Thermodynamics of the zinc sulphide transformation, sphalerite → wurtzite, by modified entrainment
- 1 January 1988
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 84 (6) , 1879-1887
- https://doi.org/10.1039/f19888401879
Abstract
The dissociative sublimation of both α- and β-zinc sulphide, ZnS(c)= Zn(g)+½S2(g), has been studied by modified entrainment in the temperature range 1010–1445 K. The following free-energy equations were derived: ΔG°(α)/J mol–1= 376 700 – 191.9T/K and ΔG°(β)/J mol–1= 374 200 – 190.4T/K from which the enthalpy and entropy changes of transformation (β→α) at the transition temperature (1293 K) were –2.5 ± 1.5 kJ mol–1 and –1.5 ± 1.3 J K–1 mol–1. The corresponding ΔH°(β→α) at 298.15 K obtained by the third-law method was –2.3 ± 0.9 kJ mol–1. This enthalpy change is at variance with the currently accepted value of ca. 13 kJ mol–1.Keywords
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