Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Edexcel as level
chemistry question
paper 1 june 2024 +
mark scheme

Please check the examination details below before entering your candidate information
Candidate surname

Centre Number

Other names

Candidate Number

Pearson Edexcel Level 3 GCE

Tuesday 14 May 2024
Morning (Time: 1 hour 30 minutes)

Chemistry

Paper
reference

8CH0/01
 

Advanced Subsidiary
PAPER 1: Core Inorganic and Physical Chemistry
You must have:
Scientific calculator, Data Booklet

Total Marks

Instructions

Use black ink or ball‑point pen
...

•
in the boxes at the top of this page with your name,
• Fill
centre number and candidate number
...

•
the questions in the spaces provided
• Answer
– there may be more space than you need
...

•
marks for each question are shown in brackets
• The
– use this as a guide as to how much time to spend on each question
...

A Periodic Table is printed on the back cover of this paper
...

•
Show all your working in calculations and include units where appropriate
...


P76893A

©2024 Pearson Education Ltd
...
If you change your mind about an
answer, put a line through the box and then mark your new answer with a cross
...


DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

4 A student was provided with three aqueous solutions of potassium chloride,
potassium bromide and potassium iodide
...




(a) (i) Give the observations that the student would make in each case
...

KBr
...



(ii) Describe how the student could confirm the halide ions present in the
products of (a)(i) by adding ammonia solutions
...



...



...



...



...



...



...



...



...




*P76893A0324*

3

Turn over

(b) Nitric acid removes other ions that would interfere with the halide test,
for example carbonate ions
...


(1)


...




(ii) State the observation when nitric acid is added to a solution of
carbonate ions
...



...

Include state symbols
...

Chlorine dioxide is a gas at room temperature and pressure (r
...
p
...




The equation for this reaction is shown
...


State two precautions that must be taken when preparing chlorine dioxide in
a laboratory
...


(2)


...




(b) Calculate the mass of sodium chlorate(III) needed to make
5
...


[Ar values: H = 1
...
0

Na = 23
...
5]

*P76893A0624*

(4)



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA




DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

5 This question is about chlorine dioxide, ClO2 , and the chlorate(III) ion, ClO2– 
...


The equation for this decomposition is shown
...
125 mol of
chlorine dioxide gas completely decomposes
...
0 dm3 mol–1]



(ii) A swimming pool contains 400 m3 water
...


Calculate the mass of chlorine dioxide needed to produce a concentration of
chlorine of 7
...

Give your answer to an appropriate number of significant figures
...




Use crosses (×) for chlorine electrons, dots (•) for oxygen electrons and a
triangle () for the extra electron
...
Justify your answer
...



...



...



...
Analysis shows that
the percentage composition, by mass, of A is 26
...
2 % hydrogen and
the remainder is oxygen
...




(ii) Calculate the molecular formula of compound A
...


DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



(b) A mass spectrometer was used to obtain the mass number and
relative abundance of each isotope of an unknown element, B
...
31

52

83
...
55

54

2
...

Give your answer to two decimal places
...




(1)

Number of protons

Number of neutrons

Number of electrons

A

3

4

3

B

6

6

6

C

12

12

10

D

35

44

36

(d) The mass spectrum of another compound, D, is shown
...


(1)


...

Include equations for any reactions that occur
...



...



...



...



...



...



...



...



...



...



...


14

*P76893A01424*



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

*(a) Potassium chloride and potassium bromide are white crystalline solids which
react with concentrated sulfuric acid
...


DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA


...



...



...



...



...



...



...



...



...



...



...



...



...

Step 2 After cleaning, the cleaned wire was dipped into a fresh, clean sample of
concentrated hydrochloric acid and then into the white powder to pick
up a sample for testing
...


Result
The flame was coloured lilac
...


(1)


...




(ii) Identify the cation present in this sample of white powder
...




(c) The thermal stability of compounds in Group 2 is investigated
...


*P76893A01624*

(2)



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

(b) A student was asked to confirm the cation present in a sample of white powder
that was known to be a Group 1 compound
...


DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



(ii) State the conditions that must be used with the apparatus shown in your
diagram to ensure that the test is fair
...



...



...


(1)


...



...


Substance

Solid state

Liquid state

potassium chloride

poor

good

iron

good

good

water

poor

poor

Explain the electrical conductivity of potassium chloride, iron and water in the
solid and liquid states
...



...



...



...



...



...



...



...



...



(a) Water is able to dissolve many compounds
...


(4)


...



...



...




(ii) Explain why methanol dissolves in water
...


(3)


...



...



...




*P76893A01924*

19

Turn over

(b) The boiling temperature of a compound is dependent on the intermolecular
forces present and the shape of the molecule
...

Compound

Formula

Boiling temperature / K

2,2‑dimethylpropane

C(CH3)4

283

pentane

CH3(CH2)3CH3

309

Explain why pentane has a higher boiling temperature than
2,2‑dimethylpropane
...



...



...



...



...


20

*P76893A02024*



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



(ii) Data about two silicon compounds are shown
...


(4)


...



...



...



...



...
The relevant half‑equations are shown
...

State symbols are not required
...

ClO– + Cl– + 2H+ → Cl2 + H2O



(i) State a reason why this is not a disproportionation reaction
...



...




(ii) Identify the reducing agent in this reaction
...


(iii) Which is the half‑equation for the chlorate(I) ion, ClO– , in this reaction?

(1)

A
ClO– + Cl– → Cl2 + ½O2 + 2e–
B
ClO– + H+ + e– → ½Cl2 + OH–
C
ClO– + 2H+ + e– → ½Cl2 + H2O
D
ClO– → ½Cl2 + ½O2 + e–

22

*P76893A02224*



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

9 This question is about some redox reactions
...
00 g sample of solid potassium chlorate(V) was heated until fully decomposed
...

2KClO3(s) → 2KCl(s) + 3O2(g)
Calculate the volume, in cm3 , of oxygen produced at a temperature of 30 °C and
pressure of 110 000 Pa
...
6 g mol–1
Gas constant (R) = 8
...
We provide a wide range of qualifications including academic,
vocational, occupational and specific programmes for employers
...
edexcel
...
btec
...
uk for our BTEC qualifications
...
edexcel
...

If you have any subject specific questions about this specification that require the
help of a subject specialist, you can speak directly to the subject team at Pearson
...
edexcel
...

You can also use our online Ask the Expert service at www
...
com/ask
...

Pearson: helping people progress, everywhere
Our aim is to help everyone progress in their lives through education
...

We’ve been involved in education for over 150 years, and by working across 70
countries, in 100 languages, we have built an international reputation for our
commitment to high standards and raising achievement through innovation in
education
...
pearson
...
Examiners must
mark the first candidate in exactly the same way as they mark the last
...
Candidates must be
rewarded for what they have shown they can do rather than penalised
for omissions
...


•

There is no ceiling on achievement
...


•

All the marks on the mark scheme are designed to be awarded
...
e
...
Examiners should also be
prepared to award zero marks if the candidate’s response is not
worthy of credit according to the mark scheme
...


•

When examiners are in doubt regarding the application of the mark
scheme to a candidate’s response, the team leader must be
consulted
...


•

Mark schemes will indicate within the table where, and which strands of
QWC, are being assessed
...


Using the Mark Scheme
Examiners should look for qualities to reward rather than faults to penalise
...
Examiners should therefore read carefully and consider every response: even if it is not what is expected it may be worthy
of credit
...

/ means that the responses are alternatives and either answer should receive full credit
...

Phrases/words in bold indicate that the meaning of the phrase or the actual word is essential to the answer
...

Candidates must make their meaning clear to the examiner to gain the mark
...
Do not give
credit for correct words/phrases which are put together in a meaningless manner
...

Quality of Written Communication
Questions which involve the writing of continuous prose will expect candidates to:
• write legibly, with accurate use of spelling, grammar and punctuation in order to make the meaning clear
• select and use a form and style of writing appropriate to purpose and to complex subject matter
• organise information clearly and coherently, using specialist vocabulary when appropriate
...

