11

(ii) The chemical equation for this reaction can be represented as shown.

H H H H

C C + Cl Cl Cl C C Cl

H H H H

The energy change for the reaction is –180 kJ / mol.

Use the bond energies in the table to calculate the bond energy of a C–Cl bond, in kJ / mol.

bond C–H C=C Cl –Cl C–C

bond energy in kJ / mol 410 610 240 350

Use the following steps.

step 1 Calculate the energy needed to break bonds.

energy needed to break bonds = .............................. kJ

step 2 Use your answer in step 1 and the energy change for the reaction to determine
the energy released when bonds are formed.

energy released when bonds form = .............................. kJ

step 3 Use your answer in step 2 and bond energy values to determine the energy of
a C–Cl bond.

bond energy of a C–Cl bond = .............................. kJ / mol

[4]

[Total: 11]

© UCLES 2022 0620/42/F/M/22 [Turn over

 9

(b) Nitrogen reacts with fluorine to form nitrogen trifluoride, NF3.

(i) The chemical equation can be represented as shown.

N≡N + 3 F–F ! 2 F–N–F

F

Some bond energies are shown in the table.

bond bond energy in kJ / mol

N≡N 945
F–F 160
N–F 300

Calculate the energy change for the reaction between nitrogen and fluorine, using the
following steps:

● energy taken in to break bonds

.............................. kJ

● energy released when bonds are formed

.............................. kJ

● energy change during the reaction.

.............................. kJ / mol
[3]

(ii) Use your answer to (i) to deduce whether this reaction is endothermic or exothermic.
Explain your answer.

.............................................................................................................................................

....................................................................................................................................... [1]

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 7

(c) Describe and explain the effect, if any, on the position of equilibrium when:

(i) the pressure is increased

.............................................................................................................................................

....................................................................................................................................... [2]

(ii) the temperature is increased.

.............................................................................................................................................

....................................................................................................................................... [2]

(d) The reaction between chlorine and carbon monoxide can be represented as shown.

O
Cl Cl + CO C
Cl Cl

When one mole of chlorine reacts with one mole of carbon monoxide, 230 kJ of energy is
released.

Some bond energies are shown in the table.

bond bond energy in kJ / mol

Cl –Cl 240
C=O 745
C–Cl 400

Use the information to calculate the energy of the bond between the C and the O in
carbon monoxide, CO.

bond energy in carbon monoxide, CO = .............................. kJ / mol [3]

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 11

(ii) The structures of the reactants and products of this reaction are shown.

H H H H H H

H C C C H + Cl Cl → H C C C H

H H Cl Cl

Some bond energies are shown in the table.

bond energy
bond
in kJ / mol
C–C 347
C=C 612
C–H 413
C–Cl 339
Cl –Cl 242

Calculate the energy change for the reaction between propene and chlorine using the
following steps.

● Calculate the energy needed to break the bonds.

.............................. kJ

● Calculate the energy released when bonds are formed.

.............................. kJ

● Calculate the energy change for the reaction between propene and chlorine.

.............................. kJ / mol
[3]

© UCLES 2020 0620/42/M/J/20 [Turn over

 8

(d) Hydrogen and chlorine react to form hydrogen chloride gas, as shown in the equation.

H2 + Cl 2 → 2HCl

This equation can be represented as shown.

H–H + Cl –Cl → 2H–Cl

Some bond energies are shown in the table.

bond energy
bond
in kJ / mol
H–H 436
Cl –Cl 243
H–Cl 432

Calculate the energy change for the reaction between hydrogen and chlorine, using the
following steps.

● Calculate the energy needed to break the bonds.

.............................. kJ

● Calculate the energy released when bonds are formed.

.............................. kJ

● Calculate the energy change for the reaction.

.............................. kJ / mol
[3]

[Total: 13]

© UCLES 2020 0620/43/M/J/20

 10

5 Carboxylic acids react with alcohols to form esters. The reaction is reversible.
The equation for the reaction between ethanoic acid and ethanol is shown.

CH3COOH + CH3CH2OH CH3COOCH2CH3 + H2O

(a) (i) What is the name of the ester formed in this reaction?

....................................................................................................................................... [1]

(ii) Draw the structure of the ester formed. Show all of the atoms and all of the bonds.

