al chemistry 2001 paper 1+2

8/14/2019 AL Chemistry 2001 Paper 1+2

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Checkers Use Only

Checker No. Hong Kong Examinations Authority

All Rights Reserved 2001A Total

2001-AL-CHEM 11B Total

HONG KONG EXAMINATIONS AUTHORITY

HONG KONG ADVANCED LEVEL EXAMINATION 2001

CHEMISTRY A-LEVEL PAPER 1

Question-Answer Book

8.30 am 11.30 am (3 hours)

This paper must be answered in English

1. There are THREE sections in this paper,

Section A, Section B and Section C.

2. Section A carries 60 marks,

Section B carries 20 marks, and

Section C carries 20 marks.

3. All questions in Sections A and B are

COMPULSORY. Answers are to be written

in this Question-Answer Book. If you use

supplementary answer sheet(s) for these twosections, write your Candidate Number on each

sheet and fasten them with string to this

Question-Answer Book.

4. Answer ONE question in Section C. Answers

are to be written in the AL(D) Answer Book.

5. Write your Candidate Number, Centre Number

and Seat Number in the spaces provided on this

cover.

6. Some useful constants and a Periodic Table are

respectively printed on pages 18 and 19 of thisQuestion-Answer Book.

Candidate Number

Centre Number

Seat Number

MarkersUse Only

ExaminersUse Only

Marker No. Examiner No.

A 1

A 2

A 3

A 4

A 5

A 6

ATotal

B 7

B 8

BTotal

2001-ALCHEM

PAPER 1


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2001-AL-CHEM 12 1

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SECTION A

AnswerALL questions in this Section. Write your answers in the spaces provided.

1. (a) Consider the phase diagram of water :

(i) What do curves AB and BC signify ?

AB :

BC:

(ii) What is the physical significance of pointB ?

(iii) Explain, in terms of structure and intermolecular force, why water is denser than ice.

pressure/atm

D

6.03 103

273.16

C

AB

temperature/K


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2001-AL-CHEM 13 2 Go on to the next page

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1. (a) (iv) Use the Le Chateliers principle to explain why curveBD has a negative slope.

(5 marks)

(b) Account for each of the following observations :

(i) At 298 K, the vapour pressure of a mixture of methyl ethanoate and trichloromethane is

lower than that predicted by Raoults Law.

(ii) At 1 atm pressure, the boiling point of an aqueous solution of sucrose is higher than

100 oC.

(4 marks)


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2001-AL-CHEM 14 3

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2. (a) (i) Provide a piece of evidence to support the statement :

The energy of an electron in an atom is quantized.

(ii) Sketch the pictorial representations of an s-orbital and a p-orbital, showing the location

of the atomic nucleus.

s-orbital

p-orbital

(4 marks)

(b) Sketch the variation of thesecondionization enthalpies of O, F, Ne, Na and Mg.

(2 marks)

O F Ne Na Mg

secondionizati

onenthalpy


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2001-AL-CHEM 15 4

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Go on to the next page

2. (c) Draw the three-dimensional structure for each molecule below, showing the lone electron pair(s),

if any, of the central atom. State the shape of each molecule.

(i) BF3

(ii) ClF3

(3 marks)

(d) The lattice structure of BaO(s) is described as the interpenetration of two simple cubic lattices,one of Ba2+ ions and the other of O2 ions.

(i) Draw the unit cell of BaO(s), labelling the Ba2+ and O2 ions.

(ii) What is the coordination number of each O2 ion in the structure ?

(2 marks)


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2001-AL-CHEM 16 5

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3. (a) In an enclosed reaction vessel at 1100 K and in the presence of a catalyst, an initial 1:1 mole ratio

mixture of SO2(g) and O2(g) was allowed to attain equilibrium:

2SO2(g) + O2(g) 2SO3(g)

(i) At 1100 K, K pof the reaction is 0.13 atm1

. Calculate the total pressure of the reactionmixture if the conversion of SO2(g) to SO3(g) is 20%.

(ii) At 700 K and under the same total pressure, Kp of the reaction is 3.0 104 atm1.

Calculate the enthalpy change for the conversion of SO2(g) to SO3(g).

(You may assume that ln Kp = constantRT

H .)

(iii) State, with explanation, the effect of each of the following changes on the position of

the above equilibrium.

