Why does an electrochemical cell stop working after some time?
The reduction potential of an electrode depends upon the concentration of a solution with which it is in contact. As the cell works, the concentration of reactants decreases. Then according to Le Chatelier’s principle, it will shift the equilibrium in the backward direction. On the other hand, if the concentration is more on the reactant side then it will shift the equilibrium in the forward direction. When a cell works, concentration in an anodic compartment in the cathodic compartment decreases, and hence E0cathodeEcathode0 cathode will decrease. Now EMF of the cell is E0cell= E0cathode - E0anodeEcell0= Ecathode0 - Eanode0 A decrease inE0cathodeE0cathode and a corresponding increase in E0anodeE0anode will mean that EMF of the cell will decrease and will ultimately become zero i.e., the cell stops working after some time.
