If 62.4 grams of white phosphorus react with 136.2 grams of chlorine, how many grams of phosphorus trichloride can be formed?

p4 + 6cl2 yields 4pcl3

The balanced chemical reaction is given to be,          
                          P4 + 6Cl2 --> 4PCl3
The masses of the involved chemicals are calculated below.
      P4 = (4)(30.97 g/mol) = 123.88 g
     6Cl2 = (6)(35.45g/mol)(2) = 425.4 g
      4PCl3 = (4)(30.97 + 3x35.45) = 549.28 g

With the given masses from this item, we solve for the mass of PCl3 by ratio and proportion.
         62.4 g P x (549.28 g PCl3 / 123.88 g P) = 276.679 g PCl3
         136.2 g Cl x (549.28 g PCl3 / 425.4 g Cl) = 175.86 g PCl3

Since, lesser PCl3 is produced from the 136.2 g of Cl then Cl is the limiting reactant and the answer is 175.86 g of PCl3.