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09: HYDROGEN

1. Hydrogen is the ___ abundant element in the unierse and the ___

most abundant element on the sur!a"e o! the globe a!ter ___ and

___.

most, third, oxygen, silicon

#. Hydrogen is an essential "onstituent o! all ___ and ___.acids and alkalis

$. Hydrogen has the ___ atomi" stru"ture among all elements. %n

elemental !orm it e&ists as a ___ mole"ule and is "alled ____.

simplest, diatomic, dihydrogen

'. (he atomi" !orm o! hydrogen o""urs only at ery high ____.

Dihydrogen is the )rodu"t o! an ___ rea"tion bet*een H+atoms.

temperatures, exothermic

,. Gie the rea"tion bet*een H atoms to )rodu"e dihydrogen. -hat is

the enthal)y o! the rea"tion

H (g) + H(g) H2(g) H0= - !"# k$%mol

/. s "om)ared to hydro"arbons hydrogen is a "lean !uel. -hy&ns'er yoursel#

2. (he rea"tion o! hydrogen *ith *ater re3uires ___ to get started.

Ho*eer on"e the rea"tion starts it is ___ and ___. 4e"ause it is an

e&othermi" rea"tion it is an ideal ___ !uel

energy, rapid, exothermic, rocket

5. ____ !orms more "om)ounds than any other element.

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Hydrogen

678EEN( O HYDROGEN %N (HE 6ER%OD%8 (47E

9. Hydrogen has ele"troni" "on!iguration o! ____. %ts ele"troni"

"on!iguration is similar to the outer ele"troni" "on!iguration o! ____

metals. On the other hand li;e ____ it is short by one ele"tron to

the "orres)onding noble gas "on!iguration.

s, alkali, halogens

more? rea"tie metals are redu"ed by

hydrogen.

reducing, less

1#. Gie the ionisation energies !or hydrogen lithium sodium and

)otassium.

Hydrogen* !2 k$%mol

ithium* 20 k$%mol

odium* . k$%mol

/otassium* k$%mol

1$. Gie e3uations to "om)are the redu"ing nature o! hydrogen @

al;ali metals:

=i? 8uO A #Na

=ii? 8uO A H#

1u + 23a 1u + 3a2

1u + H21u + H2

Di!!eren"es *ith al;ali metals

2

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1'. Di!!eren"es *ith al;ali metals: etalli" 8hara"ter: Hydrogen is a

___ *hile al;ali metals are ____.

non-metal, metals

1,. Di!!eren"es *ith al;ali metals: tomo"ity: Hydrogen is ___ *hile

al;ali metals are ____.

diatomic, monoatomic

1/. Di!!eren"es *ith al;ali metals: Nature o! o&ides: (he o&ide o!

hydrogen is ___ *hile o&ides o! al;ali metals are ___.

neutral, 4asic

12. Di!!eren"es *ith al;ali metals: Nature o! "om)ounds: 8om)ounds

o! hydrogen *ith halogens are ___ boiling )oint ___ "om)ounds

*hile halides o! al;ali metals are ___ melting )oint ___ "om)ounds.

lo', co5alent, high, ionic (or electro5alent)

15. Di!!eren"es *ith al;ali metals: %onisation Energy: Bnli;e al;ali

metals hydrogen has a ery high ___ ___ and does not )ossess ___

"hara"teristi"s under normal "onditions.

ioni6ation energy, metallic

mol.halogens, "0, !2

#0.

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#1.

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unshared, unshared

#2. 7oo; at the !igure belo* to understand the aailability o! unshared

ele"trons in halogens.

#5. Hydrogen is not as ele"tro)ositie as the al;ali metals due to its

high ___ ___.

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e&ist ____ and is al*ays asso"iated *ith other atoms or mole"ules.

(hus it is uni3ue in behaiour and is there!ore best )la"ed ___ in

the )eriodi" table.

# x 0-!

pm, 0, 200, reely, separately

4BNDN8E O HYDROGEN

$$. Hydrogen "onstitutes ___I o! the total mass o! the unierse. %t is

the )rin"i)al element in the ___ atmos)here.

90, solar

$'. (he giant )lanets u)iter and rey

$5. (he )redominant !orm o! hydrogen is ____. (errestrial hydrogen

"ontains ____I o! deuterium mostly in the !orm o! HD. (he

tritium "on"entration is about 1 atom )er ___ atoms o! )rotium.

protium, 0#0", 0

$9. mong the isoto)es o! hydrogen only ___ is radioa"tie and emits

"

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___ =high>lo*? energy ___ )arti"les. %ts hal!+li!e =t1>#? is ___ years.

tritium, lo', 4eta-, 2#!!

'0.

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'2. Ho* is the im)urity H#< remoed during the lab )re)aration o!

dihydrogen

:y passing through a solution o lead acetate#

'5. Ho* are the im)urities

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a"id:

(i) 2H3!+ 2H C

(ii) 2H3!+ "H C

2H3!+ 2H 232+ 2H2

2H3!+ "H 23 + H2

,'. Dilute sul)huri" a"id does not rea"t *ith )ure Cin". -hy

Ahis is 4ecause the initially ormed hydrogen orms a thin layer on the

surace o 6inc, 'hich pre5ents urther reaction#

,,. (he addition o! a !e* dro)s o! ____ a"id or ___ ___ brings about a

rea"tion bet*een )ure Cin" and sul)huri" a"id. (his is be"ause

*hen a little "o))er sul)hate is added a thin layer o! ___ is !ormed

on the Cin" sur!a"e. in"+"o))er ____ rea"ts readily *ith dilute

a"id.

chloroplatinic, copper sulphate, copper, couple

6RE6R(%ON O 6BRE HYDROGEN

,/. 6ure hydrogen is )re)ared by the ele"trolysis o! ____ solution using

___>___ ele"trodes. (he gas liberated is )assed oer a heated ___

gauCe to remoe o&ygen i! )resent as an im)urity. (he gas is then

)assed oer ____ to dehydrate it.

4arium hydroxide D:a(H)2E, platinum, nickely, platinum, phosphorous

pentoxide

,2. 4arium hydro&ide is )re!erred to sodium hydro&ide or )otassium

hydro&ide in the )re)aration o! )ure hydrogen be"ause in the

)ro"ess i! "arbon dio&ide is absorbed the ___ ___ )rodu"ed being

___ settles do*n and does not inter!ere *ith the ele"trolyti"

)ro"ess.

4arium car4onate, insolu4le

.

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,5. 6ure hydrogen is also obtained by the a"tion o! *ater on ___.

odium Hydride

,9. 6ure hydrogen is also obtained by the a"tion o! *ater on sodium

hydride. (he e3uation !or this rea"tion is: NaH A H#O

3aH + H2 3aH + H2F

/0. Fery )ure hydrogen is also )rodu"ed by the ____ method.

>yenoGs

/1. Gie the ByenoJs rea"tion.

2&l + 2@H + 2H2 2@&l2+ 2H2F

/#. 6ure hydrogen is also )re)ared by the a"tion o! )ure dilute

sul)huri" a"id on ____ ribbon. Gie e3uation.

magnesium

g + H2(dil) g+ H2

8OER8%7 6RODB8(%ON O HYDROGEN=i? Ele"trolysis o! *ater

/$. Ho* is dihydrogen "ommer"ially )rodu"ed -hat ;ind o!

ele"trodes are used %s any "atalyst used

Iihydrogen is commercially produced 4y the electrolysis o 'ater#

Ahe electrodes are o platinum#

Arace amounts o acids%alkalis ser5e as a catalyst

/'. %n the ele"trolysis o! *ater the anode and the "athode are

se)arated by ____ dia)hragm.

as4estos

/,. Gie e3uation !or the ele"trolysis o! *ater.

2H2 (l) 2H2(g) + 2(g)

//. Gie the rea"tions o""urring at the anode and "athode in the

0

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ele"trolysis o! *ater using a"id as "atalyst.

&t cathode*

2H++ 2e 2 H H2

&t anode*

H-H + e

H 2H2 + 2

/2. %n the ele"trolysis o! *ater using sul)huri" a"id as "atalyst

sul)hate ions are not dis"harged on the anode. -hy

:ecause the discharge potential o sulphate ions is more than that o

hydroxyl ions#

/5. Gie the rea"tions o""urring at anode and "athode *hen a base is

used as a "atalyst in the ele"trolysis o! *ater.

&t anode*

H-2H2 + 2

CC (page 2)=ii? Ele"trolysis o! barium hydro&ide solution

/9. Ho* "an high )urity = 99.9,I? dihydrogen be obtained

"ommer"ially -hat is the ele"trode used

:y electrolysing 'arm a?ueous 4arium hydroxide solution 4et'een

nickel electrodes#

=iii? Hydrogen by 8hlor+al;ali )ro"ess

20. Hydrogen is obtained as a by+)rodu"t in the manu!a"ture o!sodium hydro&ide. -hat is the )ro"ess ;no*n as

1hlor-alkali process

21. Gie the rea"tion inoled in the "hlor+al;ali )ro"ess.

Anode: 21l- (a?) 1l2(g) + 2 e-

Cathode: 2H2 (J) + 2 e- H2(g) + 2H

-(a?)

Overall: 23a

+

(a?) + 21l

-

(a?) + 2H2 (J) 1l2(g) + H2(g) + 23a

+

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(a?) + 2H-(J)

Complete reaction:

23a1l (a?) + 2H2 (l) 23aH (a?) + 1l2(g) + H2(g)

=i? Hydrogen !rom 8o;e ="oal gasi!i"ation?

2#. Ho* "an hydrogen be )rodu"ed !rom hydro"arbons or "o;e -hat

are the "onditions re3uired =t*o "onditions?

Hydrogen can 4e produced 4y the reaction o hydrocar4ons or coke

'ith steam#

High temperatures (290 @) are re?uired#

1atalyst (nickel) is re?uired#

1nH2n + 2+ nH2 n 1 + (2n + ) H2

8or example, 1H(g) + H2 (g) 1 (g) + ! H2(g)

2$. (he mi&ture o! 8O and hydrogen is "alled ___ ___. s this mi&ture

is used !or the synthesis o! ___ and a number o! hydro"arbons it is

also "alled ___ ___ or ___.

'ater gas, methanol, synthesis gas, syngas

2'. No*adays KsyngasJ is )rodu"ed !rom ____ sa*+dust s"ra) *ood

ne*s)a)ers et". (he )ro"ess o! )rodu"ing KsyngasJ !rom "oal is

"alled K____ ____J.

se'age, coal gasiication

2,. Gie the rea"tion !or "oal gasi!i"ation. -hat is the tem)erature at

*hi"h the rea"tion ta;es )la"e

1 (s) + H2 (g) 1 (g) + H2(g)

Aemperature = 290 @

2

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2/. (he mi&ture o! =8O A H#? is ;no*n as ___ ___.

