

Tahlc D. l : Specific ion int,cractiorl cocfficicnt,~ (E. in nnit,s of kg . mol-l) for nraniurn carl)onnt,c complcxcs rcviscd for t,hc cllangctl E-vnliics given in Eqs. (D.2) and (D.3). Tllc val~lc in c.rn,plrcxsizerltyl)cfncc is t,nkcn dircct,ly from Ref. [92GRE/FUG] nrltl is not, nRcct,ctl by t,his re-cvnliiation. .%l1 ionic spccics list,ctl in this t,al)lc arc nqllcons spccics. .%l1 data rcfcr to t,llc rcfcrcncc t,crnpcratiirc of 298.15 K and t,o t,llc st,arltlartl state, i .e. ; a prcssiirc of 0.1 hIPa. Tllc iinccrtaint,ics list,cd rcprcscrlt t,ot,al ~lrlccrt,aintics nrltl correspond in principle t,o t,hc statist,icnlly dcfirlcd 95% corlfitlcncc int,crxi~,l.

Tllc t,~vo vnliics of t,hc cqiii1il)riiirn const,nrlt,s for rcact,ion

from Rcfs. [72SER/YIK, SlGRE/L.%G] and t,llc four x~alncs obtaincd from rcint,crprct,at,ions of t,hc data in Rcfs. [69TSY, 79CI.%/FER.; 84GRE/FER] arc corrected t,o I = 0 usirlg Ac(D.4) = ( 0 . 3 8 * 0.04) kg. rnol-' inst,cad of ( 0 . 4 1 * 0.04) kg. rnol-'. Tllc rcviscd vnliics arc given in Tal)lc D.4.

Not,c t,hnt t,llc val~lcs of log,, ill for Rcfs. [79CI.%/FER. 84GRE/FER; 91GRE/L.4G] have been rccalciilnt,cd from the corrcspondi~lg c(l~iilil)riiim ronst,ant,s of rcact,ions irlvolving CO2 (g):

CO;+ + H2O(1) + COZ(g) + U02CO:j(aq)

corrlhincd ~vi th vnliics of log,, l ~ ' ~ ( D . 1 ) calc~llatcd from t,hc COD.4T.I Key I'al~lcs (cf. Tahlc II:.2) and the specific ion intcract,ion cqnnt,ions (cf. -4ppcntlix B) using + - = ( 0 . 0 8 * 0.03) kg . 11101-~.

Tllc \~,cight,cd average of the vnliics cxt,rapolatcd t,o I = 0 and list,ctl in Table D.4 is:

log,, p,"(D.4,%98.15 K) = 9.67 * 0.05

~vhich is csscnt,ially cqnnl to t,llc x~alnc obtaincd by Grcntllc et (11. [92GRE/FUG]: log,, p: = (9.68 * 0.04).

Covrctf oas to t11,r Ur(~rrrrrrn NEA- TDB rrrirrru

Tahlc D.2: Thcrmotlynamic data for iiraninrn carI)onat,c complcxcs and corrlpoiinds from Ref. [92GRE/FUG] rcrisctl for t,llc changcd E-va111es given in Eqs. (D.2) a11d (D.3). I'al~lcs in c.rn,plrcxsizerl t,ypcfacc arc t,akcn tlircct,ly from Ref. [92GRE/FUG] and arc not affcct,cd by t,his re-cxi~,lnat,ion. -411 ionic spccics list,ctl in this t,aI)lc arc aqiicolls spccics. Urllcss noted ot,llcr\visc, all dat,a rcfcr to the rcfcrcncc tcrrlpcrat,~lrc of 298.10 K arltl to the st,andard st,at,c; i .e . . a pressure of 0.1 hIPa anti, for aqllcons species, in fin it,^ dil~lt,ion (I = 0). The ~lrlccrt,aintics list,ctl I)clo\v each val~lc rcprc- sent t,ot,al iinccrtaint,ics and correspond in prirlciplc t,o the statist,ically tlcfincd 95% confidcrlcc int,crval. I'al~lcs oht,aincd from int,crrlal calcnlat,ion, cf. foot,not,cs (a) arltl (I)). arc ronndctl at the t,hird digit aft,cr t,hc tlccirnal point and rnay t,llcrcforc not I)c cxact,ly itlcnt,ical t,o t,hosc given in Chapter 1' of [92GRE/FUG]. Systcrnat,ically, all the valiics arc prcscnt,cd nrit,h tllrcc digit,s after the decimal point. rcgartllcss of the significance of t,hcsc tligit,~.

(a) JTa111e ~:al~:ulai,erl ir~terrlalljr ~vit11 i , l~e Git)I)s-Helr1111oltz eqi~atior~, = 4rHi1 - TlcSil (I)) \:lllle calcl~laterl ir~terrlally frorr~ reactior~ data (see Tal)le D.3).

(c) O111ji reactior~ data are select,ecl for illis corr~po~~nrl, 1:j T~al~le D.3.

Tahlc D.3: Thcrrnodynarnic tlat,a for rcact,ions irlvolving nraniurn corrlpoiinds arltl corrlplcxcs revised for the changcd E-va111es given in Eqs. (D.%) and (D.3). \:alncs in erri,plrcxsizerl typefacc arc taken tlircctly from Ref. [S%GRE/FUG] arltl arc not affected by this re-cxi~,lnat,ion. .l11 ionic species list,cd in this t,ablc arc aqiicolls spccics. Unless not,cd ot,hcr~visc. all data rcfcr to the rcfcrcncc tcrnpcratiirc of 298.15 K and to the st,andard state, i . e . ; a pressure of 0.1 l IPa and, for aqiicolls spccics; in fin it,^ diliit,ion (I = 0). The llrlccrt,aintics listed he10117 each x~alnc rcprcscrlt total iinccrtaint,ics arltl correspond in principle to the st,at,ist,ically dcfirlcd 95% confidcncc int,crval. \'al~lcs oht,ainctl from int,crrlal calciilat,ion. cf. foot,not,c (a), arc roiindcd at t,hc third tligit, aft,cr t,llc dccirrlal point and may t,llcrcforc not bc exactly idcnt,ical to t,hosc given in Chapter 1' of [92GRE/FUG]. Systcrnat,ically, all the val~lcs arc prcscrlt,ctl ~vit,ll tllrcc digit,s aft,cr the dccirrlal point,, rcgartllcss of t,hc significance of t,llcsc digit,s.

Species Reactior~ log,, K" A,(% 1, H:, ars:,

(kJ . rnol-l) (kJ . rnol-l) (J . K-' . rnol-l)

C O ; + UOzt + UO,CO,(<:r) 14.490 -82.710

(a) \:llllr calcl~laterl ir~terrlally wit11 t l ~ r Git~l~s-Helrnholtz rq~lation, 4,G:, = A,H:, - T A r S i l .


Tahlc D.4: Expcrirncntal cqiii1il)riiim tlat,a for reaction: U@+ + CO;- L - UOzCO:j(aq). This t,ahlc snpcrscdcs t,llc corresponding valiics in Tahlc \:.42. 11.309 of Ref. [92GRE/FUG].

\Ietl~o(i Ionic t log,, -i ja) log,, (j,"(a) Referer~ce \Ierlil~rr~ ("c)

ernf. g1 0.1 M (NaC1O4) 25 9.30 i 0.20(".") 10.13 f 0.20 [GSTSY] sol. sp < 0.03 RI 25 9.87 f 0.30~") [72SER/NIK] ernf. g1 3.0 M (NaC1O4) 25 8.60 i 0.18(".C) 9.14 f 0.23 [79CI..I/FER] sol 0.5 M (NaC1O4) 25 8.38 i O.lO(".C) 9.57 f 0.11 [84GRE/FER]

3.0 M (NaC1O4) 25 8.89 i 0.11)(".~) 9.43 f 0.18 ernf. g1 0.5 rn (NaCl04) 25 8.54 i 0.05 9.73 f 0.07 [9lGRE/L..IG]

(a) log,, (j1 refers to eclllilil~ri~~rn corlstar~t in the ior~ic rnecli~lrn ancl a t the t,err~perat~lre giver1 i r ~ the t,at)le, log,, (j," (in rrlolal units) a t I = 0 ancl 298.15 K.

(11) Re-evah~at,ecl 1137 Grer~tlle et ILL. [92GRE/FUG, ..Ippen(iix A]. (1:) The reporte(i corlstar~t is <:orrect,ecl for t,lle rliffererlt prot,or~at,ion corlstar~t of car-

t)or~at,e ilsecl in t l ~ e NEA reviews (cf. Ta11le IV.2) <:orre<:te(i for rnecli~lrn effect,^ wit11 t l ~ e specific ior~ interaction eclllat,ions (f:j ..Ippenrlix B), 11si11g t,lle sarrle procecl~lre as Grer~tlle f!t ILL. [92GRE/FUG. rlpperlclix A].

(cl) Ur~certair~ties estirr~aterl 1137 Grer~tlle et ILL. [92GRE/FUG].

