Write the balanced half-cell reactions that take place at the cathode and at the anode.

Question

Consider a galvanic cell in which Al³⁺ is reduced to elemental aluminum and magnesium metal is oxidized to Mg²⁺ . Write the balanced half-cell reactions that take place at the cathode and at the anode.

half cell reaction at the cathode: ?

half cell reaction at the anode:?

Answer 1

Oxidation takes place at the ANODE

Reduction takes place a the CATHODE

Oxidation half reaction:

Mg(s) ==> Mg²⁺ + 2e-

Reduction half reaction:

Al³⁺ + 3e- ==> Al(s)

In order to equalize the electrons, we must multiply oxidation rxn by 3 and reduction rxn by 2:

3Mg(s) ==> 3Mg²⁺(aq) + 6e- half cell at the anode

2Al³⁺(aq) + 6e- ==> 2Al(s) half cell at the cathode