Chlorous acid

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Chlorous acid
Chlorous acid
Chlorous acid
Identifiers
CAS number 13898-47-0 N
PubChem 24453
ChemSpider 22861 YesY
KEGG C01486 YesY
ChEBI CHEBI:29219 YesY
Jmol-3D images Image 1
Properties
Molecular formula HClO2
Molar mass 68.46 g/mol
Acidity (pKa) 1.96
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

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[edit]

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

Ba(ClO2)2 + H2SO4 → BaSO4 + 2HClO2

Stability[edit]

Chlorous acid is a powerful oxidizing agent, although its tendency to disproportionation counteracts its oxidizing potential.

Chlorine is the only halogen to form an isolable acid of formula HXO2.[1] Fluorine resists oxidation above the level of hypofluorous acid. Neither bromous acid nor iodous acid has ever been isolated. A few salts of bromous acid, bromites, are known, but no iodites.[1]

References[edit]

Media related to Chlorous acid at Wikimedia Commons

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