Questions where QWC is likely to be particularly important are indicated (QWC) in the mark scheme, but this does not preclude
others
...

Do not award any additional incorrect observations e
...

bubbles
Ignore incorrect formulae

white and precipitate forms
or
brown and precipitate forms

Acceptable Answer

Additional Guidance

An answer that makes reference to the following point:
•

Mark
(1)

Accept effervescence / fizzing
Ignore just gas given off which turns limewater cloudy
Do not award any additional incorrect observations e
...

cloudy solution
Do not award incorrect gas identified

bubbles (of carbon dioxide)

Question
Number
4(b)(iii)

Mark

Acceptable Answer

Additional Guidance
Example of ionic equation

Mark
(2)

•

correct species and balancing

(1)

2H+(aq) + CO32−(aq) → CO2(g) + H2O(l)

•

state symbols

(1)

Allow state symbols for near miss equation e
...
non ionic
equation

(Total for Question 4 = 10 marks)

Question
Number
5(a)

Acceptable Answer

Additional Guidance

An answer that makes reference to the following points:

(2)

•

use a fume cupboard

(1)

•

gloves

(1)

Question
Number
5(b)

Mark

Allow an answer that recognises the problem of a toxic
gas
Allow fume hood/box
Ignore use of mask, respirator, breathing equipment (or
anything that uses all/part of the available air)
...
)

Acceptable Answer

Additional Guidance
Example of calculation

•

molar mass of chlorine dioxide

(1)

67
...
40 ÷ 67
...
08 / 0
...
08(0) = 0
...
10 (mol)

•

molar mass of NaClO2
and
calculation of mass of NaClO2

(1)

90
...
5 × 0
...
05 / 9
...
125 × 0
...
0625 (mol)

(1)

0
...
125 × 1
...
1875
0
...
125 × 24 000 = 3000 (cm3)
4500 – 3000 = 1500 (cm3)
Ignore SF except 1 SF

Mark
(2)

Question
Number
5(c)(ii)

Acceptable Answer

Additional Guidance
Example of calculation

• calculation of moles of Cl2

(1)

(7
...
03128

• calculation of moles of ClO2

(1)

0
...
06256

• calculation of mass of ClO2 to 2 or 3 SF

(1)

0
...
5 = 4
...
2 / 4
...
82 x 10-8 mol dm-3 x 2)
moles of ClO2 in 1 dm3 ( = 1
...
564 x 10-7 x 67
...
0557 x 10-5 g
M3 mass in 400 m3 ( = 1
...
22/4
...
5 (o)

(1)

Ignore shape even if incorrect

•

4 pairs of electrons around the chlorine suggests a
tetrahedral shape / bond angle 109
...
And O is more electronegative than Cl, so O is assigned a negative
oxidation number

(Total for Question 5 = 18 marks)

Question
Number
6(a)(i)

Acceptable Answer

Additional Guidance
Example of calculation

•

percentage of oxygen

(1)

100 – 26
...
2 = 71
...
7 ÷ 12 = 2
...
2 ÷ 1 = 2
...
1 ÷ 16 = 4
...
225 ÷ 2
...
2 ÷ 2
...
444 ÷ 2
...
31) + (52 × 83
...
55) + (54 × 2
...
0569
= 52
...

Marks are awarded for indicative content and for how the
answer is structured and shows lines of reasoning
...

Number of indicative
Number of marks awarded
marking points seen in
for indicative marking
answer
points
6
4
5-4
3
3-2
2
1
1
0
0
The following table shows how the marks should be awarded
for structure and lines of reasoning
...

Answer is partially structured
with some linkages and lines of
1
reasoning
...

0

Additional Guidance
Guidance on how the mark scheme should be applied:
The mark for indicative content should be added to the mark
for lines of reasoning
...

If there are no linkages between points, the same five
indicative marking points would yield an overall score of 3
marks (3 marks for indicative content and no marks for
linkages)
...

If there is any incorrect chemistry, deduct mark(s) from the
reasoning
...


