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Hydrogen peroxide is a
chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together by chemical bonds. A homonuclear molecule, m ...
with the formula . In its pure form, it is a very pale blue
liquid A liquid is a nearly incompressible In fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics Mechanics (Ancient Greek, Greek: ) is the area of physics concerned with the motions of physical objects, ...

liquid
, slightly more
viscous The viscosity of a fluid In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, ...

viscous
than
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...
. It is used as an
oxidizer An oxidizing agent, also known as an oxidant or oxidizer, is a substance that has the ability to oxidize other substances — in other words to electron acceptor, accept their electrons. Common oxidizing agents are oxygen, hydrogen peroxi ...
,
bleach Bleach is the generic name for any chemical product that is used industrially and domestically to remove color from a fabric or fiber or to clean or to remove stains in a process called bleaching. It often refers, specifically, to a dilute so ...

bleach
ing agent, and
antiseptic Antiseptics (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") are antimicrobial substances that are applied to living tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cel ...

antiseptic
, usually as a dilute solution (3–6% by weight) in water for consumer use, and in higher concentrations for industrial use. Concentrated hydrogen peroxide, or "
high-test peroxideHigh-test peroxide (HTP) is a highly concentrated (85 to 98 per cent) solution of hydrogen peroxide, with the remainder consisting predominantly of water. In contact with a catalyst, it decomposes into a high-temperature mixture of steam and oxygen, ...
", decomposes explosively when heated and has been used as a
propellant A propellant (or propellent) is a mass Mass is the quantity Quantity is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", "less", or " ...
in
rocket A rocket (from it, rocchetto, , bobbin/spool) is a spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite alt=, A full-size model of the Earth observation satellite ERS 2 ...

rocket
ry. Hydrogen peroxide is a
reactive oxygen species Reactive oxygen species (ROS) are highly Reactivity (chemistry), reactive chemicals formed from O2. Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen (O2) produce ...
and the simplest
peroxide Peroxides are a group of compounds with the structure R−O−O−R, where R = any element. The O−O group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable. The most common peroxide is hydrogen ...

peroxide
, a compound having an oxygen–oxygen
single bond In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo duri ...

single bond
. It decomposes slowly when exposed to light, and rapidly in the presence of organic or reactive compounds. It is typically stored with a
stabilizer Stabilizer, stabiliser, stabilisation or stabilization may refer to: Chemistry and food processing * Stabilizer (chemistry), a substance added to prevent unwanted change in state of another substance ** Polymer stabilizers are stabilizers used s ...
in a weakly acidic solution in a dark bottle to block light. Hydrogen peroxide is found in biological systems including the human body. Enzymes that use or decompose hydrogen peroxide are classified as
peroxidases Peroxidases or peroxide reductases (Enzyme Commission number, EC number]1.11.1.x are a large group of enzymes which play a role in various biological processes. They are named after the fact that they commonly break up peroxides. Functionality Per ...
.


Properties

The boiling point of has been extrapolated as being , approximately higher than water. In practice, hydrogen peroxide will undergo potentially explosive
thermal decomposition Thermal decomposition, or thermolysis, is a chemical decompositionChemical decomposition, or chemical breakdown, is the process or effect of simplifying a single chemical entity (normal molecule, reaction intermediate, etc.) into two or more fra ...
if heated to this temperature. It may be safely distilled at lower temperatures under reduced pressure.


Structure

Hydrogen peroxide () is a nonplanar molecule with (twisted) C2
symmetry Symmetry (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is appro ...
; this was first shown by
Paul-Antoine Giguère Paul-Antoine Giguère, (January 13, 1910 – December 25, 1987) was a Canadian academic and chemist. Born in Quebec City Quebec City ( or ; french: Ville de Québec, officially Québec ()) is the capital city of the Canadian province of ...
in 1950 using
infrared spectroscopy Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption spectroscopy, absorption, emission spectrum, emission, or reflection (physics), reflection. ...

infrared spectroscopy
. Although the O−O bond is a
single bond In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo duri ...

single bond
, the molecule has a relatively high
rotational barrier In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they und ...
of 386  cm−1 (4.62  kJ/ mol) for rotation between
enantiomer In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in ...

enantiomer
s via the ''trans'' configuration, and 2460 cm−1 (29.4 kJ/mol) via the ''cis'' configuration. These barriers are proposed to be due to repulsion between the
lone pair In chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bondIUPAC ''Gold Book'' definition''lone (electron) pair''/ref> and is sometimes called an unshared pair or non-bonding pair. Lone p ...
s of the adjacent oxygen atoms and dipolar effects between the two O–H bonds. For comparison, the rotational barrier for
ethane Ethane ( or ) is an organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), organ Chemistry * Organic matter, matter that has come from a once-living ...
is 1040 cm−1 (12.4 kJ/mol). The approximately 100°
dihedral angle A dihedral angle is the angle between two intersecting planes or half-planes. In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, ele ...

dihedral angle
between the two O–H bonds makes the molecule
chiral Chirality is a property of important in several branches of science. The word ''chirality'' is derived from the (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from its ; that is, i ...

chiral
. It is the smallest and simplest molecule to exhibit
enantiomer In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in ...

enantiomer
ism. It has been proposed that the enantiospecific interactions of one rather than the other may have led to amplification of one enantiomeric form of
ribonucleic acid Ribonucleic acid (RNA) is a polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of ...
s and therefore an origin of
homochirality Homochirality is a uniformity of chirality Chirality is a property of asymmetry Asymmetry is the absence of, or a violation of, symmetry (the property of an object being invariant to a transformation, such as reflection). Symmetry is an impo ...
in an
RNA world The RNA world is a hypothetical stage in the evolutionary history of life The history of life on Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surfa ...
. The molecular structures of gaseous and
crystalline A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together and contain the least amount of kinet ...

crystalline
are significantly different. This difference is attributed to the effects of
hydrogen bonding A hydrogen bond (or H-bond) is a primarily Electrostatics, electrostatic force of attraction between a hydrogen Hydrogen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of ...
, which is absent in the gaseous state. Crystals of are
tetragonal In crystallography, the tetragonal crystal system is one of the 7 crystal systems. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the Cube (geometry), cube becomes a rectangular Pris ...

tetragonal
with the
space group In mathematics Mathematics (from Greek: ) includes the study of such topics as numbers (arithmetic and number theory), formulas and related structures (algebra), shapes and spaces in which they are contained (geometry), and quantities and ...
''D'P''4121.


