CLASSIFICATION OF CHEMICAL REACTIONS
Classification of reactions (the type of reaction) is based on a variety of observations or concepts.
A. Classification based on observation of a phase change
- Gas evolution: A gas is evolved from a solid or a solution.
Sodium carbonate dissolves in dilute aqueous acid.
Decomposition of hydrogen peroxide.
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- Precipitation: A solid (the precipitate) is produced from solution.
Insoluble silver chloride forms when aqueous solutions of two soluble salts, sodium chloride and silver nitrate, are mixed.
A precipitate forms when carbon dioxide is bubbled through "limewater".
- Dissolution: A solid dissolves on addition of a reactant or a solvent.
Calcium carbonate (limestone) dissolves in dilute aqueous acid.
Calcium phosphate dissolves in aqueous acid.
Common salt dissolves in water. This is not really regarded as a chemical reaction, rather a physical change.