Definition
Many decomposition reactions involve heat , light, or electricity to input energy.
Binary compounds are compounds which consist of only two elements. The simplest sort of reaction to decomposition is when a binary compound breaks down into its elements. Mercury (II) oxide, a red solid, decomposes to form mercury and oxygen gas when heated.
Also, a reaction is regarded as a decomposition reaction even if one or more of the products are still a compound. A metal carbonate breaks down to form a metal oxide and carbon dioxide gas. Calcium carbonate for example decomposes into calcium oxide and carbon dioxide.