A-Level Chemistry: Redox & Electrochemistry Revision

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What is reduction in terms of electrons?

Redox & Electrochemistry is a core part of A-Level Chemistry. Revise the key concepts and common mistakes below, then lock them in with the free games.

Key concepts

OxidationLoss of electrons; oxidation number increases.

ReductionGain of electrons; oxidation number decreases.

Oxidation numberA value showing how oxidised an atom is in a species.

Half-equationsShow electron loss or gain at each part of a redox reaction.

Oxidising & reducing agentsSpecies that accept or donate electrons.

Redox titrationUses a redox reaction to find an unknown concentration.

Oxidation & reductionElectron loss and gain (OIL RIG).

Electrode potentialTendency of a half-cell to gain electrons, measured against hydrogen.

Electrochemical cellTwo half-cells producing an EMF from a redox reaction.

ElectrolysisUsing electricity to drive a non-spontaneous redox reaction.

What your exam board covers

Where Redox & Electrochemistry sits in each exam board's specification. Tap a board to see what it lists.

EdexcelTopic 3: Redox ISpec 9CH0

Part of: Redox and inorganic chemistry / the periodic table groups

Source: Pearson Edexcel A-Level Chemistry (9CH0) specification, accessed 23 June 2026.

Eduqas/WJECPI1 — ElectrochemistrySpec A410QS (QAN 601/5645/4)

Redox and standard electrode potential
Redox reactions

Source: Eduqas/WJEC A-Level Chemistry specification (from 2015), accessed 24 June 2026.

Learn Redox & Electrochemistry step by step

Free interactive mini-lessons: short screens, worked examples and quick checks. Pick your exam board:

Other boards:CCEA OCR

Common mistakes to avoid

Questions where students often pick the tempting wrong answer — make sure you know the right one:

What is reduction in terms of electrons?✗ Reduction means losing oxygen and oxidation means gaining oxygen — full stop. ✓ Gain of electrons (the oxidation number is reduced).

In a standard hydrogen electrode used as a reference, what is the assigned electrode potential?✗ The standard hydrogen electrode actually has zero potential because hydrogen has no charge. ✓ Exactly 0 V by convention — all other electrode potentials are measured relative to it.

Is the oxidation state of an atom the same as its actual charge?✗ The oxidation state of an atom is exactly equal to its real ionic charge in every compound. ✓ Not necessarily — oxidation state is an accounting tool assuming all bonds are fully ionic; real charge is usually smaller.

OIL RIG: oxidation is.✗ Gain of electrons ✓ Loss of electrons

Practise Redox & Electrochemistry — free games

Test yourself with these quick revision games for this topic:

▶ Two Truths, One Lie ▶ Reveal Race ▶ Connections Grid ▶ Falling Words ▶ Word Web

See all 22 games in the Revision Arcade →

Redox & Electrochemistry

Key concepts

What your exam board covers

Common mistakes to avoid

Practise Redox & Electrochemistry — free games

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