$E^oFe^{3+}_{(aq)} + e^{-} \rightarrow Fe^{2+}_{(aq)}$ કેટલા ............ $\mathrm{V}$ થાય?
$Fe^{3+}\,\,_{(aq)} + 3e^{-} \rightarrow Fe_{(s)}$ ; $E^o = -0.036 \,volt; $
$Fe^{2+}_{(aq)} + 2e^{-} \rightarrow Fe_{(s)}$ ; $E^o = -0.440 \,volt$
$Fe\, \to \,F{e^{ + 2}}\, + \,2{e^ - }$ $E_2^o\,= \,- \,0.044\,volt$ , ${n_2}\, = \,2$
$E_3^ o \, = \,\frac{{-{n_1}E_1^ o \, + \,{n_2}E_2^o }}{{{n_3}}}$ $=\,\frac{{-3\,\times \,\,(0.036)\,\, + \,2\,\times \,\,0.44}}{1}$
$ =0.772\,volt$
આપેલ $\left( E _{ Cu ^{2+} / Cu ^{+}}^{0}=0.16 V \right.$ $,E _{ Cu ^{+} / Cu }^{0}=0.52 V,$ $\left.\frac{ RT }{ F }=0.025\right)$
$Cu^+_{(aq)} + e^- \rightarrow Cu_{(s)}$ માટે વિધુતધ્રુવ પોટેન્શિયલ અનુક્રમે $+ 0.15\, V$ તથા $+ 0.50\, V$ છે. $E^o_{Cu^{2+}/Cu}$ ....... $V$ થશે.
$Cr_{(s)} | Cr^{3+}_{(0.1\,M)} | | Fe^{2+}_{(0.01\,M)} | Fe;$
$E^0_{{cr}^{3+} |Cr} = -0.72 \,V,$ $ E^{0}_{{Fe}^{2+}{| Fe}}$ $= -0.42 \,V$