CONCENTRATION CELL

"A galvanic cell in which the chemical energy converted into electrical energy is arising from the concentration difference of a species at the two electrodes of the cell. An example is a divided cell consisting of two silver electrodes surrounded by silver nitrate solutions of different concentrations. Nature will tend to equalize the concentrations. Consequently, silver cations will be spontaneously reduced to silver metal at the electrode (cathode) in the higher concentration solution, while the silver electrode (anode) in the lower concentration solution will be oxidized to silver cations. Electrons will be flowing through the external circuit (from the anode or negative electrode to the cathode or positive electrode) producing a current, and nitrate anions will diffuse through the separator. This process will continue till the silver nitrate concentration is equalized in the two compartments of the cell. "