M01/420/H(3)M
INTERNATIONAL BACCALAUREATE
BACCALAURÉAT INTERNATIONAL
BACHILLERATO INTERNACIONAL
MARKSCHEME
May 2001
CHEMISTRY
Higher Level
Paper 3
16 pages
6 M01/420/H(3)M
OPTION C HUMAN BIOCHEMISTRY
C1. (a) Chemical messenger / OWTTE [1]
(b) (i) Testes [1]
(Note: Do not award [1] for ovaries, since in humans the production of
testosterone by the ovaries is extremely low in comparison with the testes.)
(ii) Use (e.g. treatment of wasting illness / to regain muscle tissue, treatment of
eczema) [1];
Abuse (e.g. increase muscle mass to enhance performance / increase strength) [1];
Second use or second abuse [1].
[3 max]
(c) Two groups circled correctly [1];
Two correct corresponding names[1].
Accept any two from the following:
Alkanol / alcohol / hydroxyl;
Alkene;
Alkanone / ketone / carbonyl.
(Do not accept CH3 / methyl / alkyl group or hydroxide )
[2 max]
(d) Allow any one from:
Cholesterol has an OH group instead of the C == O group in testosterone;
Cholesterol has an alkyl/hydrocarbon side-chain instead of the OH group in
testosterone;
There is no carbonyl group present in cholesterol;
The position of the C == C bond is different in cholesterol compared to
testosterone.
(Or any other correct answer, relating to structural differences.)
[1 max]
7 M01/420/H(3)M
C2. (a) Glycerol / propane-1,2,3-triol (accept correct structure). [1]
(b) Fatty acid(s) / salt of acid / soap / carboxylic acid / alkanoic acid / carboxylate. [1]
(c) Heat with base / alkali / KOH / NaOH (both needed). [1]
(d) Heat produced = (mass×specific heat capacity× "T ) (can be scored by implication) [1];
= (500× 4.18× 67.5) [1];
= 141.075 / 141075 J[1].
50.0
Calorific value of bar = ×141.075 ;
10.0
= 705.4 (kJ) / 705 (kJ) (accept correct value in J)
[1].
[4 max]
C3. (a) Hydrogen bond [1];
Two H-bonds shown between T and A [1];
Three H-bonds shown between C and G [1];
Deoxyribose and phosphate (both needed) [1];
Phosphate on one nucleotide bonds to (OH of) deoxyribose on the next nucleotide [1];
Condensation reaction / by covalent bonding [1].
[6 max]
(b) Award [1] each for any four of the following points:
Separate DNA from other material [1];
Cut DNA up (using restriction enzymes) [1];
Separate by electrophoresis [1];
Method of detection (e.g. UV, radioactive probe, X-ray) [1].
[4 max]
8 M01/420/H(3)M
OPTION D ENVIRONMENTAL CHEMISTRY
D1. (a) Water / CFCs / dinitrogen oxide ( ). [1]
N2O or nitrous oxide / O3 / HCFCs / HFCs / SF6
(Accept correct formula instead of a name).
(b) (i) Any two sources, [1] each
e.g. Respiration (by animals) / decay of plants or animals / oxidation of soil
humus / forest fires caused by lightning / volcanoes / combustion of
fossil fuels and wood / burning trash (rubbish).
[2 max]
(ii) Any two sources, [1] each
e.g. Bacterial fermentation / bogs or marshes / digestive tracts of ruminants.
Rotting waste in land-fill sites.
[2 max]
(c) Lower energy / longer wavelength / infrared radiation from the Earth [1];
Greenhouse gases absorb / retain / trap this energy [1];
Some reference to how the gases absorb this energy e.g. vibration [1].
[3 max]
D2. (a) (i) Solid objects / example of this (e.g. rock) [1];
Grids / screens / sand bed (do not accept filter) [1].
[2 max]
(ii) Metal ions / phosphate [1];
Ca2+
Alkali / sulfide / / calcium ions (accept a named calcium compound) [1].
[2 max]
(b) (i) Any two of the following [1] each
Similar anti-bacterial action achieved with smaller [O3] ;
O3 more effective than Cl2 (against waterborne viruses);
O3 imparts no chemical taste to water;
O3 does not form harmful chlorine containing organic compounds.
