ABSTRACT

Lithium carbonate (Li2CO3) and ammonium dihydrogen phosphate (NH4H2PO4) were used for synthesizing lithium diphosphate (Li4P2O7). The purity of the latter compound was checked up by X-ray diffraction. The heat of dissolution of (Li4P2O7) in phosphoric acid solution was measured in a C-80 SETARAM calorimeter. Many dilution and mixing processes in acid solutions of several concentrations (w/w) H3PO4, were also realized in the calorimeter in order to get the standard enthalpy of formation of this product. Two thermochemical cycles were investigated and the obtained values for the enthalpy of formation are: (-3383.4 and -3147) kJ.mol-1. The former one is in better agreement with literature data.

Compounds

#	Formula	Name
1	Li	lithium
2	P	phosphorus
3	O2	oxygen
4	H2O	water
5	H3O4P	phosphoric acid
6	ClNa	sodium chloride
7	Na4O7P2	sodium diphosphate
8	ClLi	lithium chloride
9	Li4O7P2	lithium diphosphate
10	Li3O4P	lithium phosphate

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.
Type	Compound-#	Property	Variable	Phase	Method	#Points
POMD	5 4 9	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Mass fraction - 5; Liquid Pressure, kPa; Liquid Temperature, K; Liquid Mole fraction - 9; Liquid	Liquid	Calvet calorimetry	1
POMD	6 5 4	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Mass fraction - 5; Liquid Pressure, kPa; Liquid Temperature, K; Liquid Mole fraction - 6; Liquid	Liquid	Calvet calorimetry	1
POMD	5 7 4	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Mass fraction - 5; Liquid Pressure, kPa; Liquid Temperature, K; Liquid Mole fraction - 7; Liquid	Liquid	Calvet calorimetry	1
POMD	8 5 4	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Mass fraction - 5; Liquid Pressure, kPa; Liquid Temperature, K; Liquid Mole fraction - 8; Liquid	Liquid	Calvet calorimetry	1
POMD	5 4 10	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Mass fraction - 5; Liquid Pressure, kPa; Liquid Temperature, K; Liquid Mole fraction - 10; Liquid	Liquid	Calvet calorimetry	1
POMD	5 4	Molar enthalpy of solution, kJ/mol ; Liquid	Mole fraction - 5; Liquid Temperature, K; Liquid Pressure, kPa; Liquid	Liquid	Calvet calorimetry	1
RXND	1 2 9 3	Molar enthalpy of reaction, kJ/mol			Solution calorimetry	1

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Standard enthalpy of formation of lithium diphosphate

Gmati-Ben Khaled, H., Khattech, I., Jemal, M.

ABSTRACT