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Name ___________________________
15.2
Date ___________________
Class __________________
HOMOGENEOUS AQUEOUS SYSTEMS
Section Review
Objectives
•
•
•
•
Distinguish between a solvent and a solute
Describe what happens in the solution process
Explain why all ionic compounds are electrolytes
Demonstrate how to write the formula for a hydrate
Vocabulary
• aqueous solution
• solvent
• solute
• solvation
• electrolyte
• nonelectrolyte
• strong electrolyte
• weak electrolyte
• hydrate
Key Equation
mass of water
• Percent H2O ! ##
" 100%
mass of hydrate
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Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
Water is a polar liquid and an excellent
substances. Aqueous solutions are
2
1
for many
mixtures of ions or
molecules in water. The solubility of a solute depends on solutesolvent interactions. A good rule to remember is
3
solute that is completely ionized in solution is a
electrolyte. A weak electrolyte is only
7
of an electrolyte will
solution of a
8
.A
5
ionized. A solution
an electric current, whereas a
9
10
3.
5.
6.
7.
8.
9.
is nonconducting.
Many crystals are
In the process called
6
2.
4.
.
4
Substances that dissolve as ions are known as
1.
; they contain water of hydration.
10.
, the water of hydration is lost from a
hydrate that is exposed to air.
Chapter 15 Water and Aqueous Systems
379
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Date ___________________
Class __________________
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 11. Carbon tetrafluoride is a nonelectrolyte.
________ 12. Hydrates are crystals that contain a fixed quantity of water within their
structure.
________ 13. Covalent solutes are very soluble in water.
________ 14. Solutions are always homogeneous.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
a. the dissolved particles in a solution
________ 16. solute
b. compounds that conduct electric current in aqueous
solution
________ 17. solvation
c. compounds able to remove moisture from air
________ 18. electrolyte
d. water samples containing dissolved substances
________ 19. nonelectrolytes
e. drying agents
________ 20. hydrate
f. compounds that do not conduct electric current in
aqueous solution
________ 21. hygroscopic
g. a compound that contains water of hydration
________ 22. dessicants
h. process that occurs when a solute dissolves
Part D Questions and Problems
Answer the following questions or solve the following problems in the space provided.
Show your work.
23. Calculate the percent by mass of water in Glauber’s salt (Na2SO4p10H2O).
24. Which of the following substances dissolves to a significant extent in water?
380
a. C6H6
c. Na2SO4
b. NaCl
d. N2
Core Teaching Resources
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________ 15. aqueous solutions
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Name ___________________________
Date ___________________
Class __________________
PROPERTIES OF SOLUTIONS
16.1
Section Review
Objectives
•
•
•
•
Identify the factors that determine the rate at which a solute dissolves
Identify the units usually used to express the solubility of a solute
Calculate the solubility of a gas in a liquid under various pressure conditions
Identify the factors that determine the mass of solute that will dissolve in a given
mass of a solvent
Vocabulary
• saturated solution
• solubility
• unsaturated solution
• miscible
• immiscible
• supersaturated solution
• Henry’s law
Key Equation
S
P1
S
P2
• Henry’s law: !!1 " !!2
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Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
solute alter the
2
1
of a
1.
at which a solute dissolves. The extent
2.
Changes in the temperature of a system and
to which a gas dissolves in a liquid is proportional to the
4
of the gas in accordance with
5
3
law. The solubility of a gas
3.
4.
. A solution that contains the
5.
maximum amount of solute at a given temperature is said to be
6.
decreases with increasing
6
. Two liquids that are mutually soluble in each other are
said to be
7
. Generally the
8
of a solid in water
9
with increasing temperature, but there are exceptions. A(n)
10
solution holds more solute than is theoretically possible.
7.
8.
9.
10.
Chapter 16 Solutions
399
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Name ___________________________
Date ___________________
Class __________________
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 11. The rate at which a solute dissolves can be increased by grinding.
