In chemistry, a product is a substance, such as an atom, ion, molecule, molecular entity, or chemical species that is formed during a chemical reaction. [1] A reactant, conversely, is what goes into or exists at the start of a reaction. This is diagrammed below:

Reactants Products

1. (a) Product - IUPAC Goldbook
(b) Daintith, John. (2004). Oxford Dictionary of Chemistry. New York: Oxford University Press.

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