What is the standard cell potential for the reaction below?

Question

What is the standard cell potential for the reaction below?

Mg(s) + Br2(l) → Mg2+(aq) + 2 Br-(aq)

 

         The standard reduction potential is -2.37 V for the Mg2+/Mg half-cell and +1.09 V for the Br2/Br- half-cell.

Answer 1

Using reduction potentials, the standard reduction potential is Cathode - Anode.

Reduction takes place at the cathode and oxidation takes place at the anode. So, we first find out which is which.

+1.09 V is greater than -2.37 so that tells us that Br₂/Br^- half reaction is reduction (cathode) and Mg²⁺/Mg is oxidation at the anode.

Eº = Cathode - Anode = 1.09 - (-2.37)

Eº = 3.46 V