1. Identify the oxidation and reduction:
* Oxidation: Loss of electrons (increase in oxidation number)
* Reduction: Gain of electrons (decrease in oxidation number)
In the reaction 2Mg + O₂ → 2MgO:
* Magnesium (Mg) goes from an oxidation state of 0 (elemental form) to +2 in MgO. This is oxidation.
* Oxygen (O₂) goes from an oxidation state of 0 (elemental form) to -2 in MgO. This is reduction.
2. Write the oxidation half-reaction:
The oxidation half-reaction focuses only on the species that is being oxidized.
* Mg → Mg²⁺ + 2e⁻
Explanation:
* Magnesium (Mg) loses two electrons to become a magnesium ion (Mg²⁺).
* The "2e⁻" represents the two electrons that are lost in the oxidation process.
Important Note: Half-reactions must be balanced in terms of both atoms and charge. The oxidation half-reaction above is already balanced.
