Principle of Conductometric Titration

In conductometric titrations the electrical conductivity of the solution is measured after successive additions of reagent, and the values are plotted against the volume of reagent added (Kolthoff and Sandell 1952). All ions present contribute to the electrical conductivity of the solution. 

In the titration of a strong acid with a strong base as typified by the reaction 

The end point is determined by extrapolation of the linear sections of the conductometric plot to the point of intersection. 

In the conductometric titration of sulfonic acid groups in pulp (Katz et al. 1984), it is first necessary to convert all the acid groups to their protonated form. The pulp is then dispersed in water containing 0.001 M sodium chloride and the conductivity monitored during titration with 0.1 M sodium hydroxide. The 

The initial high conductivity is attributable to the protons from the highly dissociated sulfonic acid groups. As alkali is added, the conductivity drops linearly as H+ is replaced by the less conducting Na+ ion. The horizontal portion of the curve corresponds to the titration of weaker carboxylic acid 

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The underlying principles of conductometric titration are that the solvent and any molecular species in solution exhibit only negligible conductance that the conductance of a dilute solution rises as the concentration of ions is increased and that at a given concentration the hydrogen ion and the hydroxyl ion are much better conductors than any of the other ions. 

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