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Unit 5 Study Guide: Stoichiometry
At the end of this unit, students should be able to:
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Balance a chemical equation
Write a balanced equation from a word equation
Predict the products of a chemical reaction
Explain the purpose of a mole ratio
Identify a mole ratio from a balanced equation
Perform stoichiometric calculations, including (but not limited to) problems converting from
o Moles – moles
o Mass – moles
o Mass – mass
o Particles – particles
o Moles - liters of gas at STP
o Moles – volume of solution
Define the terms limiting and excess reactants
Solve limiting reactant problems
o Find the theoretical yield
o Determine the limiting reactant
o Calculate the amount of excess reactant left over
Calculate percent yield
Sample Problems:
1. In the reaction represented by the equation: 2 C4H10 + 13 O2 → 8 CO2 + 10 H2O, what is the mole ratio of
oxygen to carbon dioxide?
2. What is the purpose of a mole ratio?
3. When the formula equation
is correctly balanced, what is the coefficient of Fe?
4. In the equation 2KClO3 → 2KCl + 3O2, how many moles of oxygen are produced when 3.0 mol of KClO3
decompose completely?
5. For the reaction represented by the equation 2H2 + O2 → 2H2O, how many grams of water are produced from
6.00 mol of hydrogen?
6. Lead (II) nitrate reacts with potassium iodide to produce potassium nitrate and lead (II) iodide. How many grams
of lead (II) nitrate are needed to produce 150.0 grams of lead (II) iodide?
7. A solution containing 15.0 grams of calcium nitrate was mixed with a solution containing 15.0 grams of sodium
sulfate.
a. What is the limiting reactant in the precipitation of calcium sulfate?
b. What is the theoretical yield of calcium sulfate?
c. How many grams of excess reactant will be left over?
8. One in a series of reactions that inflates airbags in automobiles is the decomposition of sodium azide (NaN3).
2 NaN3 (s)  2 Na (s) + 3 N2 (g)
Determine the mass of N2 produced if 1.00 x 102 g NaN3 is decomposed.
9. Given the following equation:
H3PO4 + 3 KOH ------> K3PO4 + 3 H2O
a) If 49.0 g of H3PO4 is reacted with excess KOH, determine the theoretical yield.
b) If you isolate 49.0 g of K3PO4, what is your percent yield?
10. Given the following equation: Ca(OH)2 (s) + 2 HCl (aq) → CaCl2 (aq) + 2 H2O (l)
How many liters of 0.100 M HCl would be required to react completely with 5.00 grams of calcium hydroxide?
11. Calcium carbonate decomposes at high temperatures to form carbon dioxide and calcium oxide:
CaCO3(s)  CO2(g) + CaO(s)
How many grams of calcium carbonate will I need to form 3.45 liters of carbon dioxide gas at STP?