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Evaluation of Standard Free Energies of Formation of Clay Minerals by an Improved Regression Method

Published online by Cambridge University Press:  28 February 2024

Chandrika Varadachari ,
Mahammad Kudrat  and
Kunal Ghosh
Chandrika Varadachari
Affiliation:
Department of Agricultural Chemistry and Soil Science, University of Calcutta, 35 B.C. Road, Calcutta 700 019, India
Mahammad Kudrat
Affiliation:
Department of Agricultural Chemistry and Soil Science, University of Calcutta, 35 B.C. Road, Calcutta 700 019, India
Kunal Ghosh
Affiliation:
Department of Agricultural Chemistry and Soil Science, University of Calcutta, 35 B.C. Road, Calcutta 700 019, India
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Abstract

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An improved regression method for the evaluation of standard free energies of formation (ΔG°f) of clay minerals is here proposed in an attempt to remove some of the limitations of the earlier method (Chen, 1975). Particularly, this method suggests a procedure for the assignment of rankings for Σ ΔG°f, i values. Moreover, an iterative least-squares fitting technique is applied to solve the exponential equation to obtain the estimated ΔG°f. The estimated ΔG°f data for the various standard clay minerals are derived and compared with data available in the literature; in general, there is good agreement between the values. It is also shown how the regression method can be extended to clay minerals of variable composition. The ΔG°f's for several such minerals have been evaluated; a large number of combination equations required for such computations have been listed, so that for other similar minerals the process of evaluation of ΔG°f is greatly simplified.

Keywords

Clay mineralsFree energies of formationRegression method
Type
Research Article
Information
Clays and Clay Minerals , Volume 42 , Issue 3 , June 1994 , pp. 298 - 307
Copyright
Copyright © 1994, Clay Minerals Society

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