Decomposition Reaction Definition

Decomposition Reaction Meaning and Examples

Iiquids in beakers
In a decomposition reaction, one reactant yields two or more products. Adrianna Williams/Getty Images

A decomposition reaction is a type of chemical reaction where one reactant yields two or more products.

The general form for a decomposition reaction is

AB → A + B

Decomposition reactions are also known as analysis reactions or a chemical breakdown. The opposite of this type of reaction is a synthesis, in which simpler reactants combine to build a more complex product.

You can recognize this type of reaction by looking for a single reactant with multiple products.

Decomposition reactions may be undesirable in certain circumstances, but they are intentionally caused and analyzed in mass spectrometry, gravimetric analysis, and thermogravimetric analysis.

Decomposition Reaction Examples

Water can be separated by electrolysis into hydrogen gas and oxygen gas through the decomposition reaction:

2 H2O → 2 H2 + O2

Another example is the spontaneous decomposition of hydrogen peroxide into water and oxygen:

2 H2O2 → 2 H2O + O2

The decomposition of potassium chlorate into potassium chloride and oxygen is yet another example:

2 KClO3 → 2 KCl + 3 O2