3H₂ + N₂ → 2NH₃
mole of N₂ = mass ÷ molar mass
= 2.70g ÷ (14 × 2)
= 0.096 mol
mole ratio of N₂ : H₂
1 : 3
∴ if the moles of N₂ = 0.096 mol
then the mole of H₂ = 0.096 mol × 3
= 0.289 mol
Now, mass = mole × molar mass
∴ mass of H₂ needed to react = 0.289 mol × (1 × 2)
= 0.579 g
