Types of Electrodes in Potentiometry

By Rashi Tiwari

Potentiometry is a method in electrochemistry used to determine the concentration of components in a chemical solution. Electrodes are employed to measure voltages that result from chemical reactions.

Electrochemical Cell

Two electrodes dipped in a chemical solution along with a salt bridge forms an electrochemical cell. The motion of ions in a chemical solution generates electrical potential.

Indicator Electrode

An indicator electrode is used to detect the analyte, or chemical, in an unknown solution.

Types of Indicator Electrodes

In case of metal electrodes, a potential is developed in response to a surface redox reaction. Membrane electrodes allow only certain types of ions to migrate, resulting in electrical potential. They are further classified as crystalline and non-crystalline membranes.

Reference Electrode

In order to determine the composition of an unknown solution, an electrode with fixed composition and known voltage is required. The electrode with known potential is called reference electrode. Reference electrodes follow the Nernst equation.

Types of Reference Electrodes

The two types of reference electrodes are saturated calomel electrodes and silver/silver chloride electrodes.