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Mark Scheme (Results)

January 2022

Pearson Edexcel International GCSE

In Chemistry (4CH1) Paper 2C

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Edexcel and BTEC Qualifications

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January 2022
Question Paper Log Number P70702A
Publications Code 4CH1_2C_2201_MS
All the material in this publication is copyright
© Pearson Education Ltd 2022
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General Marking Guidance

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 All candidates must receive the same treatment. Examiners
must mark the first candidate in exactly the same way as they
mark the last.
 Mark schemes should be applied positively. Candidates must
be rewarded for what they have shown they can do rather than
penalised for omissions.
 Examiners should mark according to the mark scheme not
according to their perception of where the grade boundaries
may lie.
 There is no ceiling on achievement. All marks on the mark
scheme should be used appropriately.
 All the marks on the mark scheme are designed to be awarded.
Examiners should always award full marks if deserved, i.e. if
the answer matches the mark scheme. Examiners should also
be prepared to award zero marks if the candidate’s response
is not worthy of credit according to the mark scheme.
 Where some judgement is required, mark schemes will
provide the principles by which marks will be awarded and
exemplification may be limited.
 When examiners are in doubt regarding the application of the
mark scheme to a candidate’s response, the team leader must
be consulted.
 Crossed out work should be marked UNLESS the candidate has
replaced it with an alternative response.
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Question

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Answer Notes Marks

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1 (a) (i) M1 a compound/substance/molecule containing no M1 if reference to 2

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hydrogen/H and carbon/C (atoms) element containing C

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and H OR C and H
molecules

M2 only M2 dep on M1 or near

miss

(ii) ethene has a double bond 1

(b) A colourless 1

A is the only correct answer because alkenes such

as ethene react with bromine water forming a
colourless solution
B is not correct as bromine water is orange before
it reacts with ethene
C is not correct as the solution produced is not
purple
D is not correct as the solution produced is not red

(c) (i) temperature = 300°C ACCEPT any value or 2

range of values
between 250 and
350°C If no unit given
assume it is Celsius

ACCEPT equivalent
temperatures in other
units provided the
unit is given
pressure = 60-70 atmospheres
ACCEPT any value or
range of values
between 60 and 70
atm If no unit given
assume it is atm

ACCEPT equivalent
pressures in other
units provided the
unit is given

(ii) C2H6O IGNORE size of 1

numbers

REJECT C2H5OH

Total for question = 7

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Question

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Answer Notes Marks

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number

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2 (a) (i) D nitrogen 1

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D is the only correct answer as nitrogen is the most
abundant gas in unpolluted air.
A is not correct as there are only trace amounts of
hydrogen in unpolluted air.
B is not correct as there are only trace amounts of
methane in unpolluted air.
C is not correct as there are only trace amounts of
neon in unpolluted air.

(ii) C 21% 1

C is the only correct answer as the percentage of

oxygen in the air is 21%
A is not the correct answer as the percentage of
oxygen in the air is not 0.04%
B is not the correct answer as the percentage of
oxygen in the air is not 0.9%
D is not the correct answer as the percentage of
oxygen in the air is not 35%

(b) (i) 2
cracking an alkane

complete combustion of
✔
an alkane

reaction between magnesium and

hydrochloric acid

rusting of iron

thermal decomposition of
✔
copper(II) carbonate
(ii) Any one from: ALLOW greenhouse 1
effect

M1 global warming ALLOW an effect of

global warming/climate
M2 climate change change e.g. wildfires/
melting of polar ice
caps/flooding
(iii) argon 1

(c) (i) nitric acid ALLOW HNO3/ nitrous 1

acid /HNO2

(ii) sulfur dioxide ALLOW SO2 1

ALLOW other oxides of

nitrogen

Total for question = 8

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Question

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Answer Notes Marks

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number

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3 (a) (i) M1 working shown on graph 2

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M2 56 (°C) ALLOW any value
between 56 and 57
inclusive.

(ii) M1 31-13 2

M2 18 (g) ALLOW ecf if one

incorrect reading in
M1

correct answer of
18g with or without
working scores 2

(b) (i) 5.1 (g) 1

(ii) 15 (g) 1

(iii) M1 5.1÷15 OR 0.34 (g) OR answer to (i) ÷ answer to (ii) 2

M2 34 (g) OR answer to M1 × 100

correct answer of 34
(g) with or without
working scores 2

(iv) Any one from 1

M1 (hydrated) copper(II) sulfate would become ALLOW the

anhydrous copper sulfate (hydrated) crystals
would decompose
M2 (hydrated) copper(II) sulfate would lose water
Total for question = 9
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Question

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Answer Notes Marks

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4 (a) (i) Any two from: 2

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M1 sodium moves (on the surface)

M2 sodium turns into a sphere/ball ALLOW sodium melts

M3 effervescence ALLOW fizzing / bubbles

M4 sodium gets smaller ALLOW sodium

disappears / dissolves
M5 white trail seen
IGNORE references to a
flame

(ii) blue / purple IGNORE qualifiers 1

ALLOW violet/lilac

(b) (i) same number of electrons/one electron in the outer ALLOW same number of 1
shell. valence electrons/one
valence electron

(ii) M1 lithium (atom) has a smaller atomic radius ALLOW lithium is 3

smaller (atom)/lithium
(atom) has fewer shells
/energy levels

ALLOW outer electron

in lithium (atom) is
closer to the nucleus
M2 the outer shell electron is more strongly
attracted to the nucleus OWTTE

