Liquid junction potential

Liquid junction potential (shortly LJP) occurs when two solutions of electrolytes of different concentrations are in contact with each other.

This will result in an electrical double layer of positive and negative charges at the junction of the two solutions.

Thus at the point of junction, a potential difference will develop because of the ionic transfer.

The magnitude of the potential depends on the relative speeds of the ions' movement.

The electromotive force (EMF) of a concentration cell with transference includes the liquid junction potential.

Liquid junction potential is the difference between the two EMFs of the two concentration cells, with and without ionic transport: The liquid junction potential interferes with the exact measurement of the electromotive force of a chemical cell, so its effect should be minimized as much as possible for accurate measurement.

The most common method of eliminating the liquid junction potential is to place a salt bridge consisting of a saturated solution of potassium chloride (KCl) and ammonium nitrate (NH4NO3) with lithium acetate (CH3COOLi) between the two solutions constituting the junction.

The efficiency of KCl/NH4NO3 is connected with the fact that in these salts, the transport numbers[clarification needed] of anions and cations are the same.