Aqueous solutions

In
aqueous solution An aqueous solution is a solution Solution may refer to: * Solution (chemistry) Image:SaltInWaterSolutionLiquid.jpg, upMaking a saline water solution by dissolving Salt, table salt (sodium chloride, NaCl) in water. The salt is the solute an ...
s, hydrogen peroxide differs from the pure substance due to the effects of hydrogen bonding between water and hydrogen peroxide molecules. Hydrogen peroxide and water form a eutectic mixture, exhibiting
freezing-point depression Freezing-point depression is a drop in the temperature at which a substance freezing, freezes, caused when a smaller amount of another, non-Volatility (chemistry), volatile substance is added. Examples include adding salt into water (used in ice c ...
down as low as –56 °C; pure water has a freezing point of 0 °C and pure hydrogen peroxide of −0.43 °C. The boiling point of the same mixtures is also depressed in relation with the mean of both boiling points (125.1 °C). It occurs at 114 °C. This boiling point is 14 °C greater than that of pure water and 36.2 °C less than that of pure hydrogen peroxide.
  • hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine h ...

    hydrazine
  • and water, with only
    hydroxylamine Hydroxylamine is an inorganic compound with the formula NH2OH. The pure material is a white, unstable crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a hig ...
    crystallising significantly more readily, indicative of particularly strong hydrogen bonding.
    Diphosphane Diphosphane is an inorganic compound with the chemical formula P2H4. This colourless liquid is one of several binary phosphorus hydrides. It is the impurity that typically causes samples of phosphine to ignite in air. An older name is diphosphi ...
    and
    hydrogen disulfide Hydrogen disulfide is the inorganic compound In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, ...

    hydrogen disulfide
    exhibit only weak hydrogen bonding and have little chemical similarity to hydrogen peroxide. Structurally, the analogues all adopt similar skewed structures, due to repulsion between adjacent
    lone pair In chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bondIUPAC ''Gold Book'' definition''lone (electron) pair''/ref> and is sometimes called an unshared pair or non-bonding pair. Lone p ...
    s.


    Discovery

    Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a , , , , and proponent of philosophy and . He was the younger brother of the Prussian minister, philosopher, and (1767–1835). Humboldt's quantitative work ...

    Alexander von Humboldt
    reported one of the first synthetic peroxides,
    barium peroxide Barium peroxide is the inorganic compound In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, prop ...
    , in 1799 as a by-product of his attempts to decompose air. Nineteen years later
    Louis Jacques Thénard
    Louis Jacques Thénard
    recognized that this compound could be used for the preparation of a previously unknown compound, which he described as ("oxygenated water") – subsequently known as hydrogen peroxide. Today, the term "oxygenated water" may appear on retail packaging referring to mixtures containing either water and hydrogen peroxide or water and dissolved oxygen. This could cause personal injury if the difference is not properly understood by the user. An improved version of Thénard's process used
    hydrochloric acid Hydrochloric acid +(aq) Cl−(aq) or H3O+ Cl− also known as muriatic acid, is an aqueous solution An aqueous solution is a solution Solution may refer to: * Solution (chemistry) Image:SaltInWaterSolutionLiquid.jpg, upMaking a salin ...

    hydrochloric acid
    , followed by addition of
    sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

    sulfuric acid
    to precipitate the
    barium sulfate Barium sulfate (or sulphate) is the inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, p ...

    barium sulfate
    byproduct. This process was used from the end of the 19th century until the middle of the 20th century. Thénard and
    Joseph Louis Gay-Lussac Joseph Louis Gay-Lussac (, , ; 6 December 1778  – 9 May 1850) was a French chemist and physicist. He is known mostly for his discovery that water is made of two parts hydrogen and one part oxygen (with Alexander von Humboldt Friedric ...

    Joseph Louis Gay-Lussac
    synthesized
    sodium peroxide Sodium peroxide is an inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. However, the distinction is not clearly defined; ...
    in 1811. The bleaching effect of peroxides and their salts on
    natural dye Natural dyes are dyes or colorants derived from plants, invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This includes all ...

    natural dye
    s became known around that time, but early attempts of industrial production of peroxides failed. The first plant producing hydrogen peroxide was built in 1873 in
    Berlin Berlin (; ) is the Capital city, capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3,769,495 inhabitants, as of 31 December 2019 makes it the List of cities in the European Union by ...

    Berlin
    . The discovery of the synthesis of hydrogen peroxide by
    electrolysis In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in ...

    electrolysis
    with
    sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

    sulfuric acid
    introduced the more efficient electrochemical method. It was first commercialized in 1908 in
    Weißenstein
    Weißenstein
    ,
    Carinthia Carinthia (german: Kärnten ; sl, Koroška ) is the southernmost Austrian state or ''Land''. Situated within the Eastern Alps Eastern Alps is the name given to the eastern half of the Alps, usually defined as the area east of a line from L ...
    , Austria. The
    anthraquinone processThe anthraquinone process is a process for the production of hydrogen peroxide, which was developed by BASF. The industrial production of hydrogen peroxide is based on the Reduction (chemistry), reduction of oxygen, as in the direct synthesis from th ...
    , which is still used, was developed during the 1930s by the German chemical manufacturer
    IG Farben Interessengemeinschaft Farbenindustrie AG (), commonly known as IG Farben (German for "IG Colors"), was a German chemical and pharmaceutical conglomerate Conglomerate or conglomeration may refer to: * Conglomerate (company) * Conglomerate (geo ...
    in
    Ludwigshafen Ludwigshafen, officially Ludwigshafen am Rhein (, meaning ''Ludwig's Port upon Rhine''), is a city A city is a large human settlement.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., ...
    . The increased demand and improvements in the synthesis methods resulted in the rise of the annual production of hydrogen peroxide from 35,000 tonnes in 1950, to over 100,000 tonnes in 1960, to 300,000 tonnes by 1970; by 1998 it reached 2.7 million tonnes. Early attempts failed to produce neat hydrogen peroxide. Anhydrous hydrogen peroxide was first obtained by
    vacuum distillation Vacuum distillation is distillation Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture In chemistry Chemistry is the scientific discipline involved with Chemical ele ...

