The basis of conductimetric titrations

Consider how the conductance of a solution of a strong electrolyte A + B will change upon the addition of a reagent C + D, assuming that the cation A+ (which is the ion to be determined) reacts with the ion D of the reagent. If the product of the reaction AD is relatively insoluble or only slightly ionised, the reaction may be written  

Thus in the reaction between A+ ions and D ions, the A + ions are replaced by C+ ions during the titration. As the titration proceeds the conductance increases or decreases, depending upon whether the conductivity of the C + ions is greater or less than that of the A + ions. 

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Conductimetric Titrations in Aqueous Solution. When one ion is replaced in solution by a different ion with a significantly different equivalent conductivity, a change in total conductivity occurs. As seen in Table 15.4, hydrogen ion and hydroxide ion have the highest equivalent conductivities replacing them with less conductive ions can form the basis of conductimetric titrations for acids and bases. For example, when NaOH is added to HCl, the following reaction occurs ... 

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