STOICHIOMETRY PRACTICE WORKSHEET
1 . Aluminum chloride, AlCl3, is used as a catalyst in various industrial reactions. It is prepared from hydrogen chloride
gas and aluminum metal shavings.
2Al(s) + 6HCl(g)  2 AlCl3 (s) + 3H2 (g)
a. How many moles of AlCl3 can be prepared from 10.5 moles of HCl with an excess of aluminum?
b. How many moles of hydrogen gas (H2) would be produced from the use of 32 moles of aluminum with an excess of
hydrogen chloride?
c. How many liters of aluminum (Al) can be produced from 54 moles of HCl?
2. When dinitrogen pentoxide, N2O5, a white solid, is heated, it decomposes to nitrogen dioxide and oxygen.
2N2O5(s) 4 NO2 (g) + O2 (g)
a. How many moles of nitrogen dioxide can be formed from the decomposition of 1.25 g of N2O5?
b. How many grams of oxygen can be formed from the decomposition of 2.3 g of NO2?
c. How many moles of NO2 can be made from 3.2 x 1013 particles of oxygen?
3. Chlorine is prepared from sodium chloride by electrochemical decomposition. Formerly chlorine was produced by
heating hydrochloric acid with pyrolusite [manganese dioxide or manganese(IV) oxide, Mn02], a common
manganese ore. Small amounts of chlorine may be prepared in the laboratory by the same reaction.
a. How many grams of HCl react with 5.00 g of MnO2, according to the equation?
b. If a chemist wanted to prepare 100. L of chlorine, how many grams of MnO2 are needed, assuming there is more
than enough
hydrochloric acid?
c. How many particles of water are produced from the reaction of 5.0 g of HCl?
4. Sodium is a soft, reactive metal that instantly reacts with water to give hydrogen gas and a solution of sodium
hydroxide,
2 Na + 2 H2O  H2 + 2 NaOH
a. How many grams of sodium metal are needed to give 7.81 g of hydrogen by this reaction?
b. How many sodium atoms are needed to react with 1.25 x 1024 particles of water?
5. Hematite, Fe2O3, is an important ore of iron. The free metal is obtained by reacting hematite with carbon
monoxide in a blast furnace. Carbon monoxide if formed in the furnace by partial combustion of carbon.
Fe2O3(s) + 3CO(g) 2Fe(s) + 3CO2(g)
a. How many grams of iron can be produced from 5.3 L Fe2O3?
b. How many liters of iron (Fe) will be made from 32.9 moles of carbon dioxide (CO 2)?
c. How many moles of carbon monoxide (CO) are needed to make 67.4 grams of iron?
6. Sphalerite is a zinc sulfide (ZnS) mineral and an important commercial source of zinc metal. The first step in the
processing of the ore consists of heating the sulfide with oxygen to give zinc oxide, ZnO, and sulfur dioxide, SO2.
2 ZnS +3 O2  2 ZnO + 2 SO2
a. If you have 24.7 moles of oxygen (O2), how many moles of sulfur dioxide (SO2)?
b. How many liters of oxygen gas combine with 94.8 g of zinc sulfide in this reaction?
c. How many particles can be made SO2 can be made from 58.2 L of oxygen?
7. The British chemist Joseph Priestley prepared oxygen in 1774 by heating mercury(ll) oxide, HgO. Mercury metal
is the other product. 2 HgO(s)  2 Hg (s) + O2 (g)
a. If 6.47 g of oxygen is collected, how many grams of mercury metal are also produced?
b. How many moles of oxygen can be made from 125 moles of mercury (II) oxide?
c. How many atoms of mercury can be made from 6.5 x 1020 particles of mercury (II) oxide?
8. Potassium superoxide, KO2, is used in breathing gas masks to regenerate oxygen.
2H2O(l) +2 KO2  4 KOH(s) + 3 02 (g)
STOICHIOMETRY PRACTICE WORKSHEET
a.If a reaction vessel contains 0.25 mol K02, how many grams of oxygen can be produced?
b. How many moles of oxygen can be produced from 0.345 L of water?