A comparison of equations for fitting protonation constants of carboxylic acids in aqueous tetramethylammonium chloride at various ionic strengths

The protonation of acetic, malonic, succinic, citric, 1,2,3-propanetricarboxylic, 2-methyl-1,2,3-propanetricarboxylic, 1,2,3,4-butanetetracarboxylic, and benzenehexacarboxylic acids was studied potentiometrically, at 25°C and at various ionic strengths in aqueous tetramethylammonium chloride, in the range 0 ≤I _c ≤ 3 mol-dm^-3 (0≤I _m≤ 4.4 mol-kg^-1). Protonation constants were fitted by several equations (Debye-Hückel type, Pitzer and Bromley equations) for the dependence on ionic strength. General equations, containing some common parameters, independent of the acid considered, are reported.