________ 12. As the temperature of a solvent decreases, the solubility of a solute
increases.
________ 13. Stirring a solute when adding it to a solvent should increase the rate of
its dissolving.
________ 14. Henry’s law states that the solubility of a gas in a liquid is a function of
temperature.
________ 15. Two liquids that dissolve in each other are miscible.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
a. the amount of a substance that dissolves in a given quantity
of solvent at a given temperature
________ 17. solubility
b. The solubility of a gas in a liquid is directly proportional to
the pressure of the gas above the liquid.
________ 18. unsaturated
solution
c. solution that contains the maximum amount of solute for a
given amount of solvent at a constant temperature
________ 19. miscible
d. a solution containing more solute than it can theoretically
hold at a given temperature
________ 20. immiscible
e. description of two liquids that dissolve in each other
________ 21. supersaturated
solution
f. a solution that contains less solute than possible at a given
temperature
________ 22. Henry’s law
g. description of two liquids that do not dissolve in each other
Part D Problem
Solve the following problem in the space provided. Show your work.
23. The solubility of a gas in water is 1.6 g/L at 1.0 atm of pressure. What is the
solubility of the same gas at 2.5 atm? Assume the temperature to be constant.
400
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________ 16. saturated solution
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Name ___________________________
16.2
Date ___________________
Class __________________
CONCENTRATIONS OF SOLUTIONS
Section Review
Objectives
• Solve problems involving the molarity of a solution
• Describe the effect of dilution on the total moles of solute in solution
• Define what is meant by percent by volume [%(v/v)] and percent by mass
[%(m/m)]
Vocabulary
• concentration
• dilute solution
• concentrated solution
• molarity (M)
Key Equations
moles of solute
liters of solution
M1 # V1 ! M2 # V2
• Molarity (M) ! ""
•
• Percent by volume [%(v/v)] !
volume of solute
""" # 100%
volume of solution
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mass of solute
• Percent by mass [%(m/m)] ! ""
# 100%
mass of solution
Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
The relative amounts of solute and
3
be described qualitatively as
1
2
in a
can
or concentrated. Quantitative
1.
2.
units of concentration include molar concentration, percent by
3.
volume, and percent by mass.
4.
5.
Molarity, the most important unit of concentration in
chemistry, is expressed as
4
of solute per
5
of solution. 6.
Solutions of different concentrations can be prepared by
6
a stock solution. In dilution, the moles of
the same, while the amount of
8
7
remain
7.
8.
changes.
Chapter 16 Solutions
401
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Date ___________________
Class __________________
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 9. One hundred mL of 1.0M sodium hydroxide solution is more
concentrated than 1.0 L of 5M sodium hydroxide solution.
________ 10. The amount of sodium hydroxide in 100 mL of 1.0M NaOH is less than
that in 1.0 L of 5M NaOH solution.
________ 11. Fifty mL of a 32% solution (v/v) of ethyl alcohol in water would
contain 42 mL of water.
________ 12. A dilute solution is a quantitative expression of concentration.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
a. number of moles of solute dissolved in 1 L of solution
________ 14. dilute solution
b. measure of the amount of solute that is dissolved in a
given quantity of solvent
________ 15. concentrated solution
c. solution that contains a low concentration of solute
________ 16. molarity
d. concentration expressed as volume of solute over
volume of solution ! 100%
________ 17. percent solution
e. solution that contains a high concentration of solute
Part D Problem
Solve the following problem in the space provided. Show your work.
18. What mass of sucrose, C12H22O11, is needed to make 300.0 mL of a
0.50M solution?
402
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________ 13. concentration
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Name ___________________________
Date ___________________
Class __________________
COLLIGATIVE PROPERTIES OF SOLUTIONS
16.3
Section Review
Objectives
• Identify the three colligative properties of solutions
• Describe why the vapor pressure, freezing point, and boiling point of a solution
differ from those properties of the pure solvent.