    vacuum distillation
    . Determination of the molecular structure of hydrogen peroxide proved to be very difficult. In 1892, the Italian physical chemist Giacomo Carrara (1864–1925) determined its molecular mass by
    freezing-point depression Freezing-point depression is a drop in the temperature at which a substance freezing, freezes, caused when a smaller amount of another, non-Volatility (chemistry), volatile substance is added. Examples include adding salt into water (used in ice c ...
    , which confirmed that its molecular formula is H2O2. At least half a dozen hypothetical molecular structures seemed to be consistent with the available evidence. In 1934, the English mathematical physicist
    William Penney William George Penney, Baron Penney, (24 June 19093 March 1991) was an English people, English mathematician and professor of mathematical physics at the Imperial College London and later the Rector of Imperial College London, rector of Imperial ...
    and the Scottish physicist Gordon Sutherland proposed a molecular structure for hydrogen peroxide that was very similar to the presently accepted one. Previously, hydrogen peroxide was prepared industrially by
    hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution Substitution may refer to: Arts and media *Chord substitution, in music, swapping one chord fo ...

    hydrolysis
    of
    ammonium persulfate Ammonium persulfate (APS) is the inorganic compound with the formula (NH4)2S2O8. It is a colourless (white) salt that is highly soluble in water, much more so than the related potassium salt. It is a strong oxidizing agent that is used in polyme ...

    ammonium persulfate
    , which was itself obtained by the
    electrolysis In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in ...

    electrolysis
    of a solution of
    ammonium bisulfate Ammonium bisulfate, also known as ammonium hydrogen sulfate, is a white, crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structur ...
    () in
    sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

    sulfuric acid
    : :2NH4HSO4 ->[] (NH4)2S2O8 + H2 :(NH4)2S2O8 + 2H2O ->[hydrolysis] 2(NH4)HSO4 + H2O2


    Production

    Today, hydrogen peroxide is manufactured almost exclusively by the
    anthraquinone processThe anthraquinone process is a process for the production of hydrogen peroxide, which was developed by BASF. The industrial production of hydrogen peroxide is based on the Reduction (chemistry), reduction of oxygen, as in the direct synthesis from th ...
    , which was originally developed by
    BASF BASF SE is a German multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multinational state, a sovere ...

    BASF
    in 1939. It begins with the reduction of an
    anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic hydrocarbon, aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone, however refers to the isomer, 9,10-anthraquino ...

    anthraquinone
    (such as
    2-ethylanthraquinone
    2-ethylanthraquinone
    or the 2-amyl derivative) to the corresponding anthrahydroquinone, typically by
    hydrogenation Hydrogenation is a chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical A chemical substance is a form of matter having constant ...

    hydrogenation
    on a
    palladium Palladium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

    palladium
    catalyst Catalysis () is the process of increasing the rate of a chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter In cla ...

    catalyst
    . In the presence of
    oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

    oxygen
    , the anthrahydroquinone then undergoes
    autoxidation Autoxidation (sometimes auto-oxidation) refers to oxidations brought about by reactions with oxygen at normal temperatures, without the intervention of flame or electric spark. The term is usually used to describe the degradation of organic compound ...
    : the labile hydrogen atoms of the
    hydroxy group A hydroxy or hydroxyl group is a functional group with the chemical formula -OH and composed of one oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group ( ...
    s transfer to the oxygen molecule, to give hydrogen peroxide and regenerating the anthraquinone. Most commercial processes achieve oxidation by bubbling
    compressed air Compressed air is air File:Atmosphere gas proportions.svg, Composition of Earth's atmosphere by volume, excluding water vapor. Lower pie represents trace gases that together compose about 0.043391% of the atmosphere (0.04402961% at April 2019 ...
    through a solution of the anthrahydroquinone, with the hydrogen peroxide then extracted from the solution and the anthraquinone recycled back for successive cycles of hydrogenation and oxidation.H. Riedl and G. Pfleiderer, U.S. Patent 2,158,525 (2 October 1936 in USA, and 10 October 1935 in Germany) to I. G. Farbenindustrie, Germany The net reaction for the anthraquinone-catalyzed process is : : + → The economics of the process depend heavily on effective recycling of the extraction solvents, the
    hydrogenation Hydrogenation is a chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical A chemical substance is a form of matter having constant ...

    hydrogenation
    catalyst and the expensive
    quinone The quinones are a class of organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties ...

    quinone
    .


    Other sources

    Small, but detectable, amounts of hydrogen peroxide can be formed by several methods. Small amounts are formed by electrolysis of dilute acid around the
    cathode A cathode is the from which a leaves a polarized electrical device. This definition can be recalled by using the ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in which positive charges move. Electrons ha ...
    where hydrogen evolves if oxygen is bubbled around it. It is also produced by exposing water to
    ultraviolet rays Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation is present ...

    ultraviolet rays
    from a
    mercury lamp mercury-vapor light approximately 15 seconds after starting. mercury vapor lamp. The small diagonal cylinder at the bottom of the arc tube is a resistor which supplies current to the starter electrode. A mercury-vapor lamp is a gas-discharge la ...
    , or an
    electric arc An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (ph ...

    electric arc
    while confining it in a UV transparent vessel (e.g. quartz). It is detectable in ice water after burning a hydrogen gas stream aimed towards it and is also detectable on floating ice. Rapidly cooling humid air blown through an approximately 2,000 °C
    spark gap A spark gap consists of an arrangement of two conducting Conducting is the art of directing a musical performance, such as an orchestral or Choir, choral concert. It has been defined as "the art of directing the simultaneous performance of sev ...
    results in detectable amounts. A commercially viable process to produce hydrogen peroxide directly from the environment has been of interest for many years. Efficient direct synthesis is difficult to achieve, as the reaction of hydrogen with oxygen thermodynamically favours production of water. Systems for direct synthesis have been developed, most of which employ finely dispersed metal catalysts similar to those used for hydrogenation of organic substrates. One economic obstacle has been that direct processes give a dilute solution uneconomic for transportation. None of these has yet reached a point where they can be used for industrial-scale synthesis.


    Availability

    Hydrogen peroxide is most commonly available as a solution in water. For consumers, it is usually available from pharmacies at 3 and 6 wt% concentrations. The concentrations are sometimes described in terms of the volume of oxygen gas generated; one milliliter of a 20-volume solution generates twenty milliliters of oxygen gas when completely decomposed. For laboratory use, 30 wt% solutions are most common. Commercial grades from 70% to 98% are also available, but due to the potential of solutions of more than 68% hydrogen peroxide to be converted entirely to steam and oxygen (with the temperature of the steam increasing as the concentration increases above 68%) these grades are potentially far more hazardous and require special care in dedicated storage areas. Buyers must typically allow inspection by commercial manufacturers. In 1994, world production of was around 1.9 million tonnes and grew to 2.2 million in 2006, most of which was at a concentration of 70% or less. In that year, bulk 30% sold for around 0.54
    USD The United States dollar (symbol A symbol is a mark, sign, or word In linguistics, a word of a spoken language can be defined as the smallest sequence of phonemes that can be uttered in isolation with semantic, objective or pragma ...

