P₄ + 10Cl₂ ---> 4PCl₅ stoichiometry of P₄ to PCl₅ is 1:4 number of moles of P₄ reacted - 28.0 g / 124 g/mol = 0.22 mol Cl₂ is in excess therefore P₄ is the limiting reactant, amount of product formed depends on amount of limiting reactant present according to molar ratio of 1:4 number of PCl₅ moles formed -0.22 mol x 4 = 0.88 mol 0.88 mol of PCl₅ is formed
