Solution thermodynamics of first-row transition elements. 4. Apparent molal volumes of aqueous ZnSO4 and CuSO4 solutions from 15 to 55�C

Abstract

The apparent molal volumes of ZnSO4 and CuSO4 have been determined from density data over the temperature range 15–55°C and concentration range 0–15 molal. The volume data have been fitted to the Pitzer formalism over the entire temperature and concentration range. The volume changes for the formation of ZnSO4 and CuSO4 ion pairs have been estimated over the temperature range covered and the partial molal volumes of ZnSO4 and CuSO4 ion pairs have been derived. The results were used to explain the hydration structure of the ion pair. UV spectral effects accompanying a change of temperature in the 15–65°C range in CuSO4 solution indicate direct coordination of sulfate anion to the cupric cation. The process is favored by an increase in temperature.