Difference between revisions of "Reagent"

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''This page is derived from the corresponding [http://en.wikipedia.org/wiki/Reagent reagent article] on Wikipedia.'' 
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[[Image:SulfurReagent.jpg|right|200px|thumb|Sulfur is a reagent in many reactions]]
  
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A '''reagent''' or '''reactant''' is any substance used in a [[chemical reaction]]. It usually implies a chemical that is added to bring about the chemical change.
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A '''reagent''' or '''reactant''' is a substance or compound  consumed during a [[chemical reaction]].<ref name="GoldBook">{{GoldBook|title=Reactant|file=R05163|accessdate=2009-08-25}}.</ref> [[Solvent]]s and [[catalysts]], although they are involved in the reaction, are usually not referred to as reactants.  
  
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For example [[hydrochloric acid]] is the chemical reagent that would cause [[calcium carbonate]] to release [[carbon dioxide]]. Similarly, but less obvious, 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.
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Although the terms ''reactant'' and ''reagent'' are often used interchangeably, a ''reagent'' is more specifically "a test substance that is added to a system in order to bring about a reaction or to see whether a reaction occurs". <ref name="GoldBook"/> Such a reaction is used to confirm the presence of another substance. Examples of such ''analytical reagents'' include [[Fehling's reagent]] and [[Tollens' reagent]] as well as [[pH indicator]]s such as [[phenolphthalein]]. 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]].
  
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To classify any of the chemicals involved in a chemical reaction as the "reagent" is thus largely a matter of convention or perspective.
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In another use of the term, when purchasing or preparing chemicals, "reagent-grade" describes [[chemical substance]]s of sufficient [[Purity (gas)|purity]] for use in [[chemical analysis]], [[chemical reaction]]s or physical testing.  Purity [[standardization|standards]] for reagents are set by organizations such as [[ASTM International]]. For instance, reagent-quality [[water (molecule)|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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In another use of the term, when purchasing or preparing chemicals, "reagent" describes [[chemical substance]]s of sufficient [[purity]] for use in [[chemical analysis]], [[chemical reaction]]s or physical testing.  Purity [[standardization|standards]] for reagents are set by organizations such as [[ASTM International]]. For instance, reagent-quality [[water (molecule)|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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==References==
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{{reflist}}
  
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[[Category:Organic chemistry]]
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[[Category:Reagents for organic chemistry|*]]
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[[Category:Chemical reactions]]
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{{Imported from Wikipedia|name=Reagent|id=300384640}}

Latest revision as of 19:57, 24 August 2009

Sulfur is a reagent in many reactions

A reagent or reactant is a substance or compound consumed during a chemical reaction.[1] 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, a reagent is more specifically "a test substance that is added to a system in order to bring about a reaction or to see whether 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 and Tollens' reagent as well as pH indicators such as phenolphthalein. 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.

References

  1. ↑ 1.0 1.1 Reactant, <http://goldbook.iupac.org/R05163.html> (accessed 25 August 2009), Compendium of Chemical Terminology Internet edition; International Union of Pure and Applied Chemistry (IUPAC).
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