Question

An electrochemical cell couples manganese and copper, each in the presence of its 2+ ion.

a. What is the combined redox reaction?

b. What is the value of ΔG^o for the reaction?

Answer 1

Mn2+ + 2 e− ⇌ Mn(s) −1.185

Cu2+ + 2 e− ⇌ Cu(s) +0.337

Note that, Manganese, being the most negative, will oxidize, Copper will reduce

The combined redox reaction:

Cu2+ + Mn(s) + 2 e− ⇌ Cu(s) + Mn2+(aq) + 2e-

cancel common terms

Cu2+ + Mn(s) ⇌ Cu(s) + Mn2+(aq)

b)

Fro dG°; reacall that in equilibrium:

dG° = -nF*E°Cell

n = mol of electrons transferred, 2

F = farady constant 96500 C/mol

E°cell = Ered - Eox = 0.337 - -1.185 = 1.522 V

dG° = -2*96500*1.522 = - 293746 J/mol= -293.746 kJ/mol.