REAGENT

A 'reagent' is a material used to start a chemical reaction.
For example hydrochloric acid is the chemical reagent that would cause calcium carbonate to release carbon dioxide. Similarly, but less obviously, hydrochloric acid is the chemical reagent that reacts with zinc to produce hydrogen, even though in this case the hydrogen comes from the acid and not the metal.
To classify any of the chemicals involved in a chemical reaction as the "reagent" is thus largely a matter of convention or perspective, and commonly most non-solvents involved in a reaction are referred to as reagents.
In another use of the term, when purchasing or preparing chemicals, "reagent-grade" describes chemical substances of sufficient purity for use in chemical analysis, chemical reactions or physical testing. Purity standards for reagents are set by organizations such as ASTM International. For instance, reagent-quality water must have very low levels of impurities like sodium and chloride ions, silica, and bacteria, as well as a very high electrical resistivity.

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See also

See also

★ Limiting reagent

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