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, V_ϕ, and apparent molar isobaric heat capacities, C_pϕ. Where comparisons were possible, the present V_ϕ results were in good agreement with literature data. No C_pϕ data appear to have been reported previously for any of these salts. The variations of V_ϕ and C_pϕ with concentration were well correlated using the Pitzer formalism combined with the values of V° and C_p° estimated from literature data. Both V_ϕ and C_pϕ 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.