(I) Reducing the volume of the reaction vessel

(II) Injecting helium gas while keeping the volume of the reaction vessel

unchanged

(7 marks)


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2001-AL-CHEM 17 6

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3. (b) A current of 0.50 A was passed for 6.0 minutes through an electrolytic cell containing

K[Au(CN)2](aq) and KCN(aq) to gold-plate a metal object with a surface area of 4.0 cm2.

(i) Assuming 100% current efficiency, calculate the thickness of gold deposited.

(Density of gold = 19.3 g cm3)

(ii) Suggest one way to treat the cyanide ions in the spent electrolytic solution.

(4 marks)


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2001-AL-CHEM 18 7

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4. (a) (i) What is meant by the standard reduction potential of a half cell ?

(ii) Having considered the standard reduction potentials listed below :

V/E__o

I2(aq) + 2e 2I(aq) + 0.54S2O8

2(aq) + 2e 2SO42(aq) + 2.01

a student suggested, The reaction of I(aq) with S2O82(aq) is feasible and will proceed

rapidly at room temperature.

Comment on the students suggestion.

(5 marks)


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2001-AL-CHEM 19 8

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4. (b) The overall reaction occurring in a Leclanch cell when delivering a current can be represented

by the equation:

2MnO2(s) + 2NH4Cl(aq) + Zn(s) Mn2O3(s) + 2NH3(aq) + H2O(l) + ZnCl2(aq)

(i) Write half equations for the anodic and cathodic reactions.

(ii) If the cell contains 25.0 g of MnO2(s), calculate the theoretical mass of Zn(s) that would

be consumed for the MnO2(s) to undergo complete reaction.

(4 marks)


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2001-AL-CHEM 110 9

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5. (a) Consider the reaction :

(D is deuterium, an isotope of hydrogen.)

(i) Draw the structure of the major product.

(ii) Outline a mechanism of the reaction.

(iii) Is the product optically active ? Explain your answer.

(5 marks)

C

CHH

CH3CH3CH2 D B r


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2001-AL-CHEM 111 10

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5. (b) Give the structures of the organic compounds,D,E,F, G andH.

(5 marks)

CH3

(1) O3

(2) Zn/H3O

+ D(i)

CC

OO

OCH3CH3O HOCH2CH2OH+H3O

+

E(ii)

HO2CCH2CH2CO2Hheat

F(iii)

CH2NH2 NaNO2/H3O+

~ 5 oC

Br2/NaOHG H(iv)


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2001-AL-CHEM 112 11

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6. (a) Consider the following thermochemical data :

1__omolkJ/H

(All chemical species are in gaseous state.)

(i) Deduce the stabilization energy of benzene.

(ii) Deduce the stabilization energy of cyclooctatetraene.

(iii) Comment on the significance of the values obtained in (i) and in (ii).

(4 marks)

H2

3H2

4H2

H2

+

+

+

+

119

208

96

410


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2001-AL-CHEM 113 12

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6. (b) After some lessons in organic chemistry, a student remarked, Alkanes are more stable than

alkenes, therefore alkanes do not react with chlorine but alkenes do.

Do you agree with the student ? Explain.

(3 marks)

(c) With the help of equations, explain the function of butylated hydroxytoluene (BHT) as

an anti-oxidant to prevent unsaturated oils from turning rancid.

(3 marks)

END OF SECTION A

C(CH3)3(CH3)3C

OH

CH3

BHT


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2001-AL-CHEM 114 13

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SECTION B

AnswerALL questions in this Section. Write your answers in the spaces provided.

7. (a) Suggest how you would prepare a sample of dry hydrogen chloride gas in a school laboratory.

Draw a labelled diagram of the set-up of apparatus used in the preparation.

(4 marks)


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2001-AL-CHEM 115 14

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7. (b) Office paper contains calcium carbonate (up to 50%) as an additive to enhance its brightness,

whiteness and opacity. Devise an experiment to estimate the percentage by mass of calcium

carbonate in a sample of office paper.

(4 marks)

(c) Suggest a method to remove stains of colloidal sulphur in a conical flask. State the chemistry

involved.

(2 marks)


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2001-AL-CHEM 116 15

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8. (a) The graph below shows the solubility curves of a solid organic compound X in four mutually

miscible solvents J, K, L and M.

