Question

Consider the reaction shown below, where M represents a generic metal. The standard free energy change (ΔG°) for this reaction is –533 kJ. What is the standard reduction potential of M? Is M2+ a stronger or weaker oxidizing agent than Al3+?

2Al(s) +3M2+(aq) → 2Al3+(aq) + 3M(s)

Answer 1

writing the equations for oxidation half and reduction half:

Oxidation Half: Al(s) ----> Al(+3) + 3e-

Reduction Half: M(+2) + 2e- ---> M

In order to cancel the electron we need to multiply the first reaction by 2 and second reaction by 3, hence number of electrons involved in the reaction are equal to 6

Hence value of n=6

-533*10^(3) = -6*96500 * Ecell

Ecell = 0.92055 V

Since the Delta G value is negative and EMF is positive hence the reaction is spontaneous hence M2+ is a stronger oxidizing agent since it can oxidize Al to Al(+3)