physical chemistry board exam questions

8/10/2019 Physical Chemistry Board Exam Questions

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PreparedbyJEPaa/forBSChemGraduate2006

Physical

Chemistry

INSTRUCTION:Selectthecorrectanswerforeachofthefollowing

sections. Markonlyoneanswerforeachitembyshadingthebox

correspondingtotheletterofyourchoiceontheanswersheet

provided. STRICTLYNOERASURESALLOWED. Usepencilno.1only.

1. Chemicalequilibriumreactionsarecharacterizedby

Ga. >0

b. 0G

b.


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16.Thespecificheatcapacityatconstantvolumeofaleadsilveralloy

isequalto0.0383cal/degg. Theatomicmassesofleadandsilver

are207and107,respectively. Assumingthatthealloyfollows

DulongandPetitLaw,findthemoleratioofleadtosilver.

12.At35oC,thevaporpressureofwaterisincreasedfrom30to31

mmHgagainstanexternalpressureof10atm. Ifthevapor

pressureistobemaintainedat0.0395atmfor100gofwaterat

35oCand10atm,howmuchingNaClistobeaddedtothewater?

a.

58.55

b. 61.18

c. 52.88

d. 47.36

13.Givenasolutionoftolueneinbenzeneat20oCwiththemole

fractionoftolueneequalto0.20,thepartialpressureofthe

solvent,benzene,isequalto2.19torr. TheHenryconstantfor

tolueneis10.95torr. Calculatetheactivityofthesolute.

a.

0.800

b. 1.000

c. 0.500

d. 0.200

14.

A

certain

sugar

has

a

molar

mass

of

342

g/mol.

At

0o

C,

the

osmoticpressureofanaqueoussolutionofconcentrationof1.5g

ofsugarper150cm3solventis0.649atm. Whatistheosmotic

pressureofthesolution?

a. 222atm

b. 0.32atm

c. 50atm

d. 0.65atm

15.Giventhereaction: 3 3( ) ( )KNO energy K aq NO aq+ + + ,which

ofthefollowingchangestothesystemwouldincreasethe

concentrationofK+ionsatequilibrium?

a. Thepressureofthesystemisdecreased

b. AdditionalsolidKNO3isaddedtothesolution

c.

Thetemperatureofthesolutionisincreased

d.

Thevolumeofthesolutionisaddedtothesolution

a.

b. 2

c. 1

d. 4

17.CalculatethetemperaturechangeinoCoftwomolesofa

diatomicgascontainedinapistongiventhatq=65Jandw=210J.

a.

2.5

b. 4.5

c.

5.5

d. 3.5

18.Aleadstoragebatteryinvolvesthetwohalfreactions:2

4 4( ) 2PbSO s e Pb SO + + ;E

o(volts)=0.36

22 4 4 2( ) 4 2PbO s H SO PbSO H O+ + + + ;Eo(volts)= 1.69

Foracellthatduplicatestheleadstoragebatterydischarge

reactionatunitconcentrations,whatis G inkJ?

a. 792

b.

396

c. +792

d. +396

19.Whatistheheatcapacityatconstantpressureofgraphite

assumingitobeystheDulongandPetitsLaw?

a. 6cal/Kmol

b. 6atm/molL

c. 6Latm/mol

d. 6ergs/K



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20.AsealedisothermalcontainerinitiallycontainsthreemolesofCO

gasandfourmolesofO2gas. Thefollowingreversiblereaction

tookplace:

2 2

2 ( ) ( ) 2 ( )CO g O g CO g+

Atequilibrium,thereweretwomolesofCO2inthecontainer.

Whatwasthetotalnumberofmolesofgaspresentinthe

containeratequilibrium?

a.

6

b. 4

c. 5

d. 7

21.

At1035oC,twomolesofrutheniumchangesfromthetothe

solidstate. The H forthetransitionis142J/mol. The

surroundingcoolingbathisatSTP. Find S inJ/Koftheuniverse.

a. 1.040

b. 0.642

c. 0.823

d. 0.217

22.

