(વિષમ પ્રમાણન પ્રક્રિયા )
$C{u^{ + 2}}\, + \,\,{e^ - }\,\, \to \,\,C{u^ + }$ ${E^ o }\, = \,\,0.15\,volt$
$C{u^ + }\, \to \,\,C{u^ {+2} }\, + \,\,{e^ - }$ ${E^o }\, = \,\, - \,\,0.15\,\,volt$
અથવા $2C{u^{ + 1}}\, \to \,\,2C{u^{ + 2}}\,+\,2{e^ - }$ $E_1^o \, = \,\, - 0.15\,\,volt,\,\,{n_1}\, = \,\,2$
$C{u^{ + 2}}\, + \,\,2{e^ - }\, \to \,\,Cu$ $E_2^ o \,\, = \,\,0.34\,\,volt,\,\,{n_2}\, = \,\,2$
$\therefore \,\,E_3^o \,\, = \,\,\frac{{ - 0.15\,\, \times \,\,2\,\, + \,\,0.34\,\, \times \,\,2}}{1}\,\, = \,\,0.38\,\,volt$
જ્યારે $\text{E}_{\text{3}}^{o}$ એધન છે જેથી ${\text{C}}{{\text{u}}^ + }$ એ જલીય માધ્યમમાં હાજર નથી .
${{\text{E}}^o }{\text{C}}{{\text{u}}^{{\text{2}} + }}{\text{/Cu = + 0}}{\text{.34 V, E}}_{{\text{F}}{{\text{e}}^{ + {\text{2}}}}/Fe}^o = \,\,{\text{ - 0}}{\text{.44 V}}$