Thermodynamic properties of ternary aqueous electrolyte solutions

In previous papers the mean excess chemical potential, mu(1)(E), in ternary systems of the type I sulphate + II sulphate + H2O, at 25 degrees C was de termined. Results obtained for systems with CuSO4(I), and ZnSO4(I) respecti vely, pointed out an obvious disparity between their behaviours. They show the existence of some important association phenomena partially accounting for the substantial deviations from ideal behaviour. The ternary sulphate s ystems (CuSO4 + (MeSO4)-S-I,II + H2O; ZnSO4 + (MeSO4)-S-I,II + H2O) studied were characterized against the binaries of the same ionic strength, experi mental data being obtained using both e.m.f. and spectrophotometric methods . Deviations from the ideal behaviour were discussed in terms of thermodyna mic excess functions and association constants. A comparative study between the results obtained with the two above mentioned methods is presented.