Iodous acid

Iodous acid is the chemical compound with the formula HIO₂. Its salts are named iodites; these are exceedingly unstable and have been observed but never isolated.^[1] They will rapidly disproportionate to molecular iodine and iodates.

Iodous acid

Ball-and-stick model of iodous acid Space-filling model of iodous acid
Names
IUPAC name iodous acid
Identifiers
CAS Number	12134-99-5
3D model (JSmol)	Interactive image
ChemSpider	145806
ECHA InfoCard	100.032.004
PubChem CID	166623
CompTox Dashboard (EPA)	DTXSID801030159
InChI InChI=1S/HIO2/c2-1-3/h(H,2,3)
SMILES O[I+][O-]
Properties
Chemical formula	HIO2
Molar mass	159.911
Conjugate base	Iodite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Other oxyacids

Iodous 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