The zinc/silver oxide cell is used in electric watches. The reaction is as following,Zn2++2e-→Zn;E°=-0.760 VAg2O+H2O+2e-→2Ag+2OH-;E°=0.344 V If F is 96,500Cmol-1,ΔG° of the cell will be

ΔG0 = −nFE0From the reaction, n = 2ΔG0 = −296500   Ecello  .........(1)Ecello =   Ecathodeo  −     EanodeoZn+2  +  2e−  →   Zn,    E0=−0.76VAg2O+H2O+2e¯  →    2Ag+2OH−, E0=+0.344VSRP value of Ag2O  half cell is high ∴ it acts like cathodeThus …   Anode ; Zn→Zn+2 +2e-;  Cathode; Ag2O +H2O +2e-→ 2Ag +2OH-Zn +Ag2O+H2O →   Zn+2    +   2Ag  +  2OH− Ecello =   +0.344−−0.76= + 1.104 VSubstituting  the value in ---(1)ΔG0 = −296.5   1.104kJ= –213.072 kJ