Potentiometric Titration

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What is Potentiometric Titration?
It is the procedure through which the quantity of the given test substance is determined by the measured addition of titrant until the entire test substance undergoes reaction. After the titration process, the potential difference between the two electrodes (namely the reference and indicator electrode) is measured in conditions where a thermodynamic equilibrium is maintained and the current passing through the electrodes does not disturb this equilibrium.

Potentiometric Titration Principle
Potentiometric titration is a laboratory method to determine the concentration of a given analyte. It is used in the characterization of acids. In this method, there is no use of a chemical indicator. Instead, the electric potential across the substance is measured.

Potentiometric Titration Method
Potentiometric Titration is done via the usage of two electrodes – an indicator electrode and a reference electrode (generally a hydrogen electrode or a silver chloride electrode). One half-cell is formed with the indicator electrode and the ions of the analyte, which is generally an electrolyte solution. The other half-cell is formed by the reference electrode.

The overall cell potential can be calculated using the formula given below.


Where the potential drop between the indicator and reference electrodes over the electrolyte solution is given by Esol.

The overall cell potential, Ecell is calculated in every interval where the titrant is measured and added.