[1]

(b) The reaction between ethanoic acid and ethanol is exothermic.

Draw an energy level diagram for this reaction.

On your diagram label:

● the reactants and products
● the energy change of the reaction, ∆H.

energy

progress of reaction
[3]

(c) Concentrated sulfuric acid is a catalyst for this reaction.

What is meant by the term catalyst ?

....................................................................................................................................................

.............................................................................................................................................. [2]

© UCLES 2019 0620/43/M/J/19

 5

2 A student investigated the temperature changes when two different metals, zinc and magnesium,
reacted with aqueous copper(II) sulfate.

Three experiments were done.

Experiment 1

● A measuring cylinder was used to pour 25 cm3 aqueous copper(II) sulfate into a polystyrene
cup.
● The initial temperature of the solution was measured and the timer was started.
● The temperature of the solution was measured at 30 seconds and at 60 seconds.
● At 60 seconds, 5 g of zinc powder was added to the aqueous copper(II) sulfate. The mixture
was stirred with a thermometer.
● The temperature of the mixture was measured every 30 seconds for 210 seconds. The mixture
was stirred continuously.

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(a) Use the thermometer diagrams to record the temperatures in the table.

time / s 0 30 60 90 120 150 180 210

30 30 30 50 50 50 50 50
thermometer
25 25 25 45 45 45 45 45
diagram
20 20 20 40 40 40 40 40

temperature of
mixture / °C

[2]

Experiment 2

● Experiment 1 was repeated using 5 g of magnesium powder instead of zinc powder.

(b) Use the thermometer diagrams to record the temperatures in the table.

time / s 0 30 60 90 120 150 180 210

30 30 30 60 80 80 80 80
thermometer
25 25 25 55 75 75 75 75
diagram
20 20 20 50 70 70 70 70

temperature of
mixture / °C

[1]

Experiment 3

● Experiment 1 was repeated using 5 g of zinc granules instead of zinc powder.

(c) Use the thermometer diagrams to record the temperatures in the table.

time / s 0 30 60 90 120 150 180 210

30 30 30 30 30 30 30 30
thermometer
25 25 25 25 25 25 25 25
diagram
20 20 20 20 20 20 20 20

temperature of
mixture / °C

[1]

© UCLES 2019 0620/63/M/J/19

 7

(d) Plot the results for Experiments 1–3 on the grid and draw three smooth line graphs.
Clearly label your lines.

80

70

60

50

temperature of
mixture / °C
40

30

20

10

0
0 30 60 90 120 150 180 210
time / s
[3]

(e) From your graph, deduce the temperature of the mixture in Experiment 2 after 75 seconds.

Show clearly on the grid how you worked out your answer.

.............................. °C [2]

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 8

(f) (i) From the results, which Experiment was the most exothermic? Explain your answer.

.............................................................................................................................................

....................................................................................................................................... [2]

(ii) Compare the rates of reaction in Experiments 1 and 3. Explain why the rates of reaction
are different.

.............................................................................................................................................

.............................................................................................................................................

....................................................................................................................................... [2]

(g) Predict the temperature of the mixture in Experiment 2 after 2 hours. Explain your answer.

....................................................................................................................................................

.............................................................................................................................................. [2]

(h) When doing the experiments, what would be the advantage of taking the temperature readings
every 15 seconds?

....................................................................................................................................................

.............................................................................................................................................. [2]

(i) Explain why a copper can should not be used in place of the polystyrene cup in these
experiments.

....................................................................................................................................................

....................................................................................................................................................

.............................................................................................................................................. [2]

[Total: 19]

© UCLES 2019 0620/63/M/J/19

 13

(b) The equation for the complete combustion of ethanol is shown.

H H

H C C O H + 3 O O 2 O C O + 3 H O H

H H

Use the bond energies in the table to calculate the energy change, in kJ / mol, for the complete
combustion of ethanol.

bond energy
bond
in kJ / mol
C–C 347
C–H 413
C–O 358
C=O 805
O–H 464
O=O 498

● Energy needed to break bonds.

.............................. kJ

● Energy released when bonds are formed.

.............................. kJ

● Energy change for the complete combustion of ethanol.

energy change = .............................. kJ / mol

[3]

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 7

(d) Ammonia reacts with oxygen as shown.

