ElectrolysisHow It Works
The Hall-Héroult Process — Step by Step
Part of Electrolysis of Aluminium — GCSE Chemistry
This how it works covers The Hall-Héroult Process — Step by Step 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 5 of 12 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 5 of 12
Practice
20 questions
Recall
0 flashcards
⚙️ The Hall-Héroult Process — Step by Step
- Mine bauxite ore and purify it to extract pure aluminium oxide (Al₂O₃)
- Dissolve Al₂O₃ in molten cryolite at ~950°C (cryolite lowers melting point, saving energy and money)
- Pass DC electricity through the molten mixture using carbon electrodes
- At the CATHODE (−): Al³⁺ ions gain 3 electrons → molten aluminium metal sinks to the bottom of the cell
- At the ANODE (+): O²⁻ ions lose 2 electrons → oxygen gas bubbles off
- Oxygen reacts with carbon anodes: C + O₂ → CO₂ (anodes burn away and need replacing)
- Tap off molten aluminium from the bottom of the cell