Seneca
Sign up

Redox Reactions - Oxidation

Chemistry: AQA GCSE Higher, topic 4.1.2

Oxidation and Reduction

Oxidation is the gaining of oxygen in a reaction and reduction is the loss of oxygen in a reaction. We can also describe oxidation and reduction in terms of electrons:

Oxidation

Oxidation

  • When a substance is oxidised (gains oxygen), it always loses electrons.
Reduction

Reduction

  • When a substance is reduced (loses oxygen), it always gains electrons.
OIL RIG

OIL RIG

  • A useful way of remembering the difference between oxidation and reduction reactions in terms of electrons is 'OIL RIG':
  • Oxidation
  • Is
  • Loss
  • Reduction
  • Is
  • Gain

Test yourself on Redox Reactions - Oxidation

  • Mg(s) + 2H+(aq) + 2Cl-(aq) → Mg2+(aq) + 2Cl-(aq) + H2(g)
    In this ionic equation, what's being oxidised and what's being reduced?

  • What type of reaction is happening to the zinc atoms?

  • 2Mg + O2 → 2MgO.

    Magnesium atoms lose electrons to form Mg2+ ions, and oxygen atoms gain electrons to form O2- ions.

  • What happens to a substance when it is reduced?

  • Zinc reacts with copper sulfate solution: Zn + CuSO4 → ZnSO4 + Cu. Zinc atoms lose electrons to form Zn2+ ions, and copper ions gain electrons to form copper atoms.

Practise this topic for free