1. Write the balanced chemical equation:

N₂ (g) + 3 H₂ (g) → 2 NH₃ (g)

2. Calculate the moles of hydrogen gas:

* Molar mass of H₂ = 2 g/mol

* Moles of H₂ = (3.5 g) / (2 g/mol) = 1.75 mol

3. Determine the moles of ammonia produced:

* From the balanced equation, 3 moles of H₂ produce 2 moles of NH₃.

* Moles of NH₃ = (1.75 mol H₂) * (2 mol NH₃ / 3 mol H₂) = 1.17 mol NH₃

4. Calculate the mass of ammonia produced:

* Molar mass of NH₃ = 17 g/mol

* Mass of NH₃ = (1.17 mol) * (17 g/mol) = 19.89 g

Therefore, approximately 19.89 grams of NH₃ will be produced.