Answer:
22.4 g
Explanation:
We know we will need a balanced equation with molar masses, so let’s gather all the information in one place.
M_r: 2.016
4H₂O + 2NH₃ ⟶ 2NO₂ + 7H₂; ΔH = 216 kJ/mol NH₃
1. Calculate the moles of NH₃
216 kJ ≡ 1 mol NH₃
Moles NH₃ = 685 × 1/216
Moles NH₃ = 3.171 mol NH₃
2. Calculate the moles of H₂
The molar ratio is 7 mol H₂:2 mol NH₃
Moles of H₂ = 3.171 × 7/2
Moles of H₂ = 11.10 mol H₂
3. Calculate the mass of H₂
Mass of H₂ = 11.10 × 2.016
Mass of H₂ = 22.4 g
