Thermodynamic properties and environmental chemistry of chromium
- 1 July 1984
- report
- Published by Office of Scientific and Technical Information (OSTI)
Abstract
Values of standard entropy, standard enthalpy of formation, and standard free energy of formation for Cr and its solid and aqueous species are tabulated in this report. These values were selected or recalculated after careful evaluation of the best available current thermochemical data. The basis for selection of data centered on conformation with the recent studies of Vasil'ev et al. (1977a,b, 1978, 1980, 1981) for Cr/sup 3 +/ data and O'Hare and Boerio (1975) for CrO/sub 4//sup 2 -/ data. The thermodynamic data presented in this report will be incorporated into the data base of the geochemical computer model, MINTEQ. The distribution of Cr in the environment among its aqueous inorganic species is, according to the thermodynamic data, highly dependent upon pH and Eh and the presence of complexing ligands. The speciation of Cr in natural waters is also controlled by reduction and complexation by organic matter, adsorption and oxidation by Mn-oxide in suspended particulate matter and sediment, and reduction by H/sub 2/S released from anoxic sediments. 89 references, 8 figures, 11 tables.Keywords
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