4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g)

(i) Calculate the volume of oxygen at room temperature and pressure, in dm3, that reacts with
4.80 dm3 of ammonia.

volume = .............................. dm3 [3]

(ii) The chemical equation for the reaction can be represented as shown.

4 H N H + 5 O O 4 N O + 6 H O H

Use the bond energies in the table to calculate the energy change, in kJ / mol, which
occurs when one mole of NH3 reacts.

bond N–H O=O N=O O–H

bond energy in kJ / mol 391 498 587 464

● Energy needed to break bonds.

.............................. kJ

● Energy released when bonds are formed.

.............................. kJ

● Energy change when one mole of NH3 reacts.

energy change = .............................. kJ / mol

[4]

[Total: 22]

© UCLES 2019 0620/42/O/N/19 [Turn over

 7

(c) Gaseous phosphorus(III) chloride, PCl 3, reacts with gaseous chlorine to form gaseous
phosphorus(V) chloride, PCl 5.

PCl 3(g) + Cl 2(g) PCl 5(g)

The chemical equation for this reaction can be represented as shown.

Cl Cl
Cl
Cl P Cl + Cl Cl P Cl
Cl
Cl

(i) Use the bond energies in the table to calculate the energy change, in kJ / mol, of the
reaction.

bond bond energy in kJ / mol

P– Cl 326
Cl – Cl 243

● Energy needed to break bonds.

.............................. kJ

● Energy released when bonds are formed.

.............................. kJ

● Energy change of reaction.

energy change = .............................. kJ / mol

[3]

(ii) Deduce whether the energy change for this reaction is exothermic or endothermic. Explain
your answer.

.............................................................................................................................................

....................................................................................................................................... [1]

© UCLES 2019 0620/43/O/N/19 [Turn over

 4

2 A student investigated the temperature changes when two different solids, N and O, dissolve in
water.
Two experiments were done.

Experiment 1

● Using a measuring cylinder, 30 cm3 of distilled water was poured into a polystyrene cup.
● The initial temperature of the distilled water was measured.
● Solid N was added to the distilled water, a timer started and the mixture was stirred with a
stirring thermometer.
● The temperature of the mixture was measured every 30 seconds for three minutes (180 seconds).

(a) Use the thermometer diagrams to record the temperatures in the table.

time / s 0 30 60 90 120 150 180

25 25 25 30 30 30 30
thermometer
20 20 20 25 25 25 25
diagram
15 15 15 20 20 20 20

temperature of
mixture / °C

[2]

Experiment 2

Experiment 1 was repeated using a new polystyrene cup and solid O instead of solid N.

(b) Use the thermometer diagrams to record the temperatures in the table.

time / s 0 30 60 90 120 150 180

30 20 20 20 10 10 20
thermometer
25 15 15 15 5 5 15
diagram
20 10 10 10 0 0 10

temperature of
mixture / °C

[2]

© UCLES 2019 0620/62/O/N/19

 5

(c) Plot the results for Experiments 1 and 2 on the grid. Draw two smooth line graphs.
Clearly label your graphs.

30

20

temperature
of mixture
/ °C

10

0
0 30 60 90 120 150 180 210 240
time / s
[3]

(d) (i) From your graph, deduce the time taken for the initial temperature of the solution in
Experiment 2 to change by 3 °C.

Show clearly on the grid how you worked out your answer.

.............................. s [3]

(ii) Extend your graph for Experiment 1 to give the expected temperature of the mixture after
240 seconds.

.............................. °C [2]

(e) Is the energy change in Experiment 2 exothermic or endothermic? Explain your answer.

....................................................................................................................................................

.............................................................................................................................................. [1]

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 6

(f) State two possible sources of error in these experiments. Suggest two improvements to
reduce each of these sources of error.

source of error 1 ........................................................................................................................

improvement 1 ...........................................................................................................................

source of error 2 ........................................................................................................................

improvement 2 ...........................................................................................................................
[4]

[Total: 17]

© UCLES 2019 0620/62/O/N/19

 8

4 Potassium nitrate and ammonium chloride are two salts. The energy change when they each
dissolve in water is endothermic.

Plan an experiment to show which of these two salts produces the larger endothermic energy
change per gram.

Your answer should include:

● any measurements you would take and record
● how the results could be used to draw a conclusion.

