Reagent
Encyclopedia
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of a chemical reaction". Solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...
s 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
Collins reagent
Collins reagent is the complex of chromium oxide with pyridine in dichloromethane. It is used to selectively oxidize primary alcohols to the aldehyde, and will tolerate many other functional groups within the molecule....
, Fenton's reagent
Fenton's reagent
Fenton's reagent is a solution of hydrogen peroxide and an iron catalyst that is used to oxidize contaminants or waste waters. Fenton's reagent can be used to destroy organic compounds such as trichloroethylene and tetrachloroethylene ....
, and Grignard reagent. There are also analytical reagents which are used to confirm the presence of another substance. Examples of these are Fehling's reagent, Millon's reagent
Millon's reagent
Millon's reagent is an analytical reagent used to detect the presence of soluble proteins. A few drops of the reagent are added to the test solution, which is then heated gently...
and Tollens' reagent
Tollens' reagent
Tollens' reagent is a chemical reagent most commonly used to determine whether a known carbonyl-containing compound is an aldehyde or a ketone. It is usually ammoniacal silver nitrate, but can also be other mixtures, as long as aqueous diamminesilver complex is present...
.
In another use of the term, when purchasing or preparing chemicals, reagent-grade describes chemical substance
Chemical substance
In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. They can be solids, liquids or gases.Chemical substances are...
s of sufficient purity
Purity (gas)
The purity of gas is an indication of the amount of other gases it contains. A high purity refers to a low amount of other gases. Gases of higher purity are considered to be of better quality and are usually more expensive....
for use in chemical analysis, chemical reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
s or physical testing. Purity standards
Standardization
Standardization is the process of developing and implementing technical standards.The goals of standardization can be to help with independence of single suppliers , compatibility, interoperability, safety, repeatability, or quality....
for reagents are set by organizations such as ASTM International
ASTM International
ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...
. For instance, reagent-quality water must have very low levels of impurities like sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
and chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
ions, silica, and bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, as well as a very high electrical resistivity.
See also
- ProductProduct (chemistry)Product are formed during chemical reactions as reagents are consumed. Products have lower energy than the reagents and are produced during the reaction according to the second law of thermodynamics. The released energy comes from changes in chemical bonds between atoms in reagent molecules and...
- Limiting reagentLimiting reagentIn a chemical reaction, the limiting reagent, also known as the "limiting reactant", is the substance which is totally consumed when the chemical reaction is complete. The amount of product formed is limited by this reagent since the reaction cannot proceed further without it...
- :Category:Reagents for organic chemistry
- Common reagentsCommon reagentsThis is a list of common inorganic and organic reagents often used in chemistry.-Synopsis:Reagents are "substances or compounds that are added to a system in order to bring about a chemical reaction or are added to see if a reaction occurs." Some reagents are just a single element. However, most...