Potassium iodate, KIO₃

The Potassium iodate, KIO₃ is formed by the oxidation of potassium iodide, either electrolytically, or by means of potassium permanganate or chlorate. The colourless, monoclinic crystals melt at 560° C., and have a density of 3.89. The heat of formation from the elements is given as 124.49 Cal. And 126.1 Cal. At 20° C. the solubility is 8.1 grams per 100 grams of water, the boiling-point of the saturated solution being 102° C. A semi-hydrate has been described. On heating, potassium iodate decomposes with evolution of oxygen, the decomposition being facilitated by the presence of MnO₂.

When the iodate is crystallized from - acid solution, a di-iodate, KIO₃,HIO₃, is formed. It finds application in the determination of the concentration of hydrogen ions, and also in volumetric analysis, since it reacts with potassium iodide and hydrochloric acid according to the equation

KIO₃,HIO₃ + 10KI + 11HCl = 11KCl + 12I + 6H₂O.

A tri-iodate, KIO₃,2HIO₃, has also been prepared.