CHEMISTRY SHENANIGANS

-usually one reactant gets used up first
-one reactant is completely consumed
-this determines how much product is produced
-'Guess' which reactant is limiting, and check how much of it is required

What is thelimiting reactant when 125g of P4 reacts with 323g of Cl2 to form phosphorous tricholoride?

1. P4+6Cl2--->4PCl3
2.125g X 1mol/124g X 6mol of Cl2/1mol P4 X 71g/mol = 431g of Cl2
3. Cl2 is the limiting reactant

Deternmine the theoretical yield of the previous equation

323g X 1mol Cl2/71g X 4mol PCl3/6mol CL2 X 137.4g/1mol PCl3 = 417g

Here's a link for more info on limiting reactants:
http://www.chem.tamu.edu/class/majors/tutorialnotefiles/limiting.htm