Hypochlorite
Overview
 
The hypochlorite ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

, also known as chlorate(I) anion is Cl
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

. A hypochlorite compound is a chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 containing this group, with chlorine in oxidation state
Oxidation state
In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...

 +1.

Hypochlorites are the salts of hypochlorous acid
Hypochlorous acid
Hypochlorous acid is a weak acid with the chemical formula HClO. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor...

. Common examples include sodium hypochlorite (chlorine bleach
Bleach
Bleach refers to a number of chemicals that remove color, whiten, or disinfect, often via oxidation. Common chemical bleaches include household chlorine bleach , lye, oxygen bleach , and bleaching powder...

 or bleaching agent) and calcium hypochlorite
Calcium hypochlorite
Calcium hypochlorite is a chemical compound with formula 2. It is widely used for water treatment and as a bleaching agent...

 (bleaching powder or swimming pool chlorination compound).
Encyclopedia
The hypochlorite ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

, also known as chlorate(I) anion is Cl
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

. A hypochlorite compound is a chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 containing this group, with chlorine in oxidation state
Oxidation state
In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...

 +1.

Hypochlorites are the salts of hypochlorous acid
Hypochlorous acid
Hypochlorous acid is a weak acid with the chemical formula HClO. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor...

. Common examples include sodium hypochlorite (chlorine bleach
Bleach
Bleach refers to a number of chemicals that remove color, whiten, or disinfect, often via oxidation. Common chemical bleaches include household chlorine bleach , lye, oxygen bleach , and bleaching powder...

 or bleaching agent) and calcium hypochlorite
Calcium hypochlorite
Calcium hypochlorite is a chemical compound with formula 2. It is widely used for water treatment and as a bleaching agent...

 (bleaching powder or swimming pool chlorination compound). Hypochlorites are frequently quite unstable — for example, sodium hypochlorite is not available as a solid, since removal of the water from NaClO solution converts it to a mixture of sodium chloride
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 and sodium chlorate
Sodium chlorate
Sodium chlorate is a chemical compound with the chemical formula . When pure, it is a white crystalline powder that is readily soluble in water. It is hygroscopic. It decomposes above 250 °C to release oxygen and leave sodium chloride...

. Heating of NaClO solution also causes this reaction. Hypochlorites decompose in sunlight, giving chlorides and oxygen.

Due to their low stability, hypochlorites are very strong oxidizing agent
Oxidizing agent
An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...

s. They react with many organic and inorganic compounds. Reaction with organic compounds is very exothermic and may cause ignition
Combustion
Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...

, so hypochlorites should be handled with care. They can oxidize manganese compounds, converting them to permanganate
Permanganate
A permanganate is the general name for a chemical compound containing the manganate ion, . Because manganese is in the +7 oxidation state, the permanganate ion is a strong oxidizing agent. The ion has tetrahedral geometry...

s.

Covalent hypochlorites, such as methyl hypochlorite
Methyl hypochlorite
Methyl hypochlorite is an unstable and highly toxic compound that can be produced from reacting methanol with hypochlorous acid. It is extremely unstable and can decompose explosively giving off toxic fumes. Its instability is caused by the combination of the reducing methyl group and the...

 are also known, and are typically unstable.

Preparation

The sodium salt of the hypochlorite ion, NaClO, is formed by the disproportionation
Disproportionation
Disproportionation, also known as dismutation is used to describe a specific type of redox reaction in which a species is simultaneously reduced and oxidized so as to form two different products....

 of chlorine gas bubbled through dilute aqueous sodium hydroxide at room temperature:
(g) + 2 NaOH (aq) → NaCl (aq) + NaClO (aq) + (l)


The reaction of chlorine with hot, concentrated sodium hydroxide forms chlorates of a higher oxidation state:
3 (g) + 6 NaOH (aq) → 5 NaCl(aq) + (aq) + 3 (l)

Acid reaction

Hypochlorites generate chlorine gas when mixed with dilute acids. Hypochlorite and chloride are in equilibrium with chlorine gas:
2 (aq) + (aq) + (aq) (g) + (l)


Therefore, by Le Chatelier's principle
Le Châtelier's principle
In chemistry, Le Chatelier's principle, also called the Chatelier's principle, can be used to predict the effect of a change in conditions on a chemical equilibrium. The principle is named after Henry Louis Le Chatelier and sometimes Karl Ferdinand Braun who discovered it independently...