(i) (I) Which solvent among J, K, L and M is the best for the recrystallization ofX?

(II) You are provided with a sample of X contaminated with some coloured

impurities. Outline the procedure to purify Xby recrystallization.

(ii) Decide which two of these solvents form the best solvent system for the recrystallization

ofXat 25 C.

(5 marks)

solubility

of

X

solvent J

solvent M

solvent K

solvent L

25 100

temperature/oC


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2001-AL-CHEM 117 16

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8. (b) In an experiment to prepare propanal from propan-1-ol,

a side-productN(C6H12O2) was formed.

(i) What isN? Suggest howNis formed.

(ii) Suggest one method to separate propanal from a mixture of propanal andN.

(iii) Suggest two methods to confirm the identity of propanal.

(5 marks)

END OF SECTION B

CH3CH2CH2OHCr2O7

2-/H3O

+

heatCH3CH2CHO


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2001-AL-CHEM 118 17

SECTION C

AnswerONE question only and write your answers in the AL(D) Answer Book.

Marks will be allocated approximately as follows :

chemical knowledge 50%

organization 30%presentation (including use of language) 20%

Equations, suitable diagrams and examples are expected where appropriate.

The examiners are looking for the ability to analyse, to evaluate and to express ideas clearly.

9. Write an essay on the chemistry of iron.

(20 marks)

10. Write a proposal on behalf of the Chief Executive on the improvement of the air quality in Hong Kong.

Your proposal should include the current pollution problems and possible solutions supported by chemical

principles.

(20 marks)

END OF PAPER


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2001-AL-CHEM 119 18

Useful Constants

Gas constant, R = 8.31 J K1 mol1

Faraday constant, F = 9.65 104 C mol1

Avogadro constant, L = 6.02 1023 mol1

Planck constant, h = 6.63 1034 J s

Speed of light in vacuum, c = 3.00 108 m s1

Ionic product of water at 298 K, Kw= 1.00 1014 mol2 dm6

Specific heat capacity of water = 4.18 J g1 K1

Characteristic Infra-red Absorption Wavenumber Ranges

(Stretching modes)

Bond Compound type Wavenumber range /cm1

C=C Alkenes 1610 to 1680

C=O Aldehydes, ketones, carboxylic acids, esters 1680 to 1750

CC Alkynes 2070 to 2250CN Nitriles 2200 to 2280

OH Acids (hydrogen-bonded) 2500 to 3300

CH Alkanes, alkenes, arenes 2840 to 3095

OH Alcohols, phenols (hydrogen-bonded) 3230 to 3670

NH Amines 3350 to 3500


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PERIOD

ICTABLE

GROUP

I

atom

icnum

ber

0

1H1.00

8

II

1H

1.008

III

IV

V

VI

VII

2He

4.0

03

3Li

6.94

1

4Be

9.0

12

5B

10

.81

6C

12

.01

7N

14

.01

8O

16

.00

9F

19

.00

10N

e

20

.18

11N

a

22.9

9

12M

g

24

.31

relativea

tom

icmass

13A

l

26

.98

14S

i

28

.09

15

P30

.97

16

S32

.06

17C

l

35

.45

18A

r

39

.95

19K3

9.1

0

20C

a

40

.08

21S

c

44

.96

22T

i

47

.90

23V

50

.94

24C

r

52

.00

25M

n

54

.94

26F

e

55

.85

2

7Co

5

8.9

3

28N

i

58

.70

29C

u

63

.55

30Z

n

65

.38

31G

a

69

.72

32G

e

72

.59

33A

s

74

.92

34S

e

78

.96

35B

r

79

.90

36K

r

83

.80

37R

b

85.4

7

38S

r

87

.62

39Y

88

.91

40Z

r

91

.22

41N

b

92

.91

42M

o

95

.94

43T

c

(98)

44R

u

101

.1

4

5Rh

1

02

.9

46P

d

106

.4

47A

g

107

.9

48C

d

112

.4

49I

n114

.8

50S

n118

.7

51S

b121

.8

52T

e

127

.6

53

I126

.9

54X

e

131

.3

55C

s

132

.9

56B

a

137

.3

57

*

La

138

.9

72H

f

178

.5

73T

a

18

0.9

74W

183

.9

75R

e

186

.2

76O

s

190

.2

7

7Ir

1

92

.2

78P

t

195

.1

79A

u

197

.0

80H

g

200

.6

81T

l

204

.4

82P

b

207

.2

83B

i

209

.0

84P

o

(209)

