Chemistry · Oct / Nov 2018 · Paper 11 · Question 29

An old commercial process for aluminium extraction used large quantities of sodium to convert aluminium ions into aluminium atoms. The modern aluminium extraction process uses electrolysis. Which statements are correct? In the old process: 1 The sodium acted as an oxidising agent. 2 The reaction worked because sodium is more reactive than aluminium. In the modern process: 3 The equation for the cathode reaction is Al³⁺(l) + 3e⁻ → Al(l). 4 The carbon anode needs replacing often because it is oxidised to carbon dioxide by the oxygen evolved.

1. A1 and 2 3 and 4
2. B1 and 2 3 only
3. C1 only 4 only
4. D2 only 3 and 4

As printed in the paper