Determinethebarometricdecreaseinatmosphericpressurefrom

sealeveltoanaltitudeof1.8x106cm. Assumeairtobea

uniformgasofmolecularmass29,andauniformtemperatureof

0oC.

a.

0.307

b. 0.998

c. 0.105

d.

304.1

23.Twomolesofanidealgasareexpandedreversiblyand

isothermallyat0oCfrom1atm. Calculatethefinalvolume

occupiedbythegasiftheheatabsorbedduringtheprocessisq=

750cal. Theexternalpressureoverthesystemis1atm.

a. 69.6L

b. 98.2L

c.

118.7L

d. 304.1L

24.A B C D+ +

A C D E+ +

Amultistepreactiontakesplacebytheabovemechanism.

Whichofthespeciesshownaboveisanintermediateinthe

reaction?

a. A

b. D

c. B

d. C

25.Abulbisfilledwithargongasattheambientpressureandis

foundtocontain7.98gofargonatatemperatureT. Thebulbis

thenimmersedinabathwhosetemperatureis30oChotterthan

thefirstone. Thestopcockonthebulbisopenedsothatthe

argongaspressurereturnstotheinitialvalue. Thebulbisnow

foundtocontain5.33gofargon. Whatisthevalueofthefinal

temperature? Theatomicmassofargonis39.9.

a. 242oC

b.

90.9

o

C

c.

212oC

d. 182oC

26.Ammoniadissolvesinwaterat20oCtogiveasolutioncontaining

0.040molefractionofammonia. Thetotalvaporpressureofthe

solutionis6.58x102

atmandthevaporpressureforwateris

17.00torratthesametemperature. ApplyingHenrysand

Raoultslaws,calculatetheHenrysconstant.

a.

1200

b. 50.00

c. 842.5

d. 16.98


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31.Arefrigeratorismaintainedat25o

Cinaroomatambient

temperatureof35oC. Theheatintotherefrigeratorisestimated

as104J/min. Assumingthattheunitisoperatingat45%ofits

maximumthermodynamicefficiency,determineitspower

requirementinwatts.


27.Asampleofanidealgasat29oCand420torroccupiedavolume

of382cm3. Whatwasthenumberofmolesofgasinthissample?

a. 8.5x103

b. 4.9x102

c.

6.5

d. 8.9x102

28.Thehalflifeforagivendecompositionreactionwashalvedasthe

initialconcentrationofasolereactantwasdoubled. Whatisthe

orderofthereaction?

a. 2

b.

1

c. 3

d.

0

29.Givenanatomofmass10,followingemissionofa2MeVgamma

ray,calculatetherecoilenergy.

a.

450eV

b.

198

eV

c. 214eV

d. 222eV

30.Forthefollowingreactionat25oC:

2 2( ) ( ) ( ) ( )CuO s H g Cu s H O g+ +

Valuesoftheabsoluteentropiesfortheabovesubstancesareas

follows:

S

o

(J/mol

K):

CuO=43.5; H2=130.5; Cu=33.5; H2O=188.7

Calculatethe inJ/molKofthereactionassumingstandard

conditions.

oS

a. 48.2

b. 309.2

c. 135.2

d.

18.8

a. 40.4

b. 89.8

c. 5380

d. 2299

32.Atacertaintemperature,2atmofCOareintroducedintoavessel

containingexcesssolidsulfurandafinalequilibriumpressureof

1.18atmisobserved. Giventhereaction,

2( ) 2 ( ) ( ) 2 ( )S s CO g SO g C s+ + ,finditsKp.

a. 6.33

b. 2.28

c. 0.73

d. 0.87

33.

Giventhefollowingo

fG inkJ/mol:

C6H12O6(s)=912; CO2(g)=393; H2O(l)=238;

Calculatethestandardfreeenergy(Gibbsenergy)inkJ/molfor

theoxidationofglucose,

6 12 6 2 2 2( ) 6 ( ( ) 6 ( )C H O s O g O g H O l+ +) 6C

a. 14370

b. 1842

c. 4698

d. 2874

34.Themassofanelectronis9.109x1028

g. Whatisthemolarmass

oftheelectron?

a. 4.39x1025

b.

