LIMITING REACTANTS
Practice Problems:

1. The coating you see on a corroded iron object that has been left in moist conditions is black iron
oxide (Fe3O4).  This substance can also be made in the laboratory by the reaction between iron and
steam, according to the following equation:            Fe   +   H2O
à   Fe3O4   +   H2
(A) When 36.0 grams of H2O react with 167 grams of Fe, which is the limiting reactant? (H2O)
(B) How much of the excess reactant is used when the reaction is completed?    (83.7 g)
(C) What mass (in grams) of black iron oxide is produced?    (116 g)

2. Zinc and sulfur react to form zinc sulfide according to the following equation:
Zn   +   S8
à   ZnS
(A) If 23.0 grams of Zn are heated with 19.3 grams of S8, which is the limiting reactant?  (Zn)
(B) How many grams of excess reactant remain after the reaction is completed?  (8.0 g)
(C) How many grams of product are formed?  (34.3 g)

3. Carbon reacts with steam under certain conditions to produce hydrogen and carbon monoxide.
C   +   H2O
à   H2   +   CO
(A) If 2.40 grams of carbon react with 3.10 grams of steam, which is the limiting reactant?  (H2O)
(B) How many moles of each product are formed?  (0.172 moles of each)
(C) How many grams of each product are formed?  (4.82 g CO, 0.347 g H2)

4. Aluminum reacts with hydrochloric acid according to the following equation:
Al   +   HCl
à   AlCl3  +   H2
(A) If 18 grams of aluminum are combined with 75 grams of HCl, which is the limiting reactant?  (Al)
(B) What mass of each product is formed?  (88.9 g AlCl3, 2.02 g H2)