[આપેલ : $1\,F =96500\,C\,mol ^{-1},$ $Fe$નું પરમાણ્વીય દળ $= 56\,g\,mol ^{-1}$ ]
$E.C.E\, Zn=32.5\,, \,E.C.E \,Cu=31.5)$
$M{g^{2 + }} + 2{e^ - } \to Mg(s);\,\,E = - 2.37\,V$
$C{u^{2 + }} + 2{e^ - } \to Cu(s);\,\,\,E = + 0.33\,V$
$Zn_{(s)} + Ag_2O_{(s)} + H_2O_{(l)} \rightleftharpoons $$2Ag_{(s)} + Zn^{2+}_{(aq)}+ 2OH^-_{(aq)}$
જો અર્ધકોષ પોટેન્શિયલ
$Zn^{2+}_{(aq)} + 2e^- \rightarrow Zn_{(s)}\,;\,\, E^o = - 0.76\, V$
$Ag_2O_{(s)} + H_2O_{(l)} + 2e^- \rightarrow 2Ag_{(s)} + 2OH^-_{(aq)}\,,$$E^o = 0.34\, V$
હોય, તો કોષ-પોટેન્શિયલ ......... $V$ થશે.