Sponsor Area

Electrochemistry

Question
CBSEENCH12006004

Calculate the maximum possible electric work that can be obtained from the following cell under the standard conditions at 25°C:
     Fe|Fe2+(aq) || Cu2+(aq)|Cu
E°Fe2+(aq)/Fe = -0.44 VE°Cu2+(aq)/Cu = + 0.34 V and F = 96, 500 C.

Solution

Wmax = nFE°cell

The cell is
                Fe|Fe2+(aq)|| Cu2+(aq)|Cu
                         Fe  Fe2+ + 2e
         Cu2++2e  Cu
__________________________
      
      Fe+Cu2+   Fe2++Cu
___________________________

Here,              n = 2
Therefore,   
                 E°cell = E°cathode - E°anode           = E°Cu2+/Cu - E°Fe2+/Fe           = + 0.34 V - (-0.44 V)            = 0.78 V

                Wmax =2×96500 C × 0.78 V            = 150540 J = 150.5 kJ.