Alkali iodate

Cerous iodates and the iodates of the other rare earths form crystalline salts sparingly soluble in water, but readily soluble in cone, nitric acid, and in this respect differ from the ceric, zirconium, and thorium iodates, which are almost insoluble in nitric acid when an excess of a soluble iodate is present. It may also be noted that cerium alone of all the rare earth elements is oxidized to a higher valence by potassium bromate in nitric acid soln. The iodates of the rare earths are precipitated by adding an alkali iodate to the rare earth salts, and the fact that the rare earth iodates are soluble in nitric acid, and the solubility increases as the electro-positive character of the element increases, while thorium iodate is insoluble in nitric acid, allows the method to be used for the separation of these elements. Trihydrated erbium iodate, Er(I03)3.3H20, and trihydrated yttrium iodate, Yt(I03)3.3H20,... 

A. Connell (1802) 140 obtained a white precipitate—ferrous iodate—by boiling a soln. of iron in iodic acid, and C. F. Rammelsberg found that the addition of potassium iodate to ferrous sulphate gives a yellowish-white precipitate which is decomposed when heated. It is sparingly soluble in nitric acid, and it dissolves in an excess of ferrous sulphate, and the soln., when heated, precipitates basic ferric iodate. A. Ditte mixed boiling soln. of a ferric salt and an alkali iodate and obtained a brown precipitate—ferric iodate—insoluble in hot nitric acid diluted with its own volume of water. Crystals can be obtained by mixing warm dil. soln. of ferric nitrate, acidified with nitric acid, and sodium iodate. The precipitate... 

The anhydrous salt may be obtained by maintaining for a prolonged period at 80° to 90° C. a mixed solution of cobalt nitrate and Alkali iodate in the presence of free nitric acid. It is also formed at ordinary temperatures by mixing saturated solutions of cobalt nitrate and alkali iodate and agitating with a glass rod the flocculent, rose-coloured, hydrated precipitate, when it yields the blue-violet anhydrous compound. The salt is also produced by heating the same solutions from two to three hours in a glass tube at 120° C. 

The dihydrate, Co(IOs)a. 2HaO, is obtained by mixing equivalent amounts of cobalt nitrate and alkali iodate (or free iodic acid) in ten times their weight of water and allowing to crystallise at 30° C. Microscopic crystals of lilac hue are obtained, which are the stable form of the salt up to 68° C.. 

Action of heat The alkali iodates decomposed into oxygen and an iodide. Most iodates of the bivalent metals yield iodine and oxygen and leave a residue of oxide barium iodate, exceptionally, gives the periodate (more precisely, hexoxoperiodate) ... 

Ferric iodate, Fe203.I205, is obtained as a brown precipitate5 on mixing hot solutions of an alkali iodate and a ferric salt. Small crystals may be prepared by addition of an acid solution of iron in nitric acid to sodium iodate. The precipitate first formed readily dissolves, and upon concentration of the solution the salt crystallises out. It is stable in air at ordinary temperatures, but decomposes when heated,... 

In 1815, L. N. Vauquelin n precipitated mercuious iodatc, HglOs, a soln. of mercurous nitrate by the addition of iodic acid or alkali iodate. The precipitation does not occur if too much free acid is present. A. Ditte noted the formation of a mixture of mercurous iodide and iodate during the action of aq. iodic acid on mercury, an action which proceeds slowly at ordinary temp., but rapidly if heated. Mercurous iodate volatilizes at 250°, forming mercuric iodide, mercury, and oxygen. Mercurous iodate is sparingly soluble in water boiling water does not act on the salt it is soluble in iodic acid cold nitric acid has no action hot nitric acid gives red vapours, and forms mercuric iodate, Hg(I03)2 and hydrochloric acid forms mercuric chloride. 

Alkali iodates are manufactured from the corresponding chlorates by reaction with iodine upon heating in the presence of nitric acid ... 

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