[2 max]
(ii) O3 must be produced on site (because of high reactivity) / O3 has a shorter
retention time. [1]
9 M01/420/H(3)M
D3. NOx produced in the exhaust gases [1];
Sunlight converts the oxides of nitrogen into oxygen radicals (oxygen atoms) /
NOx + sunlight Oi
[1];
The oxygen atoms react with hydrocarbons in the exhaust gases / Oi + HC [1];
This reaction produces alkanals [1];
Which form PAN / peroxyacylnitrates[1].
Any two of the following, [1] each
Cause irritation of the eyes / respiratory problems / damage to plants.
Numerous answers are possible here, all [1] each:
Use catalytic converters which convert oxides of nitrogen into harmless nitrogen;
Less car usage;
Change to othr fuels e.g. electric.
[10 max]
10 M01/420/H(3)M
OPTION E CHEMICAL INDUSTRIES
E1. (a) Heats the furnace / OWTTE [1].
Any valid reaction involving coke, e.g. reduces iron oxide / is converted to carbon
monoxide [1].
[2 max]
(b) (i) Oxygen is blown through (the molten iron). (Do not accept air here) [1];
It oxidises / converts the carbon into carbon dioxide gas (which escapes) [1].
[2 max]
(ii) Calcium oxide / lime is added (to the molten iron). (Allow limestone) [1];
Calcium oxide reacts (with the silica) to form calcium silicate / slag [1].
[2 max]
E2. (a) Any appropriate equation (must have alkane and alkene as products) [1];
One use of an alkane (e.g. fuel) [1];
One use of an alkene (e.g. polymer or name of polymer) [1].
[3 max]
(b) (i) Silica / aluminium oxide / zeolites. [1]
(ii) Heat / high temperature / temperature above 300 C ; [1]
(c) Catalytic cracking produces a mixture of alkanes and alkenes [1];
Hydrocracking produces alkanes only [1].
[2 max]
E3. Any reasonable answer e.g. the products of refining are flammable and hence there is a
risk of fire. [1]
Any reasonable answer e.g. the gas produced in the furnace must not be released as it
contains poisonous carbon monoxide. [1]
E4. 1 mol(g) 2 mol(g) so "S increases / entropy change positive [1];
At higher T, "G becomes more negative as T"S becomes greater [1];
[2 max]
500 K C CO2 more negative "G
2000 K C CO more negative "G [1];
More negative favoured [1].
"G
[2 max]
11 M01/420/H(3)M
E5. Cathode half-reaction: 2H2O(l) + 2e- H2(g) + 2OH-(aq) (state symbols not needed) [1];
Anode half-reaction: 2Cl-(aq) Cl2(g) + 2e- (state symbols not needed) [1];
[1] each for any three of the following:
Porous membrane;
Aqueous electrolyte / brine;
Positive electrode / anode: titanium graphite;
Negative electrode / cathode: steel.
Any reasonable advantage and disadvantage [1].
[6 max]
12 M01/420/H(3)M
OPTION F FUELS AND ENERGY
F1. (a) (i) 1 % [1]
(ii) Inappropriate wavelengths [1];
Reflected / heats the surface / not all areas covered by plants [1].
[2 max]
(b) (i) Photosynthesis. [1]
[1]
(ii) 6H2O + 6CO2 C6H12O6 + 6O2
(No marks if not balanced.)
(c) (i) Any two of the following, [1] each
Combustion;
Production of biogas;
Production of ethanol / fermentation.
[2 max]
(ii) (Allow [1] for any reasonable advantage and [1] for any reasonable
disadvantage.) [2]
(d) (i) Heat [1];
Pressure [1];
Absence of oxygen [1].
[3 max]
(ii) Any three of the following, [1] each
Specific example of pollution (e.g. oil spills);
Cost of production / transport;
Non-renewable;
More valuable as a feedstock.
