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[1]
2
Cathode: Al3+ + 3e- ’! Al [1]
(e) (i) (Award [1] for heat plus one other property.)
Good conductor of heat / unreactive / light / low density. [1]
(ii) (Award [1] for any two.)
Low density / corrosion resistant / good electrical conductor / low electrical
resistance. (Insist on electrical good conductor or low resistance is not
sufficient.) [1]
(f) Al is covered in inert oxide layer (preventing further reaction). [1]
[1]
E2. (a) S + O2 ’! SO2 /
S8 + 8O2 ’! 8SO2
(b) (i) Yield decreases as the reaction is exothermic. [1]
(ii) Yield increases, there are less moles of gas on right hand side / number of
moles of gas decreases from left to right.
(Need what it does and why for [1].) [1]
(c) High temperature gives a reasonable/high rate of reaction. [1]
Generation of high pressure is expensive (any reference to economic
considerations). [1] [2]
(d) Manufacture of fertilisers / soaps and detergents / paints and pigments / dyestuffs /
fibres e.g. rayon / petroleum refining / in batteries / cleaning of steels and metals /
manufacture of plastics etc.
(Award [2] for any four, [1] for any two or three.) [2]
11 M02/420/H(3)M
E3. (Award [1] for any ten of the following:)
Diaphragm cell and mercury cathode cell [1]
Diaphragm cell:
advantage: relatively cheap to build; [1]
disadvantage: lower purity product / lower concentration of product. [1]
Mercury cathode cell:
advantage: higher product purity / high concentration of product; [1]
disadvantage: toxic mercury must be removed from effluent / very expensive to build. [1]
2H+ + 2e- ’! H2 [1]
2Cl- - 2e- ’! Cl2 / 2Cl- ’! Cl2 + 2e- [1]
Sodium hydroxide two named uses, for example: [1]
production of paper products;
manufacture of organic chemicals;
manufacture of inorganic chemicals;
manufacture of soaps and detergents;
oil refining;
aluminium industry.
Chlorine two named uses, for example: [1]
manufacture of solvents;
manufacture of PVC;
manufacture of chloromethane or chloroethane;
manufacture of inorganic chemicals;
water purification;
disinfecting swimming pools.
Hydrogen two named uses, for example: [1]
manufacture of ammonia;
manufacture of methanol;
refinery processes / cracking oil / reforming;
hydrogenation of fats and oils;
reduction of metallic ores;
production of HCl. [10]
12 M02/420/H(3)M
OPTION F FUELS AND ENERGY
F1. (a) (i)
Radiation Name Charge
± alpha +2
² beta -1
³ gamma 0
(Award [1] for each radiation type that has two correct answers.) [3]
[1]
(ii) ±, ², ³.
(b) (i)
27y 27y 27y = 81 years
100 % ’! 50 % ’! 25 % ’! 12.5 %
(Award [1] for indication of three half-lives and [1] for answer.) [2]
OR
n
N = N0 ëø 1 öø where n = the number of half-lives, thus n + 3
ìø ÷ø
íø 2 øø
n
n n
12.5
1 ëø öø
ëø öø ëø öø
1
1 1
=
=
12.3 = 100 so ìø ÷ø or ìø ÷ø , thus n = 3 .
ìø ÷ø
8
íø 2 øø
íø 2 øø íø 2 øø
100
Time since explosion = 27×3 = 81 years
(ii) decay could take place at any time / random therefore, the term half-life is
meaningless. [1]
(c) n : p = 52 : 38 = 1.37 :1 (accept 1.4:1) [1]
Number of neutrons higher than protons, therefore beta emitter [1]
(Reason needs to be given for mark.)
90 90 0
Sr ’! Y + e [1]
38 39 -1
Mass of products less than that of 90Sr [1]
Mass converted to energy [1]. [5]
13 M02/420/H(3)M
F2. (a) (Award [1] for any of the following:)
Air does not freeze/boil at temperatures involved / is not corrosive / can circulate
directly to different parts. [1]
(Award [1] for any of the following:)
Water transfers heat more efficiently / higher specific heat capacity / easy to fit
piping and plumbing after building constructed. [1]
(b) Passive: no use of fans/pumps.
