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Chlorous acid

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Chlorous acid
Chlorous acid
Chlorous acid
Names
IUPAC name
Chlorous acid, Chloric (III) acid
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
KEGG
UNII
  • InChI=1S/ClHO2/c2-1-3/h(H,2,3) checkY
    Key: QBWCMBCROVPCKQ-UHFFFAOYSA-N checkY
  • InChI=1/ClHO2/c2-1-3/h(H,2,3)
    Key: QBWCMBCROVPCKQ-UHFFFAOYAO
  • O[Cl+] [O-]
Properties
H Cl O2
Molar mass 68.46 g/mol
Acidity (pKa) 1.96
Conjugate base Chlorite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Chlorous acid is an inorganic compound with the formula HClO2. It is a weak acid. Chlorine has oxidation state +3 in this acid. The pure substance is unstable, disproportionating to hypochlorous acid (Cl oxidation state +1) and chloric acid (Cl oxidation state +5):

2 HClO2 → HClO + HClO3

Although the acid is difficult to obtain in pure substance, the conjugate base, chlorite, derived from this acid is stable. One example of a salt of this anion is the well-known sodium chlorite. This and related salts are sometimes used in the production of chlorine dioxide.

Preparation

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HClO2 can be prepared through reaction of barium or lead chlorite and dilute sulfuric acid:

Ba(ClO2)2 + H2SO4 → BaSO4 + 2 HClO2
Pb(ClO2)2 + H2SO4 → PbSO4 + 2 HClO2

Stability

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Chlorous acid is a powerful oxidizing agent, although its tendency to undergo disproportionation counteracts its oxidizing potential.[citation needed]

Chlorine is the only halogen to form an isolable acid of formula HXO2.[1] Fluorine is resistant to oxidation, having a -1 oxidation state even in hypofluorous acid, and is thus unable to form any higher oxoacids; despite the name, fluorite minerals are chemically fluoride compounds. Neither bromous acid nor iodous acid has ever been isolated. A few salts of bromous acid, bromites, are known, but no iodites.[1]

References

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  1. ^ a b Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5

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