85A

t

(210)

86R

n

(222)

87F

r

(223)

88R

a

(226)

89**

Ac

(227)

104R

f

(261)

10

5

D

b

(262)

*

58C

e

140

.1

59P

r

140

.9

60N

d

14

4.2

61P

m(145)

62S

m150

.4

63E

u

152

.0

6

4Gd

1

57

.3

65T

b

158

.9

66D

y

162

.5

67H

o

164

.9

68E

r

167

.3

69T

m168

.9

70Y

b

173

.0

71L

u

175

.0

**

90T

h

232

.0

91P

a

(231)

92U

23

8.0

93N

p

(237)

94P

u

(244)

95A

m(243)

9

6Cm

(247)

97B

k

(247)

98C

f

(251)

99E

s

(252)

100F

m(257)

101

Md

(258)

102N

o

(259)

103L

r

(260)

2001-AL-CHEM 120 19


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2001 A-Level Chemistry

Paper 1

Section A

2. (d) (ii) 8

3. (a) (i) 1.01 atm

(ii) 198 kJ mol1

(b) (i) 4.76 103 cm

4. (b) (ii) 9.40 g

6. (a) (i) 149 kJ mol1

(ii) +26 kJ mol1

Paper 2

Section A

1. (a) (ii) 3850 years

(c) (ii) 0.0534 M

(iii) (I) I2 : S2O32= 1 : 2

2. (a) (i) 3838 kJ mol1

(b) (i) 2.37

(ii) 64.0 cm3

3. (a) (ii) 8.7 109 (mol dm3)2 s1

4. (a) (iii) 1.31 105 mol dm3

(b) (iii) 24.4

Section B

5. (a) (iii) (II) 3.42 g


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Hong Kong Examinations AuthorityAll Rights Reserved 2001

2001-AL-CHEM 21



CHEMISTRY A-LEVEL PAPER 2

1.30 pm 4.30 pm (3 hours)


1. There are TWO sections in this paper, Section A and

Section B.

2. Section A carries 60 marks and Section B carries 40

marks.

3. Answer THREE questions from Section A and TWO

questions from Section B.

4. Answers to questions in Sections A and B are to be

written in the AL(C)1 and AL(C)2 Answer Books

respectively.

5. Some useful constants and a Periodic Table are

respectively printed on pages 18 and 19 of this

question book.

2001-AL

CHEM

PAPER 2


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2001-AL-CHEM 22 1

SECTION A

Answer any THREE questions, using the AL(C)1 Answer Book.

1. (a) (i) Outline the principles underlying the use of carbon-14

dating in the estimation of the age of an ancient biological

specimen.

(ii) A wood sample from an ancient tomb has an activity of9.6 counts per gram of carbon per minute. A similar

piece of modern wood has an activity of 15.3 counts per

gram of carbon per minute. Estimate the age of the

wood sample from the tomb.

(Half life for the decay of carbon-14 = 5730 years.)

(5 marks)

(b) Briefly describe the principle of mass spectrometry and its use to

determine the relative atomic mass of a noble gas.

(8 marks)


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2001-AL-CHEM 26 5

3. (a) At an elevated temperature and in the presence of argon, iodine

atoms combine to form iodine molecules :

2I(g) I2(g)

The table below lists some data about the reaction :

Initial concentration / mol dm3

[I(g)] /mol dm3 [Ar(g)] / mol dm3

Initial rate

td

(g)][Id 2/

13 sdmmol

1.0 105 1.0 103 8.70 104

2.0 105

1.0 103

3.48 103

1.0 105 5.0 104 4.35 104

For this reaction,

(i) deduce the rate equation,

(ii) calculate the rate constant,

(iii) suggest a possible reaction mechanism consistent with the

rate equation, state the role of argon, and sketch the

energy profile.

(8 marks)

(b) Give two examples to illustrate the statement :

Some lithium compounds differ in their chemical properties from

corresponding compounds of other Group I elements.

(4 marks)


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2001-AL-CHEM 27 6 Go on to th e next page

3. (c) Li2O, CO

2and F

2O are oxides of the Period 2 elements.

