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.

Answer 1

Al³⁺ + 3e- ==> Al(s) reduction half reaction takes place at the cathode

Mg(s) ==> Mg²⁺ + 2e- oxidation half reaction takes place at the anode

To equalize electrons, multiply reduction rx by 2 and oxidation rx by 3:

2Al³⁺ + 6e- ==> 2Al(s) ... balanced reduction reaction

3Mg(s) ==> 3Mg²⁺ + 6e- ... balanced oxidation reaction

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2Al³⁺+ 3Mg(s) ==> 2Al(s) + 3Mg²⁺ ... balanced redox reaction