Thermodynamics Research Center / ThermoML | Thermochimica Acta

Calorimetric Study of Melts in the System KCl - K2TaF7

Nerad, I., Miksikova, E.
Thermochim. Acta 2010, 510, 1-2, 32-36
ABSTRACT
Enthalpy increment measurements on melts in the system KCl-K2TaF7 were carried out by drop calorimetry at temperatures between 298 K and 1053, 1093 and 1133 K and selected compositions. Heat capacities of melted mixtures and enthalpies of mixing were determined using the experimental data. Calorimetric experiments showed nonideality of the melt in several properties. The molar relative enthalpy and molar heat capacity of melt exhibited small negative divergence from additivity. The molar enthalpy of mixing of melt showed exothermic deviation from ideality which increased with increasing temperature. The thermal effect at mixing was assigned predominantly to additive and substitution reactions producing heteroligand complex anions TaF6Cl2-. The nonideality was also confirmed by evaluating of activities considering Margules type model for excess Gibbs energy of mixing.
Compounds
# Formula Name
1 ClK potassium chloride
2 F7K2Ta dipotassium heptafluorotantalate
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
  • 2
  • Molar enthalpy, kJ/mol ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Drop calorimetry
  • 3
  • POMD
  • 1
  • 2
  • Molar enthalpy, kJ/mol ; Liquid
  • Temperature, K; Liquid
  • Mole fraction - 2; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Drop calorimetry
  • 42