M3 so is less easily lost

ALLOW reverse
argument for sodium

(c) M1 amount lithium = 0.150 ÷ 7 OR 0.0214 mol penalise 1 sig fig in M1 4

M2 amount hydrogen = 0.0107 mol ALLOW M1÷2

ALLOW 2 or more sig

figs in answers to M1
M3 254 ÷ 0.0107 and M2

M4 23,738 ALLOW 2 or more sig

figs if all working shown

correct answers in the

range 23,707 to 24,910
cm3 to 3 or more
significant figures,
without working scores
4 marks.
Total for question = 11
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Question

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Answer Notes Marks

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number
5 (a) A description that refers to any five of the following 5
points

M1 add hydrogen peroxide to the conical flask and

add catalyst

M2 start the timer

M3 record volume of gas produced in a given time/

record the time for certain volume of gas to be
produced

M4 repeat with same mass of a different catalyst

M5 and with same volume of hydrogen peroxide

M6 plot the results on a graph and calculate

gradient (for each catalyst)

M7 the most effective catalyst gives the fastest rate

of reaction OWTTE

(b) (i) M1 a vertical line from the level of the hydrogen the line does not need 2
peroxide to the top of the curve labelled activation an arrow head
energy or Ea
ALLOW double headed
arrow

REJECT arrow pointing

down

M2 a vertical line from the level of the hydrogen ALLOW double headed
peroxide to the level of the water and oxygen arrow
labelled enthalpy change or ΔH
REJECT arrow pointing
up

(ii) curve starting from hydrogen peroxide level, below 1

the peak of the original curve, and ending at water
and oxygen level

Total for question = 8

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Question

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Answer Notes Marks

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number

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6 (a) (i) all points plotted ± half a square 1

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(ii) curved line of best fit 1

(iii) An explanation that links the following two points 2

M1 curve shows increasing mass (of negative

electrode) because (more) copper deposits/forms

M2 line becomes horizontal because there are no ALLOW line becomes

more copper(II) ions left in the solution/ all the horizontal as there is no
copper has been deposited/formed OWTTE copper sulfate solution
left
(b) (i) A description that refers to two of the following 2
points

M1 fill a test tube/measuring cylinder with copper ALLOW fill a test tube/
sulfate solution measuring cylinder with
water
M2 place the tube over the positive electrode

M3 collect gas/oxygen by displacement of

solution/water

(ii) 2H2O → O2 + 4H+ + 4e(-) 2

M1 all formulae correct

M2 correct balancing of correct formulae M2 dep on M1

OR

4OH- → O2 + 2H2O + 4e(-)

M1 all formulae correct

M2 correct balancing of correct formulae M2 dep on M1

(c) (i) M1 layers (of atoms or ions) ALLOW sheets/rows 2

M2 can slide over one another M2 dep on M1

ALLOW atoms/ions slide
over each other for M2

(ii) M1 delocalised electrons IGNORE sea of electrons 2

/free electrons

M2 are free to move (throughout the structure) M2 dep on mention of

electrons in M1

0 marks if reference to
ions moving
Total for question = 12
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Question

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7 (a) (i) REJECT any other atoms 1
in the ring.

1
(ii) ethyl ethanoate ALLOW ethylethanoate

ALLOW ethyl acetate

(iii) M1 add a metal such as magnesium, aluminium, must be a named metal 2

zinc or iron REJECT Group 1 metals

M2 effervescence/bubbles/fizzing ACCEPT test gas with

lighted splint which
pops

M2 dep on reference to
adding a metal
OR

M1 add a carbonate ACCEPT any named

carbonate
M2 effervescence/bubbles/fizzing
ACCEPT test gas with
limewater which goes
cloudy/milky

M2 dep on M1

(b) M1 C-O and one / two O-H bonds are broken and ALLOW the same bonds 2
formed are broken and formed

M2 so the same amount of energy is needed to ALLOW energy of bonds

break the bonds in the reactants as is given off formed equals energy of
when the bonds in the products are formed bonds broken

(c) (i) M1 the rate of the forward reaction equals the rate 2
of the backward reaction

M2 the concentrations of reactants and products REJECT concentration

remain constant of the reactants and
products are the same

(ii) M1 a catalyst increases the rate of forward and 2

backward reactions

M2 equally M2 dep on M1
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Answer Notes Marks

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7 (d) 3

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example calculation

M1 moles barium hydroxide = (0.150 × 22.75)÷ 1000 M1 needs to be given to

OR 0.0034125 at least 3 sig figs

M2 moles ethanoic acid = 0.006825 ALLOW M1 × 2

M3 moles ethanoic acid to 3 significant figures = ALLOW answer to M2 to

0.00683 3 significant figures.

correct answer of
0.00683 moles with or
without working scores
3 marks

ACCEPT answer in
standard form

ACCEPT 0.00682 if M1
given to 3 sig figs

6.83 with or without

working scores 2 marks

(e) 2
correct answer scores 2 marks ALLOW structure
without extension bonds

IGNORE brackets and n

and + H2O

M1 three carbons from the dicarboxylic acid and two

from the diol and the ester linkage

M2 -OH lost from the dicarboxylic acid and -H lost ALLOW -OH lost from
from the diol diol and -H lost from
dicarboxylic acid

Total for question = 15

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