Sample Question for LOCOM (Law of Conservation of Mass)

Sample LOCOM Chemical Equation Question (
A student combines 154 grams of carbon tetrachloride (CCl4) and an unknown quantity
(X) of bromine (Br) in a sealed container to produce 243 grams of
dibromodichlormethane (CHBr2Cl) and 71 grams of chlorine (Cl). How much chlorine
was used in the reaction, assuming the reactants are completely used up?
Since mass is conserved, we can set up an equality in which x represents the unknown
(CCl4 + Br CHBr2Cl + Cl)
quantity of bromine:
CCl4 + ?Br CHBr2Cl +Cl
154g + X = 243g + 71g SO…
X = the mass of bromine consumed in the reaction = 150 grams