CP Chemistry
Mrs. Klingaman
Chapter 9:
Stoichiometry
Name: ____________________________________________________
Mods: _____________
Name: _________________________________
Mods: ____________
S’mores: An Introduction to Mole Ratios
Consider the “reaction” below which details the formation of one s’more from its components:
2 graham crackers + 1 marshmallow + 4 chocolate squares  1 s’more
Using the quantities needed to make one s’more, given in the above reaction, complete the following table:
Given:
How Many?
1
6 graham crackers
marshmallows
2
6 graham crackers
chocolate squares
3
6 graham crackers
s’mores
4
2 marshmallows
chocolate squares
5
2 marshmallows
s’mores
6
2 chocolate squares
marshmallows
7
2 chocolate squares
graham crackers
8
2 chocolate squares
s’mores
9
4 s’mores
marshmallows
10
4 smore’s
chocolate squares
Work:
Answer:
Ch. 9: In-Class Notes
1.
Define stoichiometry –
2. Interpreting Chemical Equations:

Write a balanced chemical equation for the reaction of nitrogen gas with hydrogen gas to
produce ammonia gas (NH3).

Based on the balanced reaction above, fill in the table below:
N2 (g)
H2 (g)
# of Moles
Mass (g)
3. What are molar ratios?
4. Using the reaction above, what is the molar ratio between the following:

nitrogen gas and hydrogen gas? ______ : ______

nitrogen gas and ammonia? ______ : ______

hydrogen gas and ammonia? ______ : ______
NH3 (g)
Ch. 9: In-Class Notes Continued – Stoichiometric Calculations
Use the following balanced equation to answer the calculations below:
N2 (g) + 3 H2 (g)  2 NH3 (g)
1. Mole  Mole Calculations:
Example Problem: If 2.7 moles of hydrogen react with nitrogen, how many moles of ammonia
(NH3) are produced?
2. Mole  Mass Calculations:
Example Problem: If 6.5 moles of nitrogen react with hydrogen, how many grams of ammonia are
produced?
3. Mass  Mole Calculations
Example Problem: How many moles of hydrogen are needed to produce 150 grams of ammonia?
4. Mass  Mass Calculations
Example Problem: Calculate the number of grams of ammonia produced by the reaction of 5.4
grams of hydrogen with an excess of nitrogen.
Ch. 9: In-Class Notes Continued – Stoichiometric Calculations
Use the following balanced equation to answer the calculations below:
N2 (g) + 3 H2 (g)  2 NH3 (g)
5. Define Limiting Reactant-
Define Excess Reactant-
Example Problem: Suppose that 3.5 moles of nitrogen react with 5.5 moles of hydrogen. What
would be the limiting reactant? What would be the excess reactant? How many grams of
ammonia would be produced?
6. Define Theoretical Yield-
Define Actual Yield-
Give Percent Yield Formula-
Example Problem (EASY): My theoretical yield of ammonia was 36 grams, but my actual yield of
ammonia in the lab was only 27.5 grams. What is my percent yield?
Example Problem (HARD):
a) If I begin a reaction with 12 grams of hydrogen, what is my theoretical yield of ammonia?
b) What is my percent yield if 53 grams of ammonia were actually produced in the lab?
Homework
Mole  Mole Conversions
1. Potassium reacts with water to produce potassium hydroxide and hydrogen gas.
a. Write a balanced formula equation for this reaction, including symbols to describe the state of the
reactants and products.
b. What is the mole ratio of the reactants and products in this balanced equation?
c. How many moles of potassium hydroxide are produced from 3 moles of hydrogen gas?
d. How many moles of water are required to produce 7 moles of potassium hydroxide?
2. Aqueous hydrogen peroxide (H2O2) decomposes to produce water and oxygen gas.
a.
Write a balanced equation for this reaction (remember your diatomics!).
b. Determine the mole ratio of the reactant and products.
c. How many moles of oxygen gas are produced when 13.5 moles of hydrogen peroxide
decomposes?
d. How many moles of hydrogen peroxide are required to produce 4.8 moles of oxygen gas?
Mole  Mole Conversions
Homework
In the space provided below each question, solve the following problems based on the balanced
chemical equation below. Show all work, units and labels. Circle your answer.
