How many grams of phosphorus (P4) are needed to completely consume 40.5 L of chlorine gas according to the following reaction at 25 °C and?

Consider the Cl₂ gas reacted :
Pressure, P = 1 atm
Volume, V = 40.5 L
Gas constant, R = 0.08206 atm L / (mol K)
Temperature, T = (273 + 25) K = 298 K

Gas law : PV = nRT
No. of moles of Cl₂ reacted, n = PV/(RT) = 1 × 40.5 / (0.08206 × 298) = 1.656 mol

Balanced equation for the reaction :
P₄(s) + 6Cl₂(g) → 4PCl₃(l)
Mole ratio P₄ : Cl₂ = 1 : 6
No. of moles of P₄ needed = (1.656 mol) × (1/6) = 0.276 mol

Molar mass of P₄ = 31.0 × 4 = 124.0 g/mol
Mass of P₄ needed = (0.276 mol) × (124.0 g/mol) = 34.2 g

Need 4 thousand kg of methampetamine