1. Write the balanced chemical equation:

2 Al + 3 Cl₂ → 2 AlCl₃

2. Determine the mole ratio:

The balanced equation shows that 2 moles of aluminum (Al) react with 3 moles of chlorine (Cl₂) to produce 2 moles of aluminum chloride (AlCl₃).

3. Calculate the moles of aluminum chloride produced:

Since we have 4 moles of aluminum, and the mole ratio of Al to AlCl₃ is 2:2 (or 1:1), we will produce 4 moles of aluminum chloride.

Therefore, 4 moles of aluminum reacting with excess chlorine gas will produce 4 moles of aluminum chloride.