c
\(Fe^{3+} + 3e^{-} \to Fe,\)

\(\Delta G_1 = -nFE^{0}_{cell} = -3 × F × E^{0}_{Fe^{3+} | Fe}\)

\( \Delta G_1 = -3\,F(-0.036)\)     \(\Delta G_1 = 3 × 0.036\,F\)  ……  \((1)\)

\(Fe^{2+} + 2e- \to  Fe,\)

\(\Delta G_2 = -nFE^{0}_{cell} = -2 × F × (-0.439)\)

\( \Delta G_2 = 2 × 0.439\,F\)    \( Fe\to Fe^{2+} + 2e^{-}\),   

\(\Delta G_2 = -2 × 0.439\,F\)   …… \((2)\)

પરિણામ \((1) \) અને \( (2)\) નો સરવાળો કરતાં, 

\(Fe^{3+} + e^- \to  Fe^{2+} [\Delta G_1 + \Delta G_2 = \Delta G]\)

\(\Delta G = (3 × 0.036\,F) + (-2 ×  0.439)\,F\) ……. \((3)\)

પરંતુ,\(Fe^{3+} + e^{-} \to  Fe^{2+}\) માટે \(\Delta G = -nFE^{0}_{cell}\)

અહીં, પરિણામ \((3)\)  અને \( (4)\)  સરખાં છે.

\(\Delta G = -1 × F × E^{0}_{Fe^{3+} | Fe^{2+}}\)   ….…. \((4)\)

\(-1 × F × E^{0}_{Fe^{3+} | Fe^{2+}} = (3 × 0.036\,F) - (2 × 0.439\,F)  \)

\(E^{0}_{Fe^{3+} | Fe^{2+}} = 0.770\,V\)