1. Write the balanced chemical equation:

The reaction between aluminum (Al) and oxygen (O₂) produces aluminum oxide (Al₂O₃):

4 Al + 3 O₂ → 2 Al₂O₃

2. Determine the mole ratio:

The balanced equation shows that 4 moles of aluminum react with 3 moles of oxygen.

3. Calculate the moles of oxygen needed:

* Since we have 0.3 moles of aluminum, we can use the mole ratio to find the moles of oxygen:

(0.3 moles Al) * (3 moles O₂ / 4 moles Al) = 0.225 moles O₂

4. Convert moles of oxygen to grams:

* The molar mass of oxygen (O₂) is 32 g/mol.

* Multiply the moles of oxygen by its molar mass:

(0.225 moles O₂) * (32 g/mol) = 7.2 grams of oxygen

Therefore, 7.2 grams of oxygen will be required to react completely with 0.3 moles of aluminum.