1. Write the balanced chemical equation:

The reaction of acetylene (C₂H₂) with oxygen (O₂) produces carbon dioxide (CO₂) and water (H₂O).

2 C₂H₂ + 5 O₂ → 4 CO₂ + 2 H₂O

2. Determine the mole ratio:

From the balanced equation, we see that 2 moles of acetylene (C₂H₂) produce 4 moles of carbon dioxide (CO₂).

3. Calculate moles of CO₂ produced:

Since we have 3 moles of acetylene, we can use the mole ratio to find the moles of CO₂:

(3 moles C₂H₂) * (4 moles CO₂ / 2 moles C₂H₂) = 6 moles CO₂

Therefore, 6 moles of CO₂ will be produced from the reaction of three moles of acetylene with excess oxygen.