Active: use of fans/pumps. [1]
(c) (Award [1] for any one of the following:)
Relatively low cost.
No moving parts.
Low maintenance.
Reliability/long life. [1]
(d) (i) 6CO2 + 6H2O ’! C6H12O6 + 6O2
(Award [1] for formulas and [1] for correct balancing.) [2]
(ii) Chloroplasts/chlorophyll. [1]
F3. Material with conductivity intermediate between conductor and insulator. [1]
Examples: germanium or silicon. [1]
One layer doped with group (V) element / arsenic / phosphorus [1]
the other layer doped with group (III) element / gallium / indium [1]
Group V doping gives n-type / provides extra electrons [1]
Group III doping gives p-type / introduces holes in crystal [6]
[1]
14 M02/420/H(3)M
OPTION G MODERN ANALYTICAL CHEMISTRY
G1. (a) Tetramethylsilane / TMS [1]
Used as reference standard [1] [2]
(b) (i) (three) different chemical environments [1]
(ii) ratio of hydrogen atoms in each environment [1]
(iii) the number of hydrogens on adjacent carbon atoms [1]
(c) 1.3 ppm R CH2 R [1]
O
2.0 ppm CH3 C [1]
OR
R [1]
4.1 ppm R C O CH2 [3]
O
Candidates who correctly identify the structure of ethyl ethanoate may give the following
answer for shift of 1.3 ppm:
CH3 CH2 R CH3
(i.e. next to CH2 )
This answer should be awarded [1].
(d) A C H [1]
C == O
B [1]
C C O [1] [3]
(e) Ethyl ethanoate [1]
O
CH3 CH2 O C CH3 [1]
[2]
(f) MRI / magnetic resonance imaging / nuclear magnetic resonance / NMR. [1]
(g) Non-invasive / radiation is not harmful / distinguishes between different types of
soft tissue. [1]
15 M02/420/H(3)M
G2. (a) Stationary phase and a mobile phase [1];
Components dissolve / absorb / partition to differing extents between the two phases [1]. [2]
(b) Gas-liquid chromatography / GLC; [1]
Hydrocarbons are volatile; [1]
Mobile phase is a gas; [1]
Stationary phase is a liquid; [1]
Sample is vaporised; [1]
Components separated and detected. [1] [6]
(c) Molecular mass; [1]
Molecular formula. [1] [2]
16 M02/420/H(3)M
OPTION H FURTHER ORGANIC CHEMISTRY
H1. (a) (Award [1] for each correct structure.)
CH3 Cl H H H
C CH2 CH3 C CH3 H C C C Cl
H H H H H
[3]
AB C
(b) Electrophilic addition. [1]
Mechanism:
step to form carbocation; [1]
correct structure of carbocation; [1]
step to convert carbocation to product. [1]
H´+ Cl´-
Cl- H
Cl H
CH3 H
CH3 H CH3
C C
C+ C H C+ C H CH3 C C H
H H
H H H
H H H
Carbocation in B is more stable [1].
Inductive effect of methyl groups / 2 carbocation in B more stable than 1
carbocation in C [1]. [6]
17 M02/420/H(3)M
(c) (i) Elimination [1]
Heat/hot and alcoholic/ethanolic solution [1]. (Both needed for the mark.)
NaOH or KOH [1] [3]
(ii) If E1 drawn:
correct structure for carbocation; [1]
curly arrow shown correctly in 1st step; [1]
curly arrow shown correctly in 2nd step. [1] [3]
H H H H H H
H CH3
+
H C C C H H C C C H + Cl- C C
H H
H Cl H H H
If E2 drawn, award [1] for each correctly positioned curly arrow.
OH- H
H
H CH3
C C
H C C C H
H H
C Cl H
18 M02/420/H(3)M
H2. (a) (i) Reaction X: addition elimination (allow condensation) [1].
Reaction Y: nucleophilic addition. [1] [2]
H
(ii)
NH N C
C6H5
NO2
NO2
[1]
(b) 2,4-dinitrophenylhydrazine [1]
products are solids/precipitates [1]
melting points can be measured [1]
compared with data / literature values [1] [4]
(c) Useful as it can be used to introduce another C atom into a carbon chain. [1]
COOH
CH3 C OH [1]
H
chiral centre / optical isomerism [1] [3]
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