Vocabulary
• colligative properties
• freezing-point depression
• boiling-point elevation
Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
In a solution, the effects of a nonvolatile
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properties of the solvent are called
point and vapor pressure
4
2
1
3
2.
. In
3.
proportional to
4.
. They include
, and boiling point
each case, the magnitude of the effect is
6
1.
on the
5
the number of solute molecules or ions present in the
7
.
Colligative properties are a function of the number of solute
8
in solution. For example, one mole of sodium chloride
produces
9
as many particles in solution as one mole of
sucrose and, thus, will depress the freezing point of water
as much.
10
5.
6.
7.
8.
9.
10.
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 11. When added to 1000 g of water, 2 moles of a solute will increase the
boiling point by 0.512!C.
________ 12. One mole of solute A will depress the freezing point of 1000 g of water
the same as one mole of solute B.
Chapter 16 Solutions
403
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Name ___________________________
Date ___________________
Class __________________
________ 13. Addition of a nonvolatile solute will lower the boiling point of a
solvent.
________ 14. Addition of a nonvolatile solute will lower the freezing point of a solvent.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
________ 15. colligative properties
a. difference between the freezing point of a solution
and the freezing point of the pure solvent
________ 16. freezing-point depression
b. pressure exerted by a vapor that is in equilibrium
with its liquid in a closed system
________ 17. boiling-point elevation
c. difference between the boiling point of a solution
and the boiling point of the pure solvent
________ 18. vapor pressure
d. properties of solutions that depend only on the
number of particles in solution
Part D Questions and Problems
Answer the following questions in the space provided.
19. How many moles of solute particles are produced by adding one mole of each
of the following to water?
b. glucose
c. aluminum chloride
d. potassium iodide
20. An equal number of moles of NaCl and K2CO3 are dissolved in equal volumes of
water. Which solution has the higher
a. boiling point?
b. vapor pressure?
c. freezing point?
404
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a. sodium nitrate
05_CTR_ch16 7/12/04 8:14 AM Page 405
Name ___________________________
Date ___________________
Class __________________
CALCULATIONS INVOLVING
16.4 COLLIGATIVE PROPERTIES
Section Review
Objectives
• Calculate the molality and mole fraction of a solution
• Describe how the freezing-point depression and boiling-point elevation are
related to molality
Vocabulary
• molality (m)
• mole fraction
• molal freezing-point
• molal boiling-point
depression constant (Kf)
elevation constant (Kb)
Key Equations
moles of solute
kilogram of solvent
• Molality ! """
n
nB
A
• mole fractions: XA ! "
n #"
n
A
XB ! "
n #"
n
B
A
B
where nA ! moles of solute
nB ! moles of solvent
© Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved.
• $Tb ! Kb % m
• $Tf ! Kf % m
Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
Molality is an expression of concentration involving the ratio
1
of
2
particles to
moles of solute per
3
particles. Molality is expressed as
1.
2.
3.
of solvent.
Another expression of concentration is
4
, in which
4.
concentrations are expressed as the ratio of moles of solute to the
5.
total number of moles of solvent and solute. Each solvent has a
6.
characteristic
6
5
elevation constant and molal freezing-point
constant. The elevation in boiling point of a solution can
7
be calculated by multiplying the
solution by the boiling-point
8
7.
8.
concentration of the
constant of the solvent.
Chapter 16 Solutions
405
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Date ___________________
Class __________________
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 9. It is possible to calculate the molar mass of a solute if you know the
Kb or Kf of a solvent.
________ 10. Molal concentration is the same as molar concentration.
________ 11. The depression in freezing point of a solution is proportional to the
molal concentration of solute.
