Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction or is added to see if a reaction occurs " [1]. Such a reaction is used to confirm the presence of another substance. Examples of such analytical reagents include Fehling's reagent, Millon's reagent and Tollens' reagent.
Although the terms reactant and reagent are often used interchangeably, a reactant is more specifically a "substance that is consumed in the course of a chemical reaction" [1].Solvents and catalysts, although they are involved in the reaction, are usually not referred to as reactants. In organic chemistry, reagents are compounds or mixtures, usually composed of inorganic or small organic molecules, that are used to affect a transformation on an organic substrate. Examples of organic reagents include the Collins reagent, Fenton's reagent, and Grignard reagent.
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.
An aqueous reagent is used in the making of an ester (an organic compound formed by the reaction of an alcohol and carboxylic acid together), it is used to remove impurities from the impure product. It is subsequently removed using a separating funnel to leave an organic layer which contains the ester.
See also
- Product
- Limiting reagent
- Reagents for organic chemistry