2Mg+ O₂ →   2MgO

0           0             +2 -2

The diagram above shows that Mg to Mg ²+ is oxidation (reducing agent)

O₂ to O²– reduction occurs (oxidizing agent)

Half equation

Some reactions maybe written in 2 halves (the oxidation half and the reduction half). The 2 parts are called the half equations.

2Mg+ O₂ →  2MgO

Oxidation                                                                       reduction

2Mg -4e-   →     2Mg²+                                                                                          O₂ +4e-   →       2O²–

Electrons are lost                                                                                          electrons are gained

Redox Reaction

Zn + CuSO₄ →  ZnSO₄ +Cu

0      +2              +2                0

Half equations

Oxidation: Zn -2e-      →      Zn ²+     reducing agent

Reduction: Cu ²+ +2e-    →     Cu   oxidizing agent

Try:

Zn + H₂SO₄ →    ZnSO₄ +H₂