6.61x1050

c.

5.48x104

d. 1.51x1051


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39.4.000picogram(pg)of33

Pdecaysbyemissionto0.500pgin

75.9days. Findtherateconstantofthereactioninperdaybasis.


35.Howmany particlespersecondwouldbeemittedform4x1012

gramof210

Po. Thehalflifeof210

Pois138days.

a. 728

b. 543

c.

667

d. 401

36.Thevalveonacylindercontaininginitially15Lofanidealgasat

25atm,25o

Cisopenedtotheatmospherewherethepressureis

760torr. Assumingthattheprocessisisothermal,howmuch

workisKJisdoneontheatmospherebytheactionofexpanding

gas?

a.

0.86

b. 3.64

c. 4.28

d. 5.85

37.At30oC,Henryslawconstantforthesolubilityofoxygengasin

wateris2O

K =3.30x107torr. Calculatethesolubilityofoxygenin

grams

at

this

temperature

per

100

g

of

water.

Assume

air

to

be

20%O2atroomtemperature.

a. 3.1x107

b. 2.6x105

c. 4.6x106

d. 8.3x104

38.InanidealsolutionofliquidsAandB,thevaporpressureofa

mixtureof0.60molofAand2.4molofBis0.42atmat70oC.

1.80molesofAisaddedtothesolutionat70oCandthevapor

pressureofthesolutionrisesto0.55atm. Calculatethevapor

pressureifsomeofthevaporinequilibriumwiththefirstsolution

werecompletelycondensed.

a. 0.51atm

b. 0.35atm

c.

0.20atm

d. 0.80atm

a. 9.13x103

b. 2.74x102

c.

3.65x102

d. 4.18x103

40.At1482Kand12atm,theequilibriumcompositionofsodium

vaporcontains3.10molesofNamonomerand0.624molesofNa

dimer. CalculatetheKpforthedimerizationofsodiumat1482K.

a. 2.01x102

b.

3.68x101

c.

2.47

d. 2.89x101

41.At600oC,acetonedecomposesproducingCOandvarious

hydrocarbons. Thereactionisfoundtobefirstorderinacetone

concentrationwithahalflifeof81.0s. Givenat600oC,aoneliter

containerintowhichacetoneisinjectedat0.48atm,approximate

howlongwouldittakefortheacetonepressuretodropto0.45

atm?

a. 39.8s

b. 7.5s

c. 81.0s

d. 15.0s

42.Duringwinter,thegaugepressureinanautomobiletirewhen

measuredat28oFwas30poundspersquareinch(psi). thesame

tirewasusedduringsummer. Assumingthatthevolumeofthe

tiredidnotchange,andnogasleakedoutfromthetirebetween

winterandsummer,whatisthenewpressureasmeasuredonthe

gaugeifthetemperatureroseto115oF?

a. 47.6

b. 37.9

c.

25.5

d. 35.3


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48.WhichoftheofthefollowingstatementsisTRUEaboutthe

electromotiveforceofasystemwhenallconcentrationsare

unity?

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43.EstimatethezeropointentropyofNOincal/molK.

a. 0

b. 2.76

c. 1.38

d.

4.18

44.Determinetheheattransferredwhen627Jofworkisdoneona

systemconsistingof2molesofanidealgasatconstant

temperature.

a. 0

b. 627J

c. 627J

d.

1254J

45.When[C]and[D]aredoubled,theinitialrateofthereaction

C D E+ increasesbyafactorofeight. Whichofthefollowing

ratelawsisconsistentwiththisobservation?

a. Rate=k[C][D]

b. Rate=k[C]2[D]

2

c. Rate=k[D]2

d.

Rate=k[C]2[D]

46.After66minutes,asampleof44

19Kisfoundtohavedecayedto

12.5%oftheoriginalamountpresent. Whatisthehalflifeof

?44

19 K

a. 22min

b. 66min

c.

44min

d. 88min

47.Whatisthepressureofacolumnofairataheightof10kmanda

temperatureof2oC? Assumethatthepressureatzeroheightis

760mmHgandthemolarmassofairis29.

a. 449

b. 340

c.

