Strontium Pyrophosphate, Sr₂P₂O₇

Strontium Pyrophosphate, Sr₂P₂O₇, can be formed by heating distrontium orthophosphate alone, or sodium meta- or pyro-phosphate with strontium oxide, or strontium sulphate with potassium pyrophosphate, or by the precipitation of strontium nitrate with sodium pyrophosphate. The density of the anhydrous salt at 20° C. is 3.4.

Prepared in the wet way it crystallises with 1 molecule of water. It is soluble in acids, but only slightly soluble in water. Pahl obtained a hydrate with 2½ molecules of water as well as a number of acid pyrophosphates, all of which are infusible at red heat.