Bulletin of Materials Science

, Volume 18, Issue 5, pp 623–630

A critical assessment of the standard molar gibbs free energy of formation of NiWO4

  • P Markondeya Raj
Rapid Communication

DOI: 10.1007/BF02744848

Cite this article as:
Raj, P.M. Bull. Mater. Sci. (1995) 18: 623. doi:10.1007/BF02744848

Abstract

Three independent studies have been reported on the free energy of formation of NiWO4. Results of these measurements are analyzed by the “third-law” method, using thermal functions for NiWO4 derived from both low and high temperature heat capacity measurements. Values for the standard molar enthalpy of formation of NiWO4 at 298·15 K obtained from “third-law” analysis are compared with direct calorimetric determinations. Only one set of free energy measurements is found to be compatible with calorimetric enthalpies of formation. The selected value for ΔfHm0(NiWO4, cr, 298·15 K) is the average of the three calorimetric measurements, using both high temperature solution and combustion techniques, and the compatible free energy determination. A new set of evaluated data for NiWO4 is presented.

Keywords

“Third-law” analysisGibbs energy functione.m.f. measurementsenthalpy of formationheat capacityentropyphase relations

List of symbols

Cp,m0

Standard molar heat capacity

T

Thermodynamic temperature in kelvin

ΔfGm0

Standard molar Gibbs free energy of formation from elements

ΔiGm0

Standard molar Gibbs free energy change for reaction i

ΔfHm0

Standard molar enthalpy of formation from elements

cr

crystal

GEF

Gibbs energy function

Copyright information

© The Indian Academy of Sciences 1995

Authors and Affiliations

  • P Markondeya Raj
    • 1
  1. 1.Department of MetallurgyIndian Institute of ScienceBangaloreIndia