Q.
The standard reduction potential Eo for the half reactions are as: Zn→Zn2++2e−,Eo=0.76V Cu→Cu2++2e−,Eo=0.34V
The emf for the cell reaction: Zn+Cu2+→Zn2+Cu
(i)Decide cathode and anode
(ii) Ecello=EoC−EoA of electrode potential are substituted in terms of reduction potential.
Given, EZn/Zn2+o=0.76V ECu/Cu2+o=0.34V ∴Zn is anode ( ∵ it has higher oxidation potential) ∴EZn2+/Zno=−0.76V
and ECu2+/Cuo=−0.34V Ecello=EoC−EoA =−0.34V−(−0.76V) =0.34V+0.76V =0.42V