O LevelChemistryCambridge (CIE)Exam Questions9. Metals9.4 Reactivity Series

Reactivity Series (Cambridge (CIE) O Level Chemistry): Alternative to Practical Questions

Exam code: 5070

2 hours30 questions

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9.4 Reactivity Series

1a
2 marks

A student investigated the reaction between aqueous copper(II) sulfate and two different metals, zinc and iron.

Experiment 1

Using a measuring cylinder, 25 cm3 of aqueous copper(II) sulfate was poured into a polystyrene cup. The temperature of the solution was measured every half minute for one minute.

At 1 minute, 5 g of zinc powder was added to the cup and the mixture was stirred with the thermometer. The temperature was then measured every half minute for a further three minutes.

Experiment 2

Experiment 1 was repeated using 5 g of iron powder instead of the zinc powder.

The temperatures recorded in both experiments are shown in the table.

time / min

temperature in Experiment 1, zinc / oC

temperature in Experiment 2, iron / oC

0.0

20

20

0.5

21

21

1.0

21

21

1.5

32

24

2.0

39

32

2.5

42

36

3.0

44

37

3.5

45

38

4.0

45

38

Calculate the overall temperature rise in each experiment.

How did you do?

1b
5 marks

Plot the results of both experiments on the grid.

Draw a smooth line graph for each experiment and label your graphs clearly.

A blank grid for plotting a line graph. The horizontal axis is labelled time / min and runs from 0 to 4, with numbered divisions every 0.5 and fine divisions every 0.1. The vertical axis is labelled temperature / degrees Celsius and runs from 0 to 60, with numbered divisions every 10 and fine divisions every 2.

How did you do?

1c
3 marks

Use your graph to find the temperature of the reaction mixture in Experiment 1 after 1 minute 15 seconds.

Show clearly on the graph how you obtained your answer.

How did you do?

1d
1 mark

What type of chemical process occurs when zinc and iron react with aqueous copper(II) sulfate?

How did you do?

1e
2 marks

i)

Compare the temperature changes in Experiments 1 and 2.

[1]

ii)

Suggest an explanation for the difference in the temperature changes.

[1]

How did you do?

2a
4 marks

An investigation was carried out into the reactions of aqueous copper(II) sulfate with magnesium, iron and zinc.

Experiment 1

Using a measuring cylinder, 5 cm3 of aqueous copper(II) sulfate was added to each of three test-tubes. The initial temperature of the solution was measured. Zinc powder was added to the first test-tube, iron powder to the second and magnesium powder to the third. The mixtures were stirred with the thermometer. The observations were recorded and the maximum temperature reached was measured.

Use the thermometer diagrams to complete the results table.

metal added

initial temperature / oC

maximum temperature / oC

temperature difference / oC

observations

zinc

A thermometer with a vertical scale marked in degrees Celsius and a shaded liquid column to be read against the scale
A thermometer with a vertical scale marked in degrees Celsius and a shaded liquid column to be read against the scale

moderate effervescence, solution paler, brown solid

iron

A thermometer with a vertical scale marked in degrees Celsius and a shaded liquid column to be read against the scale
A thermometer with a vertical scale marked in degrees Celsius and a shaded liquid column to be read against the scale

little effervescence, brown solid

magnesium

A thermometer with a vertical scale marked in degrees Celsius and a shaded liquid column to be read against the scale
A thermometer with a vertical scale marked in degrees Celsius and a shaded liquid column to be read against the scale

rapid effervescence, pops with a lighted splint, brown solid

How did you do?

2b
4 marks

Use your results and observations to answer the following questions.

i)

Which metal is the most reactive with aqueous copper(II) sulfate?

[1]

ii)

Give two reasons why you chose this metal.

[2]

iii)

Identify the gas given off when magnesium reacts with aqueous copper(II) sulfate.

[1]

How did you do?

2c
1 mark

Suggest one improvement to the method used in Experiment 1.

How did you do?

3a
2 marks

An investigation was carried out on the reactions of four different metals. Equal masses of copper, magnesium, iron and zinc were used.

Experiment 1

A 15 cm3 sample of dilute sulfuric acid was added to each of four boiling tubes. The initial temperature of the acid was measured. Zinc was added to the first tube, iron to the second tube, magnesium to the third tube and copper to the fourth tube.

The maximum temperature reached in each tube was measured and the observations were recorded.

Complete the table by calculating the temperature difference for each metal.

metal added

initial temperature / oC

maximum temperature / oC

temperature difference / oC

observations

zinc

18

23

gas given off slowly

iron

21

24

gas given off very slowly

magnesium

19

79

gas given off rapidly, lighted splint pops

copper

22

22

no visible reaction

How did you do?

3b
3 marks

Which metal is the most reactive with dilute sulfuric acid?

Give two reasons for your choice.

How did you do?

3c
1 mark

Name the gas given off when these metals react with dilute sulfuric acid.

How did you do?

3d
1 mark

Experiment 2

A 5 cm3 sample of aqueous copper(II) sulfate was measured into a test-tube. The initial temperature of the solution was 21 oC.

Magnesium powder was added to the test-tube. The maximum temperature reached was 39 oC.

How do these results show that the reaction between magnesium and aqueous copper(II) sulfate is exothermic?

How did you do?

3e
1 mark

Use your results from Experiments 1 and 2 to put the four metals in order of reactivity.

Write the least reactive metal first.

How did you do?