In an aqueous mixture of aluminum, lead, and iron salts, which of these will be reduced first upon application of an electric current?

(A) Al3+ + 3e− → Al (s) Eo = −1.66V
(B) Pb2+ + 2e− → Pb (s) Eo = −0.13V
(C) Fe2+ + 2e− → Fe (s) Eo = −0.45V
(D) Fe3+ + 3e− → Fe (s) Eo = −0.036V

Respuesta :

Answer:

D) Fe3+ + 3e− → Fe (s) Eo = −0.036V

Explanation:

In electrolysis we have to add  electrical energy for redox reactions non-spontaneous because ΔºG is positive.

These  4 reduction reactions  are all non-spontaneous because their reduction potentials are negative   (ΔGº = - nFεº , ΔGº will be positive). So the ion most easily reduced is the least negative, in this case  Fe3+ + 3e− → Fe (s) Eo = −0.036V.