300 Chemistry
Stoichiometry
Do on separate paper or in your notebook
1. Base your answers to the questions below on the following equation:
2KBr + Cl2 → 2KCl + Br2
a. How many moles of bromine are produced when 0.056 moles of
potassium bromide react with an excess of chlorine?
b. How many moles of potassium chloride are produced when 0.056 moles
of bromine are produced?
c. How many moles of chlorine are required to react completely with 2.45
moles of potassium bromide?
2. Base your answers to the questions below on the following equation:
2CO + O2 → 2CO2
a. How many moles of carbon monoxide are needed to completely react with
5.43 moles of oxygen?
b. How many moles of carbon dioxide are produced by the reaction of 2.03
moles of oxygen with an excess of carbon monoxide?
c. How many moles of carbon dioxide are produced by the reaction of 1.18
moles of carbon monoxide with an excess of oxygen?
3. Base your answers to the questions below on the following equation:
Na3PO4 + 3KOH → 3NaOH + K3PO4
a. How many grams of potassium phosphate are produced if 25.3 g of
sodium phosphate react with an excess of KOH?
b. How many grams of potassium hydroxide are required to completely react
with 1.26 g of sodium phosphate?
c. How many grams of sodium hydroxide can be produced from 5.26 g of
sodium phosphate?
d. How many moles of potassium hydroxide are required to react to produce
15.76 g of NaOH?
4. MgCl2 + Li2CO3 → MgCO3 + 2LiCl
If you start with 1.75 g of lithium carbonate and unlimited magnesium chloride,
how many grams of magnesium carbonate will be produced? How many grams of
lithium chloride will be produced?
5. P4 + 3O2 → 2P2O3
If 5.89 g of diphosphorous trioxide were produced, how many grams of
phosphorous must have reacted? How many grams of oxygen must have reacted?
6. 2AgNO3 + Cu → Cu(NO3)2 + 2Ag
How many grams of silver can be produced if 1.09 g of copper react with an
excess of silver nitrate?
7. Base your answers to the questions below on the following equation:
C3H6O + 4O2 → 3CO2 + 3H2O
a. If 10.0 g of each reactant are available, which one is the limiting reagent?
b. What is the theoretical yield (in grams) for carbon dioxide?
c. What is the theoretical yield (in grams) for water?
d. How much of the excess reagent is leftover (grams)?
8. Base your answers to the questions below on the following equation:
2MgI2 + Mn(SO3)2 → 2MgSO3 + MnI4
a. If 4.35 g of each reagent are available, which one is the limiting reagent?
b. What is the theoretical yield (in grams) for magnesium sulfite?
c. What is the theoretical yield (in grams) for manganese(IV) iodide?
d. How much of the excess reagent is leftover (grams)?
9. Copper plus sulfuric acid yields copper(II) sulfate plus water plus sulfur dioxide.
a. Write a balanced equation for the reaction.
b. If I start with 15.0 g of sulfuric acid and 2.51 g of copper, how many
grams of sulfur dioxide can be formed?
c. What is the limiting reagent?
d. How much of the excess reagent will be leftover?
e. If, in a separate experiment, it should be possible to produce 3.45 g of
sulfur dioxide, but only 2.75 g of sulfur dioxide are actually produced,
what is the percent yield?
10. Calcium hydroxide and phosphoric acid yield calcium phosphate and water.
a. Write a balanced equation for the reaction.
b. If I start with 25.0 grams of calcium hydroxide and 15.0 g of phosphoric
acid, how many grams of calcium phosphate can be formed?
c. If 1.25 g of calcium phosphate are produced, what is the percent yield?
11. When sulfuric acid reacts with aqueous sodium hydroxide in a double
replacement reaction, what mass of sodium hydroxide would be required to react
completely with 0.75 mol of sulfuric acid?
12. In a laboratory experiment, when 10.0 g of methane (CH4) is reacted with an
excess of oxygen gas in a complete combustion reaction, 18.90 g of water are
produced. What is the percent yield of this reaction?
13. Large quantities of ammonia, NH3, are burned in the presence of a platinum
catalyst to give nitrogen monoxide, as the first step in the preparation of nitric
acid, according to the reaction below:
4 NH3 + 5 O2  4 NO + 6 H2O
Suppose a vessel contains 0.120 moles of NH3 and 0.140 moles of O2. Which is
the limiting reagent? How many molecules of NO will form?
14. How many grams of N2F4can be prepared from 4.00 g of NH3 and an excess of
F2? What is the percent yield if 10.05 g of N2F4 are actually produced? The
chemical reaction is:
2 NH3 + 5 F2  N2F4 + 6 HF
15. Ammonia, NH3, reacts with oxygen gas to produce nitrogen and water. If 10 g of
ammonia reacts with 10 g of oxygen, how many molecules of nitrogen gas form?
Percentage Yield
Percent Yield Practice Problems
1. When 84.8 g of iron(III)oxide reacts with carbon monoxide, iron metal and
carbon dioxide are produced.
a. Write the chemical equation for the above reaction.
b. Balance the equation.
c. Calculate how many grams of iron can be produced.
d. Determine the percentage yield if 57.8 grams of iron are actually
produced.
2. When 50.0g of silicon dioxide is reacted with carbon, silicon carbide (SiC) and
carbon monoxide are produced.
a. Write the chemical equation for the above reaction.
b. Balance the equation.
c. Calculate how many grams of silicon carbide can be produced.
d. Determine the percentage yield if 32.2 grams of silicon carbide is actually
produced.
3. Quicklime, CaO, can be prepared by roasting limestone, CaCO3, according to the
chemical equation below. When 2.00 x 103 g of CaCO3 are heated, the actual yield of
CaO is 1.50 x 103 g. What is the percentage yield?
CaCO3  CaO + CO2
a. Calculate how many grams of silicon carbide can be produced.
b. Determine the percentage yield.
4. Aluminum reacts with an aqueous solution containing excess copper (II) sulfate. If
1.85 g Al reacts and 5.88 g of Cu is actually produced, what is the percentage yield of the
reaction?
a.
b.
c.
d.
Write out the reactants and predict the products.
Balance the equation.
Calculate how much Cu can be made.
Determine the percentage yield of Cu.
5. The combustion of methane produces carbon dioxide and water. Assume that 2.0 mol
of CH4 burned in the presence of excess air. What is the percentage yield if the reaction
produces 87.0 g of CO2?
a.
b.
c.
d.
Write out the reactants and predict the products.
Balance the equation.
Calculate how much CO2 can be made
Determine the percentage yield.