Ionization constants of benzoic and mononitrobenzoic acids in formamide

Abstract

The ionization constants of benzoic acid and of three mononitrobenzoic acids, at 25º in formamide, have been determined from the measurements of the electro-motive forces of the cells Pt,H₂/HA(m₁),KA(m₂)KCl(m₃)AgCl-Ag The values of the ionization constants for benzoic acid, o-nitrobenzoic acid, m-nitro-benzoio acid, and p-nitrobenzoic acid thus calculated from e.m.f. data are 4.37 x 10^-7, 3.89 x 10_-5, 3.98 x 10_-6 and 1.32 x 10^-6, respectively. These values are smaller than those in water, and are in agreement with a general behaviour exhibited by weak acids in solvents of this class.