You are provided with potassium nitrate and ammonium chloride, distilled water and common
laboratory apparatus.

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

...........................................................................................................................................................

..................................................................................................................................................... [6]

Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.

To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.

Cambridge Assessment International Education is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of
Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge.

© UCLES 2019 0620/63/O/N/19

 5

2 A student investigated the temperature change when magnesium ribbon reacts with
dilute sulfuric acid.

Five experiments were done.

Experiment 1
● Using a measuring cylinder, 20 cm3 of dilute sulfuric acid were poured into a boiling tube.
● A thermometer was used to measure the initial temperature of the acid.
● A 1 cm length of magnesium ribbon was added to the acid in the boiling tube.
● The acid and magnesium ribbon in the boiling tube were stirred continuously using a
thermometer.
● The highest temperature reached by the mixture was measured.
● The boiling tube was rinsed out with distilled water.

Experiment 2
● Experiment 1 was repeated using a 2 cm length of magnesium ribbon instead of the 1 cm length.

Experiment 3
● Experiment 1 was repeated using a 3 cm length of magnesium ribbon instead of the 1 cm length.

Experiment 4
● Experiment 1 was repeated using a 5 cm length of magnesium ribbon instead of the 1 cm length.

Experiment 5
● Experiment 1 was repeated using a 6 cm length of magnesium ribbon instead of the 1 cm length.

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 6

(a) Use the information in the description of the experiments and the thermometer diagrams to
complete the table.

initial temperature highest temperature

length of temperature
experiment magnesium initial highest increase
thermometer thermometer
ribbon / cm temperature temperature / °C
diagram diagram
of acid / °C of acid / °C
30 30

1 25 25

20 20

30 30

2 25 25

20 20

30 30

3 25 25

20 20

30 40

4 25 35

20 30

30 40

5 25 35

20 30

[4]

(b) In which experiment, 1, 2, 3, 4 or 5, was the temperature increase the largest?

.............................................................................................................................................. [1]

© UCLES 2020 0620/62/M/J/20

 7

(c) Add a suitable scale to the y-axis and plot the results from Experiments 1 to 5 on the grid.
Draw a smooth line graph, making sure that your line passes through (0,0).

temperature
increase / °C

0
0 1 2 3 4 5 6
length of magnesium ribbon / cm
[5]

(d) Explain why the graph line must pass through (0,0).

....................................................................................................................................................

.............................................................................................................................................. [1]

(e) From your graph, deduce the temperature increase if Experiment 1 is repeated using a 4 cm
length of magnesium ribbon.

Show clearly on the grid how you worked out your answer.

..............................
[3]

(f) (i) Why would carrying out the experiment in a polystyrene cup rather than a boiling tube
improve the accuracy of the results?

.............................................................................................................................................

....................................................................................................................................... [1]

(ii) Sketch on the grid the graph you would expect if the experiment was repeated using a
polystyrene cup instead of a boiling tube. [1]

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 8

(g) The volume of dilute sulfuric acid could be measured with a 20 cm3 pipette.

(i) State one advantage of using a pipette rather than a measuring cylinder.

.............................................................................................................................................

....................................................................................................................................... [1]

(ii) State one disadvantage of using a pipette rather than a measuring cylinder.

.............................................................................................................................................

....................................................................................................................................... [1]

[Total: 18]

© UCLES 2020 0620/62/M/J/20

 3

2 A student investigated the temperature change when aqueous sodium hydroxide neutralises dilute
hydrochloric acid. The equation for the reaction is shown.

NaOH + HCl → NaCl + H2O

Eight experiments were done.

Experiment 1
● A polystyrene cup was placed into a 250 cm3 beaker for support.
● Using a measuring cylinder, 5 cm3 of aqueous sodium hydroxide was poured into the polystyrene
cup.
● Using a measuring cylinder, 45 cm3 of dilute hydrochloric acid was poured into the polystyrene
cup.
● The mixture was stirred and the maximum temperature reached was measured using a
thermometer.
● The polystyrene cup was rinsed with distilled water.

Experiment 2
● Experiment 1 was repeated using 10 cm3 of aqueous sodium hydroxide and 40 cm3 of
dilute hydrochloric acid.

