9.2 Reactivity Series & Corrosion of Metals

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1a3 marks

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

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. The timer was started and the temperature was measured every half a minute for one minute.

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

Use the thermometer diagrams in the table to record the temperatures.

time / min	thermometer diagram	temperature / ^oC
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0

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1b3 marks

Experiment 2

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

Use the thermometer diagrams in the table to record the temperatures.

time / min	thermometer diagram	temperature / ^oC
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0

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1c5 marks

Plot the results of both experiments on the grid below. Draw two smooth line graphs.

Clearly label your graphs.

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1d3 marks

From your graph, work out the temperature of the reaction mixture in Experiment 1 after 1 minute 15 seconds. Show clearly on the graph how you worked out your answer.

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1e1 mark

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

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1f2 marks

Compare the temperature changes in Experiments 1 and 2.

[1]

ii)

Suggest an explanation for the difference in temperature changes.

[1]

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1g2 marks

Explain how the temperature changes would differ in the experiments if 12.5 cm³ of copper(II) sulfate solution were used.

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1h2 marks

Predict the effect of using lumps of zinc in Experiment 1. Explain your answer.

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2a4 marks

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

Experiment 1

By using a measuring cylinder, 5 cm³ of aqueous copper(II) sulphate 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 tube and magnesium powder to the third tube. The mixtures were stirred with the thermometer. All the observations were recorded and the maximum temperature reached measured.

Use the thermometer diagrams to complete the results table.

Table of results

metal added	initial temperature / ^oC	maximum temperature / ^oC	temperature difference / ^oC	observations
zinc				moderate effervescence, solution paler brown solid
iron				little effervescence, brown solid
magnesium				rapid effervescence, pops with lighted splint, brown solid

How did you do?

2b4 marks

Use your results and observations to answer the following questions.

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

[1]

ii)

Give two reasons why you chose this metal.

1 ....................................................................................................

2 ....................................................................................................

[2]

iii)

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

[1]

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6 marks

The reactions of magnesium and zinc with aqueous copper(II) sulphate were investigated in more detail.

Experiment 2

By using a measuring cylinder 10 cm³ of aqueous copper(II) sulphate was poured into a polystyrene cup. The initial temperature of the solution was measured.

A 1 g sample of zinc powder was added to the cup and the temperature measured every 10 seconds for 1 minute.

Use the thermometer diagrams to complete the results table.

Experiment 3

Experiment 2 was repeated using magnesium powder instead of zinc.

Use the thermometer diagrams to complete the results table.

time / seconds	temperature / ^oC
time / seconds	Experiment 2	Experiment 3
0
10
20
30
40
50
60

How did you do?

2d4 marks

Plot the results of both Experiments on the grid below. Draw two smooth line graphs.

Clearly label the graphs.

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2e2 marks

Use your graph to estimate the temperature of the reaction mixture in Experiment 2 after 5 seconds. Indicate clearly on the graph how you obtained your answer.

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2f2 marks

Sketch lines on the grid to show the predicted results if Experiment 2 were repeated using:

larger pieces of magnesium;

ii)

iron powder.

Clearly label the lines.

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2g1 mark

Why is a polystyrene cup used instead of a glass container?

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2h1 mark

Suggest one improvement to the method in Experiment 2.

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12 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 any observations were recorded in the table.

Use the thermometer diagrams to complete the results table.

Table of results

[6]

ii)

Which metal is most reactive with sulfuric acid?

[1]

iii)

Give two reasons why you chose this metal.

1. ....................................................................................................

2. ....................................................................................................

[2]

iv)

Name the gas given off.

[1]

Experiment 2

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

Magnesium powder was added to the test-tube and the maximum temperature reached was measured.

Use the thermometer diagrams to complete the results table.

Table of results

[2]

How did you do?

4b1 mark

How do your observations show that the reaction of magnesium with aqueous copper(II) sulphate is exothermic?

How did you do?

4c1 mark

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

least reactive ..............................................................................

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

most reactive ..............................................................................

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CIE IGCSE Chemistry

Topic Questions

9.2 Reactivity Series & Corrosion of Metals