Potassium periodate

Potassium periodate
Names
	IUPAC name Potassium periodate
	Other names potassium metaperiodate
Identifiers
CAS Number	7790-21-8 ;
3D model (JSmol)	Interactive image;
ChemSpider	128877 ;
ECHA InfoCard	100.029.269
EC Number	232-196-0;
PubChem CID	516896;
UNII	Q3LOC6P66L ;
CompTox Dashboard (EPA)	DTXSID90894076 ;
	InChI InChI=1S/HIO4.K/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1 Key: FJVZDOGVDJCCCR-UHFFFAOYSA-M ; InChI=1/HIO4.K/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1 Key: FJVZDOGVDJCCCR-REWHXWOFAS;
	SMILES [K+].[O-]I(=O)(=O)=O;
Properties
Chemical formula	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)
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
Main hazards	Oxidant
Safety data sheet	External MSDS
NFPA 704 (fire diamond)	0 1 0 OX
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]

KIO 3 + Cl 2 + 2 KOH \to KIO 4 + 2 KCl + H 2 O

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.

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

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.CS1 maint: extra text: authors list (link)
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.

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[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.CS1 maint: extra text: authors list (link)

[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.