Question

When metallic aluminium is added to a solution of copper (II) nitrate, copper metal is precipitated and Aluminium ions form in solution.
1, what species is oxidized?
2, what species is reduced?
3, oxidation half equation:
4, reduction half equation:

Answer 1

Answer :

1) Oxidized species is Aluminium (Al).

2) Reduced species is copper(II)nitrate, $Cu(NO_{3})_{2}$.

3) Oxidation half equation : $2Al^{0}\rightarrow 2Al^{+3}+6e^-$

4) Reduction half equation : $3Cu^{+2}+6e^{-}\rightarrow 3Cu^{0}$

Explanation :

The Net balanced chemical reaction is,

$2Al+3Cu(NO_3)_2\rightarrorw 2Al(NO_3)_3+3Cu$

1. Oxidation means loss of electron and here 1 Al is loosing 3 electrons, therefore it is getting oxidized.

2. Reduction means gain of electrons and here 1 Cu is gaining 2 electrons, hence $Cu(NO_3)_2$ species is getting reduced.

3. Half reaction when oxidation is done:

$2Al^{0}\rightarrow 2Al^{+3}+6e^-$

4. Half reaction when reduction is done:

$3Cu^{+2}+6e^{-}\rightarrow 3Cu^{0}$