Hypoiodous acid

Hypoiodous acid
Hydrogen, H Oxygen, O Iodine, I
Names
	IUPAC name Hypoiodous acid
Identifiers
CAS Number	14332-21-9 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:29231 ;
ChemSpider	109942 ;
PubChem CID	123340;
UNII	2PYC923C5W ;
CompTox Dashboard (EPA)	DTXSID8042050 ;
	InChI InChI=1S/HIO/c1-2/h2H Key: GEOVEUCEIQCBKH-UHFFFAOYSA-N ;
	SMILES IO;
Properties
Chemical formula	HOI
Molar mass	143.911 g·mol−1
Acidity (pKa)	10.5 (in water, estimate)
Conjugate base	Hypoiodite
Related compounds
Related compounds	Hypofluorous acid; Hypochlorous acid; Hypobromous acid;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Hypoiodous acid is an inorganic compound with the chemical formula H O I. It forms when an aqueous solution of iodine is treated with mercuric or silver salts. It rapidly decomposes by disproportionation:^[2]

5 HIO → HIO₃ + 2 I₂ + 2 H₂O

Hypoiodites of alkali and alkaline earth metals can be made in cold dilute solutions if iodine is added to their respective hydroxides. Hypoiodous acid is a weak acid with a pK_a of about 11. The conjugate base is hypoiodite (IO⁻). Salts of this anion can be prepared by treating I₂ with alkali hydroxides. They rapidly disproportionate to form iodides and iodates.^[2]

Other oxyacids

Hypoiodous acid is part of a series of oxyacids in which iodine can assume oxidation states of −1, +1, +3, +5, or +7. A number of neutral iodine oxides are also known.

Iodine oxidation state	−1	+1	+3	+5	+7
Name	Hydrogen iodide	Hypoiodous acid	Iodous acid	Iodic acid	Periodic acid
Formula	HI	HIO	HIO₂	HIO₃	HIO₄ or H₅IO₆

References

^ Perrin, D. D., ed. (1982) [1969]. Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution. IUPAC Chemical Data (2nd ed.). Oxford: Pergamon (published 1984). Entry 119. ISBN 0-08-029214-3. LCCN 82-16524.
^ ^a ^b Holleman, A.F. (2001). Wiberg, Nils (ed.). Inorganic chemistry (1st English ed.). San Diego, Calif. : Berlin: Academic Press, W. de Gruyter. ISBN 0-12-352651-5.

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[P82db-1] Perrin, D. D., ed. (1982) [1969]. Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution. IUPAC Chemical Data (2nd ed.). Oxford: Pergamon (published 1984). Entry 119. ISBN 0-08-029214-3. LCCN 82-16524.

[Wiberg&Holleman-2] Holleman, A.F. (2001). Wiberg, Nils (ed.). Inorganic chemistry (1st English ed.). San Diego, Calif. : Berlin: Academic Press, W. de Gruyter. ISBN 0-12-352651-5.

[1]

[2]

v t e Iodine compounds
Iodine(−I)	HI NiI2−4 AtI other
Iodine(I)	I₂O HIO IN₃ ICN ICl IF NI₃ IBr INO₃ C₃H₅I
Iodine(II)	IO
Iodine(III)	HIO₂ ICl₃ IF₃ IBr₃ I₂(SO₄)₃
Iodine(IV)	IO ₂
Iodine(V)	HIO₃ IF₅ I₂O₅ IO₂F IOF₃
Iodine(VII)	HIO₄ H₅IO₆ IF₇ IO₃F IO₂F₃ IOF₅