Bulletin of Materials Science

, Volume 18, Issue 5, pp 623–630 | Cite as

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

  • P Markondeya Raj
Rapid Communication

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” analysis Gibbs energy function e.m.f. measurements enthalpy of formation heat capacity entropy phase 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

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References

  1. Amosse J and Mathieu J C 1974C. R. Acad. Sci. Paris C279 871Google Scholar
  2. Aune R E, Sridhar S and Du Sichen 1994J. Chem. Thermodynamics 26 493CrossRefGoogle Scholar
  3. Charette G G and Flengas S N 1968J. Electrochem. Soc. 115 796CrossRefGoogle Scholar
  4. Jacob K T 1977J. Mater. Sci. 12 1647CrossRefGoogle Scholar
  5. Jacob K T and Srikanth S 1988J. Mater. Res. 3 687CrossRefGoogle Scholar
  6. Knacke O, Kubaschewski O and Hesselmann K 1991Thermochemical properties of inorganic substances, (Berlin Heidelberg: Springer-Verlag)Google Scholar
  7. Kvernes I and Kofstad P 1973Scand. J. Metall. 2 291Google Scholar
  8. Landee C P and Westrum E F Jr 1976J. Chem. Thermodynamics 8 471CrossRefGoogle Scholar
  9. Mah A D and Pankratz L B 1976Contributions to the data on theoretical metallurgy, Bulletin 668, U.S. Department of the Interior, Bureau of Mines, Washington D.C.Google Scholar
  10. Navrotsky A and Kleppa O 1969J. Inorg. Chem. 8 756CrossRefGoogle Scholar
  11. Pankratz L B 1982Thermodynamic properties of elements and oxides, Bulletin 672, U.S. Department of Interior, Bureau of Mines, Washington D.C.Google Scholar
  12. Porshina Z V and Rezukhina T N 1960Russ. J. Inorg. Chem. 5 488Google Scholar
  13. Rezukhina T N and Zharkova L A 1958Zhur. Fiz. Khim. 32 2233Google Scholar
  14. Rezukhina T N and Kashina T A 1974Russ. J. Phys. Chem. 48 1702Google Scholar
  15. Rizzo F E, Bidwell L R and Frank D F 1969Trans. Metall. Soc. AIME 239 1901Google Scholar

Copyright information

© The Indian Academy of Sciences 1995

Authors and Affiliations

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

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