(i) Explain why Li2O and CO2 react differently with water.

(ii) What products are formed when F2O reacts with water ?

(5 marks)

(d) Suggest chemical tests to distinguish the following compounds

from one another :

NaNO2(s), NaNO3(s) and NH4NO3(s)

(3 marks)


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2001-AL-CHEM 28 7

4. (a) Consider the electrochemical cell :

(i) Name the device used for measuring the e.m.f. of the cell.

(ii) Suggest how a workable salt bridge can be prepared.

(iii) At 298 K, the reduction potential, E, of Ag+(aq) | Ag(s)

can be obtained from the equation :

__oEE =

The e.m.f. of the cell was found to be 0.17 V at 298 K.

Calculate the concentration of silver ions in the saturated

AgCl(aq).

(Given :__o

E

(iv) State, with explanation, the effect on the cell e.m.f. of

adding a small volume of KCl(aq) to the saturated

AgCl(aq).

(7 marks)

salt bridge

Ag(s)Ag(s)

saturated AgCl(aq)0.01 M AgNO3(aq)

AgCl(s)

of Ag+(aq) | Ag(s) = +0.80 V at 298 K)

+ 0.059 log10[Ag+(aq)]

+


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2001-AL-CHEM 29 8 Go on to the next page

4. (b) (i) State the partition law for the distribution of a non-volatile

solute between two immiscible solvents.

(ii) State and explain one example in which the partition law

is not applicable.

(iii) In an experiment, an aqueous solution of ammonia was

shaken with trichloromethane until equilibrium was

attained. 10.00 cm3 of the aqueous layer required

32.55 cm3 of 0.203 M hydrochloric acid for neutralization,

while 25.00 cm3 of the organic layer required 14.55 cm3 of

0.0465 M hydrochloric acid for neutralization.

Calculate the partition coefficient of ammonia betweenwater and trichloromethane.

(7 marks)

(c) Compare the oxidizing power of fluorine, chlorine and bromine.Illustrate your answer with appropriate examples.

(3 marks)

(d) Comment on the statement :

The acids HF, HCl and HBr are of comparable strength.

(3 marks)

END OF SECTION A


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2001-AL-CHEM 210 9

SECTION B

Answer any TWO questions, using the AL(C)2 Answer Book.

5. (a) CompoundA has the following structure :

(i) The carbon atom indicated by arrow a is more reactive

towards SN2 reaction with C2H5ONa than that indicated byarrow b. Explain.

(ii) 5.56 g of A is treated with 1.36 g of C2H5ONa. Deduce

the structure of the major substitution productB.

(iii) 5.56 g of A is treated with 3.00 g of C2H5ONa. The

reaction gives two products, D and E. E has the

molecular formula C11H14O.

(I) Give the structure of D.

(II) If the yield of D is 82%, calculate the mass ofDthat can be obtained.

(III) Give the structure ofE and name the types of

reactions involved in the formation ofE.

(8 marks)

CH2 BrCHBr

CH3

ab


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2001-AL-CHEM 211 10 Go on to th e next page

5. (b) (i) Give the reagent(s) and conditions for Step 1 and Step 2

in the reaction sequence below :

(ii) 4-nitrobenzoic acid can be converted to benzocaine, ananaesthetic, in not more than three steps.

Use equations to show how you would carry out theconversion. In each step, give the reagent(s), conditions

and structure of the product.

(5 marks)

(c) Consider the information below concerning the production of lowdensity polyethene from ethene.

(i) Outline a mechanism for the polymerization and nameeach mechanistic step.

(ii) Explain why benzoyl peroxide is used.

(iii) Why is high pressure needed for the polymerization ?

(iv) Is the product a single compound ? Explain.

(7 marks)

CH2 CH2n

benzoyl peroxide

high pressureCH2 CH2n

CH3 CH3

NO2

CO2H

NO2

Step 1 Step 2

4-nitrobenzoic acid

CO2CH2CH3

NH2

benzocaine


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2001-AL-CHEM 216 15

7. (b) Study the following information:

Aromatic compounds T and U have the same molecular formula

C10H12O.

Tgives positive result in iodoform test.

U reacts with hydrogen in the presence of a palladium catalyst to

give compound V (C10H14O). V can also be obtained from the

reaction ofTwith LiAlH4.

