February/March 2026 Paper 62

2026 · 4 questions · 27 parts · 40 marks

0/40 marks

0Correct0Partial0Wrong27Unattempted

Filters0 active

Questions

Select a part to jump to its question

Finish set

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

–/7 mks

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

–/17 mks

3(a)3(b)3(c)3(d)3(e)3(e)(i)3(e)(ii)3(f)3(g)

–/10 mks

–/6 mks

Context for question 2

A student investigates the time taken to make 50 cm

^{3}

of carbon dioxide gas when solid sodium hydrogencarbonate reacts with dilute citric acid of different concentrations.

sodium hydrogencarbonate + citric acid

\to

sodium citrate + water + carbon dioxide

The student does five experiments using the apparatus shown in Figure 2.1.

Figure 2.1: a 250 cm3 conical flask with a stopper and rubber delivery tube leading under water in a trough to an inverted 50 cm3 measuring cylinder held in a clamp

Experiment 1

Use a 50 cm $^{3}$ measuring cylinder to pour 50 cm $^{3}$ of dilute citric acid into a 250 cm $^{3}$ conical flask.
Use a 100 cm $^{3}$ measuring cylinder to pour 55 cm $^{3}$ of distilled water into the conical flask.
Swirl the flask to mix the contents.
Set up the apparatus as shown in Figure 2.1. Ensure the inverted measuring cylinder is full of water.
Remove the stopper from the conical flask. Ensure the delivery tube remains in the inverted measuring cylinder.
Add 1.5 g of solid sodium hydrogencarbonate to the conical flask. Do not mix the contents of the flask. Immediately replace the stopper and start the stop-watch.
Measure the time taken to collect 50 cm $^{3}$ of gas in the inverted measuring cylinder. Record the time in seconds, to the nearest whole number.
Rinse the conical flask with distilled water.

Experiment 2

Repeat Experiment 1, using 50 cm $^{3}$ of distilled water instead of 55 cm $^{3}$ .

Experiment 3

Repeat Experiment 1, using 45 cm $^{3}$ of distilled water instead of 55 cm $^{3}$ .

Experiment 4

Repeat Experiment 1, using 40 cm $^{3}$ of distilled water instead of 55 cm $^{3}$ .

Experiment 5

Repeat Experiment 1, using 30 cm $^{3}$ of distilled water instead of 55 cm $^{3}$ .

2(a)Medium3 marks

Use the information in the descriptions of the experiments and the stop-watch diagrams to complete Table 2.1.

Table 2.1: rows for Experiments 1 to 5 with a stop-watch dial drawn for each, only the 50 cm3 of dilute citric acid for Experiment 1 filled in, and the volume of distilled water and time to collect 50 cm3 of gas columns empty

Completed table (volumes and times for Experiments 1-5)

2(b)Medium4 marks

On Figure 2.2, 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)

The mean rate of reaction is calculated using the equation shown.

mean rate of reaction = \frac{volume of gas collected}{time taken to collect the gas}

2(c)(i)Easy2 marks

Calculate the mean rate of reaction in Experiment 3.

Give units for the mean rate of reaction you have calculated.

Mean rate of reaction

Units

2(c)(ii)Medium2 marks

Use your graph in Figure 2.2 to deduce the time taken to collect 50 cm

^{3}

of gas if 35 cm

^{3}

of water is used.

Show clearly on Figure 2.2 how you worked out your answer.

time to collect 50 cm

^{3}

of gas =

2(d)Medium2 marks

The gas collected in the inverted measuring cylinder contains air from the conical flask.

State what effect, if any, this air will have on the accuracy of the results of the investigation. Explain your answer.

Effect on accuracy

Explanation

2(e)

Some gas escapes in the short time between adding the solid sodium hydrogencarbonate to the conical flask and replacing the stopper in the conical flask.

2(e)(i)Medium2 marks

Explain how the apparatus can be changed so that no gas escapes. You may draw a diagram to help explain your answer.

Your answer

2(e)(ii)Easy1 mark

State the effect, if any, the gas escaping has on the time taken to collect 50 cm

^{3}

of gas compared to if the apparatus was changed so that no gas escapes.

2(f)Easy1 mark

On Figure 2.2, sketch the graph you would expect when the investigation is repeated using dilute citric acid of different concentrations at 50

^{\circ}

C instead of at room temperature.

Label this line F.

Draw with the mouse or a finger.