Acid-base equilibria in glacial acetic acid. III. Acidity scale. Potentiometric determination of dissociation constants of acids, bases and salts

Using previously determined pK values of hydrochloric acid and of pyridine, the pK values of a series of acids, bases and salts have been determined potentiometrically at 25 ± 0.1°, using a variety of cells. From the data the autoprotolysis constant of acetic acid is calculated to be 3.5 × 10^–15 (pK = 14.45). The following summarizes the data in decreasing order of degree of dissociation. pK of acids: perchloric, 4.87; sulfuric, 7.24; p-toluenesulfonic acid, 8.44; hydrochloric, 8.55. pK of bases: tribenzylamine, 5.38; N,N-diethylaniline, 5.78; pyridine, 6.10; potassium acetate, 6.15; p,p′-N,N′-dimethylaminoazobenzene, 6.32; sodium acetate, 6.68; lithium acetate, 6.79; 2,5-dichloroaniline, 9.48; urea, 10.24. pK of salts: sodium perchlorate, 5.48; diethylaniline perchlorate, 5.78; tribenzylamine hydrochloride, 6.71; diethylaniline hydrochloride, 6.84; potassium chloride, 6.88; urea hydrochloride, 6.96; lithium chloride, 7.08; dodecylamine hydrochloride, 7.45.