Treatment ofUwith ozone followed by acidified KMnO4 gives two

products, one of which is benzoic acid.

(i) Deduce the structures of T, Uand V. For each compound,

give allpossible stereoisomers.

(ii) Suggest how infra-red spectroscopy can be used to

distinguish between Tand U.

(9 marks)


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2001-AL-CHEM 217 16

7. (c) Compound Wis an artificial sweetener and has the structure shown

below.

(i) Identifyfourfunctional groups in W.

(ii) Upon treatment with dilute mineral acids, W gives two

monosaccharides. Draw a ring structure for each

monosaccharide.

(iii) Suggest two reasons for using artificial sweeteners as

substitutes for sugar.

(6 marks)

END OF PAPER

O O

O

OH

CH2OH

OOH

OHOH

CH3

OHOH

OH

C

O

(CH2)2 OH

OCH3


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2001-AL-CHEM 219 18

Useful Constants

Gas constant, R = 8.31 J K1 mol1

Faraday constant, F = 9.65 104 C mol1

Avogadro constant, L = 6.02 1023 mol1

Planck constant, h = 6.63 1034 J s

Speed of light in vacuum, c = 3.00 108 m s1

Ionic product of water at 298 K, Kw = 1.00 1014 mol2 dm6

Specific heat capacity of water = 4.18 J g1 K1

Characteristic Infra-red Absorption Wavenumber Ranges

(Stretching modes)

Bond Compound type Wavenumber range /cm1

C=C Alkenes 1610 to 1680

C=O Aldehydes, ketones, carboxylic acids, esters 1680 to 1750

CC Alkynes 2070 to 2250

CN Nitriles 2200 to 2280

OH Acids (hydrogen-bonded) 2500 to 3300

CH Alkanes, alkenes, arenes 2840 to 3095

OH Alcohols, phenols (hydrogen-bonded) 3230 to 3670

NH Amines 3350 to 3500


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2001 A-Level Chemistry

Paper 1

Section A

2. (d) (ii) 8

3. (a) (i) 1.01 atm

(ii) 198 kJ mol1

(b) (i) 4.76 103 cm

4. (b) (ii) 9.40 g

6. (a) (i) 149 kJ mol1

(ii) +26 kJ mol1

Paper 2

Section A

1. (a) (ii) 3850 years

(c) (ii) 0.0534 M

(iii) (I) I2 : S2O32= 1 : 2

2. (a) (i) 3838 kJ mol1

(b) (i) 2.37

(ii) 64.0 cm3

3. (a) (ii) 8.7 109 (mol dm3)2 s1

4. (a) (iii) 1.31 105 mol dm3

(b) (iii) 24.4

Section B

5. (a) (iii) (II) 3.42 g


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Hong Kong Examinations AuthorityAll Rights Reserved 2001



CHEMISTRY PRACTICAL EXAMINATION

(Group 01)


Three hours

Part I : Volumetric Exercise

As soon as you obtain your results, record them on Answer Sheet I.

Use a pipette and a pipette filler to transfer solutions when high precision is required.

Following the instructions given below, determine the molarity of the ammonium

iron(II) sulphate(VI) solution labelled 'A'.

Experimental Details

Standardization of the potassium manganate(VII) solution provided : Transfer

25.00 cm3 of the 0.102 M iron(II) solution labelled 'Standard' into a flask. Add to it

25 cm3 of 1 M sulphuric(VI) acid, then titrate it with the potassium manganate(VII)

solution until a permanent pale pink colour appears.

Determination of the molarity of iron(II) ions in 'A' : Transfer 25.00 cm3 of 'A'

into a flask. Add to it 25 cm3 of 1 M sulphuric(VI) acid, then titrate it with the

potassium manganate(VII) solution until a permanent pale pink colour appears.

Relevant Equation

5Fe2+ + MnO4 + 8H+ 5Fe3+ + Mn2+ + 4H2O

/P.T.O.


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Part II : Observational and Deductive Exercise

1. Carry out the instructions, listed on Answer Sheet II, on the sample contained in the tube

which is labelled with a sample number.

2. For each test, observe carefully what happens and record your observations concisely in

the space provided on Answer Sheet II. Identify any gas evolved, indicating the test(s)

you have employed.

