Pre AP Chemistry Unit 10 Practice Packet
LEGGETT
Name ______________________________________
WKS 10.1 – Using the Mole Ratio (1 page)
1. Define “stoichiometry”.
2. Define “molar mass”.
3. Define “mole ratio”.
4. Define “theoretical yield”.
5. Answer the following questions for this equation: 2 H2 + O2  2 H2O
a. What is the molar ratio of hydrogen gas to oxygen gas?
b. What is the molar ratio of hydrogen gas to water?
c. What is the molar ratio of oxygen gas to water?
d. If you had 20 moles of H2 on hand, and excess O2, how many moles of H2O could you theoretically make?
e. If you had 20 moles of O2 on hand, and excess H2, how many moles of H2O could you theoretically make?
6. Answer the following questions for this equation: N2 + 3 H2  2 NH3
a. What is the molar ratio of nitrogen gas to ammonia?
b. What is the molar ratio of hydrogen gas to ammonia?
c. What is the molar ratio of nigrogen gas to hydrogen gas?
d. What is the maximum amount of ammonia that could be made from 3.00 moles of hydrogen gas?
e. How many moles of nitrogen gas would it take to make a maximum of 15 moles of ammonia?
f.
How many moles of hydrogen gas would it take to make a maximum of 15 moles of ammonia?
Page 1 of 10
Pre AP Chemistry Unit 10 Practice Packet
Name ______________________________________
WKS 10.2 – Calculating with Mass, Moles, & Molecules (1 page)
YOU MUST SHOW WORK USING DIMENSIONAL ANALYSIS TO EARN CREDIT FOR THE PROBLEMS!
1. How many grams of ammonia (NH3) can theoretically be produced by the synthesis of excess hydrogen gas and 235
grams of nitrogen gas in a synthesis reaction? (285 g)
2. The reaction of carbon monoxide and iron (III) oxide produces pure iron and carbon dioxide as the only products.
What mass (in grams) of carbon monoxide has been used with excess iron (III) oxide if 80.4 grams of pure iron could
potentially be produced? (60.5 g)
3. How many molecules of O2 are required for the complete combustion of 23.0 grams of hexane? (1.53 X 1024 mlcl)
4. How many moles of oxygen are required to theoretically produce 100. grams of water in a synthesis reaction in which
there is excess hydrogen? (2.78 moles)
5. If a maximum of 8.54 X 1025 molecules of hydrogen gas could be produced when aluminum reacts with excess
hydrochloric acid, how many pounds of aluminum were used? There are 454 grams in 1 pound. (5.62 pounds)
Page 2 of 10
Pre AP Chemistry Unit 10 Practice Packet
Name ______________________________________
WKS 10.3 – Calculating with Molar Volume (1 page)
YOU MUST SHOW WORK USING DIMENSIONAL ANALYSIS TO EARN CREDIT FOR THE PROBLEMS!
1. How many liters of hydrogen at standard conditions are required to react with 25.0 grams of oxygen in the synthesis
of water?
(35.0 L)
2. If 37.5 grams of potassium chlorate are decomposed into potassium chloride and oxygen gas, what is the maximum
potential liters of oxygen that could be collected at STP conditions?
(10.3 L)
3. Automotive air bas inflate when a sample of NaN3 is very rapidly decomposed. What mass of NaN3 is required to
produce 375 L of nitrogen gas at STP? (728 g)
4. Using the same NaN3 reaction as the previous problem, how many sodium atoms could be produced when 375 L of
nitrogen gas at STP is theoretically produced? (6.74 x 1024 atoms)
5. How many liters of hydrogen chloride gas could theoretically be produced at STP by reacting 34.7 liters of hydrogen
gas at STP with excess chlorine gas? (69.4 L)
Page 3 of 10
Pre AP Chemistry Unit 10 Practice Packet
Name ______________________________________
WKS 10.4 – Calculating with Density (1 page)
YOU MUST SHOW WORK USING DIMENSIONAL ANALYSIS TO EARN CREDIT FOR THE PROBLEMS!