Experiment 3
● Experiment 1 was repeated using 15 cm3 of aqueous sodium hydroxide and 35 cm3 of
dilute hydrochloric acid.

Experiment 4
● Experiment 1 was repeated using 20 cm3 of aqueous sodium hydroxide and 30 cm3 of
dilute hydrochloric acid.

Experiment 5
● Experiment 1 was repeated using 30 cm3 of aqueous sodium hydroxide and 20 cm3 of
dilute hydrochloric acid.

Experiment 6
● Experiment 1 was repeated using 35 cm3 of aqueous sodium hydroxide and 15 cm3 of
dilute hydrochloric acid.

Experiment 7
● Experiment 1 was repeated using 40 cm3 of aqueous sodium hydroxide and 10 cm3 of
dilute hydrochloric acid.

Experiment 8
● Experiment 1 was repeated using 45 cm3 of aqueous sodium hydroxide and 5 cm3 of
dilute hydrochloric acid.

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 4

(a) Use the information in the description of the experiments and the thermometer diagrams to
complete the table.

volume of volume of dilute highest

thermometer
experiment aqueous sodium hydrochloric acid temperature
diagram
hydroxide / cm3 / cm3 reached / °C
30

1 5 25

20

30

2 10 25

20

30

3 15 25

20

30

4 20 25

20

30

5 30 25

20

30

6 35 25

20

30

7 40 25

20

30

8 45 25

20

[4]

© UCLES 2020 0620/63/M/J/20

 5

(b) Plot the results from Experiments 1 to 8 on the grid. Draw two straight lines through the points.
Extend your straight lines so that they cross.

34

32

30

highest
temperature 28
reached / °C

26

24

22
0 5 10 15 20 25 30 35 40 45 50
volume of aqueous sodium hydroxide / cm3
[4]

(c) The point on the graph where the two straight lines cross is where all of the
aqueous sodium hydroxide reacts with all of the dilute hydrochloric acid to form a neutral
solution.

(i) Use your graph to deduce the volume of aqueous sodium hydroxide and the volume of
dilute hydrochloric acid that react together to produce a neutral solution.
Show your working on the grid.

volume of aqueous sodium hydroxide = .............................. cm3

volume of dilute hydrochloric acid = .............................. cm3

[3]

(ii) Use your graph to determine the highest temperature reached if the volumes in (c)(i)
were mixed together.

highest temperature reached = .............................. [2]

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 6

(iii) Which solution, aqueous sodium hydroxide or dilute hydrochloric acid, was the most
concentrated?
Use your answer to (c)(i) to explain why.

most concentrated solution .................................................................................................

explanation .........................................................................................................................

.............................................................................................................................................
[1]

(d) On the graph, sketch the lines you would expect to obtain if a copper can was used instead of
a polystyrene cup. [2]

(e) Give one advantage and one disadvantage of using a burette, instead of a measuring cylinder,
to add the dilute hydrochloric acid directly into the polystyrene cup.

advantage ..................................................................................................................................

....................................................................................................................................................

disadvantage .............................................................................................................................

....................................................................................................................................................
[2]

(f) How could the reliability of the results of this investigation be checked?

....................................................................................................................................................

.............................................................................................................................................. [1]

[Total: 19]

© UCLES 2020 0620/63/M/J/20

 5

2 A student investigated the temperature decrease when sodium hydrogencarbonate reacts with
dilute hydrochloric acid.

The student did six experiments.

Experiment 1
● Using a measuring cylinder, 25 cm3 of dilute hydrochloric acid was poured into a conical flask.
● The initial temperature of the acid was measured using a thermometer.
● 1 g of sodium hydrogencarbonate was added to the conical flask. At the same time a stop-clock
was started.
● The acid and sodium hydrogencarbonate mixture in the conical flask was stirred continuously
using the thermometer.
● The temperature of the mixture after 1 minute was measured.
● The conical flask was rinsed with distilled water.

Experiment 2
● Experiment 1 was repeated using 2 g of sodium hydrogencarbonate instead of 1 g.

Experiment 3
● Experiment 1 was repeated using 3 g of sodium hydrogencarbonate instead of 1 g.

Experiment 4
● Experiment 1 was repeated using 5 g of sodium hydrogencarbonate instead of 1 g.

Experiment 5
● Experiment 1 was repeated using 6 g of sodium hydrogencarbonate instead of 1 g.

