GCE

Chemistry B

H433/01: Fundamentals of chemistry

Advanced GCE

Mark Scheme for Autumn 2021

Oxford Cambridge and RSA Examinations

 H433/01 Mark Scheme October 2021

1. Annotations

Annotation Meaning
Correct response

Incorrect response

Omission mark

Benefit of doubt given

Contradiction

Rounding error

Error in number of significant figures

Error carried forward

Level 1

Level 2

Level 3

Benefit of doubt not given

Noted but no credit given

Ignore

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 H433/01 Mark Scheme October 2021

2. Abbreviations, annotations and conventions used in the detailed Mark Scheme (to include abbreviations and subject-specific
conventions).

Annotation Meaning

/ alternative and acceptable answers for the same marking point

 Separates marking points

DO NOT ALLOW Answers which are not worthy of credit

IGNORE Statements which are irrelevant

ALLOW Answers that can be accepted

() Words which are not essential to gain credit

__ Underlined words must be present in answer to score a mark

ECF Error carried forward

AW Alternative wording

ORA Or reverse argument

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 H433/01 Mark Scheme October 2021

Section A

Q Key Mark AO
1 D 1 1.1
2 B 1 1.2
3 A 1 1.2
4 B 1 1.2
5 A 1 1.2
6 D 1 1.2
7 A 1 1.2
8 B 1 1.1
9 A 1 2.2
10 C 1 1.1
11 B 1 1.1
12 D 1 1.1
13 C 1 1.1
14 C 1 2.8
15 D 1 2.7
16 A 1 1.2
17 A 1 2.4
18 D 1 2.5
19 D 1 2.1
20 C 1 2.8
21 A 1 2.6
22 B 1 1.2
23 C 1 2.2
24 C 1 2.3
25 C 1 2.8
26 B 1 1.2
27 A 1 1.2
28 C 1 1.1
29 B 1 1.1
30 D 1 1.1
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 H433/01 Mark Scheme October 2021

Question Answer Mark AO Guidance

31 a 1 1.1 IGNORE brackets


31 b i (Warm with) sodium hydroxide AND 1 1.2
gas/ammonia/fumes turns indicator paper/red litmus paper
blue
31 b ii NH 4 + -3 2 2.6 x 2 Must have the sign
NO 3 –, +5
31 b iii NH 4 + + 2O 2  NO 3 – + H 2 O + 2H+  1 2.6 ALLOW multiples

31 b iv (colourless gas turns to) a brown gas  1 1.2

31 c i (Ba ions are) Ba2+ and (sulfate is) SO 4 2– 1 1.2

OR both ions have same/2 charge 
31 c ii CHECK ANSWER LINE 5 2.4 x 4
If answer = 62.2% award 5 marks
(Moles of Ba2+ = moles of SO 4 2- in 25 cm3= 0.0155 x 0.2) ECF throughout
= 3.1 x 10 -3 
Moles of Ba2+ = moles of SO 4 2- stated or implied AND moles
of SO 4 2- in 0.250 dm3= 0.031 moles 
Mass ammonium sulfate = 0.031 x 132.1 (= 4.0951) 
% ammonium sulfate is 4.0951/6.58 x 100 = 62.2% (to any
sf) 3.1
62.2 % (3sf)  ALLOW any calculated answer to 3 sf for last MPt.
31 c iii CHECK ANSWER LINE 3 2.2 x 3 6.02 x 1018 scores 2
If answer = 2.4(38) x 1017 award 3 marks
[SO 4 2-] =√(1x 10-10) = (1 x 10-5) in 1 dm3
No of moles of in 40.5 cm3 = (0.0405 x 1 x 10-5)
= 4.05 x 10-7 
No of ions = (4.05 x 10-7 x 6.02 x 1023) = 2.4(38) x 1017  ALLOW a calculated value x 6.02 x 1023 correctly
evaluated for last point.
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 H433/01 Mark Scheme October 2021

Question Answer Mark AO Guidance

32 a H H H H 2 2.1 x 2

Cl H C C H C C H + HCl

H H H H ALLOW absence of right-hand arrow to match text-

Half-headed arrows as shown book page 207.
HCl and ethyl radical product 

32 b i CH 3 CH 2 Cl + NH 3  CH 3 CH 2 NH 2 + HCl  1 1.1 ALLOW any unambiguous structures or molecular

formulae.
32 b ii Nucleophilic  2 1.1 x 2
Substitution 

32 c i White AND 1 1.1

(pale) yellow 

32 c ii C 2 H 5 I + H 2 O  C 2 H 5 OH + HI  2 2.7 IGNORE state symbols ALLOW H+ + I- for HI

