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

Authors

  • P Markondeya Raj
    • Department of MetallurgyIndian Institute of Science
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 Δf H m 0 (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” analysis Gibbs energy function e.m.f. measurements enthalpy of formation heat capacity entropy phase relations

List of symbols

C p,m 0

Standard molar heat capacity

T

Thermodynamic temperature in kelvin

Δf G m 0

Standard molar Gibbs free energy of formation from elements

Δi G m 0

Standard molar Gibbs free energy change for reaction i

Δf H m 0

Standard molar enthalpy of formation from elements

cr

crystal

GEF

Gibbs energy function

Copyright information

© The Indian Academy of Sciences 1995