Controversy on the Free Energy of Formation of CaO Additional Evidence in Support of Thermochemical Data

Jacob, KT and Varghese, Viji (1996) Controversy on the Free Energy of Formation of CaO Additional Evidence in Support of Thermochemical Data. In: Metallurgical And Materials Transactions B-Process Metallurgy And Materials Processing, 27 (04). pp. 647-651.

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Abstract

The standard free energies of formation of CaO derived from a variety of high-temperature equilibrium measurements made by seven groups of experimentalists are significantly different from those given in the standard compilations of thermodynamic data. Indirect support for the validity of the compiled data comes from new solid-state electrochemical measurements using single-crystal CaF2 and SrF2 as electrolytes. The change in free energy for the following reactions are obtained: CaO + MgF2 --> MgO + CaF2 Delta G degrees = -68,050 -2.47 T(+/-100) J mol(-1) SrO + CaF2 --> SrF2 + CaO Delta G degrees = -35,010 + 6.39 T (+/-80) J mol(-1) The standard free energy changes associated with cell reactions agree with data in standard compilations within +/- 4 kJ mol(-1). The results of this study do not support recent suggestions for a major revision in thermodynamic data for CaO.

Item Type:	Journal Article
Publication:	Metallurgical And Materials Transactions B-Process Metallurgy And Materials Processing
Publisher:	The Minerals, Metals & Materials Society
Additional Information:	Copyright of this article belongs to The Minerals, Metals & Materials Society.
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	01 Jun 2009 10:49
Last Modified:	19 Sep 2010 05:30
URI:	http://eprints.iisc.ac.in/id/eprint/19851

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