Calculate the standard potential for this cell at 25 °C.

Question

A galvanic (voltaic) cell consists of an electrode composed of magnesium in a 1.0 M magnesium ion solution and another electrode composed of copper in a 1.0 M copper(II) ion solution, connected by a salt bridge. Calculate the standard potential for this cell at 25 °C.

Answer 1

Find a standard reduction potential table. Magnesium is very active and Copper is not - Copper is the cathode where reduction and formation of copper from copper ions takes place.

Cu²⁺ + 2e^- ⇒ Cu (find this reduction reaction and write down potential (= E_red)

Mg ⇒ Mg²⁺ + 2e^- (find the reverse of this reaction in the table and multiply the potential by -1 (= E_ox)

E_red + E_ox = E_T (no adjustments necessary for 1M standard solutions.