'ater gas

22. -hat is the *ater gas shi!t rea"tion -hat is the "atalyst used

-hat is the tem)erature at *hi"h the rea"tion )ro"eeds -hat are

the adantages o! this rea"tion

Khen car4on monoxide o syngas mixtures is reacted 'ith steam in the

presence o iron chromate as catalyst, the reaction is kno'n as 'ater

gas shit reaction#

Ahe catalyst used is iron chromate#

Aemperature = "9! @

dantage: Ahe production o dihydrogen is increased in this reaction#

25. Gie the e3uation !or the *ater gas shi!t rea"tion.

1 (g) + H2 (g) 12(g) + H2(g)

29. Ho* is the "arbon dio&ide remoed !rom the *ater gas shi!t

rea"tion

:y scru44ing 'ith sodium arsenite solution#

=? 7aneJs 6ro"ess50. %n the 7ane )ro"ess !or the "ommer"ial )rodu"tion o! dihydrogen

steam is )assed oer hot ____. _____ is !ormed along *ith

hydrogen. (he tem)erature is maintained bet*een ___ and ___ deg

8. (his rea"tion is "alled K____ rea"tionJ and the time allotted !or

this rea"tion is about ___ min.

iron, 8e!, 0, 00, gassing, 0

51. Gie e3uation !or the 7aneJs )ro"ess the gassing rea"tion.

!

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!8e + H2 8e!+ H2F(steam) (magnetic oxide)

5#. %n the 7aneJs )ro"ess iron is regenerated by redu"ing magneti"

o&ide *ith ___ ___. (his rea"tion is "alled ___ and the time allotted

!or this rea"tion is about ____ min. (he iron re"oered is again

used.

'ater gas, 5i5iaction, 20

5$. Gie the e3uation !or ii!a"tion.

8e!+ 1 !8e + 12

8e!+ H2! 8e + H2

5'. (o ma;e the 7aneJs )ro"ess "ontinuous ___ and ___ rea"tions are

"arried out alternatiely using t*o or more !urna"es.

gassing, 5i5iaction

=i? 4O

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in *ater under )ressure o! about ___ atmos)heres. (ra"es o!

"arbon mono&ide )resent are remoed by )assing the gas through

___ ___ ___ solution under a )ressure o! ____ atmos)heres.

2-!0, ammoniacal cuprous chloride, 200

59. (he hydrogen )rodu"ed by the 4os"h )ro"ess is utilised !or the

synthesis o! ___ in *hi"h tra"es o! 8O a"ts as a ___ !or the "atalyst.

ammonia, poison

90. %n the 4os"h )ro"ess to "om)letely remoe 8O the gas is )assed

oer ____ "atalyst. Gie e3uation.nickel

1 + !H21H+ H2

=ii?

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ado)ted in the ___ )ro"ess.

00 L .00, :osch

=iii? Hydrogen dire"tly !rom hydro"arbons

9,. Hydrogen "an be dire"tly obtained !rom hydro"arbons by ___ ___

or ___. Gie e3uation.

partial oxidation, cracking

cracking

1H1 + 2H2 00001

cracking

12H"21 + !H2

cracking

1H!L 1H2L 1H!1H!L 1H = 1H2+ H2

=i&? Other methods !or "ommer"ial )rodu"tion o! hydrogen

9/. Hydrogen is also obtained as a by+)rodu"t in the manu!a"ture o!

___ ___ by the "hlor+al;ali )ro"ess =des"ribed )reiously?. (hese

rea"tions are "arried out in *hat is ;no*n as a ___ "ell or ___ "ell.sodium hydroxide, 3elson, 1astner-@ellner

92. Hydrogen is also obtained as a by+)rodu"t in the manu!a"ture o!

sodium by the ele"trolysis o! !used ___ ___ by the ___ )ro"ess.

sodium hydroxide, 1astner

95. Relatiely small 3uantities o! hydrogen are obtained by )assing a

____ =ratio? mi&ture o! a)ourised ___ and *ater oer a base metal

____ ty)e "atalyst at ___ deg 8. Gie e3uation !or the rea"tion.

*, methanol, chromite, 00

0001

1H!H 1 + 2H2catalyst

0001

1 + H2 12+ H2 catalyst

"

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99. (hese days about ___I o! "ommer"ial hydrogen is )rodu"ed !rom

)etro"hemi"als ___I !rom "oal ____I !rom ele"trolysis o!

a3ueous solutions and ___I !rom other sour"es.99, , ,

O(HER RE8(%ON< (H( Y%E7D HYDROGEN

100. 8old *ater rea"ts *ith al;ali and al;aline earth metals to eole

___. (he rea"tions are ____. (o minimise the rate o! rea"tion al;ali

metals are used in the !orm o! ____. 4y ado)ting this )ro"edure

only a small ____ o! the metal is e&)osed *hi"h redu"es the rate o!the rea"tion.

hydrogen, 5igorous, amalgam, surace

101. Gie the rea"tion o! al;ali metal *ith "old *ater:

# Na =Hg? A # H#O =

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1aH2+ 2H2 1a(H)2+ 2H2

10'. %oni" hydrides on hydrolysis eole hydrogen. %n these rea"tions

the ___ ion is o&idised to hydrogen. (hese rea"tions may be

regarded as ___ rea"tions.

hydride, acid-4ase

10,.

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i + 2 3aH + H2 3a2i!+ 2H2F odium silicate

105. Fery )ure hydrogen is obtained ra)idly by the a"tion o! "austi"

)otash on s"ra) ____. (his method is ;no*n as the ___ method and

is used !or ___ )ur)oses.

aluminium, >yenoGs, military

109. mi&ture o! 8O A H# irres)e"tie o! their "om)osition is "alled

___ ___ or ___ gas.

ynthetic gas, yn

110.

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11,. 6alladium "an adsorb ____ times its o*n olume o! hydrogen.

