2208-6108

13 pages

M08/4/CHEMI/HP2/ENG/TZ1/XX

Thursday 8 May 2008 (afternoon)

CHEMISTRY

HIGHER lEvEl

PaPER 2

INSTRUCTIONS TO CANDIDATES

•

Write your session number in the boxes above.

•

Do not open this examination paper until instructed to do so.

•

Section A: answer all of Section A in the spaces provided.

•

Section B: answer two questions from Section B. Write your answers on answer sheets. Write

your session number on each answer sheet, and attach them to this examination

paper and your cover sheet using the tag provided.

•

At the end of the examination, indicate the numbers of the questions answered in the candidate

box on your cover sheet and indicate the number of sheets used in the appropriate box on your

cover sheet.

2 hours 15 minutes

Candidate session number

0

0

© International Baccalaureate Organization 2008

22086108

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M08/4/CHEMI/HP2/ENG/TZ1/XX

Section a

Answer all the questions in the spaces provided.

1.

Thevalueofxin

Fe(NH ) (SO )

4 2

4 2

.

xH O

2

canbefoundbydeterminingtheamount,inmoles,of

sulfateinthecompound.

A0.982gsamplewasdissolvedinwaterandexcess

BaCl (aq)

2

wasadded.

Theprecipitateof

BaSO

4

wasseparatedanddriedandfoundtoweigh1.17g.

(a) Calculatetheamount,inmolesof

BaSO

4

inthe1.17gprecipitate.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

(b) Calculate the amount, in moles, of sulfate in the 0.982 g sample of

Fe(NH ) (SO )

4 2

4 2

.

xH O

2

.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[1]

(c) Calculatetheamount,inmoles,ofironinthe0.982 gsampleof

Fe(NH ) (SO )

4 2

4 2

.

xH O

2

.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[1]

(d) Determine the mass of the following present in the 0.982 g sample of

Fe(NH ) (SO )

4 2

4 2

.

xH O

2

.

[3]

(i) Iron

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(ii) Ammonium

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(iii) Sulfate

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(This question continues on the following page)

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(Question 1 continued)

(e) Useyouranswerfrompart(d)todeterminetheamount,inmoles,ofwaterpresentinthe

0.982gsampleof

Fe(NH ) (SO )

4 2

4 2

.

xH O

2

.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

(f) Determinetheamount,inmoles,of

Fe(NH ) (SO )

4 2

4 2

andhencethevalueofx.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

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2.

(a) The mass spectrometer is used to investigate the isotopic composition of elements.

Thalliumhastwoisotopes

81

203

Tland

81

205

Tl.

(i) State the symbols of the two singly charged ions that would form in the

massspectrometer.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[1]

(ii) StatewhichionwillfollowthepathmarkedXonthediagram.

[1]

detector

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(iii) Somedoublychargedionsforminthemassspectrometer.Suggestwithareason

whether they would be deflected less than or more than the ions at XandY.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

(b) Naturallyoccurringboronconsistsofthetwoisotopes,

10

B

and

11

B

.Therelativeatomic

massofboronis10.81.Determinethepercentageabundanceoftheseisotopes.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

X

Y

magnetic field

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3.

Lacticacid,

CH CH(OH)COOH

,isaweakmonoproticacid(

K

a

moldm

=

×

−

−

1 40 10

4

.

.

).

(a) Writeanequationforthereactionoflacticacidwithwater.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

(b) Statetheionizationconstantexpression,

K

a

,forlacticacid.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[1]

(c) Calculatethe

[ ]

H

+

ofa0.20mol

dm

−

solutionoflacticacid.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

(d) Calculatethe

[ ]

H

+

ofabuffersolutionof1.00

dm

volume,containing0.20mol

dm

−

of

lacticacidand0.12mol

dm

−

ofsodiumlactate.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

(e) Explain why the two values of

[ ]

H

+

in (c) and (d) are different using Le Chatelier’s

principle.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

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4.

(a) Explainwhatismeantbythetermisomers?

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[1]

(b) Drawtwostructuralisomersforeachofthefollowingwithdifferent functional groups.

Ineachcase,describeachemicaltestandtheresultsobtained,whichwoulddistinguish

betweenthetwostructuralisomers.

(i)

C H O

6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[4]

(ii)

C H O

6

2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[4]

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5.

Two1 00

3

. dm containersaandBeachcontain2.00gofthegasindicatedat

2 0

. °C

.