Ag+ + I–  AgI  1.1 ALLOW other equations forming AgI such as:
AgNO 3 + HI  AgI + HNO 3
32 c iii C-Cl is more polar than C-I  3 3.1 x 3 Mark independently
Bond strength more important and C-I bond ORA throughout
is weaker than C-Cl AW 
(ppt forms) faster with iodoethane 

32 d i 1,1,1-trichloroethane  1 1.1 IGNORE commas and dashes

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 H433/01 Mark Scheme October 2021

32 d ii Refer to marking instructions on page 5 of mark scheme for 6 1.1 x 2 Indicative scientific points include:
guidance on marking this question. 2.5 x2
3.2 x 2 Strongest type of intermolecular bonds:
Level 3 (5-6 marks) • Fats have pd-pd imbs
Correctly identifies the imbs in all three compounds with • Substance A has pd-pd forces
some explanations • Hexane has only id-id forces.
AND Explains why fat is most soluble in A in terms of (Polar and non-polar must be correctly linked
strength of imbs broken and made. to imbs)
There is a well-developed line of reasoning which is clear and How intermolecular bonds arise:
logically structured. • Pd-pd form due to differences in atoms’
electronegativity in a covalent bond
Level 2 (3-4 marks) • Cδ+=Oδ- and Cδ+-Clδ-
Makes a reasonable attempt to describe the points in all • Causing electrostatic attractions
three sections or detailed description of 2 areas • Id-id forces due to uneven distributions of
There is a line of reasoning presented with some electrons creating temporary dipoles that
structure induce dipoles in adjacent molecules OR
Mention of instantaneous dipole-induced
Level 1 (1-2 marks) dipole forces at least once in full
Makes some relevant points but may contain errors. Ability to dissolve fat molecules:
There is an attempt at a logical structure with a line of • A substance will dissolve if the strength of
reasoning. The information is in the most part relevant and intermol bonds broken < intermol bonds
correct. made OR energy required to break
compared with energy released in making.
Level 0 (0 marks) • Fat’s pd-pd bonds stronger than id-id bonds
No response or nothing worthy of credit. with hexane so less soluble.
• Fat and A form pd-pd forces of comparable
strength so soluble.
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 H433/01 Mark Scheme October 2021

Question Answer Mark AO Guidance

33 a Blue/green(white flashes) 2 1.2
(Heat energy) excites e- so they emit light when they fall AW 2.5


33 b i Ammonia acts as a base  3 1.1

NH 3 + H 2 O ⇌ NH 4 + + OH-  2.3
Pale blue ppt is Cu(OH) 2 AND Cu2+ + 2OH-  Cu(OH) 2 2.3
OR Cu2+(aq) + 2OH-(aq)  Cu(OH) 2 (s)

33 b ii [Cu(NH 3 ) 4 (H 2 O)2+]/[NH 3 ]4[Cu(H 2 O) 6 2+]  2 2.1 ALLOW as shown without multiple square backets.
IGNORE state symbols, charges on ions must be
Units: dm12 mol-4  present.
ALLOW mol-4 dm12 ALLOW units matching
incorrect expression of K c
33 b iii CHECK ANSWER ON ANSWER LINE 3 3 x 2.8
If K c = 1(.0) x 1013 award 3 marks

Moles Cu2+ at eqm (= 0.022 - 0.02) = 0.002.

