Q.

1 Faraday electricity was passed through Cu2+ (1.5 M, 1 L)/Cu and 0.1 Faraday was passed through Ag+ (0.2 M, 1 L)/Ag electrolytic cells. After this the two cells were connected as shown below to make an electrochemical cell. The emf of the cell thus formed at 298 K is:

Given: ECu2+/Cu=0.34 V

EAg+/Ag=0.80 V

2.303RTF=0.06 V                                   [2025]


Ans.

(400)

Cell reaction of the electrolytic cell:

Cu(s)+2Ag+(aq)0.1 MCu2+(aq)1 M+2Ag

Ecell=Ecathode-Eanode =EAg+/Ag-ECu2+/Cu

        =(0.8-0.34)V=0.46 V

Reaction quotient (Q):
=[Cu2+][Ag+]2=1(0.1)2=100,  logQ=log100=2

By Nernst equation:

Ecell=0.46-0.05912×2=0.4 V=400 mV