AskDefine | Define reactant

Dictionary Definition

reactant n : a chemical substance that is present at the start of a chemical reaction

User Contributed Dictionary



  1. any of the participants present at the start of a chemical reaction


participant at the start of a chemical reaction
  • Croatian: reaktant

Extensive Definition

A reagent or reactant is a substance or compound consumed during a chemical reaction. Solvents and catalysts, although they are involved in the reaction, are usually not referred to as reactants.
Although the terms reactant and reagent are often used interchangeably, reagent is often used in a more specialized sense as "a test substance that is added to a system in order to bring about a reaction or to see whether a reaction occurs". Examples of such analytical reagents include Fehling's reagent and Tollens' reagent. In organic chemistry, reagents are compounds or mixtures, usually composed of inorganic or small organic molecules, that are used to effect 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.


reactant in Arabic: كاشف كيميائي
reactant in Catalan: Reactiu
reactant in German: Edukt
reactant in Spanish: Reactivo
reactant in French: Réactif (chimie)
reactant in Indonesian: Pereaksi kimia
reactant in Italian: Reagente
reactant in Hebrew: מגיב
reactant in Lithuanian: Reagentas
reactant in Dutch: Reactant
reactant in Japanese: 試薬
reactant in Polish: Reagent
reactant in Portuguese: Reagente químico
reactant in Slovenian: Reagent
reactant in Thai: รีเอเจนต์
reactant in Ukrainian: Реагенти
reactant in Chinese: 反应物
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