The products in a decomposition reaction are usually simpler substances than the starting material. For example, when calcium carbonate (CaCO3) decomposes, it produces calcium oxide (CaO) and carbon dioxide (CO2).

The general equation for a decomposition reaction is:

AB → A + B

where AB is the starting material, A and B are the products, and the arrow indicates that the starting material decomposes into the products.

Decomposition reactions can be caused by a variety of factors, including heat, light, and electricity.