An electrochemical cell stops working after sometime. Explain.

Explanation

According to Nernst equation :
`E_(el ectrode)=E_(el ectrode)^(@)+(0.0591)/(n)"log"[M^(n+)(aq)]`
This means that the reduction potential of the electrode is directly proportional to the concentration of the metal ions or cations in solution. In an electrochemical cell, to start with the reaction potential of the cathode is more than that of the anode. As the redox reaction progresses in the cell, the concentration of the metal ions in the reduction half cell decreases and it increases in the oxidation half cell. Thus, the reduction potential of the anode gradually increases while that of the cathode decreases. This keeps on till the two become equal. At this stage, the cell stops working because its EMF will be zero. This has been shown graphically in the adjacent figure.