Trend and energetics of pK* vs. ionic strength for o-chlorobenzoic, m-nitrobenzoic and benzoic acids in aqueous KNO3 solutions at 298 K

Abstract

Ionization constants for benzoic, m-nitrobenzoic and o-chlorobenzoic acids are experimentally determined in aqueous KNO₃ solutions and ionic strength dependence of data are analysed by using Guggenheim's model for activity coefficients. Moreover, for benzoic acid, energetic contributions ΔG^ex in the minimum of the pK–ionic strength curve are calculated. It is found that ca. 20% of the total excess energy is due to the non-Debye–Hückel term. A discussion of pK*(I) in terms of solvation energy is also given.