# Iron rusting is an example of a redox reaction. Explain what is meant by a redox reaction and describe what happens to iron and oxygen in terms of electrons and oxidation states during rusting.

> AQA A-Level Chemistry (7405) — 3.1.7 Oxidation, reduction and redox equations · Explain · 5 marks

> Iron reacts with oxygen and water to form iron(III) oxide, commonly known as rust. The overall process involves the transfer of electrons between species.

## Mark scheme (5 marks)

1. A redox reaction is one in which both oxidation and reduction occur simultaneously
2. Iron loses electrons during rusting (iron is oxidised)
3. Oxygen gains electrons during rusting (oxygen is reduced)
4. The oxidation state of iron increases (e.g. from 0 to +3) during rusting
5. The oxidation state of oxygen decreases (e.g. from 0 to −2) during rusting

## Key terms

- [redox reaction](https://www.gradenine.co.uk/glossary/redox-reaction)
- [oxidation](https://www.gradenine.co.uk/glossary/oxidation)
- [oxidation state](https://www.gradenine.co.uk/glossary/oxidation-state)

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/iron-rusting-is-an-example-of-1f09083c) · Published by Druglandscape Ltd.