Rubidium phosphates

The three phosphates are prepared by the interaction of phosphoric acid and rubidium hydroxide or carbonate in appropriate proportions. The primary phosphate, RbH₂PO₄, is acidic in aqueous solution; the other two are alkaline. When heated at 244° C. the primary phosphate loses water, yielding the acid pyrophosphate, Rb₂H₂P₂O₇. The secondary phosphate forms a monohy drate, and the normal phosphate a tetrahydrate. On heating the primary salt, the metaphosphate is formed; the secondary salt is converted into the pyrophosphate by heat. In properties the phosphates resemble the corresponding potassium derivatives.