A classic example of a redox (reduction-oxidation) reaction is the reaction between hydrogen gas (H₂) and oxygen gas (O₂) to form water (H₂O).

Here’s the reaction:

2H₂ + O₂ → 2H₂O

In this reaction, hydrogen is oxidized and oxygen is reduced.

• Oxidation is the loss of electrons. In this case, each hydrogen atom (H) loses one electron, thus being oxidized.
• Reduction is the gain of electrons. Here, the oxygen molecule (O₂) gains electrons, thus it is reduced.

During the reaction, hydrogen atoms give up electrons (oxidation) and these electrons are accepted by the oxygen atoms (reduction). This transfer of electrons is what drives the reaction. The result is water, where the hydrogen and oxygen are chemically bonded, having shared electrons.

This reaction is fundamental in chemistry and is also a basis for understanding energy release, as it occurs in combustion and cellular respiration.