1. How many milliliters of liquid bromine (density = 3.12 g/mL) could theoretically be formed if 45.7 grams of sodium
bromide are reacted with excess chlorine gas? (11.4 mL)
2. Methyl alcohol (CH3OH) is completely combusted in a reaction. If 2.5 liters of methyl alcohol (density = 0.78 g/mL)
are combusted, how many grams of water could potentially form? (2.2 X 103 g)
3. Methyl butanoate, an oily substance with a strong fruity fragrance, can be made by reacting butanoic acid with
methanol according to the following balanced equation. How many liters of methyl butanoate are produced from the
reaction of 52.5 g of butanoic acid? The density of methyl butanoate is 0.90 g/mL. (6.66 x 10-2 L)
(butanoic acic) (methanol) (methyl butanoate)
C3H7COOH + CH3OH  C3H7COOCH3 + H2O
4. Gasoline (C7H16) has a density of 0.685 kg/liter. How many liters of oxygen at STP are needed to burn 15 liters of
gasoline? (2.5 x 104 L)
5. How many liters of hydrogen of STP are required to react with 85 ml of bromine (density = 3.12 g/ml) in the
synthesis of hydrogen bromide? (37 L)
Page 4 of 10
Pre AP Chemistry Unit 10 Practice Packet
Name ______________________________________
WKS 10.5 – Calculating with Percent Yield (1 page)
YOU MUST SHOW WORK USING DIMENSIONAL ANALYSIS TO EARN CREDIT FOR THE PROBLEMS!
1. If 36.0 liters of hydrogen at STP are reacted with excess iodine vapor, and 68.0 liters of hydrogen iodide vapor are
actually collected at STP, what is the percent yield of this reaction? (94%)
2. If 35.6 grams of zinc sulfate are actually produced when excess zinc chloride solution reacts with 47.3 grams of
aluminum sulfate, what is the percent yield of this reaction? (53.2%)
3. If a manufacturing company reacts 40. pounds of calcium nitrate with excess ammonium phosphate and finds that
only 22.3 pounds of calcium phosphate are actually produced, what is the percent yield of this reaction? There are 454
grams in 1 pound. (89%)
USE THE FOLLOWING BALANCED EQUATION FOR THE NEXT TWO QUESTIONS:
WO3 + 3H2  W + 3H2O
4. Tungsten (W) can be produced from its oxide by reacting the oxide with hydrogen. What is the percent yield if 56.9 g
of WO3 reacted in lab actually produces 10.0 g of water? (75.2%)
5. How many grams of tungsten will actually be produced from 3.72 g of WO3 if the efficiency of the reaction is only
92.0 %? (2.71 g)
Page 5 of 10
Pre AP Chemistry Unit 10 Practice Packet
Name ______________________________________
WKS 10.6 – Calculating with Limiting Reactants (2 pages)
YOU MUST SHOW WORK USING DIMENSIONAL ANALYSIS TO EARN CREDIT FOR THE PROBLEMS!
1. If 48.0 mL of liquid cyclohexane are reacted with 86.7 liters of oxygen at STP in a combustion…
a. How many liters of carbon dioxide gas could theoretically be produced at STP? The density of cyclohexane is
0.75 g/ml. (57.5 L)
b. Which reactant was the limiting reactant? Which was the excess reactant?
c. How many liters of the excess reactant are left over? (0.4 L)
2. If 44.0 grams of sodium reacts with 10.0 liters of chlorine gas at STP…
a. How many grams of sodium chloride could potentially be formed? (52.2 g)
b. Which reactant was the limiting reactant? Which was the excess reactant?
c. 48.6 grams of sodium chloride are actually formed when the reaction is done in lab. What is the percent yield of
this reaction? (93.1%)
Page 6 of 10
Pre AP Chemistry Unit 10 Practice Packet
Name ______________________________________
WKS 10.6 – Calculating with Limiting Reactants (continued)
YOU MUST SHOW WORK USING DIMENSIONAL ANALYSIS TO EARN CREDIT FOR THE PROBLEMS!
3. The metal terbium, is produced from terbium (III) fluoride and calcium metal by a single replacement reaction.
a. Given 27.5 g of TbF3 and 6.95 g of Ca, how many grams of Tb could theoretically be produced? (18.4 g Tb)
b. Which reactant was the limiting reactant? Which was the excess reactant?
c. How many grams of excess reactant are left over? (2.5 g)
4. A process by which zirconium metal can be produced from the mineral zirconium (IV) orthosilicate (ZrSiO4), starts
by reacting it with chlorine gas to form zirconium (IV) chloride. This process is shown in the balanced reaction
below. What mass of ZrCl4 can actually be produced if 862 g of ZrSiO4 and 950. g of Cl2 are available and the
percent yield is only 85%? (932 g ZrCl4)
ZrSiO4 + 2Cl2  ZrCl4 + SiO2 + O2
Page 7 of 10
Pre AP Chemistry Unit 10 Practice Packet
Name ______________________________________
WKS 10.7 – Mixed Stoichiometry Problems! (2 pages)
YOU MUST SHOW WORK USING DIMENSIONAL ANALYSIS TO EARN CREDIT FOR THE PROBLEMS!
