The mass of P4 required to obtain 2.30 PCl3 0.694 g
calculation
p4 + 6 Cl2→ 4 pcl3
step 1:calculate the moles of PCl3
moles= mass/molar mass
from periodic table the molar mass of PCl3 = 31 + (3 x35.5) = 137.5 g/mol
moles = 2.30 / 137.5 =0.0167 moles
step 2: use the mole ratio to find the moles of P4
from equation above the mole ratio of p4 :PCl3 is 1:3 therefore the moles of p4
= 0.0167 x1/3 =0.0056 moles
step 3: find the mass of P4
mass = moles x molar mass
from periodic table the molar mass of P4 = 31 x4= 124 g/mol
mass = 0.0056 x 124 = 0.694 g