________ 12. The sum of XA and XB for any solution is always 1.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
a. a constant for a given solvent equal to the change in
boiling point for a 1m solution
________ 14. mole fraction
b. number of moles of solute dissolved in 1 kilogram of
solvent
________ 15. molal freezing-point
depression constant
c. mass of one mole of a substance
________ 16. molal boiling-point
elevation constant
d. a constant for a given solvent equal to the change in
freezing point for a 1m solution
________ 17. molar mass
e. ratio of moles of solute in solution to the total number
of moles of solute and solvent
Part D Problem
Solve the following problem in the space provided. Show your work.
18. What is the freezing point of a solution that contains 2.0 mol of CaCl2 in 800.0 g
of water? Kf for water ! 1.86"C/m
406
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________ 13. molality
05_CTR_ch16 7/12/04 8:14 AM Page 407
Name ___________________________
16
Date ___________________
Class __________________
SOLUTIONS
Practice Problems
In your notebook, solve the following problems.
SECTION 16.1 PROPERTIES OF SOLUTIONS
1. The solubility of CO2 in water at 1.22 atm is 0.54 g/L. What is the solubility of
carbon dioxide at 1.86 atm? Assume that temperature is constant.
2. What mass of KCl will produce a saturated solution in 500.0 g of water at 20!C?
The solubility of KCl at 20°C is 34.0 g/100 g H2O.
3. A saturated solution of silver nitrate is prepared in 100.0 g of water at 20!C. The
solution is then heated to 50.0!C. How much more silver nitrate must now be
added to obtain a saturated solution? (Use Table 16.1.)
SECTION 16.2 CONCENTRATIONS OF SOLUTIONS
1. Calculate the molarity of each of the following solutions.
a. 0.40 mol of NaCl dissolved in 1.6 L of solution
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b. 20.2 g of potassium nitrate, KNO3, in enough water to make 250.0 mL of
solution
2. Calculate the number of grams of solute needed to prepare each of the
following solutions.
a. 2500.0 mL of a 3.0M solution of potassium hydroxide, KOH
b. 2.0 liters of 2.0M nitric acid, HNO3, solution
3. What is the molarity of a solution that contains 212.5 g of sodium nitrate
(NaNO3) in 3.0 liters of solution?
4. You must prepare 300.0 mL of 0.750M NaBr solution using 2.00M NaBr stock
solution. How many milliliters of stock solution should you use?
5. In order to dilute 1.0 L of a 6.00M solution of NaOH to 0.500M solution, how
much water must you add?
6. What is the concentration in percent by volume, %(v/v), of the following
solutions?
a. 60.0 mL of methanol in a total volume of 500.0 mL
b. 25.0 mL of rubbing alcohol (C3H7OH) diluted to a volume of 200.0 mL
with water
7. How many grams of solute are needed to prepare each of the following
solutions?
a. 1.00 L of a 3.00% (m/m) NaCl solution?
b. 2.00 L of 5.00% (m/m) KNO3 solution?
Chapter 16 Solutions
407
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Date ___________________
Class __________________
SECTION 16.3 COLLIGATIVE PROPERTIES OF SOLUTIONS
1. What are colligative properties of solutions? Give examples of three colligative
properties.
2. How many particles in solution are produced by each formula unit of potassium
carbonate, K2CO3?
3. How may moles of particles would 3 mol Na2SO4 give in solution?
4. What is the boiling point of a solution that contains 2 mol of magnesium
chloride in 100.0 g of water?
5. What kind of property is vapor-pressure lowering?
6. An equal number of moles of NaCl and CaCl2 are dissolved in equal volumes of
water. Which solution has the lower
a. freezing point?
b. vapor pressure?
c. boiling point?
SECTION 16.4 CALCULATIONS INVOLVING COLLIGATIVE
PROPERTIES
1. Calculate the mole fraction of solute in each of the following solutions.
a. 3.0 moles of lithium bromide, LiBr, dissolved in 6.0 moles of water
b. 125.0 g of potassium nitrate, KNO3, dissolved in 800.0 g of water
2. How many grams of sodium chloride must dissolve in 750.0 g of water to make
a 0.50 molal solution?
