Chemistry · May / June 2022 · Paper 12 · Question 17

Aluminium can be extracted by the electrolysis of aluminium oxide dissolved in molten cryolite. Which reactions take place during the electrolysis?

1. Areaction at the anode: Al⁺ + e⁻ → Al; reaction at the cathode: O²⁻ + 2e⁻ → O
2. Breaction at the anode: Al³⁺ + 3e⁻ → Al; reaction at the cathode: 2O²⁻ + 4e⁻ → O₂
3. Creaction at the anode: O²⁻ − 2e⁻ → O; reaction at the cathode: 3Al⁺ + 3e⁻ → 3Al
4. Dreaction at the anode: 2O²⁻ − 4e⁻ → O₂; reaction at the cathode: Al³⁺ + 3e⁻ → Al

As printed in the paper