Consider the N₂ gas produced:
Pressure, P = 1.2 atm
Volume, V = 16 L
Gas constant, R = 0.08206 L atm / (mol K)
Temperature, T = (273 + 23) K = 296 K
Gas law: PV = nRT
Then, n = PV/(RT)
No. of moles of N₂, n
= 1.2 × 16 / (0.08206 × 300)
= 0.79 mol
According to the given equation, mole ratio Cl₂ :
N₂ = 3 : 1
No. of moles of Cl₂ needed
= (0.79 mol) × 3
= 2.37 mol
Mass of Cl₂ needed
= (2.37 mol) × (35.5 × 2 g/mol)
= 168 g