0Explain the scientific basis of functioning of fluoride ion selective electrode.
- Indicator electrodes are usually ion-selective electrodes that are sensitive to a specific ion.
- The potential of an ideal indicator electrode changes rapidly and in a reversible way, and is strongly related with the concentration of the analyte. One important group of indicator electrodes is membrane electrodes, such as the fluoride ion selective electrode.
- A fluoride ion selective electrode is a type of ion selective electrode sensitive to the concentration of the fluoride ion. A common example is the lanthanum fluoride electrode. In the lanthanum fluoride electrode, the sensing element is a crystal membrane of lanthanum fluoride (LaF3), doped with europium fluoride (EuF2).
- The inner surface of the crystal is in contact with the inner reference solution, and the outer surface of the crystal is in contact with the solution containing the analyte . A potential develops across the membrane that depends on the difference in the concentration of fluoride ion on each side of the membrane.
- Since the concentration of the internal solution is fixed, the potential developed across the membrane is related to the concentration of the analyte.
