Potassium periodate

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Potassium periodate
Potassium periodate.svg
KIO4.jpg
Identifiers
CAS number 7790-21-8 YesY
PubChem 516896
ChemSpider 128877 YesY
EC number 232-196-0
Jmol-3D images Image 1
Properties
Molecular formula KIO4
Molar mass 230.00 g mol−1
Appearance white crystaline powder
Odor odourless
Density 3.618 g/cm3
Melting point 582 °C (1,080 °F; 855 K) (decomposes)
Solubility in water 0.17 g/100 mL (0 °C)
0.42 g/100 mL (20 °C)
4.44 g/100 mL (80 °C)
7.87 g/100 mL (100 °C)
Structure
Crystal structure tetragonal
Hazards
MSDS External MSDS
EU Index Not listed
Main hazards Oxidant
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazard OX: Oxidizer. E.g., potassium perchlorateNFPA 704 four-colored diamond
Related compounds
Other anions Potassium iodide
Potassium iodate
Other cations Sodium periodate
Related compounds Periodic acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Potassium periodate is an inorganic salt with the molecular formula KIO4. It is composed of a potassium cation and a periodate anion and may also be regarded as the potassium salt of periodic acid. Note that the pronunciation is per-iodate, not period-ate.

Unlike other common periodates, such as sodium periodate and periodic acid, it is only available in in the metaperiodate form; the corresponding potassium orthoperiodate (K5IO6) has never been reported.

Preparation[edit]

Potassium periodate can be prepared by the oxidation of an aqueous solution of potassium iodate by chorine and potassium hydroxide.[1]

KIO3 + Cl2 + 2 KOH → KIO4 + 2 KCl + H2O

It can also be generated by the electrochemical oxidation of potassium iodate, however the low solubility of KIO3 makes this approach of limited use.

Chemical Properties[edit]

Potassium periodate decomposes at 582 °C to form potassium iodate and oxygen.

The low solubility of KIO4 makes it useful for the determination of potassium and cerium.

It is slightly soluble in water (one of the less soluble of potassium salts, owing to a large anion), giving rise to a solution that is slightly alkaline. On heating (especially with manganese(IV) oxide as catalyst), it decomposes to form potassium iodate, releasing oxygen gas.

KIO4 forms tetragonal crystals of the Scheelite type (space group I41/a).[2]

References[edit]

  1. ^ Riley, edited by Georg Brauer ; translated by Scripta Technica, Inc. Translation editor Reed F. (1963). Handbook of preparative inorganic chemistry. Volume 1 (2nd ed. ed.). New York, N.Y.: Academic Press. p. 325. ISBN 978-0121266011. 
  2. ^ Al-Dhahir, T.A.; Dhanaraj, G.; Bhat, H.L. (June 1992). "Growth of alkali metal periodates from silica gel and their characterization". Journal of Crystal Growth 121 (1-2): 132–140. doi:10.1016/0022-0248(92)90182-I.