ABSTRACT

Low-temperature heat capacities of the coordination compound, chromium(III) tri(2- pyrazinecarboxylate), formulated as Cr(pyza)3, were measured by a precision automated adiabatic calorimeter over the temperature range of 78~400 K. A polynomial equation of heat capacities as a function of the temperature was fitted by a least square method. Based on the fitted polynomial equation, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated at the internal of 5 K. In accordance with a reasonable thermochemical cycle designed, the standard molar enthalpy of formation of the title complex was determined to be - 1207.86 +- 3.39 kJ*mol-1 by an isoperibol solution-reaction calorimeter.

Compounds

#	Formula	Name
1	Cr	chromium
2	H2	hydrogen
3	N2	nitrogen
4	C	graphite
5	O2	oxygen
6	CrH9O6	chromium (III) hydroxide trihydrate
7	C5H4N2O2	2-pyrazinecarboxylic acid
8	H2O	water
9	C15H9CrN6O6	chromium(III) pyrazine-2-carboxylate

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	Constraint	Phase	Method	#Points
POMD	9	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Vacuum adiabatic calorimetry	110
POMD	9	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Vacuum adiabatic calorimetry	66
POMD	9	Molar enthalpy, kJ/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Calculated	66
POMD	9	Molar entropy, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Calculated	66
RXND	9 1 2 3 4 5	Molar enthalpy of reaction, kJ/mol				Solution calorimetry	1
RXND	9 6 7 8	Molar enthalpy of reaction, kJ/mol				Solution calorimetry	1

Thermodynamics Research Center / ThermoML | Thermochimica Acta

Low-temperature Heat Capacity and the Standard Molar Enthalpy of Formation of Compound Chromium(III) Tri(2-Pyrazinecarboxylate)

Gao, S.[Shengli], Zhang, S.[Sheng], Chen, S.[Sanping], Yang, D.[Desuo]

ABSTRACT