Log K values, valid at zero ionic strength are reported for the interaction in aqueous solution of CN- with Ni2+ and Hg2+ at 10°, 25° and 40°C, and with Pd2+ at 25°C. ∆H° and ∆S° values valid at zero ionic strength and 25°C are also reported for the interaction of CN- with Hg2+ and for the reaction Pd(CN)42- + CN- = Pd(CN)53-. In connection with the study of Pd2+ - CN- interaction, log K values for the hydrolysis of Pd2+ to give PqOH+ and Pd(OH)2 and an E° value for the reaction Pd(s) = Pd2+ + 2e- are reported. A least squares computational method is developed for the calculation of the equilibrium constants, enthalpy changes and entropy changes for metal-ligand interactions from a single thermometric titration curve (Entropy Titration). This method has been tested by determining log K, ∆H° and ∆S° values for the interaction of Ag+ and Cu2+ with pyridine, Hg(CN)2 with CN- and HgCl2 with Cl-. The results indicate that both the computational method and entropy titration technique are applicable to the determination of the thermodynamics of interaction of metal-ligand systems. Log K, ∆H° and ∆S° values have been determined for the interaction of SO42+ with H+ and thirty +1, +2 and +3 metal ions. The results are compared to electrostatic predictions and deviations from electrostatic predictions are attributed to specific solvent interactions. Log K, ∆H° and ∆S° values are reported for the interaction of Hg(CN)2 with thiourea in water-ethanol solvent mixtures. The results indicate that there is a significant change in the solvolysis of the species in solution at approximately 20 mole per-cent ethanol.



College and Department

Chemistry and Biochemistry



Date Submitted


Document Type





Metals, Thermodynamics, Heat of solution, Solution (Chemistry)