Mark
(6)

Indicative content:

Ignore states in equations even if incorrect

•

IP1 potassium chloride (and bromide) produces
misty / steamy fumes (of hydrogen halide)

Allow white fumes
Ignore identification of the fumes using ammonia
Do not award white smoke for misty fumes

•

IP2 equation for reaction between potassium chloride
+ concentrated sulfuric acid

KCl + H2SO4 → KHSO4 + HCl
Allow 2KCl + H2SO4 → K2SO4 + 2HCl
Allow ions given in equation for KCl

•

IP3 brown fumes of bromine

Allow orange / orange-brown fumes of bromine
Allow orange/ brown liquid of bromine
Do not award yellow fumes
Do not award reference to ‘eggy smell’ / yellow solid of
sulfur

•

IP4 equation for HBr producing SO2 and Br2

2HBr + H2SO4 → Br2 + SO2 + 2H2O
2KBr + 2H2SO4 → Br2 + SO2 + 2H2O + K2SO4
Allow ions given in equation for KBr or HBr

•

IP5 no change in oxidation numbers of (potassium)
chloride / sulfur

•

IP6 with (potassium) bromide the sulfur is reduced to
+4 (therefore the stronger reducing agent)
Ignore any explanations or justifications, even if incorrect

Question
Number
7(b)(i)

Acceptable Answer

Additional Guidance

An answer that makes reference to the following point:
•

chlorides are more volatile (than other compounds)
...

time how long for lime water to go milky

(1)

Do not award M1 for conical flask/ beaker
Do not award M1 if additional reagents are in the container
Do not award M2 if gas syringe does not have plunger
Do not award M2 if the apparatus would not work e
...
no
bung or gas cannot move through the apparatus

Mark
(2)

Question
Acceptable Answer
Number
7(c)(ii) An answer that makes reference to any two of the following
points

Additional Guidance

Mark
(2)

•

same Bunsen flame / same Bunsen temperature

(1)

•

same distance of heat source from test tube

(1)

•

allow same moles of each carbonate

(1)

Ignore just same temperature / heat
Allow same Bunsen setting

Accept ‘amount’ of each carbonate
Do not award same mass / volume
Do not award heat under reflux for either M1 or M2

Question
Number
7(c)(iii)

Acceptable Answer
An answer that makes reference to the following point:
either
• measure the time taken for lime water to turn milky
or
• measure the time taken for a particular volume of gas
collected

Additional Guidance

Mark
(1)

Question
Number
7(c)(iv)

Answer

Mark

The only correct answer is C (carbonates: increasing, nitrates: increasing)

(1)

A is incorrect because the thermal stability of nitrates increases down the Group 2
B is incorrect because the thermal stability of nitrates increases down the Group 2
D is incorrect because the thermal stability of carbonates increases down the Group 2

Question
Number
7(d)

Acceptable Answer

Additional Guidance

An explanation that makes reference to the following points:

Mark
(4)

•

solid potassium chloride is a poor conductor because the
ions are in fixed positions

(1)

Allow just ‘the ions are not mobile’
Allow lattice for fixed position

•

liquid potassium chloride conducts because the ions are
free to move

(1)

Allow delocalised ions for ions are free to move

•

iron is a good conductor when solid or liquid because it
has delocalised electrons (which move and carry charge)

(1)

Allow electrons that are free to move for
delocalised electrons

•

water is a poor conductor because there are no charge
carriers / electrons that are free to move/ ions that are free
to move

(1)

Allow very few ions in pure water
Do not award marking points if incorrect
bonding referred to
(Total for Question 7 = 18 marks)

Question
Number
8(a)(i)

Acceptable Answer

Additional Guidance

An explanation that makes reference to the following points:
•

diagram of Ca2+ surrounded by water molecules (any
number > 1)

•

diagram of Cl− surrounded by water molecules (any
number > 1)

(4)

δ+
δ+

δ−

(1)

(1)

