Abstract:
E.m.f. measurements of the cell,
PtlHjlHCKw,), KC1(w2), methanol(Y), water,AgCl|Ag,
have been made at 298.15 K for solvent compositions X = 0, 10, 30, 40 and 45 % (w/w) of methanol,
the total ionic strength of each solution being 1 mol kg-1. The logarithm of the mean ionic molal
activity coefficient of hydrochloric acid was found to vary linearly with potassium chloride molality
for the systems in which the solvent mixture contained 0, 10 and 30 % methanol. For methanol
composition above 30 %, the activity coefficient of the acid was a quadratic function of the salt
concentration. Secondary medium effects are discussed in relation to differences in specific ionic
interactions for the different electrolyte mixtures in water and in the mixed solvents.