    USD
    / kg, equivalent to US$1.50/kg (US$0.68/ lb) on a "100% basis". Hydrogen peroxide occurs in surface water, groundwater and in the
    atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in ...

    atmosphere
    . It forms upon illumination or natural
    catalytic that utilizes a low-temperature oxidation catalyst to convert carbon monoxide to less toxic carbon dioxide Carbon dioxide (chemical formula ) is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules ...

    catalytic
    action by substances contained in water. Sea water contains 0.5 to 14 μg/L of hydrogen peroxide, freshwater 1 to 30 μg/L and air 0.1 to 1 parts per billion.


    Reactions


    Decomposition

    Hydrogen peroxide decomposes to form water and oxygen with a Δ''H''o of –2884.5  kJ/ kg and a Δ of 70.5 J/(mol·K): :2 → 2 + The rate of decomposition increases with rise in temperature, concentration, and ( being unstable under alkaline conditions), with cool, dilute, and acidic solutions showing the best stability. Decomposition is catalysed by various redox-active ions or compounds, including most
    transition metal In chemistry, the term transition metal (or transition element) has three possible definitions: * The IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations tha ...
    s and their compounds (e.g.
    manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese Manganese is a chemical element Image:Simple Periodic Table Chart- ...

    manganese dioxide
    (MnO2),
    silver Silver is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical ele ...

    silver
    , and
    platinum Platinum is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical el ...

    platinum
    ). Certain metal ions, such as or , can cause the decomposition to take a different path, with
    free radical A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Ailments of unknown cause Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabo ...
    s such as the
    hydroxyl radical The hydroxyl radical is the diatomic molecule . The hydroxyl radical is very stable as a dilute gas, but it decays very rapidly in the condensed phase. It is pervasive in some situations. Most notably the hydroxyl radicals is produced from the d ...

    hydroxyl radical
    (HO) and
    hydroperoxyl The hydroperoxyl radical (chemistry), radical, also known as the hydrogen superoxide, is the protonated form of superoxide with the chemical formula HO2. This species plays an important role in the atmosphere and as a reactive oxygen species in ...
    (HOO) being formed. Non-metallic catalysts include
    potassium iodide Potassium iodide is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...

    potassium iodide
    (KI), which reacts particularly rapidly and forms the basis of the demonstration. Hydrogen peroxide can also be decomposed biologically by the
    enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates in ...

    enzyme
    catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyst, catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in prote ...

    catalase
    . The decomposition of hydrogen peroxide liberates oxygen and heat; this can be dangerous, as spilling high-concentration hydrogen peroxide on a flammable substance can cause an immediate fire.


    Redox reactions

    The redox properties of hydrogen peroxide depend on pH as acidic conditions exacerbate the power of
    oxidizing agent An oxidizing agent, also known as an oxidant or oxidizer, is a substance that has the ability to oxidize other substances — in other words to electron acceptor, accept their electrons. Common oxidizing agents are oxygen, hydrogen peroxi ...

    oxidizing agent
    s and basic conditions the power of
    reducing agent A reducing agent (also called a reductant, reducer, or electron donor) is an element or compound that loses or "donates" an electron The electron is a subatomic particle (denoted by the symbol or ) whose electric charge is negative one ele ...
    s. As hydrogen peroxide exhibits ambivalent
    redox Redox (reduction–oxidation, pronunciation: or ) is a type of chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter ...

    redox
    properties, being simultaneously an oxidizer or a reductant, its redox behavior immediately depends on pH. In acidic solutions, is a powerful
    oxidizer An oxidizing agent, also known as an oxidant or oxidizer, is a substance that has the ability to oxidize other substances — in other words to electron acceptor, accept their electrons. Common oxidizing agents are oxygen, hydrogen peroxi ...
    , stronger than
    chlorine Chlorine is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemica ...

    chlorine
    ,
    chlorine dioxide Chlorine dioxide is a chemical compound with the formula ClO2 that exists as yellowish-green gas above 11 °C, a reddish-brown liquid between 11 °C and −59 °C, and as bright orange crystals below −59 °C. It is an oxidizi ...

    chlorine dioxide
    , and
    potassium permanganate Potassium permanganate is an inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, proper ...

    potassium permanganate
    . When used for cleaning laboratory glassware, a solution of hydrogen peroxide and sulfuric acid is referred to as
    Piranha solution Piranha solution, also known as piranha etch, is a mixture of sulfuric acid (H2SO4), water, and hydrogen peroxide (H2O2), used to clean organic compound, organic residues off substrates. Because the mixture is a strong oxidizing agent, it will remo ...

    Piranha solution
    . is a source of
    hydroxyl radical The hydroxyl radical is the diatomic molecule . The hydroxyl radical is very stable as a dilute gas, but it decays very rapidly in the condensed phase. It is pervasive in some situations. Most notably the hydroxyl radicals is produced from the d ...

    hydroxyl radical
    s (OH), which are highly reactive. is used in the Briggs–Rauscher and Bray–Liebhafsky oscillating reactions. In
    acid An acid is a or capable of donating a (hydrogen ion H+) (a ), or, alternatively, capable of forming a with an (a ). The first category of acids are the proton donors, or s. In the special case of , proton donors form the H3O+ and are ...
    ic solutions, is oxidized to (hydrogen peroxide acting as an oxidizing agent): :2 (aq) + + 2 (aq) → 2 (aq) + 2 (l) and
    sulfite Sulfites or sulphites are compounds Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the ...

    sulfite
    () is oxidized to
    sulfate The sulfate or sulphate ion is a polyatomic anion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having ...

    sulfate
    (). However,
    potassium permanganate Potassium permanganate is an inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, proper ...

    potassium permanganate
    is reduced to by acidic . Under
    alkaline In chemistry, an alkali (; from ar, القلوي ''al-qaly'' "ashes of the saltwort") is a base (chemistry), basic, ionic compound, ionic salt (chemistry), salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as ...

    alkaline
    conditions, however, some of these reactions reverse; for example, is oxidized to (as ). In basic solutions, hydrogen peroxide is a strong
    reductant A reducing agent (also called a reductant or reducer) is an element or compound that loses (or "donates") an electron to an electron recipient (oxidizing agent) in a redox chemical reaction. A reducing agent is thus oxidized when it loses electrons ...
    and can reduce a variety of inorganic ions. When acts as a reducing agent,
    oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

    oxygen
    gas is also produced. For example, hydrogen peroxide will reduce
    sodium hypochlorite Sodium hypochlorite (commonly known in a dilute solution as bleach) is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any ...

