IGCSE Chemistry 0620 Revision Questions

(i) Solid aluminium oxide is a poor conductor of electricity. It conducts either when molten or when dissolved in molten cryolite. Explain why.

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(ii) Why is a solution of aluminium oxide in molten cryolite used rather than molten aluminium oxide?

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(iii) Explain why the carbon anodes need to be replaced periodically

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(iv) One reason why graphite is used for the electrodes is that it is a good conductor of electricity. Give another reason.

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(b) Aluminium is used to make food containers because it resists corrosion. Explain why it is not attacked by the acids in food.

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(c) Aluminium is used for overhead power (electricity) cables which usually have a steel core.

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(i) Give two properties of aluminium which make it suitable for this use.

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(ii) Explain why the cables have a steel core.

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Which change is an oxidation?

• FeO to Fe2O

• Fe2O3 to FeO

• H2O2 to H2O

• H2O to H2

Which change does not increase the speed of reaction between zinc and hydrochloric acid?

• adding a catalyst

• decreasing the particle size of the zinc

• decreasing the temperature

• using more concentrated acid