Stoichiometry Problems 1

1.  When lead (II) sulfide is burned in air, lead (II) oxide and sulfur dioxide are produced.  If 0.890
moles of sulfur dioxide were produced, how many moles of oxygen gas were required to react with
the lead (II) sulfide?                                 ___ PbS  +  ___ O2
à  ___ PbO  +  ___ SO2

2.  In the synthesis reaction of aluminum and oxygen to produce aluminum oxide, how many grams of
aluminum are required to react with 0.223 moles of oxygen?
___ Al  +  ___ O2
à  ___ Al2O3

3.  Calculate the number of grams of oxygen produced if 2.50 grams of potassium chlorate are
decomposed completely by heating.
___ KClO3
à  ___ KCl  +  ___ O2

4.  How many moles of oxygen are needed for the complete combustion of 3.0 moles of methane
(CH4)?                                  ___ CH4  +  ___ O2
à  ___ CO2  +  ___ H2O

5.  Using the same equation from #4, how many grams of carbon dioxide are formed when 8.0 grams
of methane react?                  ___ CH4  +  ___ O2
à  ___ CO2  +  ___ H2O

6.  When elemental sulfur combines with oxygen gas, sulfur dioxide is formed.  What is the total
number of grams of oxygen needed to react completely with 2.0 moles of sulfur?
___ S  +  ___ O2
à  ___ SO2

7.  In the synthesis of water from its elements, what is the total number of grams of oxygen gas
needed to produce 54 grams of water?          ___ H2  +  ___ O2
à  ___ H2O

8.  How many moles of aluminum oxide will be formed when 27 grams of aluminum react completely
with excess oxygen gas?                                       ___ Al  +  ___ O2
à  ___ Al2O3

9. What mass (in grams) of sodium oxide is produced by the reaction of 1.44 grams of sodium with
excess oxygen?                                           __ Na +   __ O2
à     __ Na2O

10. What mass (in grams) of water will be given off when 1.92 x 1022 molecules of octane (C8H18) are
burned completely in air?                             __ C8H18 +     __ O2
à      __ CO2 +     __ H2O

11. How many grams of Al2(SO4)3 are need to react with KCl in order to produce 1.245 moles of K2SO4?
__ Al2(SO4)3  +     __ KCl
à      __ AlCl3  +    __ K2SO4

12. Hydrogen gas can be produced through the following unbalanced reaction.
__ Mg  +    __ HCl
à     __ MgCl2  +    __ H2

a. What mass of HCl is consumed by the reaction of 2.50 moles of magnesium?

b. What mass of each product is produced in part a.?

13. Acetylene gas, C2H2, used in welding, produces an extremely hot flame when it burns in pure
oxygen according to the following unbalanced reaction.
__ C2H2 +    __ O2
à    __ CO2 +    __ H2O
How many molecules of CO2 are produced when 2.50 x 104 grams of C2H2 burn completely?

1.)  1.34 moles O2          2.)  8.02 g Al                 3.)  0.980 g O2               4.)  6.0 moles O2            5.)  22 g CO2
6.)
64 g O2                    7.) 48 g O2                     8.)  0.50 moles Al2O3                  9.)  1.94 g Na2O
10.)
5.16 g H2O 11.)  142.1 g Al2(SO4)3                12.)  a)  183 g HCl         b)  238 g MgCl2; 5.00 g H2
13.)  1.16 x 1027 mcs CO2