    sodium hypochlorite
    and
    potassium permanganate Potassium permanganate is an inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, proper ...

    potassium permanganate
    , which is a convenient method for preparing
    oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

    oxygen
    in the laboratory: :NaOCl + → + NaCl + :2 + 3 → 2 + 2 KOH + 2 + 3


    Organic reactions

    Hydrogen peroxide is frequently used as an
    oxidizing agent An oxidizing agent, also known as an oxidant or oxidizer, is a substance that has the ability to oxidize other substances — in other words to electron acceptor, accept their electrons. Common oxidizing agents are oxygen, hydrogen peroxi ...

    oxidizing agent
    . Illustrative is oxidation of
    thioether An organic sulfide (British English sulphide) or thioether is a functional group in organosulfur chemistry with the connectivity C–S–C as shown on right. Like many other sulfur-containing compounds, Volatile organic compound, volatile sulfides h ...
    s to
    sulfoxide A sulfoxide is a containing a sulfinyl (SO) attached to two carbon atoms. It is a polar functional group. Sulfoxides are the oxidized derivatives of . Examples of important sulfoxides are , a precursor to the compound that gives freshly crushed ...

    sulfoxide
    s: :Ph + → Ph + Alkaline hydrogen peroxide is used for
    epoxidation An epoxide is a cyclic ether with a three-atom ring. This ring approximates an equilateral triangle In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilat ...

    epoxidation
    of electron-deficient alkenes such as
    acrylic acid Acrylic acid (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Science ...

    acrylic acid
    derivatives, and for the oxidation of alkylboranes to
    alcohol In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a Saturated and unsaturated compounds, saturated carbon atom. The term alcohol originally referred to the primary alcohol ethan ...

    alcohol
    s, the second step of . It is also the principal reagent in the Dakin oxidation process.


    Precursor to other peroxide compounds

    Hydrogen peroxide is a weak acid, forming
    hydroperoxide Hydroperoxides or peroxols are Chemical compound, compounds containing the hydroperoxide functional group (ROOH). If the R is organic, the compounds are called organic hydroperoxides. Such compounds are a subset of organic peroxides, which have t ...

    hydroperoxide
    or
    peroxide Peroxides are a group of compounds with the structure R−O−O−R, where R = any element. The O−O group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable. The most common peroxide is hydrogen ...

    peroxide
    salts In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...
    with many metals. It also converts metal oxides into the corresponding peroxides. For example, upon treatment with hydrogen peroxide,
    chromic acid The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid Sulfuric acid ( American spelling) or sulphuric acid ( Commonwealth spelling), also known as oil of vitriol, is a mineral acid composed of the elem ...
    ( and ) forms a blue peroxide CrO(. This kind of reaction is used industrially to produce peroxoanions. For example, reaction with
    borax Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron chemical substance, compound, a mineral, and a salt (chemistry), salt of boric acid. Powdered borax is white, consisting of soft colorless c ...

    borax
    leads to
    sodium perborate Sodium perborate is chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having ...

    sodium perborate
    , a bleach used in laundry detergents: : + 4 + 2 NaOH → 2 + converts
    carboxylic acid A carboxylic acid is an organic acid that contains a carboxyl group (C(=O)OH) attached to an R-group. The general formula of a carboxylic acid is R−COOH or R−CO2H, with substituent, R referring to the alkyl, alkenyl, aryl, or other group. ...
    s (RCO2H) into peroxy acids (RC(O)O2H), which are themselves used as oxidizing agents. Hydrogen peroxide reacts with
    acetone Acetone, or propanone, is an organic compound , CH4; is among the simplest organic compounds. In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, ...

    acetone
    to form
    acetone peroxide Acetone peroxide (also called APEX) is an organic peroxide and a primary explosive, primary high explosive. It is produced by the reaction of acetone and hydrogen peroxide to yield a mixture of linear monomer and Alicyclic compound, cyclic Dimer ...

    acetone peroxide
    and with
    ozone Ozone (), or trioxygen, is an inorganic molecule A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a cha ...

    ozone
    to form
    trioxidane Trioxidane (also systematically named μ-trioxidanediidodihydrogen), also called hydrogen trioxide or dihydrogen trioxide, is an with the (also written as or ). It is one of the unstable s. In aqueous solutions, trioxidane decomposes to form ...
    . Hydrogen peroxide forms stable
    adduct An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all comp ...
    s with
    urea Urea, also known as carbamide, is an organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the prop ...

    urea
    ( Hydrogen peroxide - urea), sodium carbonate (sodium percarbonate) and other compounds. An acid-base adduct with triphenylphosphine oxide is a useful "carrier" for in some reactions. Hydrogen peroxide is both an oxidizing agent and reducing agent. The oxidation of hydrogen peroxide by sodium hypochlorite yields singlet oxygen. The net reaction of a ferric ion with hydrogen peroxide is a ferrous ion and oxygen. This proceeds via single electron oxidation and hydroxyl radicals. This is used in some organic chemistry oxidations, e.g. in the Fenton's reagent. Only catalytic quantities of iron ion is needed since peroxide also oxidizes ferrous to ferric ion. The net reaction of hydrogen peroxide and permanganate or manganese dioxide is manganous ion; however, until the peroxide is spent some manganese ions are reoxidized to make the reaction catalytic. This forms the basis for common monopropellant rockets.


    Biological function

    Hydrogen peroxide is formed in humans and other animals as a short-lived product in biochemical processes and is Toxicity, toxic to Cell (biology), cells. The toxicity is due to oxidation of proteins, membrane lipids and DNA by the peroxide ions. The class of biological
    enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates in ...

    enzyme
    s called superoxide dismutase (SOD) is developed in nearly all living cells as an important antioxidant agent. They promote the disproportionation of superoxide into
    oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

    oxygen
    and hydrogen peroxide, which is then rapidly decomposed by the enzyme
    catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyst, catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in prote ...

    catalase
    to oxygen and water. : 2 + 2 → + : 2 H2O2 → O2 + 2 H2O Peroxisomes are organelles found in virtually all eukaryotic cells. They are involved in the catabolism of very long chain fatty acids, Branched-chain-fatty-acid kinase, branched chain fatty acids, D-amino acid, D-amino acids, polyamines, and biosynthesis of plasmalogens, ether phospholipids critical for the normal function of mammalian brains and lungs. Upon oxidation, they produce hydrogen peroxide in the following process catalyzed by flavin adenine dinucleotide (FAD): : R-CH2-CH2-CO-SCoA + O2 ->[\ce] R-CH=CH-CO-SCoA + H2O2 Catalase, another peroxisomal enzyme, uses this H2O2 to oxidize other substrates, including phenols, formic acid, formaldehyde, and
    alcohol In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a Saturated and unsaturated compounds, saturated carbon atom. The term alcohol originally referred to the primary alcohol ethan ...

