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