Chemistry 5070 · O Level · Extraction of metals

Extraction of metals — practice question

Aluminium is obtained by means of the electrolysis of molten aluminium oxide.
(a(i))[1]

Explain why aluminium is obtained by electrolysis rather than by reduction with carbon.

(a(ii))[1]

The electrolyte is a blend of aluminium oxide and cryolite. Explain the purpose of the cryolite.

(a(iii))[1]

At the positive electrode (anode), oxide ions are changed into oxygen. Construct the equation for this reaction.

(b(i))[1]

Aluminium can also be made on a small scale by reacting aluminium oxide with magnesium. $\text{Al}_2\text{O}_3 + 3\text{Mg} \rightarrow 2\text{Al} + 3\text{MgO}$ Use this equation to explain why the Al$_2$O$_3$ is reduced.

(b(ii))[2]

Calculate the greatest mass of aluminium formed when 25.5 g of aluminium oxide reacts with excess magnesium.

(c)[2]

Aluminium is a metal. Use your knowledge of metallic structure to explain why aluminium is malleable.

(d)[2]

When aluminium is heated in chlorine, aluminium chloride is produced. The reaction is exothermic. Explain, in terms of bond making and bond breaking, why this reaction is exothermic.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: aluminium is high in the reactivity series / gains electrons less readily

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI