Potassium iodate

Potassium iodate (KIO3) is an ionic chemical compound consisting of K+ ions and IO3− ions in a 1:1 ratio.

Potassium iodate
Names
IUPAC name
Potassium iodate
Other names
Iodic acid, potassium salt
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.938
EC Number
  • 231-831-9
E number E917 (glazing agents, ...)
RTECS number
  • NN1350000
UNII
Properties
KIO3
Molar mass 214.001 g/mol
Appearance white crystalline powder
Odor odorless
Density 3.89 g/cm3
Melting point 560 °C (1,040 °F; 833 K) (decomposes)
4.74 g/100 mL (0 °C)
9.16 g/100 mL (25 °C)
32.3 g/100 mL (100 °C)
Solubility soluble in KI solution
insoluble in alcohol, liquid ammonia, nitric acid
−63.1·10−6 cm3/mol
Hazards
R-phrases (outdated) R9, R22, R36, R37, R38
S-phrases (outdated) S35
NFPA 704 (fire diamond)
Flash point Non-flammable
Related compounds
Other anions
 Potassium chlorate
Potassium bromate
Other cations
 Sodium iodate
Related compounds
 Potassium iodide
Potassium periodate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Preparation and properties

Potassium iodate is an oxidizing agent and as such it can cause fires if in contact with combustible materials or reducing agents. It can be prepared by reacting a potassium-containing base such as potassium hydroxide with iodic acid, for example:

HIO3 + KOH → KIO3 + H2O

It can also be prepared by adding iodine to a hot, concentrated solution of potassium hydroxide.

3 I2 + 6 KOH → KIO3 + 5 KI + 3 H2O

Or by fusing potassium iodide with potassium chlorate, bromate or perchlorate, the melt is extracted with water and potassium iodate is isolated from the solution by crystallization:[1]

KI + KClO3 → KIO3 + KCl

Conditions/substances to avoid include: heat, shock, friction, combustible materials, reducing materials, aluminium, organic compounds, carbon, hydrogen peroxide and sulfides.

Applications

Potassium iodate is sometimes used for iodination of table salt to prevent iodine deficiency. Because iodide can be oxidized to iodine by molecular oxygen under wet conditions, US companies add thiosulfates or other antioxidants to the potassium iodide. In other countries, potassium iodate is used as a source for dietary iodine. It is also an ingredient in some baby formula milk.

Like potassium bromate, potassium iodate is occasionally used as a maturing agent in baking.

Radiation protection

Potassium iodate may be used to protect against accumulation of radioactive iodine in the thyroid by saturating the body with a stable source of iodine prior to exposure.[2] Approved by the World Health Organization for radiation protection, potassium iodate (KIO3) is an alternative to potassium iodide (KI), which has poor shelf life in hot and humid climates.[3] The UK, Singapore, United Arab Emirates, and the U.S. states Idaho and Utah are known to stock potassium iodate in tablet form. The government of Ireland also, following the September 11 attacks, issued potassium iodate tablets to all households.[4][5] It is not approved by the U.S. Food and Drug Administration (FDA) for use as a thyroid blocker, and the FDA has taken action against US websites that promote this use.[6][7]

An unopened box of potassium iodate tablets, distributed to every household in Ireland in case of a terror attack on reprocessing plants such as Sellafield and nuclear power stations such as Wylfa in the United Kingdom. A scenario that upon later expert Irish examination in 2007, was found to not have justified their distribution.[8][5] The Irish government now upon realizing their error suggests that the tablets be disposed of with municipal waste.[5]
Recommended Dosage for Radiological Emergencies involving radioactive iodine[9]
Age KI in mg KIO3 in mg
Over 12 years old 130 170
3 – 12 years old 65 85
1 – 36 months old 32 42
< 1 month old 16 21
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References
  1. Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. Astbury, John; Horsley, Stephen; Gent, Nick (1999), "Evaluation of a scheme for the pre-distribution of stable iodine (potassium iodate) to the civilian population residing within the immediate countermeasures zone of a nuclear submarine construction facility", Journal of Public Health, 21 (4): 2008–10, doi:10.1093/pubmed/21.4.412, PMID 11469363
  3. Pahuja, D.N.; Rajan, M.G.; Borkar, A.V.; Samuel, A.M. (Nov 2008), "Potassium iodate and its comparison to potassium iodide as a blocker of 131I uptake by the thyroid in rats", Health Physics, 65 (5): 545–9, doi:10.1097/00004032-199311000-00014, PMID 8225995
  4. "Archived copy". Archived from the original on 2013-10-17. Retrieved 2013-04-08.CS1 maint: archived copy as title (link)
  5. "Archived copy". Archived from the original on 2013-10-18. Retrieved 2013-05-22.CS1 maint: archived copy as title (link)
  6. http://www.nukepills.com/potassium-iodate-vs-potassium-iodide.html
  7. http://www.nukepills.com/docs/Potassium%20Iodate%20warning%20letter.pdf
  8. "Archived copy". Archived from the original on 2013-10-17. Retrieved 2013-04-08.CS1 maint: archived copy as title (link)
  9. Guidelines for Iodine Prophylaxis following Nuclear Accidents (PDF), Geneva: World Health Organization, 1999
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