O

2

a

B

(a) Calculatethepressureincontainer

B.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[3]

(b) Deducewithout calculationwhetherthepressureinaishigherorlowerthancontainer

Bandexplainyouranswer.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

H

2

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Section B

Answer two questions. Write your answers on the answer sheets provided. Write your session number

on each answer sheet, and attach them to this examination paper and your cover sheet using the tag

provided.

6.

(a) Thedecompositionofsolidbariumcarbonateisgivenbythefollowingequation:

BaCO (s)

BaO

(s) CO (g)

3

�

+

2

Compound

BaCO (s)

CO (g)

2

BaO(s)

∆

H

f

kJmol

Ö

/

−1

–1219

–94

–8

S

Ö

/ JK mol

−1

−1

+112

+214

+70

(i) Calculatethevalueof

∆

G

Ö

inkJmol

−1

at

2°C

.

[6]

(ii) Statewithareasonwhetherthereactionisspontaneousat

2°C

.

[1]

(iii) Determine the minimum temperature above which this reaction is spontaneous.

Explainyouranswer.

[4]

(b) DrawtheLewisstructuresofthefollowingmolecules.UsetheVSEPRtheorytopredict

theshapeofeachmolecule.

(i)

XeF

4

and

XeO

4

[4]

(ii)

PF

and

IF

[4]

(c) Transitionelementsformcomplexessuchas

[Fe(Cl) ]

4

−

and

[Fe(CN) ]

6

4−

.

(i) Identifythefeatureofboth

Cl

−

and

CN

−

thatenablesthemtoformthesecomplexes

andnamethetypeofbondformed.

[2]

(ii) Deducetheoxidationstateofironineachofthecomplexions.

[2]

(iii) State

two characteristic properties of transition metals other than complex

formationandvariableoxidationstate.

[2]

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7.

(a) Theoxidationofnitrogenmonoxidetakesplaceasfollows:

2NO (g) O (g)

2NO (g)

2

2

+

→

Thefollowingexperimentaldatawasobtainedataconstanttemperature.

Experiment Initial[NO]/mol

dm

−

Initial

[ ]

O

2

/mol

dm

−

Initialrate/mol

dm s

− −

1

1

0 10

2

. ×

−

1 7 10

2

. ×

−

7 10

. ×

−

2

0 10

2

. ×

−

0 10

2

. ×

−

7 0 10

. ×

−

7 00 10

2

. ×

−

7 00 10

2

. ×

−

6 00 10

2

. ×

−

(i) Deducetheorderofreactionwithrespectto

O

2

andwithrespecttoNO.

[2]

(ii) Statetherateexpressionforthereaction.

[1]

(iii) Calculatethevalueoftherateconstantandstatetheunits.

[2]

(iv) Calculate the expected rate of reaction if the reactants from experiment 2 were

placedinacontaineroftwicetheoriginalvolume.Explainyouranswer.

[2]

(v) Suggestapossibletwostepmechanismthatisconsistentwiththerateexpression.

Identifytherate-determiningstep.

[3]

(b) Thereactionin(a)isfasterat2Kthanat298K.Explaintheincreaseinrateinterms

ofcollisiontheoryandMaxwell-Boltzmannenergydistributioncurves.

[5]

(This question continues on the following page)

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(Question 7 continued)

(c) Thefollowingequilibriumisinvolvedintheindustrialproductionofnitricacidfrom

ammonia.

4

4

910

1

NH (g) O (g)

NO(g) 6H O(g)

kJmol

2

2

+

+

= −

−



∆

H

Ö

Describe the effect, if any, of each of the following changes on the equilibrium

concentrationofnitrogenmonoxideinaparticularequilibriummixture,giveareasonin

eachcase.

(i) Increasingthepressure,atconstanttemperature

[2]

(ii) Increasingthetemperature,atconstantpressure

[2]

(iii) Additionofaheterogeneouscatalyst,atconstantpressureandtemperature

[2]

(d) Deducetheequilibriumconstantexpression,

K

c

,includingunitsfortheforwardreaction

inpart(c).

[2]

(e) Identifywhichofthechangesinpart(c)willaffectthevalueof

K

c

andpredictwhether

thevalueof

K

c

willincreaseordecrease.

[2]

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M08/4/CHEMI/HP2/ENG/TZ1/XX

8.

(a) Electrolysisofanaqueoussolutionofcopper(II)sulfate,

CuSO

4

,canbecarriedoutusing

platinumelectrodes.

(i) Stateanequationforthehalf-reactionoccurringatthepositiveelectrode(anode)

and

oneobservationthatcouldbemadeasaresult.

