Abstract

The densities and isobaric volumetric heat capacities of aqueous solutions of the sulfate salts of cobalt(II), nickel(II), and copper(II) have been measured at 298.15 K and 0.1 MPa using vibrating-tube densimetry and Picker flow calorimetry, respectively, at concentrations in the range 0.01 ≲ m/mol·kg–1 ≲ 1.5. These data were used to derive the corresponding apparent molar volumes, Vϕ, and apparent molar isobaric heat capacities, Cpϕ. Where comparisons were possible, the present Vϕ results were in good agreement with literature data. No Cpϕ data appear to have been reported previously for any of these salts. The variations of Vϕ and Cpϕ with concentration were well correlated using the Pitzer formalism combined with the values of V° and Cp° estimated from literature data. Both Vϕ and Cpϕ for all three salts show remarkable similarities and can be shown to lie on a common line by applying fixed addends over almost the whole concentration range studied.