The calcium mixed phosphate Ca8P2O7(PO4)4 has been synthesized by thermal decomposition of octocalciumphosphate previously prepared by precipitation in amoniacal phosphate solution. The enthalpy of formation at 298.15 K referenced to . tricalcium phosphate and calcium pyrophosphate is determined. The . tricalcium phosphate was prepared by two methods : precipitation in amoniacal aqueous medium and high temperature solid state reaction. The calcium pyrophosphate was prepared too by high temperature solid state reaction. All the compounds and characterized by chemical analysis, X-rays diffraction and IR spectroscopy. The enthalpy of formation +10.83.0.68 kJ/mol is obtained by solution calorimetry at 298.15 K in nitric acid.
Compounds
#
Formula
Name
1
Ca3O8P2
calcium phosphate
2
Ca2O7P2
calcium pyrophosphate
3
Ca8O23P6
calcium (diphosphate) phosphate (Ca8(P2O7)(PO4)4)
Datasets
The table above is generated from the ThermoML associated json file (link above).
POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied;
the numbers refer to the table of compounds on the left.