    alcohol
    , by means of a peroxidation reaction: :H2O2 + R'H2 -> R' + 2H2O thus eliminating the poisonous hydrogen peroxide in the process. This reaction is important in liver and kidney cells, where the peroxisomes neutralize various toxic substances that enter the blood. Some of the ethanol humans drink is oxidized to acetaldehyde in this way. In addition, when excess H2O2 accumulates in the cell, catalase converts it to H2O through this reaction: : H2O2 ->[\ce] + H2O Another origin of hydrogen peroxide is the degradation of adenosine monophosphate which yields hypoxanthine. Hypoxanthine is then oxidatively catabolism, catabolized first to xanthine and then to uric acid, and the reaction is catalyzed by the enzyme xanthine oxidase:Nelson, David; Cox, Michael; Lehninger, Albert L. and Cox, Michael M
    Lehninger Biochemie
    p. 932, Springer, 2001, (in German)
    The degradation of guanosine monophosphate yields xanthine as an intermediate product which is then converted in the same way to uric acid with the formation of hydrogen peroxide. Eggs of sea urchin, shortly after fertilization by a sperm, produce hydrogen peroxide. It is then quickly dissociated to OH· radical (chemistry), radicals. The radicals serve as initiator of radical polymerization, which surrounds the eggs with a protective layer of polymer. The bombardier beetle has a device which allows it to shoot corrosive and foul-smelling bubbles at its enemies. The beetle produces and stores hydroquinone and hydrogen peroxide, in two separate reservoirs in the rear tip of its abdomen. When threatened, the beetle contracts muscles that force the two reactants through valved tubes into a mixing chamber containing water and a mixture of catalytic enzymes. When combined, the reactants undergo a violent exothermic chemical reaction, raising the temperature to near the boiling point of water. The boiling, foul-smelling liquid partially becomes a gas (flash evaporation) and is expelled through an outlet valve with a loud popping sound. Hydrogen peroxide is a signaling molecule of Plant pathology, plant defense against pathogens. Hydrogen peroxide has roles as a signalling molecule in the regulation of a wide variety of biological processes. The compound is a major factor implicated in the free-radical theory of aging, based on how readily hydrogen peroxide can decompose into a
    hydroxyl radical The hydroxyl radical is the diatomic molecule . The hydroxyl radical is very stable as a dilute gas, but it decays very rapidly in the condensed phase. It is pervasive in some situations. Most notably the hydroxyl radicals is produced from the d ...

    hydroxyl radical
    and how superoxide radical byproducts of cellular respiration, cellular metabolism can react with ambient water to form hydrogen peroxide. These hydroxyl radicals in turn readily react with and damage vital cellular components, especially those of the mitochondria. At least one study has also tried to link hydrogen peroxide production to cancer. These studies have frequently been quoted in fraudulent treatment claims. The amount of hydrogen peroxide in biological systems can be assayed using a Enzyme assay, fluorometric assay.


    Uses


    Bleaching

    About 60% of the world's production of hydrogen peroxide is used for bleaching of wood pulp, pulp- and paper-bleaching. The second major industrial application is the manufacture of sodium percarbonate and
    sodium perborate Sodium perborate is chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having ...

    sodium perborate
    , which are used as mild bleaches in laundry detergents. Sodium percarbonate, which is an adduct of sodium carbonate and hydrogen peroxide, is the active ingredient in such laundry products as OxiClean and Tide (detergent), Tide laundry detergent. When dissolved in water, it releases hydrogen peroxide and sodium carbonate, By themselves these bleaching agents are only effective at wash temperatures of or above and so, often are used in conjunction with bleach activators, which facilitate cleaning at lower temperatures. It has also been used as a flour bleaching agent


    Production of organic compounds

    It is used in the production of various organic peroxides with dibenzoyl peroxide being a high volume example. Peroxy acids, such as peracetic acid and meta-chloroperoxybenzoic acid also are produced using hydrogen peroxide. Hydrogen peroxide has been used for creating organic peroxide-based explosives, such as
    acetone peroxide Acetone peroxide (also called APEX) is an organic peroxide and a primary explosive, primary high explosive. It is produced by the reaction of acetone and hydrogen peroxide to yield a mixture of linear monomer and Alicyclic compound, cyclic Dimer ...

    acetone peroxide
    . It is used as an initiator in Radical polymerization, polymerizations.


    Sewage treatment

    Hydrogen peroxide is used in certain waste-water treatment processes to remove organic impurities. In advanced oxidation processing, the Fenton reaction gives the highly reactive
    hydroxyl radical The hydroxyl radical is the diatomic molecule . The hydroxyl radical is very stable as a dilute gas, but it decays very rapidly in the condensed phase. It is pervasive in some situations. Most notably the hydroxyl radicals is produced from the d ...

    hydroxyl radical
    (·OH). This degrades organic compounds, including those that are ordinarily robust, such as Aromatic hydrocarbon, aromatic or halogenated compounds. It can also oxidize sulfur based compounds present in the waste; which is beneficial as it generally reduces their odour.


    Disinfectant

    Hydrogen peroxide may be used for the sterilization of various surfaces, including surgical tools, and may be deployed as a vapour (Vaporized hydrogen peroxide, VHP) for room sterilization. H2O2 demonstrates broad-spectrum efficacy against viruses, bacteria, yeasts, and bacterial spores. In general, greater activity is seen against Gram-positive than Gram-negative bacteria; however, the presence of
    catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyst, catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in prote ...

    catalase
    or other peroxidases in these organisms may increase tolerance in the presence of lower concentrations. Lower levels of concentration (3%) will work against most spores; higher concentrations (7 to 30%) and longer contact times will improve sporicidal activity. Hydrogen peroxide is seen as an environmentally safe alternative to
    chlorine Chlorine is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemica ...

    chlorine
    -based bleaches, as it degrades to form oxygen and water and it is generally recognized as safe as an antimicrobial agent by the U.S. Food and Drug Administration (FDA).


