A clear visual guide to oxidation, reduction and redox reactions, using the reversible conversion between copper and copper(II) oxide as an accessible experimental example.

The resource follows the reaction visually from orange-red copper powder to black copper(II) oxide and back to orange-red copper, allowing students to see oxidation and reduction as opposite processes.

The poster covers:

Oxidation of copper in air – copper powder is strongly heated and reacts with oxygen to form black copper(II) oxide.
Reduction of copper(II) oxide by hydrogen – hydrogen is passed over heated copper(II) oxide, producing copper and water.
Balanced equations with state symbols for both reactions.
Half-equations showing oxidation as loss of electrons and reduction as gain of electrons.
Changes in the oxidation state of copper: 0 → +2 → 0.
The relationship between the traditional oxygen-transfer definitions and the electron-transfer definitions of oxidation and reduction.

The visual colour cycle:

orange-red Cu → black CuO → orange-red Cu

helps students connect the experimental observations with the underlying redox chemistry.

A final summary reinforces:

Oxidation = gain of oxygen / loss of electrons
Reduction = loss of oxygen / gain of electrons

Suitable for GCSE, IGCSE and A-level Chemistry, the resource can be used for introducing redox, practical demonstrations, revision or classroom display.

A QR code links to FranklyChemistry, where students can view the corresponding animated experiment and explore further chemistry resources.