Record no observable change where appropriate.

3. Summarize, in the space provided on the back of the sheet, your conclusions as to the

chemical nature of the sample. Deduce, where possible, what ionic and/or molecular

species are present in the sample.


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PERIOD

ICTABLE

GROUP

I

atomicnumber

0

1H1.00

8

II

1H1.008

III

IV

V

VI

VII

2He

4.003

3Li

6.94

1

4Be

9.012

5B10.81

6C12.01

7N14.01

8O16.00

9F19.00

10N

e

20.18

11N

a

22.9

9

12M

g

24.31

relativeatomicmass

13A

l

26.98

14S

i

28.09

15

P30.97

16

S32.06

17C

l

35.45

18A

r

39.95

19K3

9.1

0

20C

a

40.08

21S

c

44.96

22T

i

47.90

23V50

.94

24C

r

52.00

25M

n

54.94

26F

e

55.85

2

7Co

5

8.93

28N

i

58.70

29C

u

63.55

30Z

n

65.38

31G

a

69.72

32G

e

72.59

33A

s

74.92

34S

e

78.96

35B

r

79.90

36K

r

83.80

37R

b

85.4

7

38S

r

87.62

39Y

88.91

40Z

r

91.22

41N

b

92

.91

42M

o

95.94

43T

c

(98)

44R

u

101.1

4

5Rh

1

02.9

46P

d

106.4

47A

g

107.9

48C

d

112.4

49I

n114.8

50S

n

118.7

51S

b

121.8

52T

e

127.6

53

I126.9

54X

e

131.3

55C

s

132

.9

56B

a

137.3

57

*

La

138.9

72H

f

178.5

73T

a

18

0.9

74W

183.9

75R

e

186.2

76O

s

190.2

7

7Ir

1

92.2

78P

t

195.1

79A

u

197.0

80H

g

200.6

81T

l

204.4

82P

b

207.2

83B

i

209.0

84P

o

(209)

85A

t

(210)

86R

n

(222)

87F

r

(223)

88R

a

(226)

89**

Ac

(227)

104R

f

(261)

10

5

D

b

(262)

*

58C

e

140.1

59P

r

140.9

60N

d

14

4.2

61P

m(145)

62S

m150.4

63E

u

152.0

6

4Gd

1

57.3

65T

b

158.9

66D

y

162.5

67H

o

164.9

68E

r

167.3

69T

m168.9

70Y

b

173.0

71L

u

175.0

**

90T

h

232.0

91P

a

(231)

92U23

8.0

93N

p

(237)

94P

u

(244)

95A

m

(243)

9

6Cm

(247)

97B

k

(247)

98C

f

(251)

99E

s

(252)

100F

m(257)

101

Md

(258)

102N

o

(259)

103L

r

(260)

2001-AS-CHEM A&C2 1


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2001-AS-CHEM A&C6 5

4. (Kevlar)

(a)

(b)

(c)

6

C NH NHC

O O


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2001-AS-CHEM A&C8 7

6. (I)(I)(I)(I) (II(II(II(II))))

(I)

(PP) (PVC)

(a)

(b) ?

(c)

(i)

(ii)


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2001-AS-CHEM A&C11 10

(d) 100%

(e)

10


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2001-AS-CHEM A&C15 14

()


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2001-AS-CHEM A&C16 15

()

()


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2001

3. (b) 91.2%

8. (a) (ii) 98.9

9. (c) (i) 2806 kJ mol1

(ii) 155.8 kJ

(d) 398.0 kJ

12. (a) (i) (2) 1.58 105 mol dm3


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2001-AS CHEM B7 6 Go on to the next page

Page total

Candidate No. Centre No. Seat No.

If you attempt Question 10 (a), fill in the first three boxes above, detach this sheet

from the question book and tie it INSIDE your answer book.

80

60

40

20

040 80 120 160

time/s

volumeofoxygenproduced/cm

3


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2001-AS CHEM B8 7

This is a blank page.


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2001-AS CHEM B10 9

11. (a) In most sewage treatment plants, the sewage is treated in two

stages, namely primary treatment and secondary treatment. In

primary treatment, pieces of debris are removed. In secondary

treatment, bacteria are added and air is bubbled through the

sewage. Suspended solids in the sewage are allowed to settle and

are then removed. The bacteria are killed and the treated sewage is

discharged into the waterway.

