Contents
Key Stage 4 Foundation
Meaning
A redox reaction is a chemical reaction in which Oxygen is lost from one compound (Reduction) and gained by another compound (Oxidation).
About Redox Reactions
- Displacement reactions between metals and metal oxides are a type of redox reaction.
- During a redox reaction a less reactive metal in a metal oxide is displaced by the more reactive metal element.
In the following redox reaction:
- Aluminium + Iron Oxide → Aluminium Oxide + Iron
- <chem>2Al+Fe2O3->Al2O3+2Fe</chem>
The Aluminium is oxidised and the Iron is reduced.
Key Stage 4 Higher
Meaning
A redox reaction is a chemical reaction in which ions of a less reactive metal gain electrons (Reduction) and atoms of a more reactive metal lose electrons (Oxidation).
About Redox Reactions
- Displacement reactions between metals and metal compounds are a type of redox reaction.
- During redox reaction the less reactive metal ion is reduced when it gains electrons and the more reactive metal element is oxidised when it loses electrons.
Redox Reactions can be described by two half equations.
- Aluminium + Iron Oxide → Aluminium Oxide + Iron
- Oxidation of Aluminium: <chem>Al - 3e^- -> Al^3+</chem>
- Reduction of Iron: <chem>Fe^3+ + 3e^- -> Fe</chem>
To remember whether electrons are gained or lost the acronym OIL RIG can be used: Oxidation is lost, Reduction is gained.
References
AQA
- Redox reactions, page 205, GCSE Combined Science Trilogy 1, Hodder, AQA
- Redox reactions, page 57, GCSE Chemistry; The Revision Guide, CGP, AQA
- Redox reactions, pages 103, 111, GCSE Chemistry, Hodder, AQA
- Redox reactions, pages 139-141, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
- Redox reactions, pages 164-166, GCSE Chemistry, CGP, AQA