Tllc sclcctiorl procctlllrc for t,hc ~ ~ a l n c s of log,, L/," and log,, 9; is not affcct,cd by the change in t,hc key E-va111es. HO\ITT'C~, from t,llc val~lcs of !k2 and A E : ~ t,llc t,\~,o sclcctcd ion intcract,ion cocficicnts arc inst,cad:

Tllc sclcct,ion proccdnrc for the valllc of t,hc st,arltlard cqnilibrinrn const,ant of forrrlatiorl of t,his cornplcx, log,, &. is rlot affected by t,hc change in t,llc key E-va111es. Ho~vcvcr. t,hc valllc of t,hc sclcct,ctl iorl intcract,ion cocfficicnt is derived to l ~ c :

Tllc sclcct,ion proccdnrc for t,llc ~ralnc of the st,arltlartl cqllilihrillrn const,arlt of forrnation of t,llcsc complcxcs ((uo~)~~(co:~)~(oH):;. (U02):30(OH)z(HCO:j)+ arltl (U02)2CO:3(OH),) is not affcct,ctl by t,llc change in t,llc key ~ - ~ ~ a l n c s , bccansc the reactions considcrctl by by Grcrlt,hc et (11. [92GRE/FUG] ditl involve COz(g) as

a cornponcnt. rat,llcr t,harl carhonatc or i)icarhonatc ions, (cf. rcact,ions (\:.164) t,o (\ : . lGi) arltl Tal)lc 111.2 in Ref. [92GRE/FUG]. For the sarrlc reason; t,hc valiic of c((r;o,),c:o,(oHL ,Na+) sclc~t,cd by Grcnt,llc et al. rcrrlai~ls 1111changcd.

0.4.3. Mimd U(VI), Nli (VI) (xrrci P'ii,(VI) co,~horaatc. conl,plr:~;c..s

Tllc cqiii1il)riiim const,arlt,s at (22 * 1)"C in 3 hI YaC104 rcport,cd in [86GRE/RIG] for the re ac t ' ,ions

2 u(Iz(co:~): + A I O ~ ( C O : ~ ) : = ( uo~ )~ ( I I Io~ ) ( c ( I~ ) : + 3 c():- .\I = Np. Pn (D. 7)

arc cxtrapolat,cd t,o I = 0 assiimirlg that ~ - ~ ~ a l n c s arc the sarnc for t,hc corrlplcxcs ~vit,ll Af = L; Np and Pii. i .e. iising AE = (0.16 f 0.36) kg . rnol-l. obtai~ling

log,, h'"(D.7; A I = NI). 298.15 K) = 9 .4*1 .3 log,, h'"(D.7; A I = PII; 298.15 K) = 8 .2*1 .3

The standard Gibbs crlcrgics of format,ion for ( U ~ ~ ) ~ ( N ~ ~ ~ ) ( C ( I : ~ ) ~ arltl ( u ~ ~ ) ~ ( P I ~ ~ ~ ) ( c ( I ~ ) ~ will l)e sclcctcd i11 the fortllcomi~lg NE.% r c ~ ~ i c w 011 t,hc cl1er11- ical thcrmotlynamics of ncpt,nnillrn and plntonillrn.

Tllc sclcct,ion procedure iiscd by Grcnt,llc et o,l. t,o obt,ain t,llc valllc for the standard rcdox pot,crlt,ial for rcact,ion

is not affcct,ctl by the charlgc in t,llc key ~ - ~ ~ a l n c s , bcca~lsc no carhonatc or bicarl)onat,c ions arc involvcd in t,his rcact,ion. Ho~vcvcr. from t,hc ~ralnc of Ac(D.8) = ( 0 . 6 1 * 0.10) obtaincd by Riglct [9ORIG. p.1051, t,llc sclcct,cd ion int,cractiorl coefficient is:

Note that at each of t,llc YaC104 conccnt,rations st,iidictl by Riglct,, she rncasnrcd apparent norrnal pot,crlt,ials rclat,ivc to t,hc sto,nrlarci hj~drogcn clcct,rotlc anti; t,hcrcforc, actirit,y cocficicrlt corrcct,ions for H+ accordirlg to t,llc rcact,ion: $HZ(g) + H+ + c- arc not incllltlcd in t,hc valllc of !,E.

Tllc sclcct,ctl stcp~visc cq~lilihri~lrn constant for reaction


is not affcct,cd by the E-va111es given in Eqs. (D.2) arltl (D.3). Grcnt,llc et al. cst,i- rrlntcd t = ( 0 . 0 9 * 0.10) kg . rrlol-l [92GRE/FUG; p.3241. ~vhich is corrlhincd ~vit,ll t,hc cxpcrirncnt,al valiic of h ( D . 9 ) = (0 .13*0 .11) kg.rrlol-l t,o yicltl

6 . + = ( 0 . 3 0 f 0.15) kg . mol-l. Tllc sclcct,ctl ~ - ~ ~ a l n c s arc E(T;((:O?), ,l* )

E ~ ( ; - , ~ + = ( 0 . 0 9 f 0.10) k g . rnol-l. - - ( 0 . 3 0 f 0.15) k g . rnol-l. '(T;((:O3)~.Sa+)

Tllc valiic of which is tlcrivcd from the cstirrlat,c of E(,;(

is used in rlcxt Scctiorl t,o cxt,rapolatc t,llc valiic of log,, i& t,o I = 0.

Tllc norrnal rctlox pot,crlt,ial of t,hc rcactiori

was tlct,crrrlinctl in 3 11 NaC1(14 solllt,ions a t 25°C by Ciavatt,a e t 111. [83CI.%/FER]: E" = ( 0 . 2 7 9 * 0.001) 1'. i .e. ; log,, l i(D.lO) = ( 9 . 4 3 2 * 0.034). Tllc proccdnrc irltlicat,cd in Grcrlt,hc et 111. [92GRE/FUG. .%ppcndix .%l; will also he follo\~~ctl hcrc. Rcact,ion (D.lO) is cornl)inctl ~vit,ll the cqllilihria

U(]:+ + 2 c + 4 H+ + U'+ + 2 H20(1) (D . l l )

CO;+ + 3 C O : + U02(CO:j):f (D.12)

COa (g) + H20(1) + C O : + 2 H+ (D.13)

~vhosc sclcct,ctl const,ant,s arc cxt,rapolat,ctl to I = 3 hI XaC104 using the specific ion intcract,ion cqiiations of .%ppcndix B (\\,it11 t,hc E-va111es given by Eqs. (D.2) arltl (D.3)). oht,aining, log,, h'(D.ll) = (11.96f 0.37). log,, l i(D.12) = (22.61*0.51) arltl log,, l i(D.13) = ( 1 7 . 6 1 * 0.18). Finally, for rcact,iorl

the cqnilibrinrn const,ant is calciilat,ctl to bc log,, = (36.44 * 0.68). Tllc ~ralnc of 6 -, + = ( 0 . 3 0 f 0.15) kg. 11101-~. cstirrlat,cd in t,llc prcviolls scct,ion follo~ving E(T;((:O?), ,l* )

the proccdnrc of Grcntllc et al. (cf. pages 660 and 324 in Ref. [92GRE/FUG]). is iiscd to oht,ain k ( D . 1 4 ) = ( 0 . 6 6 f 0.22) kg . mol-l. \vhich allo~vs iis t,o calclllatc:

log,, J/9(298.15 K) = 34.1 * 1.0,

~vhich is csscnt,ially t,llc sarrlc valiic as t,llat reported 1)y Grcrlt,hc e t d., (34.0 f 0.9) [92GRE/FUG; 11.3241. Tllc large nnccrt,aint,y is dnc t,o t,hc acc~lrrliilnt,ion of iinccrtain- tics for t,llc cxtrapolat,ion of the cqllilihrillrn const,ants for rcact,ions (D. l l ) to (D.13) frorn I = 0 to I = 3 11, arltl t,hcrl for the cxt,rapolation of log,, i& i~ack t,o I = 0.

t Grerltl~e f ! t al. consistently listed E ( , , ( ~ ~ : 4- + = (0.09 f 0.10) 110th i11 p.324 arlrl in p.69'7 v),, . a 1

[92GRE/FUG]. This appears to t)e a misprint, arlrl t l ~ e va111e sho~ll(i in fact htwe a. rlegative sign.

0.4 .6 . Solid irro,niurn carhorrcxtes

Tllc four rcliablc valiics of t,llc cqnilibrinrn const,arlt,s for rcact,ion

from Rcfs. [72SER/NIK; 76YIK2; 84GRE/FER] arc corrcct,cd t,o I = 0 using ( D l ) = ( 0 . 3 8 f 0.04) kg . mol-l. Tllc revised valiics arc listed in Tahlc D.5. Tllc \~rcigllt,cd axrcmgc of t,hc val~lcs cxt,rapolatcd t,o I = 0 is:

which is csscnt,ially equal to t,llc x~alnc obtaincd by Grcntllc et (11. [92GRE/FUG]: log,, ~ q , = ( 1 4 . 4 7 * 0.04).

Tahlc D.5: Expcrirncntal cqiii1il)riiim dat,a for rcact,ion: UOzCO:j(cr) + u O ~ + + CO;-. This t,ahlc siipcrscdcs tllc corresponding x~a111es in Table 17.4%, 11.311 of Ref. [92GRE/FUG].

\Ietho(i Ionii: t l o g ~ i l ~ d ? ? log,, I<:(,a) Referer~ce \Ieclil~rr~ ("C)

sol 0.0002 to 0.02 M 25 -14.26(j) -14.26 i 0.30(") ['i2SER/NIK] sol 0.01 RI(") 25 -14.15 i 0.08 -14.50 i 0.17(") ['iGNIK2] sol 0.5 RI (1UaC104) 25 -13.31 i 0.03("~~) -14.49 i 0.04 [84GRE/FER]

3.0 RI (1UaC104) 25 -13.94 i 0.03("~") -14.48 i 0.15

(a) log,, IL.0 refers to e(lllilil)ri~nn i:onstant in t,lle iorlic rr~eclil~rr~ r%rld r%t tlle t,e~r~perr%tllre given in tlle t,at)le, loglil (in rrlnlal i111it,s) a t I = 0 r%rld 298.15 K.

