Chemical decomposition

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Chemical decomposition or analysis is the fragmentation of a chemical compound into elements or smaller compounds. It is sometimes defined as the opposite of a synthesis.

A generalized reaction formula is: AB → A + B.

An example of analysis is the electrolysis of water

2H₂O → 2H₂ + O₂.

Another recognized form of decomposition is hydrogen peroxide. If you keep it for a long time, the hydrogen peroxide will eventually decompose into water and oxygen:

2H₂O₂ → 2H₂O + O₂

Carbonates will decompose when heated, a notable exception being that of carbonic acid, H₂CO₃. Carbonic acid, the "fizz" in sodas and other carbonated bevergaes, will decompose over time (spontaneously) into carbon dioxide and water:

H₂CO₃ → H₂O + CO₂

Other carbonates will decompose when heated producing the metal oxide and carbon dioxide. In the following equation M represents a metal:

MCO₃ → MO + CO₂

A specific example of this involving calcium carbonate:

CaCO₃ → CaO + CO₂

Metal chlorates also decompose in a regular fashion when heated. A metal chloride and oxygen gas are the products.

MClO₃ → MCl + O₂

A common decomposition of a chlorate to evolve oxygen utilizes potassium chlorate as follows:

2KClO₃ → 2KCl + 3O₂

With analysis and chemical synthesis equations alone it is possible to describe all types of chemical reactions.

Chemical decomposition is often an undesired chemical reaction. The stability that a chemical compound ordinarily has is eventually limited when exposed to extreme environmental conditions like for instance heat, radiation, humidity or the acidity of a medium. The detailed decomposition process is generally not well defined and a molecule breaks up into a host of smaller fragments.

Chemical decomposition is exploited in several analytical techniques notably mass spectrometry, traditional gravimetric analysis, and thermogravimetric analysis.