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.

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

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

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

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

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

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

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

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