(I)) Re-errr%l~~ate(i t)y Grerltl~e e t 01. [92GRE/FUG, .4ppenrlix A]. (c) Tlle reported c n ~ l s t a ~ ~ t is c:orrei:te(i for t l ~ e (lifferent protonation corlstar~t of i:arl)on-

at,e ilse(i in this review Tat~le IV.2) correi:te(i for rr~erlil~rr~ effect,^ wit11 t,lle specifii: ior~ ir~teract,ior~ eqllat,ions (cf. i\ppenclix D). folio\%-ing t l ~ e proce(illre of Grer~t,lle f ! t al. [92GRE/FUG, .4ppen(iix -41.

((i) Uni:ertaintirs estirr~at,e(l t)y Grerltl~e e t 01. [92GRE/FUG]. (h) Ionii: strerlgtl~ assllrrle(i to t)e sirrlilar to t,llat reporte(i in Ref. [72SER/IiIK]. (j) \:r%111e refers to I = 0.

0.4.6.2. Na4 U02 (C0:j):j (cr)

Tllc cxt,rapolat,ion to I = 0 of t,llc mcasllrcrrlcnts [56BL.%/COL] of t,hc cqnilibrinrn const,ant for

is not affcct,ctl by tllc ncn7 E-valiics dcfirlcd in Eqs. (D.2) and (D.3). The valllc of l c (D.16) = ( 0 . 0 9 f 0.06) kg . rnol-' obtaincd by Grcntllc et (11. [92GRE/FUG.


p.3281 11ox~~ leads t,o E ( ,,02 ( ,:03 - , + = ( 0 . 1 3 * 0.07) kg . rnol-', ~vhich st,ill tliffcrs significant,ly fiorn the ~ralnc givcn in Eq. (D.6) and Tal)lc D.1.

D.5. Uranium minerals

Tllc t,hcrrnodynarnic tlat,a for nraniurn rrlincrals ha~-c bccn t,hc sllhjcct of some cx- pressed crit,icism regarding t,llc NE.4-TDB rcric\v for nranillrn. Taking int,o accollrlt, the complex chemistry of t,hcsc solid pllascs. it is t,o he cxpcctcd t,hat t,hc niimbcr of pllhlicat,ions ~vit,ll cxpcrimcrlt,al tlct,crrrlinnt,ions of thcrmotlynamic paramct,crs for nraniiim rnincrals is loxv. The cxist,irlg lit,crat,llrc on t,his siil),jcct urns rcvic\~rcd by Grcntllc et al.. [92GRE/FUG]. arltl \IT arc not aware of any ot,llcr cxpcrirncnt,al work ~vhich escaped t,llc at,tcntiorl of the NE.4-rc~icw t,carn and t,hat coiild have l)ccn iiscd to rccomrrlcnd t,hcrrnodynarnic data on iiraninrn rnincmls.

Ncvcrt,llclcss. a few piil)lications have l)ccn follrld [810BR/\VIL; 81\'0C/PIR, 83C)BR/\\'IL, 83\'OC/PEL, 84\:OC/GR.4, 84\'OC/GOE. 86\'OC/GR.k; 88AkTK/BEC, 90\:OC/H.4\'] ~vhich by rrlist,akc n7crc not incllltlcd in the disc~lssiorls of Chapter 1" in Ref. [92GRE/FUG]. -4s t,hc qllalit,y of the cxpcrimcrlt,al dat,a givcn in tllcsc rcfcrcnccs is not atlcqiiatc t,o inclndc t,hcrrl in a sclcct,ion proccdiirc. it is important t,o note t,llat t,llis orrlission tlocs not really affect t,hc set of sclcct,cd t,llcrrnodynarnic iiraninrn data given in t,llc YE.$ review.

T\vo stiidics presented by O'Bricn and TVilliarns in [81OBR/I\'IL, 830BR/\VIL] deal ~vi th t,llc st,ahilit,ics of diffcrcnt secondary iiranyl rnincmls. Tllcsc rcfcrcnccs arc Part,s 3 and 4 of a scrics of papers. Part,s 1 and 2 [iSH.4.4/II'IL. 80.4LII'/\VIL] in the sarnc scrics wcrc rcric\vctl arltl tlisciissctl by Grcnt,llc e t (11. [S%GRE/FUG] (Sections 17.5.1.3.2.c and \'..7.1.2.2.1>, pp. 254 255 arltl 328; and the comrrlcnt,~ on [79H.4.k/1\'IL] in .4ppcndix -4. pp. 646 648).

O'Bricn arltl Il'illiarns [810BR/\VIL] reported tllc Gibbs cncrgics of forrrlat,ion of

Tllcrc arc alrrlost no cxpcrirncnt,al dct,ails on t,hc t,cchniqiic arltl data analysis iiscd in this work as ~vcll as no information abollt t,hc aiixiliary data llsctl. In Part 4, [830BR/\\'IL], O'Bricn arltl i\'illiams rcport,cd t,hc thcrmotlynamic st,ahilit,ics, i .e. ; Gihhs cncrgics of f~rrnat~ion, of schrijckingcrit,~, C a : 3 S : ~ , U 0 2 ( C O : 3 ) : 3 ~ . 10H20(cr); and grimsclit,c. K:~YaU02(CO:3):3 . H2O(cr). calclllatctl from soliil)ilit,y cxpcrirncnt,~. Tllc mct,hotl iiscd for tllcsc mcasllrcrrlcnts is csscnt,ially t,hc samc as as prcviollsly nsctl by Haackc et al.. [iSHAk.4/\VIL] in Part 1 of t,llis scrics. Tllc allt,hors pcrformctl corrcctiorls for ionic st,rcngt,h cffcct,s to the cqllilihriiim const,arlt,s for the aqllcons cornplcxcs, but t,llc data suffer fiorn the samc fin117 as prc~ioiis st,lltlics. i . c:., ncglcrt of the format,ion of hydrolysis species, ~vhich in the invcstigat,cd pH range (7.69 t,o 10.00) is cxpcct,cd t,o bc irnport,ant for t,hc nraniurn system; introdiicirlg a large iinccrtaint,y in t,hc calciilat,ctl solllhilit,y prodnct,~. arltl t,hcrcforc on t,hc rcsnlt,ing ~ ~ a l n c s of the thcrrnodynarnic tlat,a.

Tllc solubility prodnct,~ of cobalt. nickel, and copper nranylphosphat,c. (rnct,a- torbcnit,c) wcrc rncasnrcd by \kcht,cn e t d., [81\:OC/PIR]. Tllc solid corrlpoiinds wcrc synt,hcsiscd and adcqllat,cly chamct,criscd. Ho\vcvcr. the solubility cxpcrirncnt,~

and t,llc corrcsporltling dat,a analysis have scrio~ls limitations, e.g., lack of nraniurn and pllosplloroiis analysis. standardisat,ion of t,hc pH clcct,rodc ~vit,ll i)iiffcr soliit,ions ~vhich n7crc out of t,llc pH range iindcr invcstigat,ion, no corrcctiorl for ionic st,rcngt,h cffcct,s on the auxiliary t,hcrrnodynarnic data (\vhich nrcrc t,akcn from Sillkn et 111.

[G4SIL/II.$R]; arltl only incliidcd nranyl phosphoriis cornplcxcs), etc. F~lrtllcrmorc; the aiit,llors ditl not specify in ~vhich ionic rrlcdi~lrrl t,hc soliil)ilit,y cxpcrirncnt,~ wcrc done. It might i)c ass~lrncd that t,llis was just piire wat,cr. Xo crloiigh dct,ails wcrc give11 for a thorough cval~lat,ion

Sah~lgalit,c is a hytlmt,ctl acid al~lrnini~lrn ~lrnnylphosphat,c ~vhich cryst,al chcrnical formula corresponds t,o H.$1(U02)1(POI)I . 1GH20(cr). Tllc stiidy pcrformctl by \'ocht,cn and Pclsrnackcrs, [83\'OC/PEL], gives sorrlc informat,ion on t,hc sol~lhilit,y of this corrlpoiind under conditiorls not nrcll tlcfincd, in t,~vo ionic mctlia, phosphoric and hydrochloric acid. Tllc lack of cxpcrirncnt,al dct,ails along ~vi th t,llc ahscrlcc of the m\v data does not allo\v fi~rt,llcr calciilat,ions of t,hcrrnodynarnic valiics.

Bassctitc is a secondary ilmnyl phosphate arltl has t,hc crystal chemical formula Fc(U02)2(P04)2 . 8H20(cr). This compo~lrltl t,ogcthcr ~vi th it,s fully oxidised for111 wcrc synthcsiscd and cxt,cnsivcly invcstigat,cd by \"ocht,cn e t 111. [84\.'OC/GR.4], using vario~ls t,cchniqi~cs, . pou~dcr diffi.ar,t,ion. hliissbaiicr and infrared spcctroscopy, zcta- potential mcasllrcrrlcnts and t,hcrrrlal analysis. The aiit,llors also mcas~lrctl the soliil)ilit,y of t,llis solitl as a fiinctiorl of t,hc acidity, at 2.4 < pH < 6.0 in HC1 rrlcdi~lrrl nntlcr nit,rogcn atmosphcrc. They rcportcd soliil)ilit,y val~lcs hascd only on the t,ot,al iron conccnt,ration in soliit,ion. The ionic st,rcngt,h of t,llc cxpcrirncnt,~ is nnkno\~,n. Tllc cxpcrimcrlt,al dct,ails arc so scarcc t,hat it is not possiblc to obtain any fiirt,hcr informat,ion.

