Thermodynamics of dissolution of chromium(III) and cobalt(III) trisacetylacetonates in water-ethanol solvents

The study presents solubility data for chromium(III) and cobalt(III) trisacetylacetonates in water-ethanol solvents over a wide range of temperatures and ethanol concentrations. The solubilities of both compounds increase as the temperature or ethanol concentration is raised, particularly in the case of Cr(acac)3 it increases to a greater extent. Noteworthy, for ethanol concentrations of 1.4–1.6 mol/L tinversion of the temperature effect on the solubilities of both compounds is observed. For ethanol concentrations lower than 1.4–1.6 mol/L, dissolution of Cr(acac)3 and Co(acac)3 is exothermic, whereas for the higher concentrations, it is endothermic. The changes in enthalpy and entropy upon dissolution of the compounds under study were evaluated using the temperature dependence of solubility.