Respuesta :

2P = 62g needs 5Cl2 = 355g Cl2 to react; so 28g P needs 355/62 x 28g Cl2 = 160.32g , so you don't have adequate chlorine so chlorine is the limiting reagent,. 
from the equation 355g Cl2 stretches 479gg PCl5 ; so 54g Cl2 gives 479/355 x 54 = 72.86g