Tllc synt,hcsis arltl propcrt,ics of several iiranyl arscrlat,cs have bccn rcportcd in [84\'OC/GOE, 8G\'OC/GR.$]. \'ocht,cn and Gocrrlinnc [84\'OC/GOE] rncasnrcd the soliil)ilit,y of copper (rnct,a-;sc~lncrit,c); cobalt (rnct,a-kirchhcirmitc) and rlickcl nranyl arscrlat,cs at room t,cmpcmt,urc. The corrcsporltling ionic mctliiim urns not specified. Tllc cxpcrimcrlt,al mct,hotlology and data analysis nrcrc basically the samc as prcvionsly dcscrihcd in ot,llcr p~lhlicat,ions by t,llc same aiit,llors (sec t,llc corrlmcrlt,~ on [81\'0C/PIR] given ~ r c ~ i o i i s l y in t,llis scct,ion). Thcrcforc. all t,hc tlat,a cxhibit analogous lirnit,at,ions. -4 sirrlilar st,~ltly on mangancsc and iron (rncta-kahlcrit,c arltl its fi~lly oxidised form) iiranyl arscnatcs urns rcport,cd by \.'ochtcn et al. [8G\'OC/GR.$]. .$gain. the samc procctl~lrcs nrcrc ~lsctl ~vhich render t,llc rncasnrcrncnt,~ iins~lit,al)lc for the cxt,ract,ion of atltlit,ional t,hcrrnodynarnic tlat,a.

Tllc st,ahilit,y field of bccqiicrclit,c. CaU60L9 . 11H20(cr), was rcport,ctl as a fimc- tion of t,cmpcmt,urc and calcium corlccntrat,ion by .$tkins e t 111. [88.4TI</BEC]. They also mcas~lrctl t,llc sol~lhilit,y of t,his solid and Ca2UOi . (1.3 l . i )H20(cr) , at 20°C in two ionic rncdia. piire nrat,cr arltl a 0.5 11 NaOH soliit,ion. 1. i . r~ fcxv dct,ails ahoiit, the cxpcrimcrlt,al proccdiirc arc given. Th~ls, t,llcsc solubility valiics do not provide siifficicnt information to extract thcrmotlynamic dat,a.

\'ocht,cn arltl \.'an Havcrhckc, [90\.'OC/H.$\'], irlvcst,igat,ctl t,llc transformation of schocpit,c, chcrnically cqiii~i~,lcnt t,o . 2H20(cr). int,o bccqiicrclit,c. l)illict,it,c arltl ~viilscntlorfit,c, nrhich correspond t,o C;tUfiOln . 11H20(cr), BaU~iOln . 11H20(cr). arltl PbU207 . 2H20(cr); rcspcct,ivcly. Tllcsc t,ransformat,ion rcact,ions nrcrc ol)t,ainctl at,


60°C. Tllc soliii)ilit,ics of t,hcsc cornpounds nrcrc also rncasnrcd at 25°C in nrat,cr as a fiinctiorl of t,llc pH. Care as taken to avoid the prcscncc of C02(g). Ho\vcvcr, the st,ahilit,y of t,hcsc solids at roorrl tcrrlpcrat,~lrc in t,hc ahscrlcc of calcinrn; bari~lrn. and lcatl; in t,hc aqllcons soliit,ion at t,hc pH valiics invcstigat,cd was not addressed. Based on t,hc solnbilitics mcas~lrctl under t,llcsc cxpcrirncntal contlit,ions. the aiit,llors calciilat,ctl t,llc soliii)ilit,y prodnct,~ for i)ccq~lcrclit,c and billict,it,c. They claimctl t,o nsc auxiliary dat,a from various sources of p~lhlisllctl t,hcrrnodynarnic tlat,a for the nranyl hydroxo spccics, hut the set of cornplcxcs along nrit,h t,llc corresponding t,llcrrnodynarnic ~ ~ a l n c s ~lsctl arc not reported. hlorcorcr, t,hcy presented two distrii)iit,ion dingrarrls for the aqncoiis iiranyl spccics involvcd in tllcsc t,wo systems, ~vhich arc clcarly irlcorrcct (for example. the cornplcx UOaOH+ prcdorninatcs at pH 2 9 in their figures). Thcrcforc, all the thcrmotlynamic data derived fiorn this stiidy will i)c

To facilit,at,c the t,ask of gcochcrrlist,~ scarclling for t,hcrrnodynarnic dat,a t,o rrlodcl nraniiim migrat,ion in aquat,ic cnvironrncnts; t,llc tables in Chapt,crs IX arltl X of Ref. [92GRE/FUG] have hccn cornl)inctl, re-organisctl; nptlat,cd ~vi th ncx~~ rcfcrcrlccs arltl purged of aqncoiis cornplcxcs. Fiirt,hcrrnorc. only solid phascs ~vhich arc i)clicrctl (perhaps arhit,mrily) t,o i)c important for rrlodclling radiorl~lclitlc rrligrat,ion wcrc left, in t,hc t,ai)lc. Thiis, solids cont,ainirlg alkali rrlct,als ot,llcr t,llan sodinrn, arltl pot,assi~lrrl have not been incliidcd. For t,hc sarrlc reason, intcrrrlct,allic cornpounds and alloys. halitlcs; nit,mt,cs, etc.. have i)ccn cxcl~ltlcd. Ot,llcr syst,cms have also bccn cxcl~ltlcd bcca~lsc t,llcy have IICCII t,horo~~ghly disc~~sscd i11 [92GRE/FUG], like sirrlplc oxides, hytlroxidcs. siilphitlcs; snlphit,cs, siilphat,cs, arscnat,cs arltl their hydrates. etc. Solid phascs for ~vhich t,llcrc is only stoiclliorrlctric or st,riict,ural inf~rrrlat~ion have also hccn cxcl~ltlcd (e.g., t,llosc having only Ref. [83FLE] in Chapter IX of [92GRE/FUG]) in order t,o prcscrlt t,hc rcadcr nrit,h a table containing litcmt,urc soiirccs of thcrmotlynamic and/or solubility data of iiraninrn minerals. Tllc solitl phascs have i)ccn rcarrarlgcd irlt,o families (phosphat,cs, snlphat,cs etc.). Tllc rcsiilt of all tllcsc changcs is given in Table D.6. It is strcssctl t,hat t,llis t,al)lc does not i~ring ncx~~ inf~rrrlat~ion t,o the rcadcr. hut it is providctl only as a convcnicncc t,o gcochcmical rnodcllcrs. Tahlc D.6 in combinat,ion ~vit,ll Chapt,cr IX in 92GRE/FUG corlstitiit,c a convcnicnt way of oh- taining hii)liographic informat,ion. It must bc rlot,cd t,llat it is irlt,crltlcd t,hat t,llcsc tables shonltl i)c as cornprchcnsirc as possible, but, any errors or omissiorl will i)c glatlly rcccirctl by the NE.% sccrctariat,.

Tahlc D.6: lIirlcrals of iiraninrn and rclat,cd solid phascs of interest for gcocllcrrlical rnodcling. Tllc inclusion of t,hcsc forrnlllac in t,his Tahlc is t,o he iindcrst,ood as irlformnt,ion on the cxist,crlcc of piil)lishctl rnatcrial. It does not imply t,llat t,hc aiit,llors of t,his -4ppcntlix give any crctlit t,o cit,llcr the thcrmodynarnic tlat,a or t,hc cllcrrlical corrlposit,ion or cxistcncc of t,llcsc species. The cornpo~mds for ~vhich sclcctcd dat,a arc prcscrlt,ctl in Chapter I11 of [92GRE/FUG]. as 117~11 as t,llosc \vllich arc discllsscd but for ~vhich no dat,a arc rccomrrlcndcd in Ref. [S%GRE/FUG]. arc rrlarkcd correspondingly.

Terno,nl cxrrci qi~,r.aterno,nl o:cicies arad laycirozidr.s("):

Pt)U207 . 2HnO(cr) rvrilser~~lorfite Ni(UOa):30:3(0H)2 . 4-6H20(cr) hln(U02)303 (OH)% .4-6HaO(cr) hZgU04 (cr) h l g U n 0 ~ (er) hlgUnO7 (er) hlgU3Olo (er) hIg(UOa)604(OH)6 . 10-13H20(cr) hIg:ju:jo1~,(l:r) CaUO4(<:r) (P - CaU04 -I - C a U 0 4 Ca3UOfi(cr) CaU2Ofi (cr)

CaU207 (cr) calciol~ranoit,e, anhylr .

