$(i)\, Cu^{2+} + 2e^- \rightarrow Cu\,,$ $ E^o = 0.337\, V$
$(ii)\, Cu^{2+} + e^- \rightarrow Cu^+\,,$ $ E^o = 0.153\, V$
તો પ્રક્રિયા $Cu^+ + e^- \rightarrow Cu$ માટે $E^o$........... $V$ થશે.
For reaction, \(C u^{2+}+2 e^{-} \rightarrow C u\)
\(\Delta G^{0}=-2 \times F \times 0.337 \ldots(i)\)
For reaction, \(C u^{+} \rightarrow C u^{2+}+e^{-}\)
\(\Delta G^{0}=-1 \times F \times 0.153 \quad \dots(i i)\)
Adding Eqs. (i) and (ii), we get
\(C u^{+}+e^{-} \rightarrow C u, \Delta G^{0}=-0.521 F\)
\(\Delta G^{0}=-n F E^{0}-0.521 F=-n F E^{0}\)
\(\therefore E^{0}=0.52 V\)
$Zn\,(s)\,\, + \,\,C{u^{2 + }}\,(aq)\, \rightleftharpoons \,Z{n^{2 + \,}}\,(aq)\, + Cu\,(s)$
$(R = 8 \,JK^{-1}\,mol^{-1},\, F = 96000\,C\,mol^{-1})$
$Zn ^{2+}+2 e ^{-} \rightarrow Zn ; E ^{\circ}=-0.760 \,V$
$Ag _{2} O + H _{2} O +2 e ^{-} \rightarrow 2 Ag +2 OH ^{-} ; E ^{\circ}=0.344 \,V$
જો $F$ $96,500 C mol ^{-1}$ હોય, તો કોષનો $\Delta G ^{\circ}$ શોધો. ($kJ mol ^{-1}$ માં)