δ+

δ−

δ+

Penalise one water molecule on each ion once
only
Penalise incorrect ion / ion charge once only
•

dipoles shown on at least one water molecule in each case

•

energy / strength of new interactions between solute and
solvent is approximately the same as (the sum of) the
energy / strength of the interactions between the solute
particles and solvent particles

(1)

(1)

Mark

Do not award if water molecule shown as ions
Energy from making bonds / bond strength
between water and ions compensates for / is
greater than the energy needed to break bonds in
water / solvent and calcium chloride / solute /
lattice

Question
Number
8(a)(ii)

Acceptable Answer

Additional Guidance

An explanation that makes reference to the following
points:
•

hydrogen bonding occurs between methanol and
water molecules
...

minimum = 3 dashes/dots
Hydrogen bond must be identified for M2 and M3
...


Question
Number
8(b)(i)

Acceptable Answer

Additional Guidance

An explanation that makes reference to the following points:

Mark
(3)

Allow reverse argument throughout
e
...
pentane has no branches for M1
•

2,2-dimethylpropane has two branches

(1)

•

Contact/surface area for 2,2-dimethylpropane is much
smaller than for pentane

(1)

•

London/van der Waals/ instantaneous dipole/temporary
dipole/fluctuating dipole forces/ dispersion forces etc
are smaller/weaker in 2,2-dimethylpropane (and
therefore a lower boiling temperature)

(1)

Allow is branched
Allow pentane has a longer chain length

Do not award if reference to different number of
electrons
Do not award if reference to covalent bonds
breaking

Question
Number
8(b)(ii)

Acceptable Answer

Additional Guidance

An explanation that makes reference to the following points:

Mark
(4)

•

identification of structure of silicon ((IV)) oxide / SiO2

(1)

Silicon ((IV)) oxide is a giant (covalent) structure /
lattice (of atoms)
Allow reference to silicon dioxide
Do not award reference to silicon ((IV)) oxide
molecules or double bonds

•

identification of structure of silicon tetrachloride / SiCl4

(1)

Silicon tetrachloride is simple molecular

•

SiO2 has strong covalent bonds which have to be
broken therefore require high amounts of energy

(1)

Penalise lack of amount of energy needed once only
in M3 and M4

•

SiCl4 only has to break weak London forces therefore
lower amounts of energy

(1)

Allow van der Waals’/dispersion forces /
instantaneous dipole – induced dipole for London
forces

(Total for Question 8 = 14 marks)

Question
Number
9(a)

Acceptable Answer

Additional Guidance
Example of equation

•

balanced equation

Mark
(1)

2S2O32− + I2 → S4O62− + 2I−
Ignore state symbols even if incorrect
Inclusion of electron scores 0

Question
Number
9(b)(i)

Acceptable Answer
An answer that makes reference to the following point:
•

Question
Number
9(b)(ii)

Additional Guidance

a single species is not oxidised and reduced
or
two different species are not oxidised and reduced
(to form the same species)

Acceptable Answer
An answer that makes reference to the following point:
•

(reducing agent is the) chloride ion / Cl−

Mark
(1)

Allow reaction identified as ‘reverse
disproportionation’ / comproportionation
Allow ions for species
Ignore one species is oxidised and one species is
reduced

Additional Guidance

Mark
(1)

Question
Number
9(b)(iii)

Answer
The only correct answer is C (ClO− + 2H+ + e− → ½Cl2 + H2O)
A is not correct because this equation shows both oxidant and reductant
B is not correct because this equation produces hydroxide ions which would not be possible in acid conditions
D is not correct because oxygen is not a product of the overall reaction

Mark
(1)

Question
Number
9(c)

Acceptable Answer

Additional Guidance
Example of calculation

Mark
(5)

•

moles of KClO3

(1)

= 5
...
6 = 0
...
5 = 0
...
061175 × 8
...
400302 × 10−3 (m3)
= 1400 (cm3)
Allow TE throughout
Ignore SF except one for M5 only
Correct final answer with no working scores (5)
(Total for Question 9 = 9 marks)
TOTAL FOR PAPER = 80 MARKS

Pearson Education Limited

---