Potassium pyrophosphate, K₄P₂O₇

The Potassium pyrophosphate, K₄P₂O₇, is produced by heating dipotassium hydrogen phosphate, or by neutralizing anhydrous phosphoric acid with potassium hydroxide dissolved in absolute alcohol. Its specific heat is 0.1910 between 17° and 98° C. It is soluble in water, forming a slightly alkaline solution, and yields a trihydrate.