STANDARD ENTHALPY OF FORMATION OF ANHYDROUS, MONOHYDRATED, AND DIHYDRATED ZIRCONIUM BIS(MONOHYDROGENPHOSPHATE)

The enthalpies of solution of amorphous and crystalline Zr(HPO4)2 · H2O, of Zr(HPO4)2, and Zr(HPO4)2 · 2H2O have been measured calorimetrically and the standard enthalpies of formation derived. The results obtained are as follows: {A table is presented}. In order to establish an unambiguous assessment of the degree of crystallinity of these exchangers, the ΔHo of other Zr(HPO4)2 · H2O samples prepared by different techniques with various conditions have also been determined. © 1979.