Studies on the application of the quinhydrone electrode in formamide. VI. The ionization constant of benzoic acid and standard potential of themercury-mercurous benzoate electrode from E.M.F. measurements at 25°

Abstract

The cells                  Ag-AgCl|KCl(m₃), KOBz(m₂), HOBz(m₁), QH₂-Q|Pt and                         Hg-Hg₂(OBz)₂|HOBz(m), QH₂-Q|Pt have been used to redetermine the ionization constant of benzoic acid in formamide and the standard potential of the Hg-Hg₂(OBz)₂ electrode in formamide at 25°. The ionization constant of benzoic acid is found to be 4.79 x 10^-7 and is in good agreement with the value 4.37x10^-7 obtained earlier. The value 0.2535±0.0005 V for the standard potential of the Hg-Hg₂(OBz)₂ electrode is in good agreement with the values 0.2541±0.0003 and 0.2545±0.0005 V obtained previously from two independent cells.