Question

Calculate the Delta G for the following reaction at 25 degrees Celcius

3Co^+2 (aq) + 2Al(s) <-> 3Co(s)+2Al^+3(aq)

Answer 1

oxidation :

Al -----------------------> Al+3 + 3e- , Eo = -1.66 V

reduction:

Co+2 + 2e- -----------------------> Co + 2e- , Eo = -0.28 V

Eocell = Eo reduction - Eo oxidation

           = -0.28 - (-1.66)

            = 1.38 V

n = number of electrons transfered

Delta G = -n F Eo

             = - 6 x 96485 x 1.38 x 10^-3 kJ

            =   -799 kJ /mol

Delta G = - 799 kJ /mol