Oxidizing agent

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The international pictogram for oxidizing chemicals.

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Dangerous goods label for oxidizing agents

An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or "accepts"/"receives" an electron from a Template:Em (called the Template:Em, Template:Em, or electron donor). In other words, an oxidizer is any substance that oxidizes another substance. The oxidation state, which describes the degree of loss of electrons, 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, hydrogen peroxide, and the halogens.

In one sense, an oxidizing agent is a chemical species that undergoes a chemical reaction 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, many explosives, and organic redox reactions involve atom-transfer reactions.

Electron acceptors

File:Tetracyanoquinodimethane Formula V.1.svg

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 ion Template:Chem, which accepts an electron to form Fe(C₅H₅)₂. One of the strongest acceptors commercially available is "Magic blue", the radical cation derived from N(C₆H₄-4-Br)₃.<ref name=Geiger>Template:Cite journal</ref>

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.<ref>Template:March6th</ref> Examples include Template:Chem (permanganate), Template:Chem (chromate), OsO₄ (osmium tetroxide), and especially Template:Chem (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 Template:Chem to Template:Chem,ie permanganate to manganate.

Common oxidizing agents

• Oxygen (O₂)
• Ozone (O₃)
• Hydrogen peroxide (H₂O₂) and other inorganic peroxides, Fenton's reagent
• Fluorine (F₂), chlorine (Cl₂), and other halogens
• Nitric acid (HNO₃) and nitrate compounds such as potassium nitrate (KNO₃), the oxidizer in black powder
• Potassium chlorate (KClO₃)
• Xenon difluoride (XeF₂)
• Xenon tetrafluoride (XeF₄)
• Xenon hexafluoride (XeF₆)
• Krypton difluoride (KrF₂)
• Sulfur (S₈)
• Peroxydisulfuric acid (H₂S₂O₈)
• Peroxymonosulfuric acid (H₂SO₅)
• Hypochlorite, chlorite, chlorate, perchlorate, and other analogous halogen oxyanions
• Fluorides of chlorine, bromine, and iodine
• Hexavalent chromium compounds such as chromic and dichromic acids and chromium trioxide, pyridinium chlorochromate (PCC), and chromate/dichromate compounds such as Sodium dichromate (Na₂Cr₂O₇)
• Permanganate compounds such as potassium permanganate (KMnO₄)
• Sodium perborate (Template:Chem·Template:Chem)
• Nitrous oxide (N₂O), Nitrogen dioxide/Dinitrogen tetroxide (NO₂ / N₂O₄)
• Sodium bismuthate (NaBiO₃)
• Cerium (IV) compounds such as ceric ammonium nitrate and ceric sulfate
• Lead dioxide (PbO₂)

Dangerous materials definition

Template:See also The dangerous goods definition of an oxidizing agent is a substance that can cause or contribute to the combustion of other material.<ref>Australian Dangerous Goods Code, 6th Edition</ref> 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, which does not pass the dangerous goods test of an oxidizing agent.

The U.S. Department of Transportation 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."<ref>49 CFR 172.127 General Requirements for Shipments and Packagings; Subpart D</ref>

Common oxidizing agents and their products

Agent	Product(s)
O2 oxygen	Various, including the oxides H2O and CO2
O3 ozone	Various, including ketones, aldehydes, and H2O; see ozonolysis
F2 fluorine	F−
Cl2 chlorine	Cl−
Br2 bromine	Br−
I2 iodine	I−, Template:Chem
ClO− hypochlorite	Cl−, H2O
Template:Chem chlorate	Cl−, H2O
HNO3 nitric acid	NO nitric oxide (Dilute nitric acid) NO2 nitrogen dioxide (Concentrated nitric acid)
H2SO4(l) Concentrated sulphuric acid SO3 Sulphur trioxide	SO2 Sulphur dioxide (non-aqueous) H2SO3 Sulphurous acid (In aqueous solution)
SO2 sulfur dioxide	S sulfur (Claus process, ultramarine production, more commonly reducing agent)
Hexavalent chromium CrO3 chromium trioxide Template:Chem chromate Template:Chem dichromate	Cr3+, H2O
Template:Chem permanganate Template:Chem manganate	Mn2+ (acidic) or MnO2 (basic)
Ag+ ion Silver ion	Ag (Metal)
SbF5 antimony pentafluoride	SbF6− hexafluoroantimonate or SbF3 antimony trifluoride
PtF6 platinum hexafluoride	PtF6− hexafluoroplatinate
Template:Chem ruthenium tetroxide Template:Chem osmium tetroxide	in organic lab scale synthesis
H2O2, other peroxides	Various, including oxides and H2O
Tl(III) thallic compounds	Tl(I) thallous compounds, in organic lab scale synthesis

See also

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External links

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