Potassium periodate

Potassium periodate

150px
200px
Names
IUPAC name Potassium periodate
Other names potassium metaperiodate
Identifiers
CAS Number	7790-21-8 Y
ChemSpider	128877 Y
EC Number	232-196-0
Jmol 3D model	Interactive image
PubChem	516896
InChI InChI=1S/HIO4.K/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1 Y Key: FJVZDOGVDJCCCR-UHFFFAOYSA-M Y 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
Vapor pressure	{{{value}}}
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).
Y verify (what is YN ?)
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.

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.

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).