This exam focus covers Worked Model Answer within Electrolysis of Aluminium for GCSE Chemistry. Revise Electrolysis of Aluminium in Electrolysis for GCSE Chemistry with 21 exam-style questions and 14 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 12 of 13 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
📝 Worked Model Answer
Question: "Explain why aluminium is extracted by electrolysis rather than carbon reduction." (4 marks)
Aluminium is more reactive than carbon, so it sits above carbon in the reactivity series. [1] This means carbon is not reactive enough to displace aluminium from its oxide — carbon cannot reduce aluminium oxide. [1] Electrolysis is used instead, which uses electrical energy to decompose the aluminium oxide: aluminium ions gain electrons at the cathode (Al³⁺ + 3e⁻ → Al). [1] To allow the ions to move, the aluminium oxide is dissolved in molten cryolite, which reduces the operating temperature from 2072°C to approximately 950°C, significantly reducing energy costs. [1]
Examiner note: The four marks correspond to: Al is more reactive than carbon, carbon cannot reduce Al₂O₃, electrolysis decomposes the oxide (with cathode equation or mechanism), and the role of cryolite in lowering the melting point. Simply stating "electrolysis is used because carbon doesn't work" earns only 1 mark. The cryolite point is often missed — it is a stand-alone mark that rewards students who understand the practical challenge of the high melting point.
→ See also: Electrolysis of Aqueous Solutions — what happens when water is present and ions compete for discharge.
Practice questions for Electrolysis of Aluminium
Why is aluminium extracted by electrolysis rather than by reduction with carbon?
Explain why aluminium is extracted by electrolysis rather than by reduction with carbon.