What is the Difference Between Indicator Electrode and Reference Electrode?

The main difference between an indicator electrode and a reference electrode lies in their response to changes in the analyte concentration. An indicator electrode has a potential that varies in a known way with changes in the concentration of an analyte, while a reference electrode has a fixed potential that remains constant at a constant temperature and is independent of the analyte solution composition.

Indicator electrodes are one of the two electrodes in potentiometric measurements, and their response changes according to the changes in the analyte. Some examples of indicator electrodes include glass electrodes and metal ion indicator electrodes. On the other hand, reference electrodes have a stable and constant response, and their potential is well-known. Examples of reference electrodes include saturated calomel electrodes, silver/silver chloride electrodes, standard hydrogen electrodes, and pH electrodes.

In a potentiometric electrochemical cell, the cathode is the indicator electrode, and the anode is the reference electrode. The cell potential is calculated as the difference between the potential of the indicator electrode and the potential of the reference electrode, plus the junction potential. The voltage measured in these cells is simply the difference between the potential at each electrode.

In summary, the key differences between indicator electrodes and reference electrodes are:

• Indicator electrodes have a changeable electrode potential, while reference electrodes have a fixed potential.
• Indicator electrodes respond to changes in the analyte concentration, while reference electrodes do not.

Comparative Table: Indicator Electrode vs Reference Electrode

The difference between an indicator electrode and a reference electrode can be summarized in the following table:

In potentiometric measurements, the indicator electrode detects or responds to the presence of the analyte, while the reference electrode maintains a constant potential and serves as a reference for the measurement.