1. Ethyl acetate is a sweet-smelling solvent used in varnishes and fingernail-polish remover. It is produced industrially
by heating acetic acid and ethanol together in the presence of sulfuric acid. Determine the percent yield if 68.3 g of
ethyl acetate is actually produced when 72 mL of acetic acid is reacted with excess ethanol. The density of acetic acid
is 1.05 g/mL. (62% yield)
Acetic acid
Ethanol
Ethyl Acetate
HC2H3O2(l) + CH3CH2OH  CH3COOCH2CH3 + H2O
2. 90.0 g of FeCl3 reacts with 52.0 g of H2S in a double-replacement reaction.
a. What is the maximum mass of HCl that could theoretically be produced? (60.8 g)
b. Which reactant is the limiting reactant?
c. What mass of excess reactant remains after the reaction? (23.7 g)
3. How many molecules of water could potentially be formed when excess phosphoric acid neutralizes 34.5 grams of
barium hydroxide? (2.43 X 1023 molecules)
Page 8 of 10
Pre AP Chemistry Unit 10 Practice Packet
Name ______________________________________
WKS 10.7 – Mixed Stoichiometry Problems! (continued)
YOU MUST SHOW WORK USING DIMENSIONAL ANALYSIS TO EARN CREDIT FOR THE PROBLEMS!
4. Hydrogen gas will react with chlorine gas to produce hydrogen chloride gas. How many liters of hydrogen chloride
could theoretically be produced if 34.2 liters of hydrogen are reacted with an excess of chlorine gas at STP? (68.4 L)
5. Although poisonous, mercury compounds were once used to kill bacteria in wounds and on the skin. One was called
“ammoniated mercury” and is made from mercury (II) chloride according to the equation shown.
a. What is the maximum mass of Hg(NH2)Cl that could potentially be produced from 0.91 g of HgCl2 and 0.15 g
of NH3? (0.84 g )
HgCl2(aq) + 2NH3(aq)  Hg(NH2)Cl(s) + NH4Cl(aq)
b. How much limiting reactant is remaining? Explain your answer.
c. How many grams of the excess reactant are remaining after the experiment? (0.036 g)
Page 9 of 10
Pre AP Chemistry Unit 10 Practice Packet
Name ______________________________________
WKS 10.8 – General Stoichiometry Review (1 pages)
1. What is the difference between a “theoretical yield” and an “actual yield”?
2. What is the difference between a “limiting reactant” and an “excess reactant”?
3. To convert between moles and volume, we can either use “22.4 L = 1 mole”, or we can use density. Why would
we pick one conversion over another for a particular problem?
True or False: For each of the following statement, state if it is true or false. If it is false, correct the statement.
4. A mole ratio can only be determined from a correctly balanced chemical equation.
5. You must know the masses of all of the reactants in order to determine a theoretical mass of a product, even if a
reactant is in excess.
6. Mole ratios are used to determine the number of significant figures needed in a calculation’s answer.
7. For any given chemical equation, all of the reactants will always be converted into products.
Multiple Choice: Choose an answer and justify each of the following…
8. If a chemist calculates the maximum amount of product that could be obtained in a chemical reaction, he or she is
calculating the:
a. Theoretical yield
c. Mole ratio
b. Percent yield
d. Actual yield
Justification:
9. The coefficients in a chemical equation represent the:
a. masses in grams of all reactants and products
b. relative number of moles of reactants and products
c. number of atoms of each element in each compound in a reaction
d. number of valence electrons involved in a reaction
Justification:
10. Which of the following would not be studied within the topic of stoichiometry?
a. the mole ratio of Al to Cl in the compound aluminum chloride
b. the mass of carbon produced when a known mass of sucrose decomposes
c. the number of moles of hydrogen that will react with a known quantity of oxygen
d. the amount of energy required to break the ionic bonds in CaF2
Justification:
11. When the limiting reactant in a chemical reaction is completely used, the:
a. Excess reactants begin combining.
c. The reaction speeds up.
b. Reaction slows down.
d. The reaction stops.
Justification:
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