Question

A student wants to determine the polarization in an electrochemical cell where the anode is made of zinc and the cathode is made of copper. The electrolyte used is CuSO4. The current through the cell is 0.5 A and the measured potential difference is 1.5 V. What is the polarization of this electrochemical cell?

Answer 1

To determine the polarization of the electrochemical cell, we first need to find the theoretical potential difference  E  of the cell using the standard reduction potentials of the two half-cells involved. The standard reduction potential for the zinc anode  Zn  and the copper cathode  Cu  are as follows:Zn + 2e  Zn  s   E = -0.76 VCu + 2e  Cu  s   E = +0.34 VThe overall cell reaction is:Zn  s  + Cu  Zn + Cu  s To find the theoretical potential difference, we subtract the standard reduction potential of the anode  Zn  from the cathode  Cu :E cell  = E cathode  - E anode  = 0.34 V -  -0.76 V  = 1.10 VNow that we have the theoretical potential difference, we can calculate the polarization of the electrochemical cell. Polarization is the difference between the measured potential difference and the theoretical potential difference:Polarization = Measured potential difference - Theoretical potential differencePolarization = 1.5 V - 1.10 V = 0.4 VThe polarization of the electrochemical cell is 0.4 V.