Automatic titration by stepwise addition of equal volumes of titrant. Part V. Extension of the Gran I method for calculation of the equivalence volume in acid-base titrations

Abstract

A very simple method for numerical calculation of the equivalence volume (V_e) from titration data is presented. It is based on the method of stepwise addition of equal volumes of titrant combined with an extended version of the Gran I method.

The expressions derived may be summarised in a general equation: [graphic omitted] where V_i and V_j are two additions of titrant (V_i is iV_p, where V_p is the volume of each addition). The term a_ij is different for strong acids and weak acids and for conditional titrations, but in all instances only the ratio between hydrogen ion concentrations is required. E. g., for a weak acid [graphic omitted].

The titration method can also be used for the determination of the conditional normal potential E′_o and the constant j_H in the junction potential j_H[H] for an electrode couple in a given medium.