Thermodynamics Research Center / ThermoML | International Journal of Thermophysics

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Potassium Benzoate C7H5O2K(s)

Yang, W.-W.[Wei-Wei], Di, Y.-Y.[You-Ying], Yin, Z.-F.[Zhen-Fen], Kong, Y.-X.[Yu-Xia], Tan, Z.-C.[Zhi-Cheng]
Int. J. Thermophys. 2009, 30, 2, 542-554
ABSTRACT
Potassium benzoate C7H5O2K (CAS Registry No. 582-25-2) was synthesized by the method of liquid phase reaction. Chemical and elemental analyses, FTIR, and X-ray powder diffraction (XRD) techniques were applied to characterize the composition and structure of the compound. Low-temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature range from 78K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by the least-squares method. Smoothed heat capacities and thermodynamic functions of the compound were calculated based on the fitted polynomial. In accordance with Hess's law, a reasonable thermochemical cycle was designed, and 100mL of 1 mol * dm?3 NaOH solution was chosen as the calorimetric solvent. The standard molar enthalpies of dissolution for the reactants and products of the supposed reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. Finally, the standard molar enthalpy of formation of the title compound C7H5O2K (s) was derived to be -(610.94 +- 0.77) kJ * mol?1.
Compounds
# Formula Name
1 K potassium
2 H2 hydrogen
3 C graphite
4 O2 oxygen
5 C7H5KO2 potassium benzoate
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
  • 5
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • VADIAC:UFactor:4
  • 90
  • POMD
  • 5
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • VADIAC:UFactor:4
  • 65
  • RXND
  • 5
  • 1
  • 2
  • 3
  • 4
  • Molar enthalpy of reaction, kJ/mol
  • solution calorimetry
  • 1