, a high pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 drives the reaction to the left by consuming ions, promoting the disproportionation of chlorine into chloride and hypochlorite, whereas a low pH drives the reaction to the right, promoting the release of chlorine gas.

Bleaching action

Hypochlorites are used as bleaches to remove dyes.

As an oxidising agent

Hypochlorite is the strongest oxidising agent of the generalized chlorate
Chlorate
The chlorate anion has the formula ClO. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; chlorates are the salts of chloric acid. "Chlorate", when followed by a roman numeral in parentheses, e.g...

s. For example, it oxidises to permanganate
Permanganate
A permanganate is the general name for a chemical compound containing the manganate ion, . Because manganese is in the +7 oxidation state, the permanganate ion is a strong oxidizing agent. The ion has tetrahedral geometry...

:
2 + 5 + 6 → 2 + 3 + 5

Metabolism

Hypochlorite is created in vivo
In vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...

 when the human immune system destroys pathogens. Viruses and bacteria are engulfed into an intracellular vacuole, the phagosome, where they are digested. For this purpose, several proteases (e.g. elastase
Elastase
In molecular biology, elastase is an enzyme from the class of proteases that break down proteins.- Forms and classification:There exist eight human genes for elastase:Bacterial forms: Organisms such as P...

) are released into the phagosome
Phagosome
In cell biology, a phagosome is a vacuole formed around a particle absorbed by phagocytosis. The vacuole is formed by the fusion of the cell membrane around the particle. A phagosome is a cellular compartment in which pathogenic microorganisms can be killed and digested...

 from intracellular granules
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

. In addition, there is also an enzyme-mediated ‘respiratory burst’, which results in the production of a set of reactive oxygen-derived compounds. Contact with a foreign particle causes the activation of membrane bound NADPH-oxidase, which produces superoxide
Superoxide
A superoxide, also known by the obsolete name hyperoxide, is a compound that possesses the superoxide anion with the chemical formula O2−. The systematic name of the anion is dioxide. It is important as the product of the one-electron reduction of dioxygen O2, which occurs widely in nature...

 in the phagosome. Superoxide dismutates to oxygen and hydrogen peroxide : the hydrogen peroxide formed is used as a substrate for the myeloperoxidase
Myeloperoxidase
Myeloperoxidase is a peroxidase enzyme that in humans is encoded by the MPO gene. Myeloperoxidase is most abundantly expressed in neutrophil granulocytes . It is a lysosomal protein stored in azurophilic granules of the neutrophil...

-catalysed reaction, which converts chloride to hypochlorite.

Stability

Hypochlorite is the least stable of the chlorine oxyanions. Many hypochlorite compounds exist only in solution, as is also the case with hypochlorous acid
Hypochlorous acid
Hypochlorous acid is a weak acid with the chemical formula HClO. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor...

 (HClO) itself.

Hypochlorite is unstable with respect to disproportionation
Disproportionation
Disproportionation, also known as dismutation is used to describe a specific type of redox reaction in which a species is simultaneously reduced and oxidized so as to form two different products....

. Upon heating, it degrades to a mixture of chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...

, oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 and other chlorates:
2 (aq) → 2 (aq) + (g)

3 (aq) → 2 (aq) + (aq)

See also

  • Clorox
    Clorox
    The Clorox Company is a US-based manufacturer of various food and chemical products based in Oakland, California, which is best known for its bleach product, Clorox.- History :...

  • Hypochlorite metabolism
  • Hypochlorous acid
    Hypochlorous acid
    Hypochlorous acid is a weak acid with the chemical formula HClO. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor...

  • Sodium hypochlorite
  • Methyl hypochlorite
    Methyl hypochlorite
    Methyl hypochlorite is an unstable and highly toxic compound that can be produced from reacting methanol with hypochlorous acid. It is extremely unstable and can decompose explosively giving off toxic fumes. Its instability is caused by the combination of the reducing methyl group and the...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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