10.10 : Potentiometric Titration: Overview

Potentiometric titration is a quantitative analytical technique that determines the concentration of an analyte by measuring the potential difference between the two electrodes in the solution. The endpoint of a potentiometric titration is the point at which there is a significant change in the potential difference. It occurs when the stoichiometric reaction between the analyte and the titrant is complete. The endpoint is usually determined graphically by plotting the measured potential difference as a function of the volume of titrant added. The resulting graph is called a titration curve. Derivative curves are obtained by plotting the derivative of the titration curve with respect to the volume of titrant added. They help identify the endpoint more precisely. The derivative curve typically exhibits a maximum or minimum point at the endpoint, allowing for a more accurate endpoint determination. Potentiometric titration is highly versatile and can be used for acid-base, precipitation, complexometric, or redox reactions. Acid-base titrations typically employ glass electrodes to measure pH against titrant volume.

In contrast, precipitation titrations use ion-selective electrodes designed to respond selectively to a particular ion in the solution. Redox titrations, on the other hand, employ inert metal electrodes like platinum, and the titration curve helps in selecting a suitable visual indicator for the titration process. Complexometric titrations utilize ion-selective electrodes to record changes in metal-ion concentration by adding EDTA.