219

d. 759

a. EEo

49.AhypotheticalgasempiricalformulaisBCB. Predictthe

structureofthegasiftheratioofheatcapacities /P VC C is1.32.

a. Nonlinear

b.

Trigonal

c. Linear

d. Cannotbedetermined

50.AmixtureofthevaporsoftwoliquidsXandYwhichformideal

solutionsiscontainedinacylinderwithapistonatconstant

temperatureT. Themixturecontains60%X,withvaporpressures

oXP and oYP givenas1.2and0.4atm,respectively. Themixtureis

thenslowlycompressed. Calculatethetotalpressureatwhichthe

liquidfirstcondenses.

a. 0.475atm

b. 1.200atm

c. 0.800atm

d. 0.666atm


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55.FindthestandardenergyinkJofthecombustionreactionof

propeneat25oCassumingallreactantsandproductsbehaveas

idealgases.

10


SITUATIONAL

PROBLEMS:

Situation#01Theactivationenergyforthethermaldecomposition

ofgaseousacetaldehydeis190.37kJ/molandthemolecular

diameter,

,

of

a

molecule

of

acetaldehyde

is

5

x

10

8

cm.

This

decompositionisasecondorderreaction.

51.Determinethenumberofmoleculescollidingpermilliliterper

secondat800Kand760torr.

a. 2.10x1031

b. 4.75x1015

c. 9.17x1021

d.

2.88

x

10

28

52.

Calculatethesecondorderrateconstant,k,inL/molsec.

a. 6.9x102

b. 7.7x102

c. 8.3x104

d. 6.0x1023

53.

Determine

the

pre

exponential

factor

A

at

800

K.

a. 1.10x1013

b. 2.07x1011

c. 1.86x1015

d. 2.24x1017

Situation#02Thestandardenthalpyofthehydrogenationof

propeneis214kJ/mol. Thestandardenthalpyoftheoxidationof

propanetocarbondioxideandwateris2222kJ/mol. Thestandard

heatofformationofwateris286kJ/mol.

54.FindthestandardenthalpyinkJ/molofthecombustionreaction

ofpropaneat25oC.

a. 2076

b. 2068

c.

2060

d. 2084

a. 2068

b.

2075

c. 2069

d. 2094

56.FindWinkJofthecombustionreactionofpropeneat25oC.

a. 2.0

b. 1.0

c. 4.0

d.

0

Situation#03Akilogramofacetylenewascompressedfrom102

L

to103

Lataconstanttemperatureof150oC. Calculatetheminimum

workthatmustbeexpendedinthecompressionprocessassuming

thegastobe

57.IDEAL.

a. 1.09x103J

b.

3.12x105J

c. 1.11x105J

d. 3.08x103J

58.vanderWaals. ThevaluesofvanderWaalsconstantsaandbare

4.47L2atmmol

2and0.0571L/mol,respectively.

a. 4.98x109J

b. 1.55 x107J

c.

8.15x109J

d. 0.95x107J

59.IfacetylenesatisfiesthevanderWaalsequation,whatwouldbe

itscriticalpressureinatm?

a. 282

b. 197

c. 50.8

d.

1371


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64.theadiabaticexpansioninkJwherethefinaltemperaturewas

243oC.

10


Situation#04Amovingboundaryexperimentwasperformed

initiallyat25oCwith0.100MKClonthebottomand0.0700MNaCl

ontop. ThetransportnumbersofK+andNa

+ionsinthesesolutions

are0.490and0.388,respectively. Theboundarymoveddownward.

Thecrosssectionalareaofthetubewas0.100cm2. Thecharge

passedthroughwas96.5coulombs.

60.Howmanyequivalentsweretransported?

a. 1.00x103

b. 1.43x103

c. 0.25x103

d.

0.68x103

61.

Howfar(incentimeters)didtheboundarymove?

a. 65.4

b. 79.2

c. 49.0

d.

