Abstract The potentiometric titration in water, methanol, dimethyl sulphoxide, dimethylformamide, and acetonitrile has been used for determination of pK values of 13 N- arylbenzenesulphonamides. The validity of the Hammett and Yukawa-Tsuno models using several sets of substituent constants has been evaluated by the test to check adequacy of the regression function and by the factor analysis. It has been found that the substituent ...