Experiment 6
● Experiment 1 was repeated using 7 g of sodium hydrogencarbonate instead of 1 g.

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 6

(a) Use the thermometer diagrams to complete the table and calculate the temperature decreases.

mass of sodium initial temperature temperature

thermometer thermometer
experiment hydrogencarbonate temperature after 1 minute decrease
diagram diagram
/g of acid / °C / °C / °C

30 25

1 1 25 20

20 15

30 25

2 2 25 20

20 15

30 20

3 3 25 15

20 10

30 20

4 5 25 15

20 10

30 20

5 6 25 15

20 10

30 20

6 7 25 15

20 10

[4]

© UCLES 2021 0620/61/M/J/21

 7

(b) Plot the results from Experiments 1 to 6 on the grid.

Draw two best-fit straight lines through your points. The first straight line should be for the first
three points and must pass through (0,0). The second straight line should be for the last three
points and must be horizontal. Extend your straight lines so that they meet each other.

12

10

temperature
decrease / °C
6

0
0 1 2 3 4 5 6 7
mass of sodium hydrogencarbonate / g
[4]

(c) (i) From your graph, determine the temperature decrease and mass of sodium
hydrogencarbonate where your two straight lines meet. Include appropriate units in your
answer.

Show clearly on the grid how you worked out your answer.

temperature decrease = ..............................

mass of sodium hydrogencarbonate = ..............................

[3]

(ii) Explain why the temperature decrease becomes constant for high masses of sodium
hydrogencarbonate.

.............................................................................................................................................

....................................................................................................................................... [1]

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 8

(d) The investigation was repeated with dilute hydrochloric acid of half the concentration, but the
same volume.

Sketch on the grid the graph you would expect to obtain.

Label your line D. [2]

(e) Suggest two changes that could be made to the apparatus that would improve the accuracy of
the results. For each change explain why it would improve the accuracy of the results.

change 1 ....................................................................................................................................

explanation 1 .............................................................................................................................

....................................................................................................................................................

change 2 ....................................................................................................................................

explanation 2 .............................................................................................................................

....................................................................................................................................................
[4]

[Total: 18]

© UCLES 2021 0620/61/M/J/21

 4

2 A student investigated the temperature change when zinc reacted with two different aqueous
solutions of copper(II) sulfate, solution Q and solution R.

Two experiments were done.

(a) Experiment 1

● A polystyrene cup was placed in a 250 cm3 beaker for support.

● Using a measuring cylinder, 25 cm3 of solution Q was poured into the polystyrene cup.
● Using a thermometer, the initial temperature of solution Q was measured.
● 3 g of zinc powder was added to the polystyrene cup. At the same time a stop-clock was
started.
● Using the thermometer, the mixture in the polystyrene cup was continually stirred and the
temperature measured every 30 seconds.

initial temperature in Experiment 1 23 °C

Use the thermometer diagrams and the initial temperature to complete the table.
Calculate the temperature changes using the equation:

temperature change = temperature – initial temperature

time / s 30 60 90 120 150 180 210 240

45 50 55 55 55 55 55 55

thermometer diagram 40 45 50 50 50 50 50 50

35 40 45 45 45 45 45 45

temperature / !C

temperature change / !C

[3]

© UCLES 2021 0620/63/O/N/21

 5

(b) Experiment 2
● The polystyrene cup was washed out with distilled water.
● Experiment 1 was repeated using solution R instead of solution Q.

initial temperature in Experiment 2 24 °C

Use the thermometer diagrams and the initial temperature to complete the table.

time / s 30 60 90 120 150 180 210 240

35 40 45 45 45 45 40 40

thermometer diagram 30 35 40 40 40 40 35 35

25 30 35 35 35 35 30 30

temperature / !C

temperature change / !C

[3]

(c) Complete a suitable scale on the y-axis and plot the results from Experiment 1 and Experiment 2
on the grid. Draw two curves of best fit. Both curves must start at (0,0). Label your curves.

temperature
change / !C

0
0 50 100 150 200 250
time / s
[5]

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 6

(d) From your graph, deduce the temperature change at 110 seconds in Experiment 1.

Show clearly on the grid how you worked out your answer.

