Cambridge IGCSE Chemistry · Syllabus 0620 · Electrochemistry
Reduction
What is Reduction?
The gain of electrons by a species. In electrolysis it happens at the cathode, where positive ions arriving from the electrolyte take electrons from the electrode and are released as neutral atoms; in a half-equation the electrons are written on the left-hand side.
This definition is part of the Electrochemistry chapter in Cambridge IGCSE Chemistry.
Common mistakes with Reduction
- 4. "Oxidation is gain of electrons." Supplement 4.1.11 Repair Oxidation is loss of electrons and happens at the anode; reduction is gain of electrons and happens at the cathode — write the full words, then check the side your electrons are on. Taught in Lesson F.
- 8. "Connect the spoon you want to plate to the positive terminal." Core 4.1.7 Repair The cathode is the electrode where metal from the solution is deposited, so the object being plated is the negative cathode and the coating metal is the positive anode. Connected the other way round, the object is the electrode that dissolves. Extended candidates can add the electron reason: depositing a metal ion is a reduction, and reduction happens at the cathode Supplement 4.1.11 Taught in Lesson I.