MARK SCHEME for the June 2004 question papers 9701 CHEMISTRY

[Pages:41]UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS

GCE Advanced Subsidiary Level and GCE Advanced Level

MARK SCHEME for the June 2004 question papers

9701/01 9701/02

9701/03 9701/04

9701/05 9701/06

9701 CHEMISTRY

Paper 1 (Multiple Choice), maximum raw mark 40 Paper 2 (Theory 1 ? Structured Questions), maximum raw mark 60 Paper 3 (Practical 1), maximum raw mark 25 Paper 4 (Theory 2 ? Structured Questions), maximum raw mark 60 Paper 5 (Practical 2), maximum raw mark 30 Paper 6 (Options), maximum raw mark 40

These mark schemes are published as an aid to teachers and students, to indicate the requirements of the examination. They show the basis on which Examiners were initially instructed to award marks. They do not indicate the details of the discussions that took place at an Examiners' meeting before marking began. Any substantial changes to the mark scheme that arose from these discussions will be recorded in the published Report on the Examination.

All Examiners are instructed that alternative correct answers and unexpected approaches in candidates' scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated.

Mark schemes must be read in conjunction with the question papers and the Report on the Examination.

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CIE will not enter into discussion or correspondence in connection with these mark schemes.

CIE is publishing the mark schemes for the June 2004 question papers for most IGCSE and GCE Advanced Level syllabuses.

Grade thresholds taken for Syllabus 9701 (Chemistry) in the June 2004 examination.

Component 1 Component 2 Component 3 Component 4 Component 5 Component 6

maximum mark

available 40 60 25 60 30 40

minimum mark required for grade:

A

B

E

31

28

18

47

41

27

19

17

10

46

41

24

23

21

15

27

24

15

The thresholds (minimum marks) for Grades C and D are normally set by dividing the mark range between the B and the E thresholds into three. For example, if the difference between the B and the E threshold is 24 marks, the C threshold is set 8 marks below the B threshold and the D threshold is set another 8 marks down. If dividing the interval by three results in a fraction of a mark, then the threshold is normally rounded down.

? University of Cambridge International Examinations 2004

JUNE 2004

GCE A AND AS LEVEL

MARK SCHEME

MAXIMUM MARK: 40

SYLLABUS/COMPONENT: 9701/01 CHEMISTRY

Paper 1 (Multiple Choice)

Page 1

Question Number

1 2 3 4 5

6 7 8 9 10

11 12 13 14 15

16 17 18 19 20

Mark Scheme CHEMISTRY ? JUNE 2004

Question Number

C

21

B

22

C

23

B

24

C

25

C

26

D

27

B

28

B

29

D

30

D

31

C

32

B

33

A

34

A

35

A

36

D

37

A

38

D

39

B

40

Syllabus Paper

9701

1

Key

B D D B A

D C D A D

A D C D B

C A B D C

TOTAL 40

? University of Cambridge International Examinations 2004

JUNE 2004

GCE A AND AS LEVEL

MARK SCHEME

MAXIMUM MARK: 60

SYLLABUS/COMPONENT: 9701/02 CHEMISTRY

Theory 1 (Structured Questions)

Page 1

Mark Scheme CHEMISTRY ? JUNE 2004

Syllabus Paper

9701

2

1 (a)

The volume of the gas molecules / atoms / particles is insignificant compared with the volume of the vessel. There are no forces of attraction between the gas molecules. All collisions by the gas molecules are perfectly elastics. Any two.

[2]

(b) (i) The pressure of / exerted by the gas.

[1]

Pa / Nm -2

[1]

(ii) The volume of the containing vessel

[1]

m3 / dm3 / cm3

[1]

(iii) The absolute temperature

[1]

In K or 273 + ?C

[1]

(c) (i) pV w/m x RT

m = (0.103 x 8.31 x 297) / (99.5 x 103 x 63.8 x 10-6)

[1]

= 40.0

[1]

The gas is argon

[1]

(ii) The hydrogen bonds between ammonia molecules (1) are stronger than the Van De Waals' forces between N2 and Ar molecules (1)

Ammonia is polar / has a dipole (1)

(Any two)

[2]

Total = [13]

2 (a)

1s2

2s2 2p6

3s2 3p3

[1]

(b)

5 or V

[1]

(c) (i) 3NaOH + H3PO4

Na3PO4 + 3H2O

[1]

(ii) (50 x 0.5) / 1000 = 0.025 (moles)

[1]

(iii) conseq. on (i)

3 x .025 = 0.075 (moles)

[1]

(d) (i) P4S3 + 8O2

OR

+ 6O2

P4O10 + 3SO2 (or 2P2O5)

P4O6 + 3SO2 (or 2P2O3)

(ii) P4O10 + 6H2O OR P4O6 + 6H2O

SO2 + H2O (if SO3 then e.c.f.)

4H3PO4 4H3PO3 H2SO3

balanced = 2 marks unbalanced = 1 mark

[2] [1]

[1] Total = [9]

? University of Cambridge International Examinations 2004

Page 2

Mark Scheme CHEMISTRY ? JUNE 2004

Syllabus Paper

9701

2

3 (a)

CO(NH2)2 + H2O

2NH3 + CO2

balanced equation (1)

(1) colourless gas

[2]

(b) (i) N2 + 3H2 2NH3

(ii) 100 ATMs or over 400 - 500?C iron catalyst

(iii) Fertiliser, making nitric acid, explosives etc. 1 mark for each [4]

(c) (i) (1.2) / (2.4) = 1/20 or 0.05 moles

[1]

(ii) 2NH3 + H2SO4

(NH4)2SO4

or equivalent

[1]

(iii) 0.025 mols of H2SO4 are required

Vol. of 0.50 mol dm-3 H2SO4 required = (0.025 x 1000) / 0.5 = 50cm3

[1]

(d)

+

1 mark for each diagram, 1 mark for each correct bond angle If not 3-dimensional diagram ? 1 penalty.

(e)

4NH3 + 3O2

2N2 + 6H2O

N goes from -3 to 0 O goes from 0 to -2

oxidation reduction

[4]

[1]

[1] [1]

Total = [16]

? University of Cambridge International Examinations 2004

Page 3

Mark Scheme CHEMISTRY ? JUNE 2004

Syllabus 9701

4 (a) (i) Acid or base, heating / reflux / warm

(ii) CH3(CH2)2CO2CH3 + H2O

CH3(CH2)2CO2H + CH3OH

(iii) Solvents (polyesters not in AS syllabus, but allow as plastics, textiles)

(b) (i)

Paper 2

[1] [1] [1]

HOCH2CH2

H

C = C

H

CH2CH3

1 mark for this diagram (ii)

CH3CH2

C = C

H

CH2CH2 ? O ? C ? CH3 || O

H

1 mark for ester link, 1 mark for rest of molecule [3]

(c) (i) C6H12O 72 + 12 + 16

Mr = 100

[1]

CH2 = CH ? CH = CH ? CH2CH3

[1]

dehydration / elimination

[1]

? University of Cambridge International Examinations 2004

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