57.6

62.Whilethecurrentwasflowing,whatwastheconcentrationin

mol/LofNaCljustabovetheboundary?

a. 7.92x102

b. 2.18x101

c. 8.14x104

d. 6.24x105

Situation#05Fourmolesofanidealnitrogengaswasexpanded

from10Lto25L. Theinitialtemperaturewas35oC. AssumeCv=2.5

R. Calculatethemaximumworkobtainedby:

63.theisothermalexpansioninJ.

a. 92.7

b. 9385.4

c.

7039.6

d. 2243.0

a. 16.7

b. 9.2

c.

5.8

d. 23.1

65.FindtheenthalpychangeinJifthefinaltemperaturewas243oC.

a. 24,210

b. 59,164

c. 8,090

d.

32,358

Situation#06At1atm,120gofbenzeneisvaporizedatitsboiling

pointof80.2oC. Theheatofvaporizationis94.4cal/g.

66.CalculateWinunitsofjoule.

a.

4522

b.

293.6

c. +293.6

d. +4522

67.Calculateqinjoules.

a. 39497

b. 7480

c. 15627

d.

395

68.Calculate injoules.U

a. 34975

b. 44019

c. 0

d. 15921


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Situation#07TwoequimolarsolutionsAandBwithequalvolume

ofsolutionsaremixedtogetherandthereactionA B C+ occurs.

After60minutes,Ais75%reacted. HowmuchofAwillNOTreact

aftertwohoursif:

69.thereactioniszeroorderinbothAandB?

a. 50%

b. 0%

c. 25%

d. 75%

70.ifthereactionisfirstorderinbothAandB?

a.

62.8%

b. 25.0%

c. 35.7%

d. 14.3%

71.thereactionisfirstorderinAandzeroorderinB?

a. 21.7%

b. 6.26%

c. 32.2%

d. 52.08%

Situation#08Twogramsofliquidwaterat100oCisinitiallyat1.00

atmpressureandisconfinedtoavolumeinwhichnovaporis

present. Avalveisthenopenedandthewaterevaporatesintoan

evacuatedspaceofsuchvolumethatthefinalpressureis0.10atm.

Theentireapparatusisinaheatreservoirat100oC.The E forthe

vaporizationofwateris2259J/gat100oC. Assumingthatthevaporis

anidealgasandthatthevolumeoftheliquidisnegligibleas

comparedtothevolumeofthevapor,calculate:

72.qinjoulesforthewater.

a.

4173

b. 4863

c.

2617

d. 1914

73. S forwaterinJ/K.

a. 50.40

b. 28.16

c. 14.24

d.

45.20

74. S fortheuniverseinJ/K.

a. 34.01

b. 3.05

c. 15.68

d. 25.43

Situation#09Threemolesofanidealmonoatomicgasinitiallyat1

atmand300Kareputthroughthefollowingcycle,allstagesofwhich

arereversible:

(I) isothermalcompressionto2atm

(II) isobarictemperatureincreaseto400K

(III)returntotheinitialstatebythepath,P=a+bT,whereaandb

are

constants.

75.Calculate injoulesforthesecondstep.U

a. 3741

b. 1247

c. 8107

d. 6236

76.

Calculate inJ/Kforthefirststep.S

a. 8.6

b. 17.3

c. 5.8

d. 14.2


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79.Determinethevolumeadsorbedat3500secifVeisequalto0.451

cm3.

Situation#10GiventhedatabelowwhereVeisthevolume

adsorbedatequilibriumandVisthevolumeadsorbedattimet. The

adsorptionratefollowsfirstorderkinetics.

t(sec) 1380 3000 4260 7320

VeV(cm3

) 0.284 0.179 0.121 0.043

77.WhichofthefollowingstatementsisTRUEabout U and S for

thecycledescribed?

U

78.

DeterminetherateconstantKinpersecond.

a. Both and arezero.

S

b. ispositiveand iszero.

S

U S

c.

iszeroand ispositive.

S

U

d. ispositiveand isnegative.U

80.

DetermineVeViftis800seconds.

a. 3.20x104

b. 1.80x102

c. 1.60x103

d.

2.30x105

a. 0.281

b. 0.302

c. 0.325

d. 0.290

a. 0.354

b. 0.418

c. 0.166

d. 0.201

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