[3 max]
13 M01/420/H(3)M
F2. (a) Metals conduct electricity well, insulators do not, semiconductors are intermediate;
(Must have all 3 points for [2], 2 correct points for [1])
[2 max]
(b) Converts solar energy to electricity [1];
Si or Ge [1];
Doped with group 5/As or other example [1];
Doped with group 3/B or other example [1];
Light stimulates electron flow [1].
If mention n-type and p-type but do not explain, award only [1] of the [2] doping
marks.
Any reasonable advantage and disadvantage [1].
[6 max]
(c) voltage depends on materials used [1];
Power depends on the quality of materials [1].
[2 max]
14 M01/420/H(3)M
OPTION G MODERN ANALYTICAL CHEMISTRY
G1. (a) Mass spectrometry. [1]
(b) Chlorine exists as two isotopes. [1]
37
(c) II: Cl+ [1]
37
(35Cl
IV: - Cl)+ [1]
[2 max]
37 35
(d) The ratio of the isotopes is 1: 3 /25 % Cl and 75 % Cl [1];
This is the ratios of the peak heights/intensities [1].
(Graph must be referred to for second mark.)
[2 max]
(e) (i) By bombarding with electrons. [1]
(ii) The molecular mass of the compound. [1]
G2. (a) d to d transitions / transitions within the d sub-level. [1]
(b) X-ray crystallography. [1]
O
G3. (a) [1];
HH
O == C == O (accept linear shape without double bond) [1];
Bond length changes / stretching [1];
Bond angle changes / bending [1];
Dipole moment changes [1].
[5 max]
(b) (i) CH3CH2OCH2CH3 / ethoxyethane / diethylether [1];
H H H H
H C C O C C H[1];
H H H H
No broad brand at 3230 2550 cm-1 / no OH present [1];
Therefore not alkanol or acid [1];
No absorption 1680 1750 cm-1 / C=O present [1];
Therefore not acid or ester [1].
[6 max]
(ii) CH3CH2CO2H has absorptions at 2500 3300 and 1680 1750 cm-1 [2];
CH3CH2CH2OH has an absorption at 3230 3550 cm-1 [1];
CH3CH2CO2CH2CH3 has an absorption at 1680 1750 cm-1 [1].
[4 max]
15 M01/420/H(3)M
OPTION H FURTHER ORGANIC CHEMISTRY
H1. (a) (i) CH3 CH3
C C
H H
cis-but-2-ene
CH3 H
C C
H CH3
trans-but-2-ene
Each correct structure [1] each;
Both correct names [1].
[3 max]
(ii)
H H H H
H H H H
C
C C C
H H C C C C
H H
+
Br´+ H
H
Br- H
H Br
Br´-
[1] [1] [2 max]
H
CH3
CH2CH3
(b) (i) A: B:
CH3
H
H
H3C
H
CH3 CH3
C: D:
CH3
H
(Award [1] for each correct structure. Use ECF where possible if straight chain
C5 molecules given)
[4 max]
(ii) Structural: A and D / A and B / A and C / B and D / C and D [1].
Geometrical: B and C [1].
[2 max]
16 M01/420/H(3)M
(iii) (iii) H3C
H3C
H
H
Chiral centre
H C
H
OR 3
Chiral centre
HC
H3C
Correct structure [1].
Chiral centre marked [1]. [2 max]
(c) No rotation (in either but-2-ene or cycloalkanes) [1];
Without breaking the Ä„ component (in but-2-ene) and the ring (in cycloalkanes) [1];
(Both points are needed for the second mark here.)
[2 max]
[1]
(d) More strain / bond angles <109.5 .
OH
H2. (a) OH
NO2
NO2
XY
Structures for nitrophenols, [1] each.
OH OH OH
Z
NO2 O2N NO2 O2N NO2
NO2 NO2
Structure for dinitrophenol/trinitrophenol (Only one of structures above is needed.) [1]
In phenol, lone pair of electrons on oxygen overlaps with delocalised ring [1].
Activates the ring / attracts electrophiles or NO+ more strongly / increases electron
2
density [1].
[5 max]
(b) Nitro group is electron-withdrawing [1];
Bond polarity of O H increased / more H+ ions released [1];
Z has the most electron-withdrawing groups [1];
Correct reference to the stability of the anion [1].
[4 max]
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