000

11/. (he adsor)tion o! hydrogen by "ertain metals is used !or the ___ o!

hydrogen be"ause only ____ ____ is adsorbed.

puriication, pure hydrogen

8HE%87 6RO6ER(%E< O HYDROGEN

112. (he "hemi"al behaiour o! dihydrogen as *ith any other mole"ule

is determined to a large e&tent by bond ____ ____.

dissociation enthalpy

115. (he H+H bond disso"iation enthal)y i! the ____ =lo*est>highest? !or

a single bond bet*een t*o atoms o! any element. %t is be"ause o!

this !a"tor that the disso"iation o! dihydrogen into its atoms is only

about ____I at around #000 P and in"reases to ____I at ,000P.

highest, 0#0, .#

119. Hydrogen is relatiely inert at room tem)erature be"ause o! the

high H+H ___ ____. or this reason atomi" hydrogen "an be

)rodu"ed only at a high tem)erature in an ___ ___ or under ____

radiations.

4ond enthalpy, electric arc, ultra5iolet

1#0. endothermi"?. Gie e3uation !or the rea"tion.

20

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exothermic

catalyst or heating

2H2(g) + 2(g) 2H2 (J) H = - 2#. k$%mol

=b? Rea"tion *ith halogens1##. Hydrogen "ombines dire"tly *ith non+metals li;e halogens o&ygen

sul)hur nitrogen et". to gie stable ____ "om)ounds.

co5alent

1#$. Gie "hemi"al e3uation !or rea"tion o! hydrogen *ith halogens.

H2(g) + 2(g) 2H (g) ( = 8, 1l, :r, ;)

1#'. Ho* is the rea"tion o! hydrogen di!!erent !or !luorine and iodine

Kith luorine reaction proceeds e5en in the dark# Kith iodine, a catalyst

is re?uired#

1#,. Hydrogen rea"ts *ith "hlorine in the )resen"e o! ___ or on heating.

%t rea"ts *ith bromine on ____.

sunlight, heating

="? Rea"tion *ith nitrogen

1#/. Hydrogen rea"ts *ith nitrogen to gie ___ in the )resen"e o! ___

"atalyst and a )ressure o! ____ atm at ___ deg 8. (he rea"tion is

used in the )re)aration o! ___ by the ____ )ro"ess.

ammonia, iron, 200, 00, ammonia, Ha4er

1#2. (he rea"tion bet*een hydrogen and ammonia in the HaberJs)ro"ess is: #H#=g? A N#=g?

2H2(g) + 32(g) 23H! (g) H = - .2#" k$%mol

=d? Rea"tion *ith metals metal ions @ metal o&ides

1#5. Hydrogen is not a ery ____ element. (he H+H bond disso"iation

energy !or hydrogen is ____ ;>mol and is the highest !or a single

bond bet*een t*o atoms o! any element.

reacti5e, !"

2

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1#9. Hydrogen is only 0.051I disso"iated at #000 P and /.,I at ,000P.

(here!ore most o! the rea"tions o! hydrogen o""ur at ___

tem)eratures. Gie rea"tionhigh

000@

H2(g) 2H (g)

1$0. t ___ tem)eratures hydrogen rea"ts *ith al;ali metals to )rodu"e

metal hydrides. (hese are ____ "om)ounds that "ondu"t ele"tri"ity

in the !used state.

high, electro5alent

H2(g) + 2 (g) 2H (s)M 'here is an alkali metal

1$1. Hydrogen redu"es some metal ions in ___ ___ and o&ides o! metal

=less a"tie than ___? into "orres)onding ____.

a?ueous solution, iron, metals

1$#. Gie the rea"tion o! dihydrogen *ith metal ions and metal o&ides.

=i? H#=g? A 6d#A=a3?

=ii? yH#=g? A &Oy

H2(g) + /d2+(a?) /d (s) + 2H+ (a?)

yH2(g) + xyx (s) + y H2 (J)

=e? Rea"tion *ith organi" "om)ounds

1$$. Hydrogen rea"ts *ith many organi" "om)ounds in the )resen"e o!

"atalysts to gie use!ul ____ )rodu"ts o! "ommer"ial im)ortan"e.

hydrogenated

1$'. ____ o! egetable oils using ni";el as "atalyst gies edible !ats.

Hydrogenation

1$,. ____ o! ole!ins yields aldehydes *hi"h !urther undergo redu"tion

22

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to gie al"ohols.

Hydroormylation

1$/. Gie t*o rea"tions to sho* the hydro!ormylation o! ole!ins:

=i? H#A 8O A R8H L 8H#

=ii? R8H#8H#8HO A H#

H2+ 1 + N1H = 1H2N1H21H21H

N1H21H21H + H2N1H21H21H2H

1$2. 8omment on the rea"tions o! dihydrogen *ith "hlorine sodium and

"o))er =%%? o&ide.&ns'er yoursel (ee page 29. o 31ONA :ook)

=!? Rea"tion *ith sul)hur

1$5. Hydrogen "ombines *ith sul)hur on ____ to )rodu"e ___ ___.

ignition, hydrogen sulphide

H2+ H2

=g? Rea"tion *ith "arbon

1$9. Hydrogen "ombines *ith "arbon at ___ deg 8 to !orm ____ in small

amounts.

200, methane

1 + 2H21H

=h? Redu"ing rea"tions o! hydrogen

1'0. Hydrogen has a great ____ !or o&ygen. Hen"e it is used to redu"e

o&ides o! ___ =less>more? ele"tro)ositie metals.

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8e!+ H2!8e + H2

=i? Rea"tion *ith "arbon mono&ide

1'1. Hydrogen rea"ts *ith "arbon mono&ide at about ____ P and under

high )ressure and in )resen"e o! a "atalyst =____? to !orm ___.

