Potentiometric methods for determination of autoprotolysis constants of amphiprotic nonaqueous solvents: Part II. Titration of a weak protolyte with another weak protolyte

A method for the determination of autoprotolysis constants of nonaqueous amphiprotic solvents is proposed, which makes use of the data of a potentiometric titration of a weak acid with a weak base. The method is based on a least-squares treatment of the data combined with the “pit-mapping” procedure developed by Sillén. The acid-base constants of the two weak protolytes along with the autoprotolysis constant are obtained simultaneously. The method is checked by determination of the autoprotolysis constant of the classical amophiprotic solvent-water. The pK_W^T-values as well as the acid-base constants of acetic. acid, ammonia, monochloroacetic acid, triethylamine and potassium biphthalate obtained by the proposed method are in a good agreement with the data reported by other authors.