Moles of ammonia at eqm (= 0.081 – (4 x 0.02))= 0.001
K c = (0.02/(0.0014 x 0.002) = 1.0 x 1013  ALLOW ecf from first two mpts and (b)(ii).
INGORE units

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 H433/01 Mark Scheme October 2021

33 b iv Refer to marking instructions on page 5 of mark scheme for 6 1.2 x4 Indicative scientific points include:
guidance on marking this question. 3.3 Setting up colorimeter:
Level 3 (5-6 marks) 3.4 • Select a filter
There is a clear outline of the experiment which includes • Orange filter/ complementary colour/ filter
detailed descriptions of most points in each section and which with greatest absorbance
would produce valid results. • Zero with a cuvette of distilled water.
There is a well-developed line of reasoning which is clear and Calibration:
logically structured. • Make up set of solutions of the complex of
known concentration. AO 3.3
Level 2 (3-4 marks) • calc of mass to produce conc ≥ 0.02M
Most of the experimental details are described and there is • Use concentrations more and less
reference to all three sections or two in detail. concentrated than the unknown (details of
There is a line of reasoning presented with some structure dilution to get the concs). AO3.4
• Measure absorbance of the solutions.
Level 1 (1-2 marks) AO1.2
Some details are described, but one of the sections may be • Plot a graph of concentration against
omitted. absorbance. AO1.2
There is an attempt at a logical structure with a line of • Draw a line of best fit.
reasoning. The information is in the most part relevant and Measuring the concentration of the unknown
correct. sample: AO1.2
• Place cuvette of sample in the machine
Level 0 (0 marks) • Record absorbance
No response or nothing worthy of credit. • Use the graph to read concentration of that
absorbance
Calibration and measuring may be from a diagram.
ALLOW % transmittance for absorbance.
33 c i Bidentate  1 1.1 ALLOW polydentate  .
c ii 6 3 1.1 x 3 Mark independently
octahedral 
90o 
33 d Conc H 2 N CH 2 CH 2 NH 2 = 4.5/60 = 0.075 mol dm–3  4 2.8 ALLOW alternative method involving ratios for
Amt H 2 N CH 2 CH 2 NH 2 in 20 cm3 = 1.5 x 10–3 mol  MP2 and 3
Amt Cu2+ = 7.5 x 10-4 mol  H 2 N CH 2 CH 2 NH 2 :Cu2+ 20x 0.075 :15 x 0.05
Ratio 2:1 so formula is [Cu(H 2 N CH 2 CH 2 NH 2 ) 2 ]2+  multiples or any correct ratio 
1.5:0.75 

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 H433/01 Mark Scheme October 2021

Question Answer Mark AO Guidance

34 a i Condensation  1 1.1 ALLOW acylation

34 a ii (Secondary) amide/ peptide  1 1.1 Primary or tertiary are CON

34 b HCl  1 1.1

34 c products are: 4 3.1 x 4 NOT names

NH 3 +CH(CH 3 )COOH , NOT -NH 3 without a charge
(one mark if NH 2 not protonated)
C 2 H 5 OH 
CH 3 CH 2 COOH 
34 d ANY THREE FROM 3 1.2 x 3
Select a solvent in which the product is much more soluble at high
temperature 
Dissolve solid in minimum volume of hot solvent 
Filter when hot to remove insoluble impurities 
then cool and collect purer solid by filtration 

34 e i SOCl 2  1 2.5

e ii The product molecules have functional groups on both ends so reactions 1 3.2
can continue AW 

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 H433/01 Mark Scheme October 2021

Question Answer Mark AO Guidance

35 a i Rate is not proportional to concentration AW  1 3.1 ALLOW numerical examples

35 a ii Scales and labels on axes, must take up half the graph paper  3 2.6 x 3
Correct calculation of squares  look for values on the table for this
marking point can be subsumed by
Plotting of points on a correct numerical scale and line of best fit correct numbers on x-axis
ALLOW MP1 and 3 as ECF if conc not
squared or rate squared.

35 a iii Rate = k x [N2O]2  1 2.6

35 a iv Evidence of use of graph to find gradient (lines on graph or working 3 2.2.x 3

consistent with the graph) 
An answer that rounds to 4 x 104  ALLOW 2.5 x 10-5 as ECF if axes
reversed in (a)(ii). No other ECF
Units dm3mol-1 s-1

35 b i Zero order  2 3.2 x 2

Constant gradient so rate is constant AW 

35 b ii The surface of the catalyst is completely covered so adding more gas 1 3.1
doesn’t increase the rate. AW 

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This mark scheme is published as an aid to teachers and students, to indicate the requirements
of the examination. It shows the basis on which marks were awarded by examiners. It does not
indicate the details of the discussions which took place at an examiners’ meeting before marking
commenced.

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candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills
demonstrated.

Mark schemes should be read in conjunction with the published question papers and the report
on the examination.

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