900, Bn%1r2!, methanol

=Q? Hydro!ormylation o! ole!ins to aldehydes

1'#. Ole!ins "ombine *ith "arbon mono&ide and hydrogen in the

)resen"e o! ____ as "atalyst under ___ =lo*>high? tem)erature and

)ressure to !orm ____ *hi"h "an be !urther redu"ed to ___.

octacar4onyldico4alt (/ronounce* octa-car4onyl-di-co4alt) 1o2(1),

lo', aldehyde, alcohol

1'$. Gie e3uation !or hydro!ormylation o! ole!ins:

H#

R+8HL8H#A H#A 8O H2

N-1H=1H2+ H2+ 1 N1H2L 1H2L 1H N1H2L 1H2L H

B

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8reshly reduced iron ha5ing moly4denum as promoter#

1'5. Dihydrogen is used in the manu!a"ture o! anas)ati !at by the ___

o! ____ egetable oils li;e soyabean "otton seeds et".hydrogenation, polyunsaturated

1'9. Hydrogen is used in the manu!a"ture o! bul; organi" "hemi"als

)arti"ularly ____. %n this )ro"ess ___ ___ enri"hed *ith hydrogen

is "om)ressed to ___ atmos)heres and then )assed oer a "atalyst

"onsisting o! ___ and ___ at ___ deg 8 *hen the al"ohol is

)rodu"ed.methanol, 'ater gas, 200, Bn, 1r!, !00

1,0. Gie the rea"tion !or the )re)aration o! methanol !rom hydrogen. co4alt catalyst

1 (g) + 2H2(g) 1H!H (J)

(Note that the catalyst here is different from that given in Arihant)

1,1. Hydrogen is used in the manu!a"ture o! metal ____. %t is also used

in the )re)aration o! hydrogen ____ *hi"h is a use!ul "hemi"al.

hydrides, chloride

1,#. %n metallurgi"al )ro"esses dihydrogen is used to redu"e ___ metal

o&ides to metals.

hea5y

1,$. ____ hydrogen and ____ tor"hes !ind use !or "utting and *elding

)ur)oses. O&yhydrogen !lame )rodu"es a tem)erature o! ___ deg

8.

&tomic, oxy-hydrogen, 200

1,'. tomi" hydrogen atoms )rodu"ed by the disso"iation o!

dihydrogen *ith the hel) o! an ___ ___ are allo*ed to re"ombine

2

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on the sur!a"e to be *elded to generate a tem)erature o! ____ P.

lit. Hydrogen also

has the highest ___ ___ amongst all ;no*n !uels. (he lo* density

and high "alori!i" alue ma;es is suitable !or s)a"e trael.

rocket uel, 0#0.9, caloriic 5alue,

1,/. 7oo; at the !igure belo* to understand the arrangement o! !uel

tan;s in s)a"e shuttles.

1,2. 7i3uid hydrogen storage tan; *ith li3uid o&ygen is used to )o*er

the main ro";et o! the ___ ___.space shuttle

1,5. Dihydrogen is used in ___ ___ !or generating ele"tri"al energy. %t

has many adantages oer the "onentional !ossil !uels and ele"tri"

)o*er. %t does not )rodu"e any ___ and releases greaterPPP PPP PPP

PPPo! !uel in "om)arison to gasoline and other !uels.

uel cells, pollution, energy per unit mass

2"

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1,9. (he energy released by hydrogen )er gm is ____.

2 k$

1/0. Hydrogen e"onomy means re)la"ing "onentional !uels *ith ___.

hydrogen

1/1. Hydrogen is used !or "reating a redu"ing atmos)here in )ro"esses

li;e ___ and ___.

annealing, deoxidising

1/#. -ith helium hydrogen is used !or !illing balloons em)loyed !or ___

___.atmospheric study

1/$. One maQor use o! hydrogen is in the ____ industry.

petrochemical

HYDROGEN+OYGEN BE7 8E77

1/'. (he !uel "ell *as inented by ___ ___. %t di!!ers !rom the ordinary

"ell in that the rea"tants are not "ontained *ithin the "ell but

su))lied to it !rom an ___ ___.

Killiam

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1//. Dihydrogen under "ertain rea"tion "onditions "ombines *ith

almost all elements e&"e)t ___ ___ to !orm binary "om)ounds

"alled ___. hydride "an be e&)ressed as EH &=Eg. gH#? or EmHn

=4#H,? *here E is the element.no4le gases, hydrides

1/2. (he hydrides are "lassi!ied into three "ategories. Name them.

(i) ;onic or saline or salt-like hydrides#

(ii) 1o5alent or molecular hydrides#

(iii) etallic or non-stoichiometric hydrides#

1/5. 7oo; at the 6eriodi" (able belo* and understand the distribution

o! di!!erent ty)es o! halides.

%ON%8 HYDR%DERb>8s A H#

=iii? 8a>4a A H# 2i + H22iH "em&erature ' deg *

23a%@%N4%1s + H223aH "em&erature ' + deg *

1a%r%:a + H21aH2, rH2, :aH2 "em&erature ' - % deg*

6hysi"al )ro)erties o! ioni" halides

12'. %oni" hydridies are ___ "oloured ____ ="rystal stru"ture? _____

=olatility? and ____ ="ondu"tion? in solid state. Ho*eer their ____

"ondu"t ele"tri"ity and on ele"trolysis liberate dihydrogen gas at

the ____ *hi"h "on!irms the e&isten"e o! H+ions.

greyish, crystalline, non-5olatile, non-conducting, melts, anode

12,. Gie rea"tion to sho* the ele"trolysis o! ioni" hydrides. anode

2H-(melt) H2(g) + 2e-

2.

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12/. %oni" halides hae ___ =lo*>high? melting and boiling )oints.

high

122. (he density o! the ioni" halide is ___ =lo*er>higher? than the

density o! the metal !rom *hi"h they are !ormed. (his is be"ause

the hydrogen ions o""u)y ___ ___ in the metal latti"e.

higher, interstitial spaces

125. (he stability o! the saline hydrides ___ =in"reases>de"reases? as the

siCe o! the "ation in"reases.

decreases

&lkali metals* iH Q 3aH Q @H Q N4H Q 1sH

&lkaline earth metals* 1aH2Q rH2Q :aH2

8hemi"al )ro)erties o! ioni" halides

129.