SrU04 (cr) SraUOi (er) S-UOH (er) SraU:j011 (cr) SrU4013 (er) DaU03(cr) DaU04 (cr) Da:3U06 (cr) DaUa07(<:r) t ) a~~rano i te , ar~l~yr l r Da2U207(~:r) DafiDy2(UOH)3 ((:I)

[SOVOC/H.iV] [SlVOC/H.iV] [SlVOC/H.iV] data selected in [92GRE/FUG] [81GOL/TRE2] [81GOL/TRE2] data selected in [92GRE/FUG] [SlVOC/H.iV] [83FUG] data selected in [92GRE/FUG] data selected in ['ilN.iU/RYZ] data selected in [92GRE/FUG] data selected in [92GRE/FUG] [81GOL/TRE. 82\10R, 83FUG, 85PHI/PHI. 86\10R, 88PHI/HAiL]

[81GOL/TRE. 82\10R, 83FUG, 85PHI/PHI. 86\10R, 88PHI/HAiL]

[88ATK/BEC, SOVOC/H.iV, 94CAS/DRU, 94S.iN/GR.i]

data selected in [92GRE/FUG] data selected in [92GRE/FUG] [7ST.&G/FUJ, 86RIORl [83KOH] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] [82RIOR]

Covrctf oas to t11,r Ur(~rrrrrrn NEA- TDB rrrirrru

Tahlc D.G (continnctl)

Terno,nl cxrrci qi~,r.aterno,nl o:cicies arad 1rylrl~o:cicie.s (coratira?reci,l:

Ba2hlgUOs (cl:) Ba2CaUOs (cl:) Ba2SrUOs (cl:) BaUsOls . llHnO(c1:) NaUO? (cl:) o - NaaU04 (j - NaaU04 Na:3U04(cr) Na4UO5 (cl:)

data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG]

t)illiet,ite [9O\'OC/H..I\T] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] data selected in [92GRE/FUG] [71COR/L00, 78COR/OH..I, 81LIN/UES, 82HE\I, 821T..IG/E\:1, 83FUG, RSPHI/PHI, 85TSO/BRO. 86RIOR, 88PHI/H..IL]

data selected in [92GRE/FUG] [78COR/OH..I] data selected in [92GRE/FUG] [71COR/L00, 81LIN/UES, 82HEhI, 82RIOR, 82K1G/EVA.I. 83FUG, 86\10R]

[821T..IG/E\'..I] [65\IUT, 82K1G/EVA.I] data selected in [92GRE/FUG] [8lCOR/OUW, 81LIN/BES. 82HEhI, 82RIOR, 83FUG. 83K..IG/K\iS, 85PHI/PHI. 86\10R, XXPHI/H..ILl

data sk1ect;d iin [92GRE/FUG] [81LIN/BES]

K2Ua07(cr) data selected in [92GRE/FUG] [750H..I/HOE2. 81LIN/UES, %FUG, 86\10R]

K2U401:3(<:1:) [81LIN/BES] K2U6Ol9 . 11H20(cr) cornpreignacite [94S..IN/GR..I] K2U70p2(<:1:) [81LIN/BES]


[73\10S, 78..lLL/U~..l](~) data selected in [92GRE/FUG] [71\10S, 84VIE/T..lR, 86\Y..lIi](" [55SC~](g' data selected in [92GRE/FUG] See footrlote (h) See footrlote (h) See footrlote (h) See footr~otes (h) ancl (i) [ ~ ~ S C H / U A E ] ( ~ ) data selected in [92GRE/FUG] data selected in [92GRE/FUG] [92S..llU/BRU] data selected in [92GRE/FUG] [61K..lR. 71lU..lU/RYZ, 84VIE/T..lR, 88PHI/H..lL]

[56CHU/STE. 65\'ES/PEK. 84\'IE/T..lR. 85PHI/PHI. 86K1N](k)

[78L..llU. 88PHI/H..lL] [83\'OC/PEL] [84GEN/\YEI] [84lURI2] [84GEN/\YEI] [65\IUT/HIR] [ 8 4 ~ ~ 1 2 ] ( ' ) [78L..llU. 85PHI/PHI. 88PHI/H..lL]



salrritr salrritr, anhyrlr.

Srr footrlotr (o)


(Uo%)3(.is04)2(<:r) UOaH.is04(cr) NH4UOa.is04 (er) Pt)aU02 ('is04)a (cr) Zn(U0a)a (.is04)2 (er) Cll(UOa)a (-.ls04)2 (cr) C I I ( U O ~ ) ~ ( . & S O ~ ) % .8HaO(cr) Ni(I;O2)2(dsO4)% . 'iHaO(cr) C0(UO%)% (As04)a (m) Co(Uo%)%(. i~Oq)a . 7H20(1:1)

Fe(UO%)% (.is04)2 (er) Fr(UO%)%(.isOq)2 . 8H%O(<:r) h l n ( U O ~ ) n ( . i ~ 0 4 ) a . 8H20(1:r) hlg(U0a)a (.isOq)% (er) Ca(U02)% (As04)a (cr) Ca(U02)d (As04)a (OH)4 (er) Ba(U02)2(dsO4)%((:1) NaUOn.is04 . 4H20(1:r) NaUOn.is04(cr) KUOn.is04(~:r)

data selected in [92GRE/FUG] [ ~ ~ R I E R / S K O ] ( " ) data selected in [92GRE/FUG] data selected in [92GRE/FUG]

data selected m [92GRE/FUG] [56CHU/SH.i. 84GEN/\TEI] [56CHU/SH.i] [84GEN/ITEI] [84GEN/ITEI] [84GEN/ITEI] [84VOC/GOE] [84VOC/GOE] [84GEN/ITEI] [84VOC/GOE]

UOaC0:j (cr) rl~t,l~rrforrlir~r data selected in [92GRE/FUG] UOaC0:j . HaO(cr) [82HEhI] ('1)

UOa(HCO3)2 . H%O(<:r) [76BOU/BON. 78COR/OH.i. 82IT.&G/E\'A, 83FUG, 86\10R]

Ca3NaUOa(CO3)3FS04 . 10HaO(cr) schrorckingrrit,r [82HEhI. 830BR/\TIL]

Ca2U02(CO:j):j . 10-llHaO(cr) lirl)igit,r [8OBEN/TEA. 80ALJTjWIL. 82HER1, ~ ~ O B R / W L ] ( ' )



Ba(U02)2(\'04)a(cr) fran<:rvillit,r, anhy(ir NaUO2\704 (er) strrlkinitr, anhyrlr. K2(UO2)%(\704)2 .3H2O(<:r) carr~ot,itr K2(UO2)2 (\704)2 (er) carnot,itr, anhyrlr.

[82HERI] data selected in [92GRE/FUG] [830BR/\YIL]

data selected in I92GREIFUG1


Footnotes: (a) Sirr~ple oxirles and l~yrlroxirles of llrar~illrr~ are rl isc~~sse~l in Sect,ior~ V.3.3 (pp.131-148) of

[92GRE/FUG]. (11) Only t)inary arlrl terrlary slllphates are listed. Sirnple ilrarlillrr~ slllphat,es are (iiscllsse(i in

Sect,ior~ V.5.1.3.2 (1111.249-254) nf [92GRE/FUG].

(c) It sho~~lcl 11e not,e<l that t,l~ere is sorrle ~lisagreernent in t,he lit,erat,l~re on the mnn11er of rrat,er r r~ole~:~~les in t l ~ e forrrllllae of t,lle zippeit,e family.

(11) See Sect,inr~ 17.5.1.3.2.(: (pp.254-255) ancl the clis<:~~ssion of Ref. [79HAi.i/n7L] in .ippenrlix A (p.646) of [92GRE/FUG].

(e) See t,lle rlisc~~ssior~ in Sectior~ V.6.2.2.5.1) (p.294) of [92GRE/FUG].

(f) See t,lle rlisc~~ssior~ in Sectior~ V.6.2.2.7.1) (p.297) of [92GRE/FUG]. (g) See t,lle rlisc~~ssior~ in Sectior~ V.6.2.2.9 (p.298) of [92GRE/FUG]. (h) Corr~po~~nrls X%-it,h forrr1111a. H2(UO%)a(PO4)% . :rHaO(<:r) (z = 0 to 10) are ~ l i s< :~~s se~ l in Sec:.

t,ior~s 17.6.2.1.1.11 arlrl V.6.2.2.10.c (1111. 284-286 and 299-300 respectively) of [92GRE/FUG]. Grerltl~e f ! t al. select,ecl therrno(iynarnic data for UOaHP04 . 4H20(1:r), 1:j Tat~le 111.1 in [92GRE/FUG].

(i) See t,lle rlisc~~ssior~ of Ref. [65RIUT] in .ippen(iix rl (p.599) of Ref. [92GRE/FUG]. (j) See t,lle rlisc~~ssior~s in Sections 17.6.2.1.1.11 and 17.6.2.2.8 (1111. 284-286 and 298) arlrl t,lle

<:ornrnents on [54SCH/U,iE] in .ippenrlix .i (p.564) of Ref. [92GRE/FUG].

(k) 1Tpselj. e t r1,1. [65\'ES/PEK] reporter1 sol111)ility pro<ll~<:ts for h y d ~ r ~ t f ! d alkali phosphat,es. Grerltl~e 6.t al. [92GRE/FUG] reinterprete(i t,lle reslllts of Ref. [65VES/PEK], cf. Tat~le V.40 (p.283), Sect,ior~ V.6.2.1.1.t) (1111.286), ancl rlppenclix .L (pp.600-601) of [92GRE/FUG]. It, shol~l(i 1)e not,e<l that Lar~grrll~ir [78LrllU] incorre<:tly referred as sorlillrr~ ancl potassill11 all- t,l~r~it,e the a r ~ l ~ y r l r o ~ ~ s <:ornpo~mcls.