[2]

(ii) Stateanequationforthehalf-reactionoccurringatthenegativeelectrode(cathode)

and

oneobservationthatcouldbemadeasaresult.

[2]

(iii) Describe

two changes or observations in the electrolyte as result of these

halfreactions.

[2]

(iv) Determinetherelativeamount,inmoles,ofproductsformedateachelectrode.

[1]

(v) Identifyanothercompoundwhichwillformthesameproductsatthepositiveand

negativeelectrodes.

[1]

(vi) Thesameprocessiscarriedoutusingcopperelectrodesinsteadoftheplatinum

electrodes. Describe the changes or observations that take place at both the

electrodesandintheelectrolyte.

[3]

(b) Identify

twofactorsthataffectthequantityofcopperproducedduringtheelectrolysisof

anaqueouscopper(II)sulfatesolution.

[1]

(c) Considerthefollowinghalfcellreactionsandtheirstandardelectrodepotentials.

Ni (aq)

e

Ni(s)

V

2+

−

+

= −

2

0 2



E

Ö

.

MnO (aq) 8H (aq) e

Mn (aq) 4H O (l)

V

2

2

4

1 1

−

+

−

+

+

+

+

= +



E

Ö

.

(i) State the conditions needed for the electrode potentials to be described as

standard.

[1]

(ii) Deduceabalancedequationfortheoverallreactionwhichwilloccurspontaneously

whenthetwohalfcellsareconnected.

[2]

(iii) Identify the reducing agent in the above reaction and determine the change in

oxidationnumberforthe

oxidizing agent.

[2]

(iv) Determinethecellpotentialwhenthetwohalfcellsareconnected.

[1]

(v) Drawandlabeladiagramofthevoltaiccellfrompart(c).Indicatetheanode,

cathode, the direction of the electron movement and ion flow.

[5]

(d) Outline

twodifferencesbetweenanelectrolyticcellandavoltaiccell.

[2]

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9.

(a) Ahydrocarboncontains8.6%bymassofcarbonandhasamolarmassof6.1

gmol

−1

.

(i) Determinetheempiricalandmolecularformulasofthehydrocarbon.

[3]

(ii) Drawthestructureoftheunsaturatedbranchedisomerandpredicttheratioofthe

peakareasinits

1

HNMR

spectrum.

[2]

(iii) Thesecondstructuralisomerofthehydrocarbonisunsaturatedandsymmetrical.

Drawitsstructureandstateitsname.

[2]

(iv) Draw the structure of the third structural isomer of this hydrocarbon which is

unsaturated, unbranched and unsymmetrical. This isomer is formed when an

alcoholisheatedwithconcentratedsulfuricacid.Identifythetypeofreaction

occurringanddeducethestructureofanalcoholthatformsthisisomer.

[3]

(b) The hydrolysis of 2-bromo-2-methylbutane by 0.10 mol

dm

−

potassium hydroxide

solutiontoform2-methylbutan-2-olisanexampleofan

S 1

N

reaction.

(i) Explainhowthis

S 1

N

reactionoccurs,usingcurlyarrowstorepresentthemovement

ofelectronpairs,andshowingthestructureoftheorganicintermediate.

[4]

(ii) Identifytheratedeterminingstepandstateareasonforyourchoice.

[1]

(c) State and explain whether the rate of each of the following reactions is greater than,

lessthanorequaltotherateofthereactioninpart(b).

(i) 2-chloro-2-methylbutane is reacted with 0.10 mol

dm

−

KOH (aq) at the

sametemperature.

[1]

(ii) 2-bromo-2-methylbutane is reacted with 0.20 mol

dm

−

KOH (aq) at the same

temperature.

[1]

(This question continues on the following page)

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M08/4/CHEMI/HP2/ENG/TZ1/XX

(Question 9 continued)

(d) (i) Discuss the structure of benzene including the hybridization and bond

anglespresent.

[4]

(ii) State, with a reason, the number of main peaks in the

1

HNMR

spectrum of

benzene.

[2]

(e) (i) Cyclohexenereactswithhydrogentoformcyclohexane.

Calculate the enthalpy change of hydrogenation of benzene to cyclohexane,
assumingithasthecyclohexatriene

structure.

[1]

(ii) The experimental value for the hydrogenation of benzene to cyclohexane is

–207

kJmol

−1

.Explainwhythisvaluediffersfromthevaluecalculatedin(e)(i).

[1]

→

H

2

+

∆

H

Ö

=

−

–120

1

kJ mol

1313