Aluminium is extracted by electrolysing aluminium oxide dissolved in molten cryolite. The molten electrolyte contains aluminium ions, Al3+\text{Al}^{3+}Al3+, and oxide ions, O2−\text{O}^{2-}O2−.
Write a balanced half equation for the reaction at the positive electrode. Explain why this reaction is an oxidation.
76 exam-style questions on AQA GCSE Chemistry 4.3 Electrolysis, covering 4.3.1a The process of electrolysis, 4.3.1b Half equations in electrolysis, 4.3.2 Electrolysis of molten ionic compounds, 4.3.3 Using electrolysis to extract metals, 4.3.4 Electrolysis of aqueous solutions, and 4.3.5 Representation of reactions at electrodes as half equations. Each one has a worked solution and a mark scheme showing where the marks go.