(1) lUriag11 gives 4 waters of hy(iration for this rr~irleral [84NRI", Tat~le l ] . (m) Tlle st,oi~:hinrr~etr~~ of the rr~ir~err~l rer~ardit,e is I I O ~ clear, ancl it is relate11 to (iemin~ltite:

P ~ I : ~ ( I O % ) ~ ( P ~ ~ ) ~ O % ( O H ) ~ . 12HaO(s) (see [91FIN/EW]). (n) \111to, Hirorlo ancl Kllrat,a give 10 rr~ole~:~~les of \%-,lter of hylration for this rrlirleral

[65RIUT/HIR]. (o) This forrrlllla is related to rnet,a-anl<oleit,e: Ka(UO2)2(PO4)2 . GH%O(<:r). (11) See t,lle rlisc~~ssior~ of Ref. [67RIER/SKO] in .ippen(iix A (p.603) of [92GRE/FUG]. (11) Herr~ingrnt~y [82HEhI] incorre<:tly assigne(i the rlarrle of sharpit,e t,o t,l~is solid.

(r) Discllsserl in Section 17.7.1.2.2.11 (1111.327-328) of [92GRE/FUG]. (S) There is sorr~e ~lncertainty in t,lle corr~position of t)oltsroo(iite arlrl Na-l)olt,moorlite. rf.

[81STO/S\II, 91FIN/EW. 92lUGU/SIL]. (t,) Herr~ingrnt~y [82HEhI] reports estirr~aterl data for a solid wit11 6 water r r~ole~:~~les .


D.6. References to Appendix D

Ginnil~gs; D.C.> Corri~ccini; R.J., Heat cal~acities a t l ~ i g l ~ telnperat,ures of ilranium, i ~ r a l ~ i i l n ~ t,richloride, ancl iural~iiln~ t,et,rach1ori(iel J . Res. Nat. Bur. St,ancl., 39 (1947) 309 316.

Schreyer; J.M., Bars, C.F., Jr. , T l ~ e so111l)ility of ilranium(V1) or tho~~hos- p l~ates in phosphoric acid soli~t,iol~s; J . Aln. C h e n ~ . Soc., 76 (1954) 354 357.

Schreyer; J.M., T l ~ e soli~l~ility of ilraniiln~(IV) o r t l ~ o ~ ) l ~ o s ~ ) l ~ a t e s ill 11110s- pl~oric acid solutions, J . Am. C h e n ~ . Soc.; 77 (1955) 2972 2974.

Blakel C.A.> Colen~a l~ ; C.F.> Browl~, K.B.> Hilll D.G.> Lowrie; R.S.> Schmitt, J.M., St,uclies in t,he ca r l~o l~a te -u ran i i~~r~ syst,en~; J . Aln. Cheln. Soc., 78 (1956) 5978 5983.

Cln~kl~lant,sev, V.G.> Sharova, A.K.; Solul~ility procluct,s of urarlyl arsenates; J . Il~org. C h e n ~ . ~ USSR, 1 (1956) 39 44.

Cln~kl~lant,sev, V.G.; Steparn)vl S.I., Solilt)ilit,y of 11ra11yl a r ~ l t11orii1111 pl~ospl~ates, Zh. Neorg. Khirn.; 1 (1956) 487 494, in R i~ss ian~ CA 51:47c; Engl. tral~sl.: J . Il~org. C h e n ~ . USSR, 1 (1956) 135 141.

Karpov, V.I., The solul~ility of triurarlyl phosphate1 Russ. J. Inorg. Cl~em.; 6 (1961) 271 272.

Host,et,ler> P.B.> Garrels; R.M.> Transportat,iol~ and 1)recipitation of U and V a t low temperatilre wit11 special reference t,o sanclstol~e-type U (iel~osits, Ecol~. Geol., 57(2) (1962) 137 167.

Cor(ifunke, E.H.P.> Aling, P,> Thern~a l ~1ecolnl)osition of l~y(irate(i i l r a 11ii1n1 peroxicles, Rec. n a v . Chirn. Pays-Bas; 82 (1963) 257 263.

Sill611; L.G.; Martell, A.E., Stal~ility col~stant,s of metal-iou complexes; Special Pi1111. No. 17, Chen~ical Societ,y; Lol~(iol~; 1964> 7541).

Mi1t,ol T. , Thern~ochen~ical stat)ilit,y of nil~gyoit,e, Mineral. J .> 4 (1965) 245 274.

Mi1t,ol T . > Hirol~o; S.> Kurata, H.> Some aspects of fixation of uraniinn fiom natural watersl Mirlillg Ge01.~ 15(74) (1965) 287 298; in Japanese; Engl. t,ransl.: Report NSJ-Tr 911 Japanese Atonlie Energy Researell In- stitute; Tokai-Mural Japan, 271).

Vesel?; V.> Pekirek; V.> A l ~ l ~ r e n t , ~ M.; A st,ucly of ilranyl phosphates: 111. Soli~t)ilit,y pro(111cts of urarlyl llyclrogen ~ ~ h o s ~ ~ h a t , e , i ~ r a l ~ y l ort110~1110~~111at,e a l ~ ( i some alkali ilranyl ~ ~ h o s ~ ~ h a t , e s , J . Il~org. Nilcl. Cheln., 27 (1965) 1159 1166.

Cor(ifunke, E.H.P.> Ther~rn)~lynamic propert,ies of hexavalel~t uraniinn compoi~n(ls, in: Tl~ermo(lynan~ics; Vol. 2, Proc. Sylnl). held 22 27 Jilly,

1965; in Vierlr~a~ Ai~st,ria, Vienna: Ir~ternat,iol~al At,omic Energy Age~~cy , 1966; pp.483 495.

[67MER/SKO] Merki~sl~eva, S.A.; Skorik; N.A., Ki1nlokl V.N.> Serel~rennikov~ V.V.> Tho- riilnl and i~ ra l~ i i ln~( IV) ~)yropl~ospl~ates> Sov. Ra(liorhelnl 9 (1967) 683 685.

[69TSY] Tsylr~l~al , C.> Col~tri l~ution ir. la ellinlie (le l'i~ranium(VI) ell solution, P11.D. tl~esis; Report CEA-R-3479, Ul~iversit,k cle Grenot)le, Grem)l)lel Fral~ce, 1969> 97p, ill Frel~ch.

[71COR/LOO] Cor(lfunke, E.H.P.; Loopst,ral B.O.> Socliinn ilranat,es: Preparation and ther~m~che~nical properties, J . Im~rg. Nilcl. Cheln., 33 (1971) 2427 2436.

[71MOS] Moskvir~~ A.I., Correlation of the soli11)ility procluct,s of actinide coln- poi111(1s wit11 the properties of t,he rnetal ions al1(1 acid anions forlnil~g thelr~, Sov. Ra(liocheln., 13(2) (1971) 299 300.

[71NAU/RYZ] Nailnlov; G.B., Ryzhel~ko; B.N., Kho(lakovskiy, I.L.> Hal~(ll)ook of t,her- ~m)clynamic (lat,al Moscow: Atonliz(1at; 1971; ill Russial~; Engl. t,ransl.: Report USGS-WRD-74 l101 (Soleirnani, G.J.> Barl~es I.> Speltzl V.> rds.), U.S. Geological Si~rvey, Me1110 Park, Califi~rnia; USA, 1974, 3281).

[72SER/NIK] S~rgeyeva~ E.I.> Nikit,il~; A.A.> Kho(lakovskiy, I.L., Nailn~ov, G.B.> Ex- perilnent,al ir~vest,igation of equilil~ria ill t,he systelr~ UO:3-COa-HzO ill 25 200°C telnperat,ure intervall Geocl~en~. I l~t . ; 9 (1972) 900 910.

[73MOS] Moskvir~~ A.I.; Son~e ther~rn)~lynamic charact,eristics of the processes of fi)rmat,iou of actinide compoiln(1s in a soli(1 forln: I. Energy al1(1 ent,ropy of the cryst,al lat,ticel heats of forlnatiol~ al1(1 heats of sol i~t ion~ Sov. Ra- (liocl~em.; 15 (1973) 356 363.

[750HA/HOE2] OIHare, P.A.G., Hoekstra, H.R.> Tl~ern~ochen~ist ,ry of ilranium coln- poi111(1s: VI. Stan(lar(1 ent,halpy of fi)rmation of CsaUz071 t l~ermo(lynan~- ics of forlnation of cesiinn al1(1 rul)i(liinn i ~ r a l ~ a t e s at elevated t,enq)era- tilres; J . C h e n ~ . T h e r n ~ o ( l y l ~ . ~ 7 (1975) 831 838.

[76BOU/BON] B o ~ s q u e t , ~ J .> Bonnet,ot; B.; Clail(1y; P.; Matln~rin, D., T11rc.k~ G.; En- thalpies (le forlnation stal~(iar(i cles fornliates (l ' i~ral~yle anhy(1re et hydrate par calorirni.t,rie (1e rkaction, Ther~rn)c l~in~. Act,&, 14 (1976) 357 367, ill French.

[76NIK2] Nikolaeva, N.M.> Soli~t)ilit,y pro(l11ct UOzC0:j at elevated t,enq)erati~re~ Izv. Sit). Ot(1. Akacl. Nauk SSSR, 6 (1976) 30 31; ill Ri~ssian.

[78ALL/BEA] Allard; B.> Beall; G.W., Pre(lict,iol~s of actinide species in the groiln(1- water; paper presm~te(i ill: Workshop on t,he erlvirolnnent,al researcl1 for actinide elemel~ts, held 8 12 Octot)er; 1978, in Warrent,onl Virginia, USA, 1978.

[78COR/OHA] Cor(lfunke, E.H.P., O'Harel P.A.G., The chen~ical tl~ermo(lynan~ics of actinide elelnent,s al1(1 conq)oin~(ls: Part 3. Miscellaneoi~s actinide coln- poi111(1s, Vienna: I l~terl~ational At,omic Energy Agerlcy; 1978; 831).