N2 (g) + 3 H2 (g)  2 NH3 (g)
1) How many moles of ammonia are produced when 7.0 moles of nitrogen react with hydrogen gas?
2) How many moles of ammonia are produced when 6.0 moles of hydrogen gas react with nitrogen
gas?
3) How many moles of ammonia are produced when 0.60 moles of nitrogen gas react with hydrogen
gas?
4) How many moles of nitrogen gas would I need to produce 10.0 moles of ammonia?
5) How many moles of hydrogen gas would I need to produce 5.5 moles of ammonia?
MoleMass Calculations
Homework
Multiple Choice: Show your dimensional analysis in the space provided and circle your final answer.
1)
Given the balanced equation:
2 NO2 (g)  N2O4 (g)
What mass, in grams, of N2O4 is produced when 10 moles of NO2 is consumed?
a) 153
2)
b) 690
c) 368
Given the balanced equation:
d) 460
e) 1150
ZnSO4 (aq) + SrCl2 (aq)  SrSO4 (s) + ZnCl2 (aq)
What number of moles of SrCl2 is consumed when 54 g ZnCl2 is produced?
a) 0.16
3)
b) 0.3
c) 0.79
Given the balanced equation:
d) 1.58
e) 0.4
Pb(NO3)2 (aq) + K2CrO4 (aq)  PbCrO4 (s) + 2 KNO3 (aq)
What number of moles of Pb(NO3)2 is consumed when 54 g KNO3 is produced?
a) 0.13
4)
b) 0.18
c) 0.27
Given the balanced equation:
d) 1.34
e) 0.67
2 C8H18 (l) + 25 O2 (g)  16 CO2 (g) + 18 H2O (l)
What number of moles of CO2 is produced when 60 grams of C8H18 is consumed?
a) 3.37
b) 7.02
c) 5.26
d) 2.11
e) 4.21
MoleMass Calculations
Homework
In the space provided below each question, solve the following problems based on the balanced
chemical equation below. Show all work, units and labels. Circle your answer.
3 Mg(NO3)2 (aq) + 2 Cr (s)  2 Cr(NO3)3 (aq) + 3 Mg (s)
1) Calculate the molar masses of each compound in the equation so you may refer to them as needed.
Mg(NO3)2 = _________________________
Cr = ________________________
Cr(NO3)3 = _________________________
Mg = ________________________
2) How many grams of magnesium metal are produced if 1.8 moles of magnesium nitrate are used in
the reaction?
3) How many moles of chromium metal are required to produce 167.6 grams of chromium (III) nitrate?
4) How many moles of magnesium nitrate would be needed to react with 39.0 grams of chromium
metal?
5) If 4.6 moles of magnesium metal were produced by the reaction, how many grams of chromium (III)
nitrate were also produced?
6) Calculate the number of moles of chromium (III) nitrate needed to produce 91.5 grams of
magnesium nitrate.
MassMass Calculations
Homework
Multiple Choice: Show your set-up in the space provided and circle the answer of your choice.
2 AlI3 (aq) + 3 HgCl2 (aq)  2 AlCl3 (aq) + 3 HgI2 (s)
1) Given the balanced equation:
What mass, in grams, of AlI3 is consumed when 46 grams of HgI2 is produced?
a)
2)
27.5
b) 6.9
c) 137.6
Given the balanced equation:
d) 82.5
e) 68.8
CaBr2 (aq) + 2 KOH (aq)  Ca(OH)2 (aq) + 2 KBr (aq)
What mass, in grams, of CaBr2 is consumed when 96 grams of Ca(OH)2 is produced?
a)
3)
173
b) 52
c) 86
Given the balanced equation:
d) 155
e) 259
3 H2 (g) + N2 (g)  2 NH3 (g)
What mass, in grams, of NH3 is produced when 77 g of N2 is consumed?
a)
4)
187
b) 31.2
c) 18.7
Given the balanced equation:
d) 46.8
e) 93.5
3 AgNO3 (aq) + K3PO4 (aq)  Ag3PO4 (s) + 3 KNO3 (aq)
What mass, in grams, of Ag3PO4 is produced when 19 g of K3PO4 is consumed?
a)
46.8
b) 15
c) 37.5
d) 18.7
e) 112.4
Homework
MassMass Calculations
In the space provided below each question, solve the following problems based on the balanced
chemical equations below. Show all work, units and labels. Circle your answer.
