Potassium perborates

Potassium forms perborates by reactions similar to those employed for the preparation of the corresponding salts of sodium. A perborate of the formula KBO₃,½H₂O is precipitated as a crystalline powder by the interaction of a solution of potassium metaborate and 3 per cent, hydrogen peroxide. At 15° C. 100 grams of water dissolve 2.5 grams of the salt. In warm water it undergoes partial decomposition into boric acid, potassium hydroxide, and hydrogen peroxide. At ordinary temperature the dry salt is stable, but it decomposes suddenly between 150° and 160° C., leaving a residue of metaborate, and evolving oxygen.

A perborate with similar properties and the formula KBO₃,½H₂O₂ is produced by the action of 30 per cent, hydrogen peroxide on potassium metaborate. At 15° C. its solubility is 0.70 gram per 100 grams of water.