Question

Balance the following net ionic equationAl(s) + Cu2+(aq) n Al3+(aq) + Cu(s)

Answer 1

Given:

$Al_{(s)}+\text{ Cu}_{(aq)}^{2+}\rightarrow Al_{(aq)}^{3+}+\text{ Cu}_{(s)}$

Required: To balance the equation.

Solution

Step 1: Write the half reactions.

The aluminum is oxidized since the oxidation state increases from zero to plus three. The copper is reduced since the oxidation state decreases from 2+ to zero. The half reactions are as follows.

$\begin{gathered} Cu_{(aq)}^{2+}\text{ + 2e}^-\rightarrow Cu_{(s)}\text{ \lparen reduction\rparen} \\ \\ Al_{(s)}\rightarrow Al_{(aq)}^{3+}+\text{ 3e}^-\text{ \lparen oxidation\rparen} \end{gathered}$

Step 2: Multiply by an appropriate factor to balance the equation

Multiply the reduction reaction by 3

Multiply oxidation reaction by 2

Add the half reactions to get the net ionic equation:

Answer

$3Cu_{(aq)}^{2+}\text{ + 2Al}_{(s)}\rightarrow3Cu_{(s)}\text{ + 2Al}_{(aq)}^{3+}$