A Cell is prepared by dipping a copper rod in 0.01 M copper sulphate solution, and zinc rod in 0.02 M ZnSO4 solution. The standard reduction potentials of copper and zinc are + 0.34 V and – 0.76 V respectively.
(a) What will be the cell reaction?
(b) How will the cell be represented?
(c) What will be the emf. of the cell?
(a) As E°Zn2+/Zn < E°Cu2+/Cu . Zinc electrode acts as anode and copper electrode acts as a cathode. The cell reaction is
Zn(s) + Cu2+(aq) (0.01 M) → Zn2+(aq) (0.02 M) + Cu(s)
(b) The cell is represented as
Zn(s) | Zn2+(aq) (0.02 M) || Cu2+(aq) (0.01 M) + Cu(s)
(c) The emf of the cell can be calculated by using Nernst equation
= 1.05 V – 0.0295 x log 80
= 1.05 V – 0.0295 x 1.9031
= 1.05 V – 0.056 = 0.99 V.