A half-reaction is a part of a chemical reaction that shows either the oxidation or the reduction process separately.
In a redox reaction, electrons are transferred from one substance to another. A half-reaction focuses on only one side of this electron transfer:
- Oxidation half-reaction – shows the substance losing electrons.
- Reduction half-reaction – shows the substance gaining electrons.
By combining the oxidation and reduction half-reactions, you get the complete redox reaction.
Half-reactions are useful because they help track electron flow and are essential in understanding electrochemical cells, batteries, and electrolysis.