Thermodynamics of ion pair in mixed solvents: II. The system (HCl + MgSO4) in {0.06455C2H5OH + 0.93545H2O}

The standard association constants of the ion pair [MgSO4]0, Kass, in the {0.06455 ethanol + 0.93545 water} were determined from precise e.m.f. measurements of cell (I) without liquid junction: equation(I)Pt,H2(101.325kPa)|HCl(m1),MgSO4(m2),(0.06455ethanol+0.93545water)|AgCl-Ag,where mi means molality of species i. The dependence of pKass on temperature T is expressed by the empirical equations: pKass = a1 + a2(K/DT). The other thermodynamic functions of the association process were also calculated and showed that the driving force for the formation of the ion pair is the entropy of association.