1) LiOH (aq) + HBr (aq)  LiBr (aq) + H2O (l)
If you start with 15 grams of lithium hydroxide, how many grams of lithium bromide will be produced?
2) C2H4 (l) + 3 O2 (g)  2 CO2 (g) + 2 H2O (g)
If you start with 32 grams of ethylene (C2H4), how many grams of carbon dioxide will be produced?
3) 2 HCl (aq) + Na2SO4 (aq)  2 NaCl (aq) + H2SO4 (aq)
If you start with 28 grams of hydrochloric acid, how many grams of sulfuric acid will be produced?
4) 2 LiCl (aq) + CaCO3 (s)  Li2CO3 (aq) + CaCl2 (aq)
If you start with 6.5 grams of lithium chloride, how many grams of calcium chloride will be produced?
Stoichiometric Calculations - Practice #1
Use the balanced equation below to complete the following stoichiometric calculations.
4 NH3 (aq) + 3 O2 (g)  2 N2 (g) + 6 H2O (l)
1) Calculate the molar masses of each compound in the equation so you may refer to them as needed.
NH3 = _________________________
N2 = ________________________
O2 = _________________________
H2O = ________________________
2) How many moles of water are produced from 6.23 moles of oxygen gas?
3) How many grams of ammonia (NH3) are needed to produce 2.75 moles of nitrogen gas?
4) How many moles of nitrogen gas are produced from 51.8 grams of oxygen gas?
5) How many grams of oxygen gas are needed to produce 48.3 grams of water?
Stoichiometric Calculations - Practice #2
Use the balanced equation below to complete the following stoichiometric calculations.
C2H4 (l) + 3 O2 (g)  2 CO2 (g) + 2 H2O (l)
1) Calculate the molar masses of each compound in the equation so you may refer to them as needed.
C2H4 = _________________________
O2 = ________________________
CO2 = _________________________
H2O = ________________________
2) How many moles of carbon dioxide are produced from 9.14 moles of oxygen gas?
3) How many moles of ethylene (C2H4) are needed to produce 28.2 grams of water?
4) How many grams of oxygen gas are needed to produce 3.35 moles of water?
5) How many grams of ethylene (C2H4) are needed to produce 18.6 grams of carbon dioxide (CO2)?
Homework
Limiting& Excess Reactants
Use the balanced equation below to complete the following problems.
N2 (g) + 3 H2 (g)  2 NH3 (g)
1) Suppose that 2 moles of nitrogen gas react with 3 moles of hydrogen gas. What is the limiting
reactant? What is the excess reactant? How many moles of ammonia (NH3) would be produced?
2) Suppose that 7.5 moles of nitrogen gas react with 25 moles of hydrogen gas. What is the limiting
reactant? What is the excess reactant? How many grams of ammonia (NH3) would be produced?
3) Suppose that 26 grams of nitrogen gas react with 26 grams of oxygen gas. What would be the
limiting reagent? What would be the excess reagent? How many grams of nitrogen gas (N2) would
be produced?
Homework
Limiting & Excess Reactants
Use the balanced equation below to complete the following problems.
4 NH3 (g) + 3 O2 (g)  2 N2 (g) + 6 H2O (l)
4) Suppose that 1.5 moles of ammonia (NH3) react with 2.2 moles of oxygen gas. What would be the
limiting reagent? What would be the excess reagent? How many moles of water would be
produced?
5) Suppose that 0.75 moles of ammonia (NH3) react with 0.33 moles of oxygen gas. What would be
the limiting reagent? What would be the excess reagent? How many grams of water would be
produced?
6) Suppose that 3.16 grams of ammonia (NH3) react with 6.5 grams of hydrogen gas (H2). What would
be the limiting reagent? What would be the excess reagent? How many grams of ammonia (NH3)
would be produced?
Homework
1)
Actual, Theoretical, & Percent Yield
LiOH (aq) + KCl (aq)  LiCl (aq) + KOH (aq)
a) I began this reaction with 20 grams of lithium hydroxide. What is my theoretical yield of lithium
chloride?
b) I actually produced 6 grams of lithium chloride. What is my percent yield?
2)
C3H8 (l) + 5 O2 (g)  3 CO2 (g) + 4 H2O (g)
a) If I start with 5 grams of C3H8, what is my theoretical yield of water?
b) I got a percent yield of 75%. How many grams of water did I actually make in the lab?
