Barium Peroxyhydrate

By the action of hydrogen peroxide on the crystallised peroxide, or of more than one equivalent of hydrogen peroxide on barium hydroxide, or of hydrogen peroxide and ammonia on a barium salt, between 30° and 60° C., barium monoperoxyhydrate, BaO₂.H₂O₂, is obtained in monoclinic crystals. At room temperature it soon becomes yellow without evolution of oxygen. Then oxygen begins to escape, and after four or five days, when half the available oxygen has gone, the yellow colour disappears. At 50°-60° C. decomposition takes place in a few minutes. The reaction is probably as follows, with the possible intermediate formation of a monohydrate: -

2BaO₂.H₂O₂ = 2BaO₂ + 2H₂O + O₂.

The heat of formation from barium peroxide and hydrogen peroxide is 51 Cal. De Forcrand supposed the compound to have the structural formula .

By the action of an excess of hydrogen peroxide on a cooled barium salt solution and precipitation by ammonia, a diperoxy-hydrate, BaO₂.2H₂O₂, is obtained.