Oxidation & Reduction (Oxford AQA International A Level Chemistry)

Oxidation & Reduction

• There are three definitions of oxidation and reduction  used in different branches of chemistry

• The different definitions of oxidation and reduction, with an example are shown below:

• We will focus on oxidation and reduction in terms of electrons

• In order to remember the definition in terms of electrons, we can use the phrase, OIL RIG

• A redox reaction is one in which oxidation and reduction occur simultaneously

  • E.g. The reaction between copper oxide and magnesium

    CuO (s) + Mg (s) → Cu (s) + MgO (s)

Cu²⁺ + 2e^- → Cu

Mg - 2e^- → Mg²⁺

• Copper gains electrons so has been reduced

• Magnesium loses electrons so has been oxidised

Oxidising & Reducing Agents

Oxidising agents

• An oxidising agent is a substance that oxidises another atom or ion by causing it to lose electrons

• An oxidising agent itself gets reduced – it gains/accepts electrons

• Oxidising agents can therefore be referred to as electron acceptors

• The oxidation state of an oxidising agent will decrease

Reducing agents

• A reducing agent is a substance that reduces another atom or ion by causing it to gain electrons

• A reducing agent itself gets oxidised – loses/donates electrons

• Reducing agents an be referred to as electron donors

• The oxidation state of a reducing agent will increase