[78LAN] Lallglnuir; D., Uraniinn solution - n~ineral eqiti1it)ria at low telnperat,ures wit,k~ applications to se(iin~ertary ore cleposits; Geochirn. Cosnlochiln. Acta, 42 (1978) 547 569.

[79CIA/FER] Ciavatt,al L.> Ferri, D.; G r i n ~ a l d i ~ M,, Palonll~ari, R., Salvat,ore, F.> Diox- o i~ra l~i i tn~(VI) cart)onat,e colnplexes ill acid sol i~t ion~ J . Im~rg. Nilcl. Cllem.; 41 (1979) 1175 1182.

[79HAA/WIL] Haackel D.F.; Williarns, P.A., The aqueoils chenlist,ry of itranium n~inerals: Part I. Divaler~t cat,iou zippeitel Milleral. Mag., 43 (1979) 539 541.

[79TAG/FUJ] Tagawal H.; Fi1,jillo; T.; Yalnashita, T . , Format,iol~ all(1 some chenlical properties of alkaline-earth rnetal monoi~ral~ates; J. Illorg. Nilcl. C h e n ~ . ~ 41 (1979) 1729 1735.

[XOALW/WIL] A l w a r ~ ~ A.A.> Willian~s, P.A., The aqueoils ellemistry of itranium n~inerals: Part 11. Minerals of the liebigite groiq); Mineral. Mag., 43 (1980) 665 667.

[XOBEN/TEA] Benson, L.V., Teagi~e, L.S.; A tal~illation of tllerrno(1ynanlic data for chenlical react,iol~s irlvolving 58 elen~ent,s comnloll to ra(1ioactive waste package syst,en~s; Report LBL-11448> Lawrence Berkeley Lat)orat,ory, Berkeleyl USA, 1980; 9711.

[XOCIA] Ciavatt,al L., The specific int,eraction theory in evalilating ionic eqitilit)rial Ann. C l ~ i n ~ . (Ronla), 70 (1980) 551 567.

[81COR/OUW] Cor(lfunke, E.H.P.> Oi~welt jes~ W.> Stanclarcl erltllalpies of fornlation of i lral~ii tn~ ~ o n q ) o i ~ l ~ ( i s : VI. MUOt3 (M = Lil Na; K; ancl Rt))> J . Cheln. Tl~ermo(lyn.; 13 (1981) 187 192.

[81GOL/TRE] Golhev , V.P., Tret,yakovl A.A., Kerko, P.F., Bar i rn~v~ V.I., Thernlody- llalrlic charact,eristics of calcium i~ra l la tes~ Vest. Aka(1. Navtvuk Belarilskai SSR Ser. Fiz. Ener.> (1981) 24 29; ill Russial~.

[81GOL/TRE2] Golhev , V.P.> Tret,yakovl A.A., Kerkol P.F.; Barinov, V.I., Malevicl~; V.M., Tl~ermo(lynanlic charact,eristics of nlagllesiinn itranat,es, Vest,. Aka(1. Navitk Belaruskai SSR Ser. Fiz. E r ~ e r . ~ 1981, 18 23; ill Rilssian.

[81LIN/BES] Lin(lelner, T.B., Besnlaln~; T.M., Johnsol~; C.E., Tl~ermo(lynanlic review all(1 calci~lat,iol~s: Alkali-metal oxide systelr~s with nuclear fitels, fissiou pro(li~cts, ancl st,ruct,ural materials, J . Nilcl. Mater.> 100 (1981) 178 226.

[81OBR/WIL] 03Brienl T.J .> Willialr~s~ P.A., Tlle atliieous ellemistry of i l ral~ii tn~ n~inerals: Part 3. Mom)valent cation zippeitesl Im~rg. Nitcl. Cllem. Letters; 17 (1981) l05 107.

[81STO/SMI] Stohll F.V.; Smi t l~ ; D.K., Tlle crystal chenlist,ry of the urarlyl silicates ~nillerals; Am. Mineral., 66 (1981) 610 625.

[81VOC/PIR] Vocklter~~ R.; Piret; P,, Goemirlr~e, A., Syllthesis, crystallograpllic data; solitt)ilit,y and elect,rokil~etic propert,ies of copper-; 11icke1- arid col)alt,- i ~ r a l ~ y l ~ ) l ~ o s ~ ) l ~ a t , e , Bi111. Mineral.; 104 (1981) 457 467.

Helnil~gway~ B.S.> Themlo(1yllalnic properties of selectecl uraniinn coln- poi111(1s all(1 atlitmi~sq)ecies at 298.15 K and 1 1)ar all(1 at higher telnper- atitres. Prelilnillary im)clels for t,he origiu of coffir~ite (leposit,sl O p e l ~ File Report 82 619> US Geological Si~rvey, 1982, 891).

[82MOR] Morss, L.R.> Colnplex oxi(1e systelr~s of t,he act,il~i(les; ill: Actinides ill perspective, Oxfor(1: Pergarnon Pressl 1982; pp.381 407.

[82WAG/EVA] Wagman, D.D., Evalls; W.H., Parkerl V.B., Schumn~; R.H.> Halow, I.; Bailey, S.M., C ~ I I I ~ I I P ~ , K.L., Nuttall, R.L.> The NBS tal~les of chenlical ther~rn)~lynamic properties: Selectecl values fix im~rganic ancl Cl ancl Ca orgallie sul~stallces in S1 units, J. Pllys. Cllem. Ref. Data, 11, Sitppl. No. 2 (1982) 1 392.

[83CIA/FER] Ciavatt,al L.; Ferri; D.; Grellthe; I.> Salvat,ore, F., Spa l~ iu~ K., Sti~(iies 011 inet,al cart)onat,e ~(luil i l~ria: 4. Recl~~ction of t,he tris(carl)onato)(lioxo- i~rallate(VI) ion, UO~(CO:~):-; in hy(1rogen carl~onate solitt,iol~s; Im~rg. Cllem.; 22 (1983) 2088 2092.

Fleischer; M,, Glossary of n~ineral species 1983, Tncsol~; Arizona: Miner- alogical Recordl 1983; 20211.

F i~ge r~ J .> Cllerniral t,hernlo(iyllalnic properties selecte(1 values, ill: Grnelir~ Han(1t)ook of inorganic chelnistry; 8th HI.; Uranium, Supl). Vol. A6, Berlin: Spril~ger-Verlagl 1983> p~1.165 192.

[83KAG/KYS] Kaganyitk, D.S., Kyskin, V.I., Kazin, I.V.> Calci~lat,iol~ of el~thalpies of fi)rmat,iou fix ra(1ioelenlert conq)oin~(ls~ Sov. Ra(liocheln., 25 (1983) 65 69.

[83KOH] Kohli; R.; Heat capacit,y al1(1 t,hern~o(iynamic propert,ies of alkali rnetal compoitn(1s: 11. Estirnat,iou of the t l~ern~o( iy~~a ln ic propert,ies of cesiitn~ all(1 ri~l)i(lium zirconat,es, Thernlochiln. Act,&, 65 (1983) 285 293.

[830BR/WIL] 03Brienl T.J .> Willialr~s~ P.A., The atlileous cllemistry of i ~ r a l ~ i i t n ~ n~inerals: 4. Schrijckingerit,e, grilnselite; alld related alkali itranyl carl~ollates; Mineral. Mag.> 47 (1983) 69 73.

[83VOC/PEL] Vocllter~~ R.> Pelsnlaekers, J . , Syrltl~esis~ s01lil)ility~ electrokir~et,ic properties all(1 refined crystallograpllic data of sal)ugalit,e, Pllys. Cllem. Miner- als, 9 (1983) 23 29.

[84GEN/WEI] Va11 Gen(lerenl A.C.G., va11 cler Weij(lenl C.H., Prediction of G i l ~ l ~ s energies of format,io11 all(1 stat)ilit,y constant,^ of some secoll(1ary uraniinn lrlillerals cont,ail~ing t,he i~rallyl gro111)~ Uranium, 1 (1984) 249 256.

[84GRE/FER] Grellthe; I.> Ferril D., Salvatore; F.; Riccio, G., Stit(1ies on n~e ta l cart)on- a t e i i i l i . Part 10. A solul~ility sti1(1y of t,he conlplex forlnation ill the uraniinn(V1) water-cart)onat,e (lioxicle syst,en~ at 25"C1 J. Cheln. Soc. Dalt,on T r a l ~ s . ~ (1984) 2439 2443.

372 Covrctf o a s to t11,r Urarrrrrrn NEA- TDB rrrirrru

Nriagul J.O., Forlrtion ancl st,al)ility of tmse n~e ta l pllospllates in soils all(1 se(1in1erts (Nriagi~, J.O., Moore> P.B.> rds.), Berlin: Springer-Verlag, 1984, pp.318 329.

Vieillard, P,, Tardy, Y.> Thernlochenlical propert,ies of phosphatesl in: Phosphat,e lrlillerals (Nriagi~, J.O.; Moore> P.B.; rtls.)> Berlin: Spril~ger- Verlag; 1984, pp.171 198.

Vocllter~~ R.> Goelrlilll~e~ A., Synt,hesis, crystallographie (lat,al soli11)ility all(1 electrokinetic properties of inet,&-zeuneritp1 rnetakircl~l~ein~erite and 11icke1-i~ral~ylarsel~atr; Pllys. Chen~ . Millerals; 11 (1984) 95 100.