(i) Suggest one way to remove pieces of debris from thesewage in primary treatment.

(ii) Explain why in secondary treatment,

(1) bacteria are added, and

(2) air is bubbled through the sewage.

(iii) Explain why the biochemical oxygen demand (BOD) of

the sewage is greatly reduced after secondary treatment.

(iv) Suggest how the bacteria that have been added can bekilled when secondary treatment has been completed.

(7 marks)


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11. (b) 2-chloro-2-methylpropane can be prepared by reacting

2-methylpropan-2-ol with concentrated hydrochloric acid.

This preparation consists of four stages as outlined below:

Stage 1 : Add concentrated hydrochloric acid slowly into a

vessel containing 2-methylpropan-2-ol while shaking

until the acid is in excess.

Stage 2 : Allow the mixture to settle into two layers. Separatethe organic layer and add to it sodium

hydrogencarbonate solution to neutralize the excessacid.

Stage 3 : Transfer the organic layer obtained at the end of

Stage 2 into a conical flask. Add enough anhydrous

sodium sulphate(VI) and swirl the flask.

Stage 4 : Filter off sodium sulphate(VI) from the mixture

obtained in Stage 3. Distil the filtrate and collect

2-chloro-2-methylpropane in the temperature range

from 47C to 53C.

(i) A turbid mixture is formed in Stage 1. Explain.

(ii) How can one know that the excess acid has beenneutralized in Stage 2 ?

(iii) Why is anhydrous sodium sulphate(VI) used in Stage 3 ?

State the expected observation at the end of this stage.

(iv) Draw a labelled diagram for the experimental set-up that

is used in the distillation process in Stage 4.

(v) The boiling point of 2-methylpropan-2-ol is 82C.

Explain why the boiling point of 2-methylpropan-2-ol ishigher than that of 2-chloro-2-methylpropane.

(8 marks)

(CH3)3COH + HCl (CH3)3CCl H2O+


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2001-AS CHEM B12 11

12. (a) Solid sodium hydroxide was added in small amounts into a buffersolution containing equal number of moles of butanoic acid andsodium butanoate. The graph below shows the variation in pH ofthe resulting solution at 298 K.

(i) (1) Write an expression for the dissociation constant,Ka , of butanoic acid.

(2) From the initial pH, calculate Ka of butanoic acid.

(ii) Explain why

(1) the pH change of the solution was small for theinitial addition of solid sodium hydroxide (from0.01 mole to 0.04 mole).

(2) the pH of the solution rose rapidly upon theaddition of 0.12 mole of sodium hydroxide.

(iii) Suggest one application of buffer solutions.

12

10

8

6

40 0.04 0.08 0.12 0.16

number of moles of NaOH(s) added

pH

(7 marks)


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12. (b) Answer EITHER (I) OR (II).

(I) Chemistry and food

(i) The browning of apples is initiated by the aerial oxidation

of phenols in apples to diquinones. The oxidation is

catalysed by enzymes present in apples. The diquinones

formed then polymerize to give a brown substance in a

short period of time.

Suggest, with explanation, two methods that can be used

to prevent apples from browning.

(ii) For each of the following food additives, suggest one

application and state its function.

(1) butylated hydroxytoluene (BHT)

(2) caramel

(8 marks)

(This question is continued on the next page.)

OH

OH

R

O

O

R

oxygen in air

enzymes

polymerization a brown

substance

a phenol a diquinone


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2001-AS CHEM B14 13

(II) Chemistry and home hygiene

(i) A synthetic detergent has the following structure :

With reference to its structure, explain why

(1) the detergent can be used to remove oily dirt,

(2) the detergent is not environmentally friendly.

(ii) Some washing powders contain phosphates as builders,

which improve the cleaning effect.

(1) One function of builders is to provide a mild

alkaline condition. Write a chemical equation to

illustrate that aqueous solutions of phosphates are

alkaline.

(2) Explain why alkaline conditions can assist

cleaning.

(3) Explain in detail why phosphates in washingpowders are also not environmentally friendly.

(8 marks)

END OF SECTION B

SO3-Na

+CH3CHCH2CHCH2CHCH2CHCH2

CH3 CH3 CH3 CH3


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al chemistry 2001 paper 1+2

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