Transport in aqueous solutions of group IIB metal salts at 298.15 K. Part 2.—Interpretation and prediction of transport in dilute solutions of cadmium iodide: an irreversible thermodynamic analysis

Abstract

The transport data of Part 1 have been used to obtain the binary mobility coefficients (L_ik) and corresponding resistance coefficients (R_ik) of the salt in the range 0.05–0.60 mol dm^–3. It is shown that these binary mobility coefficients are summations of the more fundamental mobility and coupling coefficients (l_ik) between the component ions of the complexed salt: Cd²⁺, CdI^2–x_x(x= 1, 2, 3, 4) and I^–. The distribution of these complexes at each concentration have been obtained from stability constant data and used in an optimisation procedure to obtain equivalent ionic conductances of the complex ions at infinite dilution (λ^°_x). These data were used to estimate l_ik coefficients (using Pikal's method), to predict binary coefficients (L_ik) and to predict the transport numbers, conductances and salt diffusion coefficients of the salt in dilute solutions. Predicted and observed data are in good agreement in dilute solutions.