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*here is the metal

2H 2 + H2

H2 + H2

15$. Gie the rea"tion o! saline hydrides *ith ethyl al"ohol:

7iH A 8#H,OH

iH + 12HH 12Hi + H2F

15'. Gie the rea"tion o! saline hydrides *ith "arbon dio&ide:

7iH A 8O#

iH + 12

H1i

15,. ___ ___ metal hydrides and 7iH "ombine *ith nitrogen *hen

heated in its atmos)here. (he rea"tions are:

=i? / 7iH A N#

=ii? $8aH#A N#

&lkaline earth

" iH + 322 i!3 + !H2F

!1aH2+ 321a!32+ !H2F

15/.

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=i? 57iH A l#8l/

=ii? #7iH A 4#H/

=iii? #NaH A 4#H/

ithium hydride, moderate

iH + &l21l"2i&lH+ " i1l

2iH + :2H"2i:H

23aH + :2H"23a:H

Bses o! ioni" hydrides155. %oni" hydrides are used as ___ agents as ___ !uels and !or ready

synthesis o! hydrogen by ___.

reducing, solid, hydrolysis

8OF7EN( HYDR%DEhigher? than those o!

subse3uent grou) member hydrides. Ho*eer due to higher ____

o! N O and the magnitude o! ___ ___ in their hydrides *ill be3uite a))re"iable. Hen"e the boiling )oints o! ammonia *ater and

H *ill be ___ =lo*er>higher? than the hydrides o! their subse3uent

grou) members.

lo'er, electronegati5ity, hydrogen 4onding, higher

#0#. (he thermal stability o! "oalent halides in a grou) ____ =in"rease>

de"reases? as the ele"tronegatiity de"reases *ith an in"rease in siCe

o! the "entral atom.

decreases

3H!Q /H!Q &sH!Q 4H!Q :iH!

#0$.

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#0,. etalli" hydrides are "om)ounds "ontaining a ___ metal and

hydrogen. 8ommonly the !ormula o! these "om)ounds is H&

*here & is not an ___. etalli" hydrides are so "alled be"ause they

are ele"tri"ally ___.transition, integer, conducting

#0/. etalli" or non+stoi"hiometri" =or ____? hydrides are !ormed by

___ and ___ elements. Ho*eer the metals o! Grou) ___ ___ and

___ do not !orm hydride. Een !rom Grou) / only ___ !orms a

hydride.

;nterstitial, d-4lock, -4lock, 9, , ., chromium

#02. (he region o! the )eriodi" table !rom Grou) / to 9 is re!erred to as

the ____ ____.

hydride gap

#05. etalli" hydrides are )re)ared by ___ hydrogen dire"tly at

a))ro)riate tem)eratures by metals. %n some "ases the metals are

used as ____ in the ele"trolysis o! a3ueous solutions so that

hydrogen eoled at the ___ is adsorbed.

adsorption, cathodes, cathode

#09. (he "om)osition o! these hydrides may not "orres)ond to sim)le

*hole number ratios and there!ore they are "alled ____ hydrides.

(heir "om)osition aries *ith the "onditions o! ___ and ___.non-stoichiometric, temperature, pressure

#10. Non+stoi"hiometri" "om)osition o! metalli" halides sho*s that the

hydrogen atoms o""u)y some but not all ___ sites in the metalli"

latti"e. O!ten hydrogen atoms enters the holes in ____ amounts.

interstitial, non-stoichiometric

#11. etalli" halides are bla"; ___ ___ substan"es *ith metalli" lustre

!"

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and ___ )ro)erties.

po'dery, hard, magnetic

#1#. etalli" halides are ___ =good>bad? "ondu"tors o! ele"tri"ity.

Ho*eer the "ondu"tiity ___ =in"reases>de"reases? *ith in"rease

in tem)erature.

good, decreases

#1$. (he density o! these hydrides is ___ =lo*er>higher? than those o!

metals !rom *hi"h they are !ormed sin"e the "rystal latti"e ___ due

to the absor)tion o! hydrogen.lo'er, expands

#1'. etalli" hydrides "ondu"t heat and ele"tri"ity though not as

e!!i"iently as their ____ metals do. Bnli;e saline hydrides they are

almost al*ays ____ being de!i"ient in ___. or e&am)le 7aH#.52

YbH#.,, (iH1.,+1.5 rH1.$+1.2, FH0.,/ NiH0./+0.2 6dH0./+0.5 et". %n su"h

hydrides the la* o! "onstant "om)osition does not hold good.parent, non-stoichiometric, hydrogen, constant composition

#1,. Earlier it *as thought that in metalli" hydrides hydrogen o""u)ies

____ in the metal latti"e )rodu"ing ____ *ithout any "hange in its

ty)e. 8onse3uently they *ere termed as ____ hydrides. Ho*eer

re"ent studies hae sho*n that e&"e)t !or hydrides o! ___ ___ ___

and ___ other hydrides o! this "lass hae a latti"e that is ___ !rom

that o! the )arent metal. (he )ro)erty o! absor)tion o! hydrogen

on transition metals is *idely used in ___ redu"tion>hydrogenation

rea"tions !or the )re)aration o! a large number o! "om)ounds.

interstices, distortion, interstitial, 3i, /d, 1e, &c, dierent, catalytic

#1/.

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media. (his )ro)erty has high )otential !or ___ storage and as a

sour"e o! ___.

/d, /t, hydrogen, energy

#12. 8an )hos)horous *ith outer ele"troni" "on!iguration $s#$)$ !orm

6H,

&ns'er yoursel# (/age 2 o 31ONA text4ook)

#15. lthough )hos)horous e&hibits ___ and ___ o&idation states it

"annot !orm 6H,. 4esides some other "onsiderations high aH

alue o! dihydrogen and egH alue o! hydrogen do not !aour toe&hibit the highest ___ state o! ___ and "onse3uently the !ormation

o! 6H,.