.............................. °C
[2]

(e) Predict the temperature of the solution in Experiment 2 after 5 hours. Explain your answer.

....................................................................................................................................................

.............................................................................................................................................. [2]

(f) (i) Suggest why the experiments were done in a polystyrene cup rather than a glass beaker.

....................................................................................................................................... [1]

(ii) Describe how the results would be different if a glass beaker is used in place of the
polystyrene cup.

....................................................................................................................................... [1]

(g) Suggest one change that could be made to the apparatus that would improve the accuracy of
the results. Explain why this change would improve the accuracy of the results.

change .......................................................................................................................................

explanation ................................................................................................................................

....................................................................................................................................................
[2]

[Total: 19]

© UCLES 2021 0620/63/O/N/21

 5

2 A student investigated the temperature change when anhydrous lithium chloride dissolves in water.

The student did six experiments.

(a) Experiment 1
● Using a measuring cylinder, 30 cm3 of distilled water was poured into a 100 cm3 beaker.
● The initial temperature of the water was measured using a thermometer.
● 1.0 g of anhydrous lithium chloride was added to the water in the beaker. At the same time
a timer was started.
● The water and lithium chloride mixture was continually stirred using a thermometer.
● The temperature of the mixture was measured after 30 seconds.
● The beaker was rinsed with distilled water.

Experiment 2
● Experiment 1 was repeated using 1.5 g of anhydrous lithium chloride instead of the 1.0 g
of anhydrous lithium chloride.

Experiment 3
● Experiment 1 was repeated using 2.0 g of anhydrous lithium chloride instead of the 1.0 g
of anhydrous lithium chloride.

Experiment 4
● Experiment 1 was repeated using 2.5 g of anhydrous lithium chloride instead of the 1.0 g
of anhydrous lithium chloride.

Experiment 5
● Experiment 1 was repeated using 3.0 g of anhydrous lithium chloride instead of the 1.0 g
of anhydrous lithium chloride.

Experiment 6
● Experiment 1 was repeated using 4.0 g of anhydrous lithium chloride instead of the 1.0 g
of anhydrous lithium chloride.

© UCLES 2022 0620/62/F/M/22 [Turn over

 6

Use the thermometer diagrams to complete the table and calculate the temperature changes.

mass of initial after 30 seconds

anhydrous temperature
experiment change
lithium chloride thermometer temperature thermometer temperature
/g diagram / !C diagram / !C / !C

30 30

1 1.0 25 25

20 20

30 30

2 1.5 25 25

20 20

30 35

3 2.0 25 30

20 25

30 35

4 2.5 25 30

20 25

30 40

5 3.0 25 35

20 30

30 40

6 4.0 25 35

20 30

[5]

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 7

(b) Complete a suitable scale on the y-axis and plot the results from Experiments 1 to 6 on the
grid.

Draw a straight line of best fit through your points. The straight line must pass through (0,0).

temperature
change / !C

0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
mass of anhydrous lithium chloride / g

[5]

(c) From your graph, deduce the temperature change when 3.2 g of anhydrous lithium chloride
is dissolved in 30 cm3 of distilled water.

Show clearly on the grid how you worked out your answer.

temperature change = .............................. °C [2]

(d) Estimate the temperature change if Experiment 6 is repeated using 60 cm3 of water instead of
30 cm3 of water. Give a reason for your answer.

....................................................................................................................................................

....................................................................................................................................................

.............................................................................................................................................. [2]

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(e) Suggest two changes that could be made to the apparatus to improve the accuracy of the
results. For each change explain why it improves the accuracy of the results.

change 1 ....................................................................................................................................

explanation 1 .............................................................................................................................

....................................................................................................................................................

change 2 ....................................................................................................................................

explanation 2 .............................................................................................................................

....................................................................................................................................................
[4]

[Total: 18]

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4 The energy given out when different liquid alcohols are burned can be compared using the apparatus
shown.

thermometer

test-tube

water

spirit burner
liquid alcohol

Describe how the apparatus shown can be used to compare the amount of energy given out by
three different liquid alcohols, ethanol, propanol and butanol. Your answer should include how the
results can be used to determine which fuel gives out the most energy.

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..................................................................................................................................................... [6]

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reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.

To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.

Cambridge Assessment International Education is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of
Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge.

© UCLES 2021 0620/63/M/J/21