decomposition reaction

chemistry

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June 25, 2026

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In chemistry, a decomposition reaction is a process where a chemical compound breaks down into simpler substances. These reactions typically require an input of energy, such as heat or electricity.1

For example, heating potassium chlorate (KClO₃) breaks it down into solid potassium chloride (KCl) and oxygen gas (O₂). Another example is the electrolysis of molten sodium chloride (NaCl) to produce liquid sodium (Na) and chlorine gas (Cl₂). Historically, the decomposition of mercury oxide (HgO) by heat into mercury (Hg) and oxygen (O₂) was crucial for early experiments on oxygen.1

A specific type of decomposition reaction is hydrolysis, where water is one of the reactants, causing a compound to break apart.2

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chemical reaction
Decomposition reactions
Decomposition reactions are processes in which chemical species break up into simpler parts. Usually, decomposition reactions require energy input. For example, a common method of producing oxygen gas in the laboratory is the decomposition of potassium chlorate (KClO₃) by heat
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Decomposition reactions are processes in which chemical species break up into simpler parts. Usually, decomposition reactions require energy input. For example, a common method of producing oxygen gas in the laboratory is the decomposition of potassium chlorate (KClO₃) by heat
Read More

carbene
Formation.
The photolytic decomposition of certain ketenes, substances the molecules of which contain two carbon atoms and an oxygen atom joined by double bonds,
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The photolytic decomposition of certain ketenes, substances the molecules of which contain two carbon atoms and an oxygen atom joined by double bonds,
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photosensitization
…excited ethylene molecules subsequently undergo decomposition. Another mode of photosensitization observed in many reactions involves direct participation of the sensitizer in the reaction itself.
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…excited ethylene molecules subsequently undergo decomposition. Another mode of photosensitization observed in many reactions involves direct participation of the sensitizer in the reaction itself.
Read More