An iodate is the polyatomic anion with the formula IO3. It is the most common form of iodine in nature, as it comprises the major iodine-containing ores.[1] Iodate salts are often colorless. They are the salts of iodic acid.


The iodate anion, IO3

Space-filling model of the iodate anion
3D model (JSmol)
  • InChI=1S/HIO3/c2-1(3)4/h(H,2,3,4)/p-1
  • [O-]I(=O)=O
Molar mass 174.902 g·mol−1
Related compounds
Related compounds
Periodate, Fluoroiodate, Bromate, Chlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Structure Edit

Iodate is pyramidal in structure. The O–I–O angles range from 97° to 105°, somewhat smaller than the O–Cl–O angles in chlorate.[2]

Reactions Edit

Redox Edit

Iodate is one of several oxyanions of iodine, and has an oxidation number of +5. It participates in several redox reactions, such as the iodine clock reaction. Iodate shows no tendency to disproportionate to periodate and iodide, in contrast to the situation for chlorate.

Iodate is reduced by sulfite:[1]

6HSO3 + 2IO3 → 2I + 6HSO4

Iodate oxidizes iodide:

5I + IO3 + 3H2SO4 → 3I2 + 3H2O + 3SO4^2

Similarly, chlorate oxidizes iodide to iodate:

I + ClO3 → Cl + IO3

Iodate is also obtained by reducing a periodate with a sulfide. The byproduct of the reaction is a sulfoxide.[3]

Acid-base Edit

Iodate is unusual in that it forms a strong hydrogen bond with its parent acid:[2]

IO3 + HIO3 → H(IO3)2

The anion H(IO3)2 is referred to as biiodate.

Principal compounds Edit

Natural occurrence Edit

Minerals containing iodate are found in the caliche deposits of Chile. The most important iodate minerals are lautarite and brüggenite, but also copper-bearing iodates such as salesite are known.[6]

References Edit

  1. ^ a b Lyday, Phyllis A. (2005). "Iodine and Iodine Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. pp. 382–390. doi:10.1002/14356007.a14_381.
  2. ^ a b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  3. ^ Qiu, Chao; Sheng Han; Xingguo Cheng; Tianhui Ren (2005). "Distribution of Thioethers in Hydrotreated Transformer Base Oil by Oxidation and ICP-AES Analysis" (abstract). Industrial & Engineering Chemistry Research. 44 (11): 4151–4155. doi:10.1021/ie048833b. Retrieved 2007-05-03. Thioethers can be oxidized to sulfoxides by periodate, and periodate is reduced to iodate
  4. ^ "Radiological Protection Institute of Ireland | | Media | Press releases | Radioactivity released from Wylfa nuclear power plant is extremely low and of no health significance". Archived from the original on 2013-10-17. Retrieved 2013-04-08.
  5. ^ "Decision to Discontinue the Future Distribution of Iodine Tablets". Archived from the original on 2013-10-18. Retrieved 2013-05-22.
  6. ^ "Home".