4. Find the molality of each of the following solutions.
a. 2.3 moles of glucose dissolved in 500.0 g of water
b. 131 g of Ba(NO3)2 dissolved in 750.0 g of water
5. Find the boiling points of the following solutions.
a. 2.00m solution of sodium chloride, NaCl
b. 1.50m solution of calcium chloride, CaCl2
6. Find the freezing points of the following solutions.
a. 0.35 moles of sodium chloride, NaCl, dissolved in 900.0 g of water
b. 126.0 g of table sugar, C12H22O11, dissolved in 2500.0 g of water
408
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3. How many grams of lithium sulfide must be dissolved in 1600.0 g of water to
make a 2.0 molal solution?
05_CTR_ch18 7/12/04 8:16 AM Page 457
Name ___________________________
18.1
Date ___________________
Class __________________
RATES OF REACTION
Section Review
Objectives
• Describe how to express the rate of a chemical reaction
• Identify four factors that influence the rate of a chemical reaction
Vocabulary
• rate
• collision theory
• activation energy
• activated complex
• transition state
• inhibitor
Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
1
measure the speed of any change that occurs within
2
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a time interval. Collision theory states that particles
they collide, provided that they have enough
3
when
4
7
higher the activation energy barrier, the
6
5.
. The
6.
7.
the reaction.
8.
Chemists help reactants overcome the activation barrier in a
8
9.
. Rates of reaction
10.
number of ways. Two effective methods are to increase the
at which the reaction is done or use a
can also be increased by
10
9
4.
5
energy barrier. The activation energy is the
energy that reactants must have to be converted to
2.
3.
.
The rate at which a chemical reaction occurs is determined
by an
1.
the concentration of reactants.
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 11. An increase in temperature will increase the rate of a reaction.
Chapter 18 Reaction Rates and Equilibrium
457
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Name ___________________________
Date ___________________
Class __________________
________ 12. A catalyst is considered as a reactant in a chemical reaction.
________ 13. The speed of a reaction can be increased by increasing reactant
concentration or decreasing particle size.
________ 14. An enzyme is a biological catalyst.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
________ 15. rate
a. synonym for an activated complex
________ 16. collision theory
b. speed of a change that occurs over time
________ 17. activation energy
c. substance that interferes with the action of a catalyst
________ 18. transition state
d. Particles can react to form products when they
collide, provided they have enough kinetic energy.
________ 19. activated complex
e. an unstable arrangement of atoms that forms
momentarily at the peak of the activation energy
barrier
________ 20. inhibitor
f. minimum energy that particles must have in order
to react
Answer the following question and solve the following problem in the space provided.
21. An ice machine can produce 120 kg of ice in 24 hours. Express the rate of ice
production in kg/h.
22. Which of the following will increase the rate of a reaction?
a. increase particle size
b. increase temperature
c. decrease concentration
d. add a catalyst
458
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Part D Questions and Problems
05_CTR_ch18 7/12/04 8:16 AM Page 459
Name ___________________________
Date ___________________
Class __________________
REVERSIBLE REACTIONS AND
18.2 EQUILIBRIUM
Section Review
Objectives
• Describe how the amounts of reactants and products change in a chemical
system at equilibrium
• Identify three stresses that can change the equilibrium position of a chemical
system
• Explain what the value of Keq indicates about the position of equilibrium
Vocabulary
• reversible reaction
• chemical equilibrium
• equilibrium position
• Le Châtelier’s principle
• equilibrium constant (Keq)
Key Equation
[C]c # [D]d
[A] # [B]
When aA $ bB 1 cC $ dD
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• Keq ! "
a "
b
Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
In principle, all reactions are
2
in the
5
the
3
1
. That is, reactants go to
direction, and products go to
4
in
1.
2.
3.
direction.
8
6
to
4.
position. The
5.
