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, ...
, 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, ...
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 ...
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 ...
, 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 ...
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 ...
, 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 ...
. 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 explosivethermal 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) C2symmetry
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. ...
. 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 ...
, 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 ...
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 ...
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 ...
. 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 ...
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 ...
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 ...
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
Inaqueous 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.
Today, hydrogen peroxide is manufactured almost exclusively by the 
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 
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.
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.
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.
;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 
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