    Propellant

    High-concentration is referred to as "high-test peroxide" (HTP). It can be used either as a monopropellant (not mixed with fuel) or as the oxidizer component of a bipropellant rocket. Use as a monopropellant takes advantage of the decomposition of 70–98% concentration hydrogen peroxide into steam and oxygen. The propellant is pumped into a reaction chamber, where a catalyst, usually a silver or platinum screen, triggers decomposition, producing steam at over , which is expelled through a nozzle, generating thrust. monopropellant produces a maximal specific impulse (''I''sp) of 161 s (1.6 newton-second, kN·s/kg). Peroxide was the first major monopropellant adopted for use in rocket applications. Hydrazine eventually replaced hydrogen-peroxide monopropellant thruster applications primarily because of a 25% increase in the vacuum specific impulse. Hydrazine (toxic) and hydrogen peroxide (less-toxic [ACGIH TLV 0.01 and 1 ppm respectively]) are the only two monopropellants (other than cold gases) to have been widely adopted and utilized for propulsion and power applications. The Bell Rocket Belt, reaction control systems for Bell X-1, X-1, X-15, Centaur (rocket stage), Centaur, Project Mercury, Mercury, Little Joe (rocket), Little Joe, as well as the turbo-pump gas generators for X-1, X-15, Jupiter, Redstone and Viking used hydrogen peroxide as a monopropellant. As a bipropellant, is decomposed to burn a fuel as an oxidizer. Specific impulses as high as 350 s (3.5 kN·s/kg) can be achieved, depending on the fuel. Peroxide used as an oxidizer gives a somewhat lower ''I''sp than liquid oxygen, but is dense, storable, non-cryogenic and can be more easily used to drive gas turbines to give high pressures using an efficient ''closed cycle''. It may also be used for regenerative cooling of rocket engines. Peroxide was used very successfully as an oxidizer in World War II German rocket motors (e.g. T-Stoff, containing oxyquinoline stabilizer, for both the Walter HWK 109-500 ''Starthilfe'' RATO externally podded monopropellant booster system, and for the Walter HWK 109-509 rocket motor series used for the Me 163B), most often used with C-Stoff in a self-igniting hypergolic combination, and for the low-cost British Black Knight (rocket), Black Knight and Black Arrow launchers. In the 1940s and 1950s, the Hellmuth Walter Kommanditgesellschaft, Hellmuth Walter KG-conceived gas turbine, turbine used hydrogen peroxide for use in submarines while submerged; it was found to be too noisy and require too much maintenance compared to Submarine#Propulsion, diesel-electric power systems. Some torpedoes used hydrogen peroxide as oxidizer or propellant. Operator error in the use of hydrogen-peroxide torpedoes was named as possible causes for the sinking of HMS Sidon (P259), HMS ''Sidon'' and the Russian submarine Kursk, Russian submarine ''Kursk''. SAAB Underwater Systems is manufacturing the Torpedo 2000. This torpedo, used by the Swedish Navy, is powered by a piston engine propelled by HTP as an oxidizer and kerosene as a fuel in a bipropellant system.


    Household use

    Hydrogen peroxide has various domestic uses, primarily as a cleaning and disinfecting agent. ;Hair bleaching Diluted (between 1.9% and 12%) mixed with aqueous ammonia has been used to bleach human hair. The chemical's bleaching property lends its name to the phrase "peroxide blonde". Hydrogen peroxide is also used for tooth whitening. It may be found in most whitening toothpastes. Hydrogen peroxide has shown positive results involving teeth lightness and chroma shade parameters. It works by oxidizing colored pigments onto the Tooth enamel, enamel where the shade of the tooth may become lighter. Hydrogen peroxide may be mixed with baking soda and salt to make a homemade toothpaste. ;Removal of blood stains Hydrogen peroxide reacts with blood as a bleaching agent, and so if a blood stain is fresh, or not too old, liberal application of hydrogen peroxide, if necessary in more than single application, will bleach the stain fully out. After about two minutes of the application, the blood should be firmly blotted out. ;Acne treatmment Hydrogen peroxide may be used to treat Acne vulgaris, acne, although benzoyl peroxide is a more common treatment.


    Niche uses

    ;Glow sticks Hydrogen peroxide reacts with certain di-esters, such as phenyl oxalate ester (cyalume), to produce chemiluminescence; this application is most commonly encountered in the form of glow sticks. ;Horticulture Some horticulturalists and users of hydroponics advocate the use of weak hydrogen peroxide solution in watering solutions. Its spontaneous decomposition releases oxygen that enhances a plant's root development and helps to treat root rot (cellular root death due to lack of oxygen) and a variety of other pests. For general watering concentrations around 0.1% is in use and this can be increased up to one percent for anti-fungal actions. Tests show that plant foliage can safely tolerate concentrations up to 3%. ;Fishkeeping Hydrogen peroxide is used in aquaculture for controlling Fish mortality, mortality caused by various microbes. In 2019, the U.S. FDA approved it for control of ''Saprolegniasis'' in all coldwater finfish and all fingerling and adult coolwater and warmwater finfish, for control of external columnaris disease in warm-water finfish, and for control of ''Gyrodactylus'' spp. in freshwater-reared salmonids. Laboratory tests conducted by fish culturists have demonstrated that common household hydrogen peroxide may be used safely to provide oxygen for small fish. The hydrogen peroxide releases oxygen by decomposition when it is exposed to catalysts such as
    manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese Manganese is a chemical element Image:Simple Periodic Table Chart- ...

    manganese dioxide
    .


