Potassium periodate
Names
IUPAC name
Potassium periodate
Other names
potassium metaperiodate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.269
EC Number
  • 232-196-0
UNII
  • InChI=1S/HIO4.K/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1 checkY
    Key: FJVZDOGVDJCCCR-UHFFFAOYSA-M checkY
  • InChI=1/HIO4.K/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1
    Key: FJVZDOGVDJCCCR-REWHXWOFAS
  • [K+].[O-]I(=O)(=O)=O
Properties
KIO4
Molar mass 230.00 g mol−1
Appearance white crystalline powder
Odor odourless
Density 3.618 g/cm3
Melting point 582 °C (1,080 °F; 855 K) (decomposes)
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
tetragonal
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Oxidant
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
1
0
0
OX
Safety data sheet (SDS) External MSDS
Related compounds
Other anions
 Potassium iodide
Potassium iodate
Other cations
 Sodium periodate
Related compounds
 Periodic acid
Except where otherwise noted, 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 the metaperiodate form; the corresponding potassium orthoperiodate (K5IO6) has never been reported.

Preparation

Potassium periodate can be prepared by the oxidation of an aqueous solution of potassium iodate by chlorine 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

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. [2]

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).[3]

References

  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.). New York, N.Y.: Academic Press. p. 325. ISBN 978-0121266011. {{cite book}}: |first= has generic name (help)CS1 maint: multiple names: authors list (link)
  2. ↑ M. Venugopalan and K. J. George: "Determination of cerium by potassium periodate" in Naturwissenschaften, 43(15), S. 348–349. doi:10.1007/BF00755157
  3. ↑ 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. Bibcode:1992JCrGr.121..132A. doi:10.1016/0022-0248(92)90182-I.
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