+!, +, oxidation, /

#19. etal hydrides !ormed as a result o! o""lusion "an be used as

hydrogen ___ media.

storage

##0. etalli" hydrides are *idely used in ___ redu"tion and ____.

reduction, hydrogenation

##1. 4esides ioni" "oalent and metalli" hydrides there are t*o more

ty)es o! hydrides *hi"h are "alled ___ and ___ hydrides.

polymeric, complex

###. 6olymeri" Hydrides are !ormed by elements haing

ele"tronegatiity in the range o! ___ to ___. (hey are generally ___.

#, 2#0, solids

##$. 6olymeri" hydrides "onsist o! mole"ules that are held together in

t*o or three dimensions by ___ ___ =three+"enter+t*o+ele"tron

bonds?.hydrogen 4ridges

!

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#$0. Bnder atmos)heri" "onditions ordinary hydrogen "onsists o! ___I

ortho hydrogen and ____I )ara hydrogen.

9, 2

#$1. t ery lo* tem)eratures =around #0 P? hydrogen has ___I

ortho hydrogen and ___I )ara hydrogen.

0#, ..#2

#$#. ___ =Ortho>6ara? hydrogen is more stable than the ___+hydrogen.

rtho

#$$. 6ure ___ =ortho>)ara? hydrogen "an be obtained at ery lo*

tem)eratures. Ho*eer )ure ___+hydrogen is ery di!!i"ult toobtain.

para, ortho

#$'. (he t*o !orms o! hydrogen =Ortho and 6ara? di!!er in their

)hysi"al )ro)erties but sho* similar ____ )ro)erties.

chemical

ORE ON %

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-(ER

-hat is the estimated *orld *ater su))ly in the !ollo*ing sour"es:

=i? O"eans =ii?

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5aporisation and high heat o usion in comparison to H2 and H2e#

%n "om)arison to other li3uids *ater has a higher ___ heat ____

"ondu"tiity ____ ____ ____ moment and ____ "onstant. (hese)ro)erties allo* *ater to )lay a ;ey role in the bios)here.

speciic, thermal, surace, dipole, dielectric

(he high heat o! a)orisation and heat "a)a"ity o! *ater are

res)onsible !or moderation o! the ____ and body ___ o! liing

beings. %t is an e&"ellent ___ !or trans)ortation o! ions and

mole"ules re3uired !or )lants and animal metabolism.climate, temperature, sol5ent

Due to ___ ___ *ith )olar mole"ules een "oalent "om)ounds li;e

al"ohol and "arbohydrates dissole in *ater.

hydrogen 4onding

%n the gas )hase *ater is a ____ mole"ule *ith a bond angle o! ___

degrees and O+H bond length o! ___ )m. %n the li3uid )hase *ater

mole"ules are asso"iated together by ____ bonds. (he ___ !orm o!

*ater is i"e.

4ent, 0#, .#9, hydrogen, crystalline

7oo; at the !igure belo* and understand the stru"ture o! the *ater

mole"ule. lso noti"e the orbital oerla).

!

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t atmos)heri" )ressure i"e "rystallises in the ____ !orm. Ho*eer

at ery lo* tem)eratures it "ondenses to ____ !orm.

hexagonal, cu4ic

Density o! i"e is ___ =less>more? than that o! *ater. (here!ore i"e

!loats on *ater. %n *inters an i"e !ormed on the sur!a"e o! a la;e

)roides ____ ____ *hi"h ensures the surial o! a3uati" li!e. (his

!a"t is o! great e"ologi"al signi!i"an"e.

thermal insulation

%"e has a ___ ___ ___ ___ hydrogen bonded stru"ture. E&amination

o! i"e "rystals *ith &+rays sho*s that ea"h o&ygen atom is

surrounded ____ by !our other o&ygen atoms at a distan"e o! ___

)m.

highly ordered three dimensional, tetrahedrally, 29"

Hydrogen bonding gies i"e a rather ___ ty)e stru"ture *ith *ide

holes. (hese holes "an hold some other mole"ules o! a))ro)riate

siCe ____.open, interstitially

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m)hoteri" nature o! *ater

-ater has an ____ nature it a"ts as an a"id as *ell as a base. %n

the 4ronsted sense it a"ts as an a"id *ith ___ and a base *ith ___

____.

amphoteric, ammonia, hydrogen sulphide

Gie e3uation to sho* the am)hoteri" nature o! *ater.

H2 (J) + 3H!(a?) H-(a?) + 3H+(a?)

H2 (J) + H2(a?) H!+(a?) + H-(a?)

Gie e3uation to sho* the auto+)rotolysis =sel!+ioniCation? o! *ater.

H2 (J) + H2 (J) H!+(a?) + H-(a?)

acid L 4ase-2 acid-2 4ase-

(acid) (4ase) (conRugate acid) (conRugate 4ase)

8ommon rea"tions *ith *ater

-ater "an be easily redu"ed to ___ by highly ____ metals.

(here!ore it is a great sour"e o! ____. Gie e3uation.

dihydrogen, electropositi5e, dihydrogen

2H2 (J) + 23a (s) 23aH (a?) + H2(g)

-ater is o&idised to ___ during )hotosynthesis. Gie e3uation.

oxygen

" 12(g) + 2 H2 (J) 1"H2"(a?) + " H2 (J) + " 2(g)

___ also o&idises *ater to o&ygen. Gie e3uation.

8lourine

282(g) + 2H2 (J) H+(a?) + 8-+ 2(g)

Due to high ___ ___ *ater has a ery strong hydrating tenden"y. %t

dissoles many ioni" "om)ounds. Ho*eer "ertain "oalent and

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some ioni" "om)ounds are ____ in *ater.

dielectric constant, hydrolysed

Gie e3uations =!our? to sho* the hydrating and hydrolysing a"tion

o! *ater.