    Safety

    Regulations vary, but low concentrations, such as 5%, are widely available and legal to buy for medical use. Most over-the-counter peroxide solutions are not suitable for ingestion. Higher concentrations may be considered hazardous and typically are accompanied by a safety data sheet (SDS). In high concentrations, hydrogen peroxide is an aggressive oxidizer and will corrode many materials, including human skin. In the presence of a
    reducing agent A reducing agent (also called a reductant, reducer, or electron donor) is an element or compound that loses or "donates" an electron The electron is a subatomic particle (denoted by the symbol or ) whose electric charge is negative one ele ...
    , high concentrations of will react violently. High-concentration hydrogen peroxide streams, typically above 40%, should be considered hazardous due to concentrated hydrogen peroxide's meeting the definition of a United States Department of Transportation, DOT oxidizer according to U.S. regulations, if released into the environment. The United States Environmental Protection Agency, EPA Reportable Quantity (RQ) for D001 hazardous wastes is , or approximately , of concentrated hydrogen peroxide. Hydrogen peroxide should be stored in a cool, dry, well-ventilated area and away from any flammable or combustible substances. It should be stored in a container composed of non-reactive materials such as stainless steel or glass (other materials including some plastics and aluminium alloys may also be suitable). Because it breaks down quickly when exposed to light, it should be stored in an opaque container, and pharmaceutical formulations typically come in brown bottles that block light. Hydrogen peroxide, either in pure or diluted form, may pose several risks, the main one being that it forms explosive mixtures upon contact with organic compounds. Distillation of hydrogen peroxide at normal pressures is highly dangerous. It is also corrosive, especially when concentrated, but even domestic-strength solutions may cause irritation to the eyes, mucous membranes, and skin.For example, see a
    MSDS for a 3% peroxide solution
    .
    Swallowing hydrogen peroxide solutions is particularly dangerous, as decomposition in the stomach releases large quantities of gas (ten times the volume of a 3% solution), leading to internal bloating. Inhaling over 10% can cause severe pulmonary irritation.H2O2 toxicity and dangers
    Agency for Toxic Substances and Disease Registry website
    With a significant vapour pressure (1.2 kPa at 50 °C), hydrogen-peroxide vapour is potentially hazardous. According to U.S. NIOSH, the immediately dangerous to life and health (IDLH) limit is only 75 ppm. The U.S. Occupational Safety and Health Administration (OSHA) has established a permissible exposure limit of 1.0 ppm calculated as an 8-hour time-weighted average (29 CFR 1910.1000, Table Z-1). Hydrogen peroxide also has been classified by the American Conference of Governmental Industrial Hygienists (ACGIH) as a "known animal carcinogen, with unknown relevance on humans". For workplaces where there is a risk of exposure to the hazardous concentrations of the vapours, continuous monitors for hydrogen peroxide should be used. Information on the hazards of hydrogen peroxide is available from OSHA and from the ATSDR.


    Adverse effects on wounds

    Historically hydrogen peroxide was used for disinfecting wounds, partly because of its low cost and prompt availability compared to other
    antiseptic Antiseptics (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") are antimicrobial substances that are applied to living tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cel ...

    antiseptic
    s. Now it is thought to inhibit healing and to induce scarring, because it destroys newly formed skin cells. One study found that only very low concentrations (0.03% solution, this is a dilution of typical 3% Peroxide by 100 times) may induce healing, and only if not applied repeatedly. A 0.5% solution was found to impede healing. Surgical use can lead to gas embolism formation. Despite this, it is still used for wound treatment in many developing countries, and, in the United States, is prevalent as a major first aid antiseptic. Dermal exposure to dilute solutions of hydrogen peroxide causes whitening or bleaching of the skin due to microembolism caused by oxygen bubbles in the capillaries.


    Use in alternative medicine

    Practitioners of alternative medicine have advocated the use of hydrogen peroxide for various conditions, including emphysema, influenza, AIDS, and in particular cancer. There is no evidence of effectiveness and in some cases it has proved fatal.Hydrogen Peroxide, 3%. 3. Hazards Identification
    Southeast Fisheries Science Center, daughter agency of NOAA.
    Both the effectiveness and safety of hydrogen peroxide therapy is scientifically questionable. Hydrogen peroxide is produced by the immune system, but in a carefully controlled manner. Cells called phagocytes engulf pathogens and then use hydrogen peroxide to destroy them. The peroxide is toxic to both the cell and the pathogen and so is kept within a special compartment, called a phagosome. Free hydrogen peroxide will damage any tissue it encounters via oxidative stress, a process that also has been proposed as a cause of cancer. Claims that hydrogen peroxide therapy increases cellular levels of oxygen have not been supported. The quantities administered would be expected to provide very little additional oxygen compared to that available from normal respiration. It is also difficult to raise the level of oxygen around cancer cells within a tumour, as the blood supply tends to be poor, a situation known as tumor hypoxia. Large oral doses of hydrogen peroxide at a 3% concentration may cause irritation and blistering to the mouth, throat, and abdomen as well as abdominal pain, vomiting, and diarrhea. intravenous therapy, Intravenous injection of hydrogen peroxide has been linked to several deaths. The American Cancer Society states that "there is no scientific evidence that hydrogen peroxide is a safe, effective, or useful cancer treatment." Furthermore, the therapy is not approved by the U.S. FDA.


    Historical incidents

    * On 16 July 1934, in Kummersdorf, Germany, a propellant tank containing an experimental monopropellant mixture consisting of hydrogen peroxide and ethanol exploded during a test, killing three people. * During the World War II, Second World War, doctors in Nazi concentration camps, German concentration camps experimented with the use of hydrogen peroxide injections in the killing of human subjects. * In April 1992, an explosion occurred at the hydrogen peroxide plant at Jarrie in France, due to technical failure of the computerised control system and resulting in one fatality and wide destruction of the plant. * Several people received minor injuries after a hydrogen peroxide spill on board a flight between the U.S. cities of Orlando and Memphis on 28 October 1998. * The Russian submarine Russian submarine Kursk (K-141), K-141 ''Kursk'' sailed to perform an exercise of firing dummy torpedoes at the Russian battlecruiser Pyotr Velikiy, Pyotr Velikiy, a Kirov-class battlecruiser, ''Kirov''-class battlecruiser. On 12 August 2000, at 11:28 local time (07:28 UTC), Russian submarine Kursk explosion, there was an explosion while preparing to fire the torpedoes. The only credible report to date is that this was due to the failure and explosion of one of the Kursk's hydrogen peroxide-fueled torpedoes. It is believed that High test peroxide, HTP, a form of highly concentrated hydrogen peroxide used as propellant for the torpedo, seeped through its container, damaged either by rust or in the loading procedure back on land where an incident involving one of the torpedoes accidentally touching ground went unreported. The vessel was lost with all hands. A similar incident was responsible for the loss of HMS Sidon (P259), HMS ''Sidon'' in 1955. * On 15 August 2010, a spill of about of cleaning fluid occurred on the 54th floor of 1515 Broadway, in Times Square, New York City. The spill, which a spokesperson for the New York City fire department said was of hydrogen peroxide, shut down Broadway between West 42nd and West 48th streets as fire engines responded to the HAZMAT, hazmat situation. There were no reported injuries.


    See also

    * FOX reagent, used to measure levels of hydrogen peroxide in biological systems. * Hydrogen chalcogenide * Retr0bright, a process utilizing hydrogen peroxide to restore yellowed items such as plastic Home computer, computer cases and Video game console, game consoles.


    References

    Notes Bibliography * * A great description of properties & chemistry of . * *


    External links


    Hydrogen Peroxide
    at ''The Periodic Table of Videos'' (University of Nottingham)
    Material Safety Data Sheet







    Process flow sheet of Hydrogen Peroxide Production by anthrahydroquinone autoxidation

    Hydrogen Peroxide Handbook by Rocketdyne

    IR spectroscopic study J. Phys. Chem.
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