Acid-Base Equilibria in Glacial Acetic Acid. IV. Quantitative Interpretation of Acid-Base Titrations in Glacial Acetic Acid

Acid-base titrations in anhydrous acetic acid are no longer an empirical subject: it is now possible to calculate quantitatively the characteristics of such titrations carried out either potentiometrically or with indicators. The equations governing the shape of potentiometric titration lines of bases in anhydrous acetic acid have been derived and experimentally verified. These relationships have been used to explain the apparent paradoxes described in the classical studies of Conant, Hall and Werner, to predict the shape of the titration line of urea with perchloric acid, the e.m.f. or pure salt solutions, and the change in e.m.f. in the vicinity of the equivalence point in the titration of sodium acetate with perchloric acid. The relationships determining the ratio of the acid to basic color of an indicator base over the titration range in acetic acid have also been established and used to predict the color of p-naphtholbenzein (PNB) in diethylaniline perchlorate and sodium perchlorate solutions. The change in color of PNB on the addition of sodium acetate to a sodium perchlorate solution was found to be in agreement with the calculated values.