This exam focus covers Worked Model Answer within Electrolysis of Aluminium for GCSE Chemistry. Revise Electrolysis of Aluminium in Electrolysis for GCSE Chemistry with 20 exam-style questions and 0 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. 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.
Topic position
Section 12 of 13
Practice
20 questions
Recall
0 flashcards
📝 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.