/0(s) + "H2 (J) H!/(a?)

i1l(J) + 2H2 (J) i2(s) + H1l (a?)

3!-(s) + !H2 (J) 3H!(g) + ! H-(a?)

-ater o! "rystallisationany salts are "rystallised !rom their a3ueous solutions as ___

salts.

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Hardness o! *ater

____ *ater does not !orm lather *ith soa). %t is "aused by the ___

___ and ___ salts o! ___ =metal? and ___ metal.

Hard, hydrogencar4onate, chloride, sulphate, calcium, magnesium

-ater !ree !rom soluble salts o! "al"ium and magnesium is "alled

___ *ater. %t easily !orms lather *ith soa).

sot

Hard *ater !orms ____>___ *ith soa).

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magnesium hydrogen"arbonate is "onerted into insoluble ____ ___

*hile "al"ium hydrogen"arbonate is "onerted to insoluble ___ ___.

%t is be"ause o! high solubility )rodu"t o! ___ as "om)ared to that

o! ____ that ____ is )re"i)itated. (hese )re"i)itates "an be remoed

by !iltration. (he !iltrate thus obtained *ill be ___ *ater.

magnesium hydroxide Dg(H)2E, calcium car4onate D1a1!E,

g(H)2, g1!, g(H)2, sot

Gie e3uations !or so!tening o! *ater by boiling. Heating

g(H1!)2g(H)2S + 2 12F

Heating

1a(H1!)21a1!S + H2 + 12F

%n 8lar;Js method a "al"ulated amount o! ___ is added to hard

*ater. %t ____ out "al"ium "arbonate and magnesium hydro&ide

*hi"h "an be !iltered o!!. Gie e3uations.

lime, precipitates

1a(H1!)2+ 1a(H)221a1!S + 2 H2

g(H1!)2+ 21a(H)221a1!+ g(H)2S + 2 H2

6ermanent hardness

6ermanent hardness is "aused due to the )resen"e o! soluble salts o!

magnesium and "al"ium in the !orm o! ___ and ___ in *ater.6ermanent hardness is not remoed by ___.

chlorides, sulphates, 4oiling

Name !our methods !or remoing )ermanent hardness.

(i) Areatment 'ith 'ashing soda (sodium car4onate)

(ii) 1algonGs method

(iii) ;on-exchange method

(i5) ynthetic resins method

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=i? Remoal o! )ermanent hardness: (reatment *ith *ashing soda

Gie rea"tions !or so!tening o! )ermanent hard *ater *ith *ashing

soda.

1l2+ 3a21!1!S + 23a1lM 0 ' 0g, *a

+ 3a21!1!S + 3a2

=ii? Remoal o! )ermanent hardness: 8algonJs method

%n 8algonJs method !or so!tening *ater *ith )ermanent hardness

___ ___ =___? "ommer"ially "alled K____J is added to hard *ater.

(he ____ ____ ;ee)s the magnesium and "al"ium ions in solution.

sodium hexametaphosphate, 3a"/", calgon, complex anion

Gie the rea"tions inoled in the 8algonJs method.

3a"/"23a+ + 3a/"

2- 0 ' 0g, *a

2++ 3a/"2-D3a2/"E

2-+ 23a

=iii? Remoal o! )ermanent hardness: %on+e&"hange method

(he ion+e&"hange method is also "alled the ___>___ )ro"ess.6eolite, permutit

Hydrated ___ ___ ____ =___? is Ceolite> )ermutit. -hen this is

added in hard *ater ____ rea"tions ta;e )la"e.

sodium aluminium silicate, 3a&li, exchange

or the sa;e o! sim)li"ity sodium aluminium sili"ate "an be *ritten

as Na. (hen gie rea"tion o! ion+e&"hange method.

23aB (s) + 2+(a?) B2(s) + 2 3a+(a?) = g, 1a

%n the ion+e&"hange )ro"ess !or so!tening *ater )ermutit> Ceolite is

said to be e&hausted *hen all the ___ in it is used u). %t is

regenerated !or !urther use by treating *ith an a3ueous ___ ___

solution.

sodium, sodium chloride

.

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Gie e3uation !or regeneration o! )ermutit>Ceolite in the ion+

e&"hange method o! so!tening o! *ater.

B2(s) + 23a1l (a?) 23aB (s) + 1l2(a?)

=i? Remoal o! )ermanent hardness: insoluble?. %on

e&"hange resin =R

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)ure de+mineraliCed *ater.

2NH (s) + 2+(a?) N2(s) + 2H+(a?)

%n the se"ond stage the anion e&"hange )ro"ess + ___ e&"hanges

!or anions li;e ___ ____ ____ et". )resent in *ater. ___ ions thus

liberated neutralise the ___ ions set !ree in the "ation e&"hange.

H-, 1l-, H1!-,

2-, H-, H+

De+ionised *ater: Gie e3uation !or the se"ond stage =anion+

e&"hange stage?.

N3H2(s) + H2 (J) N3H!+#H-(s)

N3H!+#H-(s) + -(a?) N3H!

+#-(s) + H-(s)

De+ionised *ater: Gie e3uation !or neutralisation in se"ond stage.

H+(a?) + H-(a?) H2 (J)

De+ionised *ater: (he e&hausted "ation and anion e&"hange resin

beds are regenerated by treatment *ith ___ ___ and ___ solutions

res)e"tiely.

dilute acid, alkali

6GE ##1: (andon: %ndustrial ))li"ations

6age 10 hydrogen )ero&ide

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2

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!

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