Chromium, molybdenum, and tungsten: thermodynamic properties, chemical equilibriums, and standard potentials

Enthalpies of formation of Cr3+(aq) and the inner sphere complexes CrF2+(aq), CrCl2+(aq), CrBr2+(aq), and CrSO4+(aq)

“…Earlier d In K/dT results of Espenson and King (18) lead to an enthalpy of reaction 10 (taken to be 5 kcal mol-I in our review (2)) that is significantly smaller than the value we have obtained above.…”

“…Dellien et al (2) have recently reviewed seven different paths to this enthalpy of formation and have calculated AH; values ranging from -5 1 to -62 kcal mol-I for Cr3+(aq). We (2) selected AH; = -57 kcal mol-' for Cr3+(aq) and the corresponding AH; = -57 + 6(-68.3 15) = -467 kcal mol-I for Cr(H20)63+(aq) as 'best' values.…”

Ab-initio structure, energy and stable Cr isotopes equilibrium fractionation of some geochemically relevant H-O-Cr-Cl complexes

“…Part a of the same Figure is included merely for comparative purposes, since by comparing parts a and b of the same Figure one has an immediate perception of the role of solvent b . Aqueous speciation calculations were conducted on the basis of selected literature values of the Gibbs free energy of formation from the elements at standard state of the various species of interest (Latimer, 1952;Garrels and Christ, 1965;Baes and Mesmer, 1976;Dellien et al, 1976;Vasil'ev et al, 1977;Barner and Scheuerman, 1978;Wagman et al, 1982;Palmer et al, 1987;Brito et al, 1997;Cruywagen et al, 1998), with some assumed values for the Cr oligomer SBD and for [Cr(H 2 O) 3 Cl 3 ] 0 . Speciation calculations at I 0 involved the estimate of individual ionic activity coefficients with the modified Debye-Hückel equation (Helgeson and Kirkham, 1974) Different choices of standard state thermodynamic properties, such as the set of internally consistent values recently proposed by Ball and Nordstrom (1998) do not significantly alter the overall picture.…”

Ab initio thermochemistry of some geochemically relevant molecules in the system Cr-O-H-Cl

“…b Wagman et al (1982). c Dellien et al (1976). d Based on G f,aq°o f Cr (OH) 3 of Ball and Nordstrom (1998) Garrels and Christ (1965).…”