3)
Be (s) + 2 HCl (aq)  BeCl2 (aq) + H2 (g)
a) My theoretical yield of beryllium chloride (BeCl2) was 10.7 grams. If my actual yield was 4.5
grams, what was my percent yield? (Hint – this is an easy problem)
Homework
1)
Actual, Theoretical, & Percent Yield
2 NaCl (aq) + CaO (s)  CaCl2 (aq) + Na2O (s)
a) What is my theoretical yield of sodium oxide if I start with 20 grams of calcium oxide?
b) Some of my product spills, and I only produce 10.6 grams of sodium oxide. What is my percent
yield?
2)
FeBr2 (aq) + 2 KCl (aq)  FeCl2 (aq) + 2 KBr (aq)
a) What is my theoretical yield of iron (II) chloride if I start with 34 grams of iron (II) bromide?
b) What is my percent yield of iron (II) chloride (FeCl2) if my actual yield is 4 grams?
3)
TiS (s) + H2O (l)  H2S (g) + TiO (s)
a) My theoretical yield of titanium (II) oxide was 22 grams. If my percent yield was 89.5%, what was
my actual yield of titanium (II) oxide produced in the lab? (Hint- this is an easy problem)
Homework
Actual, Theoretical, & Percent Yield
4) U (s) + 3 Br2 (g)  UBr6 (aq)
a) If I start with 100 grams of uranium, what is my theoretical yield of uranium hexabromide?
b) What is my percent yield of uranium hexabromide if my actual yield of 250.2 grams?
5)
H2SO4 (aq)  H2O (l) + SO3 (g)
a) If I start with 89.0 grams of sulfuric acid, what is my theoretical yield of water?
b) If my percent yield of water is 43.6%, what is my actual yield of water in the lab?
Chapter 9: Vocabulary Review
Matching: Match the correct vocabulary term to each numbered statement. Write the letter of the correct
term on the line provided.
Column A
Column B
_______ 1. the starting materials in an equation
a. a mole
_______ 2. the amount of substances in grams or
moles
b. stoichiometry
_______ 3. the maximum amount of product that
could be formed in a reaction
c. mass-mass calculations
_______ 4. Avogadro’s number of particles
d. reactants
_______ 5. the substance being used up in a
chemical reaction
_______ 6. the ratio of how much product is
produced compared to how much is
expected
e. excess reagent
f.
theoretical yield
_______ 7. the calculations of quantities in a
chemical reaction
g. limiting reagent
_______ 8. the actual amount of product in a
chemical reaction
h. quantity
_______ 9. the substance left over after a
chemical reaction takes place
i.
actual yield
_______ 10. determining the mass of products
from the given mass of reactants
j.
percent yield
Stoichiometry Review Problems for Chapter 9 Test
Complete the following 6 problems. Be sure to show your work and include units.
Balance the following equation and then use for #1 & #2:
____ Al2O3(aq) + ____ HNO3(aq)  ____ Al(NO3)3(aq) + ____ H2O(l)
1)
How many moles of water are formed when 6.50 moles of aluminum oxide react with nitric acid?
2) How many grams of nitric acid are needed to produce 4.67 moles of aluminum nitrate?
Balance the following equation and then use for #3 & #4.
____ Na2SO4 (aq) + ____ FeCl3 (aq)  ____ Fe2(SO4)3 (aq) + ____ NaCl (aq)
3) How many grams of sodium chloride are produced when 367.8 grams of sodium sulfate react with
iron (III) chloride?
4) Suppose that 8.4 moles of sodium sulfate reacted with 7.6 moles of iron (III) chloride, what would be
the limiting reagent? The excess reagent? How many grams of iron (III) sulfate would be
produced?
Use the following balanced equation to complete #5 & #6:
2 AlPO4(aq) + 3 FeCl2(aq)  Fe3(PO4)2(s) + 2 AlCl3(aq)
5) If I make 32.4 grams of aluminum chloride during a lab in which I should have made 38.5 grams of
aluminum chloride, what is my percent yield?
6) I start my reaction with 480.5 grams of iron (II) chloride.
a) What is my theoretical yield of iron (II) phosphate?
b) In the lab, I actually produced 425.35 grams of iron (II) phosphate. What is my percent yield?