1. Balance the Chemical Equation

The equation you provided is already balanced:

4NH₃ + 7O₂ → 4NO₂ + 6H₂O

2. Determine the Mole Ratio

From the balanced equation, we see that 7 moles of O₂ are required to produce 4 moles of NO₂.

3. Calculate Moles of O₂ Needed

* Use the mole ratio to find the moles of O₂ needed:

(4.50 moles NO₂) * (7 moles O₂ / 4 moles NO₂) = 7.875 moles O₂

4. Convert Moles of O₂ to Grams

* Multiply the moles of O₂ by the molar mass of O₂ (32.00 g/mol):

(7.875 moles O₂) * (32.00 g/mol) = 252 g O₂

Therefore, 252 grams of oxygen are necessary to produce 4.50 moles of NO₂.