Magnesium Iodate, Mg(IO₃)₂

Magnesium Iodate, Mg(IO₃)₂.4H₂O, is more stable than the chlorate or bromate. The monoclinic crystals lose three molecules of water at 150° C. and the fourth at 210° C. At higher temperatures the anhydrous salt decomposes. It is prepared by the double decomposition of magnesium nitrate and an alkaline iodate, or by dissolving magnesia in iodic acid. It dissolves in 9.4 parts of water at 15° C. and in 314 parts at 100° C.

A supersaturated solution of magnesium iodate, cooled to 0° C. and stirred, deposits rhombic plates of the dodecahydrate which melts at 50° C. and passes into the tetrahydrate.