Stoichiometry
Practice Problem #1:
Oxygen gas can be produced by decomposing potassium chlorate using the reaction below. If 138.6 g of KClO 3 is heated and
decomposes completely, what mass of oxygen gas is produced?
KClO3 (s) --> KCl (s) + O2 (g)
[unbalanced]
54.286 g of O2 produced
Practice Problem #2:
Identify the limiting reagent for the given combination of reactants. Calculate how many grams of whatever substance will be in
excess and how many grams of HF will be made.
F2 (g) + NH3 (g) --> N2F4 (g) + HF (g)
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5.33 mol 2.22 mol
[unbalanced]
127.92 g HF produced
Practice Problem #3:
How many grams of aluminum sulfate are produced if 23.33 g Al reacts with 74.44 g CuSO 4?
Al (s) + CuSO4 (aq) --> Al2(SO4)3 (aq) + Cu (s)
[unbalanced]
53.23 g Al2(SO4)3 produced
Practice Problem #4:
Given the following reaction, answer Parts A and B.
NaClO3 (s) --> NaCl (s) + O2 (g)
[unbalanced]
A: 12.00 moles of NaClO3 will produce how many grams of O2?
576.00 g O2 produced
B: How many grams of NaCl are produced when 80.0 grams of O 2 are produced?
97.417 g NaCl produced
Practice Problem #5:
How many liters of 0.100 M HCl would be required to react completely with 5.00 grams of calcium hydroxide?
0.0135 moles of HCl to react with 5.00 g Ca(OH)2. Using the equation M = mol/L, this translates to
0.135 L of 0.100 M HCl
Practice Problem #6:
A. If you combined 15.0 grams of calcium hydroxide with 75.0 mL of 0.500 M HCl, how many grams of calcium chloride would
be formed?
2.08 grams
B. What is the limiting reagent from the reaction in part A?
HCl
C. How many grams of the excess reagent will be left over after the reaction in part A is complete?
13.6 grams of Ca(OH)2