Thermodynamic properties of Pd chloride complexes and the Pd2+(aq) ion in aqueous solutions

• Published in: Geochemistry international 2014-01, Vol.52 (1), p.46-56
• Main Authors: Polotnyanko, N. A., Khodakovskii, I. L.
• Format: Article
• Language: English
• Subjects: Earth and Environmental Science; Earth Sciences; Geochemistry
• ISSN: 0016-7029; 1556-1968
• DOI: 10.1134/S0016702914010054

Based on the expert review of literature data on the thermodynamic properties of species in the Cl-Pd system, stepwise and overall stability constants are recommended for species of the composition [PdCl n ] 2 − n , and the standard electrode potential of the half-cell PdCl 4 2− /Pd(c) is evaluated at E 298,15 ° = 0.646 ± 0.007 V, which corresponds to Δ f G 298.15 ° = −400.4 ± 1.4 kJ/mol for the ion PdCl 4 2− (aq). Derived from calorimetric data, Δ f H 298.15 ° PdCl 4 2− (aq) = −524.6 ± 1.6 kJ/mol and Δ f H 298.15 ° Pd 2+ (aq) = 189.7 ± 2.6 kJ/mol. The assumed values of the overall stability constant of the PdCl 4 2− ion and the standard electrode potential of the PdCl 4 2− /Pd(c) half-cell correspond to Δ f G 298.15 ° = 190.1 ± 1.4 kJ/mol and S 298.15 ° = −94.2 ± 10 J/(mol K) for the Pd 2+ (aq) ion.