what will be the emf of the cell

Question

What will be e.m.f of the cell

2 Ag⁺ + Cu gives Cu⁺² + 2Ag

 

Given:

E_o Ag/Ag⁺ = -0.8v

 

E_o Cu⁺²/Cu = 0.3v

 

Options:

a)-0.6V b)0.5V c)-1.1V d) 1.1V

Answer 1

To find the EMF of a Redox cell, you need the EMF for the Reduction half-cell and the EMF for the Oxidation half-cell.

 

The potentials you listed are for the oxidation of Ag to Ag+ (-0.8 V) and the reduction of Cu2+ to Cu (0.3 V).  This is not what is happening in the redox cell, it is the opposite!

 

In the described reaction, Ag+ is reduced to Ag, so the potential for that should be + 0.8 V

And Cu is oxidized to Cu2+, so the potential for that is -0.3 V

 

The cell potential for a RED-OX reaction is the sum of the half-cells, so this would be +0.8 V + (-0.3 V) = +0.5 V