The point at which the rate of conversion of
7
and vice versa is equal is the
9
of a reversible reaction, Keq, is useful for determining the
position of equilibrium. It is essentially a measure of the
10
6.
7.
of products to reactants at equilibrium. The direction of change in
8.
the position of equilibrium may be predicted by applying
9.
11
principle.
10.
11.
Chapter 18 Reaction Rates and Equilibrium
459
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Name ___________________________
Date ___________________
Class __________________
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 12. The concentrations of reactants and products in a system at dynamic
equilibrium are always changing.
________ 13. A change in the pressure on a system can cause a shift in the
equilibrium position.
________ 14. For a chemical equilibrium to be established, the chemical reaction
must be irreversible.
________ 15. The Keq for a certain reaction was 2 ! 10"7. For this reaction at
equilibrium, the concentration of the reactants is greater than the
concentration of the products.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
a. state of balance in which forward and reverse
reactions take place at the same rate
________ 17. chemical equilibrium
b. relative concentrations of reactants and products of a
reaction that has reached equilibrium
________ 18. equilibrium position
c. When stress is applied to a system at equilibrium, the
system changes to relieve the stress.
________ 19. Le Châtelier’s principle
d. reaction in which conversion of reactants to products
and products to reactants occur simultaneously
________ 20. equilibrium constant
e. ratio of product concentrations to reactant
concentrations with each raised to a power given by
the number of moles of the substance in the balanced
equation
Part D Problem
Solve the following problem in the space provided. Show your work.
21.
460
2SO3(g) → 2SO2(g) # O2(g)
Calculate Keq for this reaction if the equilibrium concentrations are:
[SO2] $ 0.42M, [O2] $ 0.21M, [SO3] $ 0.072M
Core Teaching Resources
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________ 16. reversible reaction
05_CTR_ch18 7/12/04 8:16 AM Page 465
Name ___________________________
Date ___________________
Class __________________
THE PROGRESS OF CHEMICAL REACTIONS
18.5
Section Review
Objectives
• Describe the general relationship between the value of the specific rate constant,
k, and the speed of a chemical reaction
• Interpret the hills and valleys in a reaction progress curve
Vocabulary
• rate law
• specific rate constant
• first-order reaction
• elementary reaction
• reaction mechanism
• intermediate
Key Equation
• rate ! k[A]a[B]b
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Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
The
2
1
of a reaction is dependent in part on the
1.
of the reactants. An equation that relates reaction
3.
3
rate to reactant concentration is called a
.
5.
The power to which a reaction concentration is raised is called
6.
equation, k is known as the
the
4
4.
. In a rate law
5
7.
of the reaction in that reactant. A reaction whose rate
8.
is directly proportional to the concentration of one reactant is
called a
6
two reactants is
determined by
9.
reaction. A reaction that is first order for each of
7
8
overall. The actual order of a reaction is
10.
.
A single-step reaction is called an
reactions combine to form the
10
9
. A series of elementary
of a complex reaction.
Chapter 18 Reaction Rates and Equilibrium
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Name ___________________________
Date ___________________
Class __________________
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 11. The rate order of a reaction can be determined from the balanced
equation.
________ 12. There is at least one intermediate product in a chemical reaction.
________ 13. There is at least one activated complex in a chemical reaction.
________ 14. An elementary reaction is a one-step reaction.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
a. a single-step reaction
________ 16. specific rate constant
b. reaction in which the rate is directly proportional to
the concentration of one reactant
________ 17. first-order reaction
c. a product of a reaction that becomes a reactant in
another step of the reaction
________ 18. elementary reaction
d. expression relating the rate of a reaction to the
concentration of the reactants
________ 19. reaction mechanism
e. series of elementary reactions that take place during
a complex reaction
________ 20. intermediate
f. proportionality constant relating the concentrations
of reactants to the reaction rate
Part D Question
Answer the following question in the space provided.
