Ionization constants of benzoic and mononitrobenzoic acids in formamide

Abstract

The ionization constants of benzoic acid and of three mononitrobenzoic acids, at 25� 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.