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U.S. Geological Survey
Open-File Report 02-161
Online Version 1.0

Thermodynamic Data for Modeling Acid Mine Drainage Problems: Compilation and Estimation of Data for Selected Soluble Iron-Sulfate Minerals

By Bruce S. Hemingway, Robert R. Seal, II and I-Ming Chou


Enthalpy of formation, Gibbs energy of formation, and entropy values have been compiled from the literature for the hydrated ferrous sulfate minerals melanterite, rozenite, and szomolnokite, and a variety of other hydrated sulfate compounds. On the basis of this compilation, it appears that there is no evidence for an excess enthalpy of mixing for sulfate-H2O systems, except for the first H2O molecule of crystallization. The enthalpy and Gibbs energy of formation of each H2O molecule of crystallization, except the first, in the iron(II) sulfate - H2O system is -295.15 and -238.0 kJ·mol-1, respectively. The absence of an excess enthalpy of mixing is used as the basis for estimating thermodynamic values for a variety of ferrous, ferric, and mixed-valence sulfate salts of relevance to acid-mine drainage systems.

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Contact Information

Inquiries about this product should be addressed to:

Robert R. Seal
U.S. Geological Survey MS 954
National Center
12201 Sunrise Valley Drive
Reston, VA 20192

Tel: 703-648-6290

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