Thermodynamic Studies on Cobalt Complexes. IV. On the Thermal Dissociation and the Solubility of Aquopentamminecobalt(III) Chloride

Abstract
1. The standard free energy of formation of aquopentamminecobalt(III) chloride in the solid state was calculated by measuring its dissociation pressure. 2. From this value and the standard free energy of formation of aquopentamminecobalt(III) ion, the free energy change of the solution of aquopentamminecobalt(III) chloride was calculated. From this value and the solubility data the activity coefficient of aquopentamminecobalt(III) chloride in the saturated aqueous solution was calculated. The free energy changes of the solutions of hexamminecobalt(III) chloride, bromide, nitrate and perchlorate as well as of aquopentamminecobalt(III) chloride were found to be a linear function of the logarithms of their solubilities. 3. The thermodynamic stability of hexamminecobalt(III), aquopentamminecobalt(III) and chloropentamminecobalt(III) chlorides in the solid state and in the aqueous solution was discussed.