An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or
electron acceptor) is a substance in a
redox
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
chemical reaction that gains or "
accepts"/"receives" an
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
from a (called the , , or ). In other words, an oxidizer is any substance that
oxidizes another substance. The
oxidation state, which describes the degree of loss of
electrons
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
, of the oxidizer decreases while that of the reductant increases; this is expressed by saying that oxidizers "undergo reduction" and "are reduced" while reducers "undergo oxidation" and "are oxidized".
Common oxidizing agents are
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
,
hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...
and the
halogens.
In one sense, an oxidizing agent is a chemical species that undergoes a
chemical reaction
A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...
in which it gains one or more electrons. In that sense, it is one component in an
oxidation–reduction (redox) reaction. In the second sense, an oxidizing agent is a chemical species that transfers electronegative atoms, usually oxygen, to a substrate.
Combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combus ...
, many explosives, and
organic redox reactions involve atom-transfer reactions.
Electron acceptors
100px, is an organic electron-acceptor.">Tetracyanoquinodimethane is an organic electron-acceptor.
Electron acceptors participate in
electron-transfer reactions. In this context, the oxidizing agent is called an electron acceptor and the reducing agent is called an electron donor. A classic oxidizing agent is the
ferrocenium
Ferrocenium tetrafluoroborate is an organometallic compound with the formula e(C5H5)2F4. This salt is composed of the cation e(C5H5)2sup>+ and the tetrafluoroborate anion (). The related hexafluorophosphate is also a popular reagent with simi ...
ion , which accepts an electron to form Fe(C
5H
5)
2. One of the strongest acceptors commercially available is "
Magic blue", the radical cation derived from N(C
6H
4-4-Br)
3.
Extensive tabulations of ranking the electron accepting properties of various reagents (redox potentials) are available, see
Standard electrode potential (data page).
Atom-transfer reagents
In more common usage, an oxidizing agent transfers oxygen atoms to a substrate. In this context, the oxidizing agent can be called an oxygenation reagent or oxygen-atom transfer (OAT) agent. Examples include (
permanganate), (
chromate), OsO
4 (
osmium tetroxide), and especially (
perchlorate). Notice that these species are all
oxides.
In some cases, these oxides can also serve as electron acceptors, as illustrated by the conversion of to ,
manganate.
Common oxidizing agents
*
Oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
(O
2)
*
Ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...
(O
3)
*
Hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...
(H
2O
2) and other inorganic
peroxides,
Fenton's reagent
Fenton's reagent is a solution of hydrogen peroxide (H2O2) with ferrous iron (typically iron(II) sulfate, FeSO4) as a catalyst that is used to oxidize contaminants or waste waters as part of an advanced oxidation process. Fenton's reagent can be us ...
*
Fluorine (F
2),
chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
(Cl
2), and other
halogens
*
Nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
(HNO
3) and
nitrate compounds such as
potassium nitrate
Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitr ...
(KNO
3), the oxidizer in
black powder
*
Potassium chlorate (KClO
3)
*
Sulfuric acid (H
2SO
4)
*
Peroxydisulfuric acid (H
2S
2O
8)
*
Peroxymonosulfuric acid (H
2SO
5)
*
Hypochlorite,
chlorite,
chlorate,
perchlorate, and other analogous
halogen compounds like household bleach (NaClO)
*Hexavalent
chromium compounds such as
chromic and dichromic acids and chromium trioxide,
pyridinium chlorochromate
Pyridinium chlorochromate (PCC) is a yellow-orange salt with the formula 5H5NHsup>+ rO3Clsup>−. It is a reagent in organic synthesis used primarily for oxidation of alcohols to form carbonyls. A variety of related compounds are known with simil ...
(PCC), and
chromate/dichromate compounds such as
Sodium dichromate (Na
2Cr
2O
7)
*
Permanganate compounds such as
potassium permanganate
Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as K+ and , an intensely pink to purple solution.
Potassium permanganate is widely used in the c ...
(KMnO
4)
*
Sodium perborate
Sodium perborate is chemical compound whose chemical formula may be written , , or, more properly, ·. Its name is sometimes abbreviated as PBS (not to be confused with phosphate-buffered saline).
The compound is commonly encountered in anhydr ...
(·)
*
Nitrous oxide
Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...
(N
2O),
Nitrogen dioxide
Nitrogen dioxide is a chemical compound with the formula . It is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year for use primarily in the productio ...
/
Dinitrogen tetroxide (NO
2 / N
2O
4)
*
Sodium bismuthate (NaBiO
3)
*Cerium (IV) compounds such as
ceric ammonium nitrate
Ceric ammonium nitrate (CAN) is the inorganic compound with the formula . This orange-red, water-soluble cerium salt is a specialised oxidizing agent in organic synthesis and a standard oxidant in quantitative analysis.
Preparation, properties, ...
and
ceric sulfate
*
Lead dioxide (PbO
2)
Dangerous materials definition
The
dangerous goods definition of an oxidizing agent is a substance that can cause or contribute to the combustion of other material. By this definition some materials that are classified as oxidizing agents by analytical chemists are not classified as oxidizing agents in a dangerous materials sense. An example is
potassium dichromate
Potassium dichromate, , is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. As with all hexavalent chromium compounds, it is acutely and chronically harmful to health ...
, which does not pass the dangerous goods test of an oxidizing agent.
The
U.S. Department of Transportation
The United States Department of Transportation (USDOT or DOT) is one of the executive departments of the U.S. federal government. It is headed by the secretary of transportation, who reports directly to the President of the United States and ...
defines oxidizing agents specifically. There are two definitions for oxidizing agents governed under DOT regulations. These two are
Class 5; Division 5.1(a)1 and Class 5; Division 5.1(a)2. Division 5.1 "means a material that may, generally by yielding oxygen, cause or enhance the combustion of other materials." Division 5.(a)1 of the DOT code applies to solid oxidizers "if, when tested in accordance with the UN Manual of Tests and Criteria (IBR, see § 171.7 of this subchapter), its mean burning time is less than or equal to the burning time of a 3:7 potassium bromate/cellulose mixture." 5.1(a)2 of the DOT code applies to liquid oxidizers "if, when tested in accordance with the UN Manual of Tests and Criteria, it spontaneously ignites or its mean time for a pressure rise from 690 kPa to 2070 kPa gauge is less than the time of a 1:1 nitric acid (65 percent)/cellulose mixture."
[49 CFR 172.127 General Requirements for Shipments and Packagings; Subpart D]
Common oxidizing agents and their products
See also
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References
{{Authority control
Chemical properties
Electrochemistry
Redox