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THE STRUCTURE OF LIVTNG MATTER

ion areoiientedwith theiroxygensnex to theion. and.molculasaround anesative

ion turntheirliydrogensto-wardthe ion.Thus thewatermolecuiesact ascageswhichseprateand neu-tralize theions. Thisesplainswhy wateris soeflective asoivent forelectrolvtes

(substances whichdissociate ir.toions)such assodiumchloride.

Water

isgenerallysupposedto be agoodconductor ofelectricity. Everylinemanknowsthedanger ofhandlinghigh-voltageelectricallineswhestand-ingor amoist surf

ace,Actuallythe con-ductvityis due toimpuritiesdissolvedin thewater.

Water issuch asood soi -vent forelectroiytes.includingcarbn,dicxiderom theatmosphere, hat anymoist surface rnaybeassumedto.be agoodconductor.But purwater(which is

80

HYDRATE is fanasri wiien a oreigr molecie in valer is eiectricaU" neutral sur! jus the righsiz- for liie v-ater XTOiecnie to eollect around t in crTstalline caze. Tbi? cage can tbsn groi>' toE n-uch iarger crysi.al. It E par*, of t. repeating unit of 136 molecnles.

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difficult tokeep pur it must be keptout of contactwith airand in avessel ofan inertmaterial

such asquartz) isa ven.-goodinsuiatorindeed.The rea-son is thatwhile thehydrosrenand oxy-gen atomsin a watermoiecue

are in asensecharged,or ionized.theycannotmoveabouiseparatelybecausethey areattached toeachother. and

henee can -not careyan eiectriocurrent.

Onec theanomalous

properties ofliquidwater ists highspedficheat or

heat-holding-capaciry. Thespecificheat of asubstance is thequantityof heatrequiredto raisethetemperat

ure of one Sramonedesreecentigrade. The-specificheat ofliquidwater ismorethantwice asgreat as

that ofice. Theexpiana-tion ishat theliquid'sionizedoxysenandhydrogenatoras,thoughheld to-gether,

behavelike freeions intheircapaciryto vbrateinresponseto heat.Thusthey canabsorb asmuchenergy asif theions

werereally free.

Thestrong

bondingof watermolecuiesaccountsfor thefact thatwater has

unusuallyhishmeltingand

boiling pcints. Itaisoexplainswhy it isso diffUcult tovaporizaice, To dothis we

must break allthehydrogen

bondsholdingthemoieciilestogether,Calculations indcatethat thetotalenergy of

the hydro -gen bondsin onemole ofwater (18grams) isequivalentto 6.000calories.

Hydrates

Formore than60 vean

physicalchemistshavestudiedwaterlargely intrras cfsoluonsofelectrolvtes. This

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study hasproducedconsidera

ble infor-maionaboutelectrolvtes andions. bunot agreat deal

about thepropertiesof wateritsel.Strangelvenoueh.in recentyears wehaveiearneclmuchmoreaboutwater bvexarninin

g its-behaviorwithsubstances whichfoi all

practica!pur-posesareinsolublein water!

Thisbehaviorwas callea

to the at-tention ofchemistsin adramaticfash-ion

by certaiasurprisins; natural

phe-nomena.One wasthe facthat ccrnsometmes showedfrosteffectswhen thetemperature was 40desreesF... wellabovefreezing.Anotherwas thediscov-ery that

pipelines

carrvingnaturalgas often

becamecloggedwith aslushy"snow."containingwater, at

tempera-tures ashigh as68degreesF. The

plainindication wasthatthesefreeze-ups weredue tothe

water.'-But thisraisedsomestartlingandinterestins;questioas. Whamadewaterfreeze atthese

highternperatures?Howcouldwatercom-

bine, orbecome"bounc."withsub-stanceswhichwere ali

butinsoiubiein it?Themysterywas notlessenedwhen itwasdiscovered thateven thenoblegases

such as

argn andkrypton.whichrefuse alichemicalreactions.couid joinwithwater toform aquasi

compound.Let us

look atthesequestionsin thelight ofwhat wehaveiearnedabouwater'sstructureand

properties. Tenyears agoin Illinoiswe begana study cfthe water-solubiiityof certainhydro-carbons.Methanegas willserve as

anexample.Themethanemoiecuedoes notform ionsin water,or doesit ac-ceptthehydrogen

bonds.There isvery littleattraction

between itand thewatermoiecue.It is.howevsr.sligysoluble inwater, andthedissolvingmethanemolecuies

form

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compounds withwater"hvdrates"

inwhichsevera!watermoie-cules are

joined to

one of methane.The

resctionliberares10 timesas muchheat aswhenmethanedissolvesin hexane.althoughit is muchmore

soluble inhexanetaar.- inwater.This fact

becoaiesevenmoresurprismgon ciseexamnation. Themethanemoiecue

occupiesmore thaniwice thevol-umeof a watermoiecue,Te formthisreiativeiylargecavitv foritself ondis-solving, agreat dea!of enerzywould beraquired:it should

besomewhatgreaterthan theheat of vaporization of watersay10,000

calories

perrnoie.Howcouid somuchenergv

beprovided?The.forces of

attraconbetweenmethaneand wa -ter areapparentiv tooslisht tosuppivanvapprecia

bl-3 partof suchan

arnouni.There

is analternative

possibiil*.'. The

presenceof thsmethanernavdras-ticallvohanse

the-.vatsrstructureitseli.