Vocllter~~ R.> De Grave; E., Pels~rlaekers~ J . , Mineralogical stildy of tms- set& in relation to its oxidation, Anl. Mineral., 69 (1984) 967 978.

F i ~ g e r ~ J.; T11errnocl1emistry of t,he alkali n~e ta l ancl alkaline eartll-actinide complex oxides, J. Nilcl. Mater.> 130 (1985) 253 265.

Phi l l i l~s~ S.L.> Phi l l i l~s~ C.A., Skeen, J . ; Hydrolysis, fi)rmat,iou ancl ion- ization const,arlts a t 25"C, ancl at 11igl1 t,enq)erati~re-higl~ ionic strengtl~; Report LBL-14996; Lawrence Berkeley Lat)orat,ory, Berkeleyl Califi~rnia, USA, 1985.

(lyllalnics of t,he actinoicl elemellts: Part 6. The preparation ancl heat,s of forlnation of some socliinn i ~ r a l ~ a t e s ( V I ) ~ J . Cllem. Soc. Daltou T r a l ~ s . ~ (1985) 1853 1858.

Grellthe; I., Riglet, C.> Vitorge; P.; St,uclies of metal-cart)onat,e colnplexes: 14. Colnl~osition ancl equilil~ria of t,rillilclear neptilnium(V1)- and ~)li~t,oniinn(VI)-c:art)or~at,es complexes; Illorg. Cllem.; 25 (1986) 1679 1684.

Morss, L.R.; Ther~rn)~lynamic propert,ies, ill: Tlle chelr~istry of the actinide elemellts, 2nd ecl. (Kat,z, J.J.> Sea l~org~ G.T., Morss; L.R.> rds.), Vol. 2, Loll(1o11: C h a ~ ) n l a l ~ all(1 Hall, 1986> pp.1278 1360.

Vocllter~~ R.> de Grave, E.> Pels~rlaekers~ J.> Syrltllesis; crystallograpllic all(1 spect,roscopic (lat,al solul~ility all(1 electrokinet,ic properties of n~e ta - kalllerite and its Mn analogue, Aln. Mineral., 71 (1986) 1037 1044.

Wanner, H.> Mo(lellil~g illteraction of clrep groin~(lwaters wit,l~ l)ertol~it,e all(1 ra(1iom1clicle speciation, Report EIR-Bericht Nr. 589 ancl Nagra NTB 86 21; Nat,iollal Cooperative for the Storage of Ra(1ioactive Wast,e (Na- gm), Ba(le11; Switzerlandl 1986; 1031).

At,kil~s; M,, Beckley, A.; Glasser, F.; Influence of cenlert on the near field er~virolnnent all(1 its specific int,eraction with i lral~ii ln~ and iodine; Racliochiln. Acta, 44/45 (1988) 255 261.

Lemire, R.J.; Effects of l1ig11 ionic strerlgtl~ groundwaters on calcillat,e(l e(l11ilil)riinn col~cent,rations in the uranium-wat,er system, Report AECL- 9549; At,omic Energy of Calla(1a Ltd.> Pinawal Mal~it,ol)a~ Calla(1a; 1988, 401).

Philli1)sl S.L., Hale, F.V.> Silvesterl L.F., Siegel, M.D.; Thern~o(iyl~alnic tables for llilclear waste isolationl an atlileoils soli~t,iol~s (lat,al)ase, Vol. 1; Report NUREGICR-4864> US Nilclear Regillatory Colnmissiol~; Wash- ingt,onl D.C.; USA, Report LBL-22860, Lawrel~ce Berkeley Lal~oratory; Berkeleyl Califi~rnia, USA, Report SAND87 0323> Sandia National L a b oratories, A l t ) i ~ ( ~ i ~ e r ( l i ~ e ~ New Mexico1 USA, 1988> 1811).

Cor(ifunke, E.H.P.; Kol~ings, R. J.M.> Westriln~; E.F.> Jr., Recent t,her- ~m)cl~elnical research 011 reactor mat,erials and fission pro(lilcts, J . Nucl. Mat,., 167 (1989) 205.

Cox, J.D., Wagnlall; D.D.> Me(lve(iev, V.A., CODATA Key Valiles for Tl~ermo(lynanlics, New York: Hemisphere Pu1)lishing Corp., (1989); 2711).

Riglet, C.> Chirnie (111 nept,uniinn et aut,res actinides ell iniliei~ car1)ollate; P11.D. t,hesisl Univ. Paris VI1 17 March 1989> Report CEA-R-5535, Com- missariat A 1'Energie Atolniqi~e~ Gif-snr-Yvet,tel Frallce, 19901 2671)., ill French.

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C l i G.R.> Matllilr, J.N.> Hy(1rolysis of actir~yl(VI) cat,iol~s; Ra- ( l iocl~in~. Act,&, 52/53 (1991) 25 28.

Falck; W.E., Hooker, P.J., Uranium solilt)ilit,y and solilt)ilit,y controls ill select,ed Nee(11e's Eye gmi~ndwat,ers, Report DoE/HMIP/RR/91/008, UK Departlnent of the Ellvironnlent, 1991, 241).

Finch, R.> Ewir~g, R.; Ural~inite alteration in an oxidizing environmel~t all(1 its releval~ce to the (lisposal of spel~t nuclear fuell Report SKB-TR- 91-15; Swedish Nilcl. File1 Wast,e Manag. Co., St,ockholm, Swe(lel~; 1991, 13711.

Grellthe; I., Lagern~al~; B.; St,uclies on the inet,al car1)ollate equilil~ria: 22. A coillon~etric stil(ly of t,he i~ral~ii~n~(VI)-cart)or~at,e system, t,he colnpo- sit,iou of the mixed hy(1roxi~le cart)onate species; Acta Cheln. Scal1(1.~ 45 (1991) l22 128.

V o c l ~ t e r ~ ~ R.; Van Havert)ekel L.; Sot)ryl R.> Tran~sforn~ation~ of schoepit,e int,o urar~yl oxide hy(lrat,es of the l~ivalrnt cations Mg"+; Mi" +and Ni2+; J. Mat,er. Cheln., 1 (1991) 637 642.

Bischoff; H., Kramer-Schnal)el> U,, Esser, V.> Xi, R.H., Heppner; P.M., Marx, G.> Deterrnir~ation of fi)rmat,iou col~stant,s~ soli~l)ilities, all(1 iollic speciation of i lral~ii ln~; pliltonilim and tlloriiln~ ill a(li1eo1is an~d sat,lirated salt soli~tions for ~m)clelling safet,y asprct,s of ILW reposit,oriesl Sci. Basis Nilcl. Wast,e Managelnent XV (Somt)rrt; C.G.; d.)> Mat. Res. Soc. Symp. Proc.> 257 (1992) 331 336.

Covrctf o a s to t11,r Ur(~rrrrrrn NEA- TDB rrrirrru

Grel~the; I.> Fuger, J . , Konil~gs; R.J.M.> Le~n i r e~ R.J., Muller, A.B., Ngi~yel~-Trung~ C., Waln~er~ H., Chelnical ther~m)~lynarnics of uraniinn (Waln~er~ H.; Forest, I.> rds.), Amst,er(ialn: Elsevier Scierlce Pi~l~lishers B.V., 1992> 7151).

Ngilyel~, N.S.> Silval R.J.> Weedl H.C., Andrews, J.E.> Jr .> Stal~(iar(i G i l ~ l ~ s fire el~ergies of for~rlation at the telr~perat,lire 303.15 K of four i~ r a l~y l silicates: so~l~lyite, i ~ r anop l~an r~ so(iii1n1 l)olt,woo~lite al1(1 socliinn weeksite> J. C11em. T11ermo.; 24 (1992) 359 376.

Sal~(iino, A.> Brurn)> J . , T l ~ e soli~l~ility of (U02):3(P01)2 . 4H20(s) and the forlnation of U(V1) phosphate con~plexes: Their i~lfl i le~~ce i r ~ ilra- 11ii1n1 speciation ill i~atilral watersl Geochirn. Cosn~ochiln. Act,&, 56 (1992) 4135 4145.

Silva, R.J.> Mecllarlislr~s for the retartiation of uraniinn(V1) ~nigration~ Sci. Basis Nilcl. Waste Managen~ert XV (Solrll~ret,~ C.G.> d.), Mat. Res. Soc. Synq). Proc., 257 (1992) 323 330.

Casas; I., Brilno, J.; Cera, E.; Finch, R.J.> Ewir~g, R.C.> Kinetic and ther~rn)~lynamic stil(1ies of uraniinn minerals. Assesslnent of t,he long-term evoli~tion of spent mlclear fi~el; Report SKB-TR-94-161 Swe(iis11 Nilcl. File1 Waste Manag. Co., St,ockholm, Sweden; 1994> 731).

Sal~(iino, A.> Gramt)ow, B., Soli~l~ility eq11ilit)ria ill the U(V1)-Ca-K-Cl- HaO system: transforlnation of scl~oepite illto t)rcquerelite al1(1 coln- preiggl~acite, Ra(lioc11irn. Act,&, 66/67 (1994) 37 43.

Torrero, M.E.> Casas, I., (le Pal~lo; J., Sal~(iino, M.C.A.> Gralrll~ow~ B.; A con~parison l~etween i~nirracliate(i UOa(s) al1(1 schoepit,e solu1)ilities ill l M NaCl rne(iii1n1; Racliochiln. Act,&, 66/67 (1994) 29 35.

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chemical thermodynamics of americium

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