Nernst’s equation

Nernst’s equation expressed as the electrical potential of an electrode in contact with a solution of ions depends on the activity of these ions. The equation can be experimentally verified by using an electrochemical cell formed by an inert electrode coupled with a convenient reference electrode. The potential of the indicator electrode and then the electromotive force of the cell are monitored when the ionic composition of the electrolyte solution is varied. An electrode of silver chloride is used as the reference electrode by measuring the potential of a platinum electrode in contact with solutions containing different concentrations of iron ions (II) and iron (III).