Q27. The electrochemical cells
Zn|Zn2+||Cu2+|Cu and Fe|Fe2+||Cu2+| Cu are
connected in series, What will be the net emf of the
cell at 25°C?
Given: E° of Zn2+|Zn = -0.76V
E° of Cu2+|Cu = +0.34 V
E° of

Question

Q27. The electrochemical cells
Zn|Zn2+||Cu2+|Cu and Fe|Fe2+||Cu2+| Cu are
connected in series, What will be the net emf of the
cell at 25°C?
Given: E° of Zn2+|Zn = -0.76V
E° of Cu2+|Cu = +0.34 V
E° of Fe2+ |Fe = -0.41 V
(a) +1.85 V
(b) -1.85 V
(c) +0.83 V
(d) -0.83 V

FirstInTest · Accepted Answer

Correct answer: a. Emf of the cell, Zn (s)|Zn2+ (aq)||Cu2+ (aq)|Cu(s) is:E°cell1 = E°Cu2+/Cu - E°Zn2+/Zn = +0.34 - (-0.76) = 1.10VEmf of the cell, Fe(s)|Fe2+ (aq)||Cu2+ (aq)|Cu(s) is:E°cell2 = E°Cu2+/Cu - E°Fe2+/Fe = +0.34 - (-0.41) = 0.75 VSince the two electrodes are connected in series, the net emf of the cell is:Net emf = E°cell1 + E°cell2 = 1.10 + 0.75 = +1.85 V

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