1. Balanced Chemical Equation:

First, we need the balanced chemical equation for the reaction:

4 Al + 3 O₂ → 2 Al₂O₃

2. Mole Ratio:

The balanced equation tells us that 3 moles of O₂ react to produce 2 moles of Al₂O₃.

3. Moles of Al₂O₃:

Since we have 3 moles of O₂, we can use the mole ratio to find the moles of Al₂O₃ formed:

(3 moles O₂) * (2 moles Al₂O₃ / 3 moles O₂) = 2 moles Al₂O₃

4. Grams of Al₂O₃:

To convert moles of Al₂O₃ to grams, we need its molar mass:

* Al: 26.98 g/mol

* O: 16.00 g/mol

* Al₂O₃: (2 * 26.98) + (3 * 16.00) = 101.96 g/mol

Now, we can calculate the mass:

(2 moles Al₂O₃) * (101.96 g/mol) = 203.92 g Al₂O₃

Therefore, 203.92 grams of Al₂O₃ are formed from 3 moles of O₂.