Practice Problems (Chapter 5): Stoichiometry
CHEM 30A
Part I: Using the conversion factors in your tool box
Tool Box:
To convert between
g A ↔ mol A
mol A ↔ particles A
mol A ↔ mol B
Use
molar mass
Avogadro’s #
molar ratio
1. How many moles CH3OH are in 14.8 g CH3OH?
2. What is the mass in grams of 1.5 x 1016 atoms S?
3. How many molecules of CO2 are in 12.0 g CO2?
4. What is the mass in grams of 1 atom of Au?
From
periodic table
memory
coeff. in bal. eqn.
Part II: Stoichiometry problems
5. If 54.7 grams of propane (C3H8) and 89.6 grams of oxygen (O2) are available in the balanced
combustion reaction to the right:
a) Determine which reactant is the limiting reactant.
b) Calculate the theoretical yield of CO2 in grams.
C3H8 + 5 O2  3 CO2 + 4 H2O
54.7 g
89.6 g
Limiting Reactant: ________________
Theoretical Yield: ________________
6. A reaction has a theoretical yield of 124.3 g SF6, but only 113.7 g SF6 are obtained in the lab, what is
the percent yield of SF6 for this reaction?
Answer: ________________
7. If 23.2 grams of butane (C4H10) and 93.7 grams of oxygen (O2) are available in the following
reaction:
____ C4H10 + ____ O2  ____ CO2 + ____ H2O
23.2 g
93.7 g
a) Balance the equation for the reaction.
b) Determine which reactant is the limiting reactant.
c) Calculate the theoretical yield of CO2 in grams.
Limiting Reactant: ________________
Theoretical Yield: ________________
d) If the actual yield of CO2 is 69.2 g CO2, what is the percent yield?
Answer: _______________________