Critical evaluation and selection of standard state thermodynamic properties for chromium metal and its aqueous ions, hydrolysis species, oxides, and hydroxides

Abstract

This review critically evaluates the reported thermodynamic data on chromium metal, oxides, hydroxides, free aqueous ions, and hydrolysis species. Several discrepancies and inconsistencies have been uncovered and resolved to improve equilibrium calculations for chemical modeling and related engineering purposes. A revised set of data is derived from evaluation of electrochemical measurements, silver chromate solubility measurements, and auxiliary post-1980 data, reevaluation of earlier data, and reconsideration of the path for the thermodynamic network. The recommended thermodynamic values for Cr(cr), Cr(aq)2+, Cr(aq)3+, CrO4(aq)2-, Cr2O7(aq)2-, Cr2O3(cr), CrO3(cr), FeCr2O4(cr), CrCl2(cr), CrCl3(cr), and KFe3(CrO4)2(OH)6(cr) at 25 °C, 1 bar, and infinite dilution are given.