GCSE Chemistry · Edexcel 1CH0 · Topic 3C
Electrolysis
Key points
- Electrolysis splits an ionic compound using electricity. The electrolyte must be molten or dissolved so the ions can move.
- Cations (positive) go to the cathode (negative electrode) and gain electrons: reduction. Anions go to the anode and lose electrons: oxidation.
- Molten compounds: the metal forms at the cathode and the non-metal at the anode, e.g. lead bromide gives lead and bromine.
- In solutions: hydrogen forms at the cathode if the metal is more reactive than hydrogen; oxygen forms at the anode unless a halide is present.
- Core practical: electrolysis of copper sulfate with inert electrodes, and with copper electrodes (the anode loses mass, the cathode gains mass), used to purify copper.
- Higher tier: write half equations, e.g. and .
Topic notesPremium
Electrolysis uses a direct current to break down ionic compounds. It is used to extract reactive metals, purify copper and make chlorine. These notes cover how electrolysis works, predicting products from molten and dissolved compounds, the…
Unlock the full notes with Premium
Premium includes full topic notes, the paper generator, self-quizzes and progress tracking.
Practise this topicPremium
Premium members can generate an exam-style paper with a mark scheme, or take a quick quiz, on Electrolysis.