The mean activity coefficients of LaCl3 in dilute aqueous solution at 298.15 K

The electromotive forces of a symmetrical concentration cell with transference, Ag; AgCl|LaCl3 (m*):LaCl3 (m)|AgCl; Ag, were measured over the concentration range from 8.762 × 10−4 mol kg−1 to 6.788 × 10−2 mol kg−1 at 298.15 K to obtain the mean activity coefficients of LaCl3. The mean activity coefficient for reference solution at 298.15 K and the ion size parameter for LaCl3 in the extended Debye–Hückel equation are evaluated by using an approach extrapolating concentration to unlimited dilution. A modified Debye–Hückel equation with new parameters has been established for the studied concentration range. A comparison is done of the thermodynamic data of LaCl3 that are determined by this experiment with those reported by previous literatures, and evaluated by some models.