May/June 2026 Paper 61

2026 · 4 questions · 22 parts · 40 marks

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1(a)(i)1(a)(ii)1(b)(i)1(b)(ii)1(b)(iii)1(c)(i)1(c)(ii)

–/8 mks

2(a)2(b)2(c)2(d)2(e)2(f)(i)2(f)(ii)2(g)2(h)

–/18 mks

3(a)3(b)3(c)3(d)(i)3(d)(ii)

–/8 mks

–/6 mks

Context for question 2

A student investigates the temperature change when citric acid reacts with sodium carbonate. The student does five experiments.

Experiment 1

Use a 10 $cm^{3}$ measuring cylinder to pour 1.0 $cm^{3}$ of distilled water into a boiling tube.
Use a thermometer to measure the initial temperature of the distilled water.
Record this temperature to the nearest $0.5^{\circ} C$ .
Add 4 g of solid citric acid and 4 g of solid sodium carbonate to the boiling tube.
Stir the contents of the boiling tube with the thermometer and measure the lowest temperature reached by the mixture.
Record this temperature to the nearest $0.5^{\circ} C$ .
Rinse out the boiling tube with distilled water.

Experiment 2

Repeat Experiment 1 using 2.0 $cm^{3}$ of distilled water instead of 1.0 $cm^{3}$ .

Experiment 3

Repeat Experiment 1 using 4.0 $cm^{3}$ of distilled water instead of 1.0 $cm^{3}$ .

Experiment 4

Repeat Experiment 1 using 6.0 $cm^{3}$ of distilled water instead of 1.0 $cm^{3}$ .

Experiment 5

Repeat Experiment 1 using 8.0 $cm^{3}$ of distilled water instead of 1.0 $cm^{3}$ .

2(a)Medium5 marks

Complete Table 2.1, using the information in the descriptions of the experiments and the thermometer diagrams. Calculate the temperature decrease using the equation shown.

temperature decrease = initial temperature - lowest temperature

Table 2.1, five rows for Experiments 1 to 5 with columns experiment, volume of distilled water / cm3, initial temperature / degrees Celsius (21.0, 21.0, 21.5, 21.5, 22.0), thermometer diagram for lowest temperature, lowest temperature / degrees Celsius and temperature decrease / degrees Celsius; only the 1.0 cm3 of Experiment 1 is filled in and each row shows a thermometer with its liquid level, the other cells are empty.

Your answer

2(b)Medium4 marks

On Figure 2.1, write a suitable scale on the

y

-axis, and plot the results from Experiments 1 to 5. Draw a line of best fit.

Draw with the mouse or a finger.

2(c)Medium1 mark

State if the energy change in the reaction is exothermic or endothermic. Use the results in Table 2.1 to explain your answer.

2(d)Medium2 marks

Use your graph in Figure 2.1 to predict the temperature decrease if the experiment is repeated using 5.5 cm

^{3}

of distilled water. Show your working on Figure 2.1.

temperature decrease =

2(e)Easy1 mark

Describe the relationship between the volume of distilled water and the temperature decrease.

Your answer

2(f)(i)Medium2 marks

Explain why wrapping the boiling tube in cotton wool would improve the accuracy of the results.

Your answer

2(f)(ii)Easy1 mark

Explain why placing the boiling tube in a water-bath at room temperature would not improve the accuracy of the results.

Your answer

2(g)Easy1 mark

Explain why the volume of distilled water was measured using a 10

cm^{3}

measuring cylinder rather than a 25

cm^{3}

measuring cylinder.

Your answer

2(h)Easy1 mark

On Figure 2.1, sketch the graph obtained if all of the experiments were repeated using 2 g of solid citric acid and 2 g of solid sodium carbonate.

Draw with the mouse or a finger.