Lead Phosphite, PbHPO₃

Lead Phosphite, PbHPO₃, is a white powder obtained by precipitating a lead salt solution by a soluble phosphite, or by neutralising phosphorous acid with lead carbonate. When heated it is converted into phosphine and phosphate. Its heat of formation from its elements is 227,700 calories. The acid salt Pb(H₂PO₃)₂ is obtained by dissolving PbHPO₃ in phosphorous acid, and by ignition in a vacuum yields the pyrophosphite PbH₂P₂O₅. A basic phosphite exists which is 3PbO.P₂O₃.2H₂O or 4PbO.P₂O₃.2H₂O.