21. Below is the reaction progress curve for a complex reaction. Describe the
reaction represented by the curve (number of steps and the significance of
points A, B, C, and D).
A
C
Energy
B
D
Reaction Progress
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Core Teaching Resources
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________ 15. rate law
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Name ___________________________
18
Date ___________________
Class __________________
REACTION RATES AND EQUILIBRIUM
Practice Problems
In your notebook, solve the following problems.
SECTION 18.1 RATES OF REACTION
1. List three ways that reaction rates can generally be increased.
2. Ethyl acetate (C4H8O2) reacts with a solution of sodium hydroxide (NaOH) in
water to form sodium acetate (C2H3O2Na) and ethyl alcohol (C2H6O). Suppose
at 25°C two moles of ethyl acetate react completely in four hours. How would
you express the rate of reaction?
3. How would the following actions likely change the rate of the reaction in
problem 2?
a. the temperature is lowered to 4°C.
b. the concentration of sodium hydroxide in water is increased.
4. Ethyl acetate and water are not miscible; thus, the reaction in problem 2 only
occurs at the interface of the two liquids. What would be the effect on the
reaction rate of adding a solvent to make the reaction homogeneous?
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SECTION 18.2 REVERSIBLE REACTIONS AND EQUILIBRIUM
1. Write the expression for the equilibrium constant for this reaction:
2N2O5(g)1 4NO2(g) ! O2(g)
2. Calculate the equilibrium constant for the reaction in problem 1 if the
equilibrium concentrations are [N2O5] " 0.50 mol/L, [NO2] " 0.80 mol/L, [O2] "
0.20 mol/L.
3. How would the equilibrium position for the equation in problem 1 be affected
by
a. an addition of O2 to the reaction vessel?
b. a decrease in the pressure?
4. The equilibrium constant for the reaction of nitrogen dioxide to form dinitrogen
tetroxide is 5.6.
2NO2 (g) 1 N2O4 (g)
In a one-liter container, the amount of N2O4, at equilibrium, is 0.66 mol. What is
the equilibrium concentration of NO2?
5. Write the equilibrium constant expression for each of the following reactions.
a. 4NO(g) ! 2O2(g) 1 2N2O4 (g)
b. 2NO(g) ! Br2(g) 1 2NOBr(g)
c. CO(g) ! 2H2(g) 1 CH3OH(g)
d. SO2(g) ! NO2(g) 1 SO3(g) ! NO(g)
6. What effect would an increase in pressure have on the equilibrium position
of each reaction in problem 5?
Chapter 18 Reaction Rates and Equilibrium
467
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Name ___________________________
Date ___________________
Class __________________
7. Which value of Keq indicates most favorably for product formation,
Keq ! 1 " 1012, Keq ! 1.5, or Keq ! 5.6 " 10#4?
8. Hydrogen sulfide gas decomposes into its elements and establishes an
equilibrium at 1400 °C.
2H2S(g) 1 2H2(g) $ S2(g)
A liter of this gas mixture at equilibrium contains 0.18 mol H2S, 0.014 mol H2,
and 0.035 mol S2. Calculate the equilibrium constant, Keq, for this reaction.
SECTION 18.3 SOLUBILITY EQUILIBRIUM
1. Write the solubility product expression for a. Ca(OH)2 and b. Ag2CO3.
2. What is the concentration of silver ions in a saturated solution of silver carbonate?
The Ksp of Ag2CO3 is 8.1 " 10#12.
3. The equilibrium concentration of hydroxide ions in a saturated solution of iron(II)
hydroxide is 1.2 " 10#5M at a certain temperature. Calculate the Ksp of Fe(OH)2 at
this temperature.
4. Strontium carbonate has a Ksp ! 9.3 " 10#10 at 25%C. What is the concentration of
strontium ions in a saturated solution of SrCO3?
5. What is the equilibrium concentration of silver ions at 25%C in a 1.0-L saturated
solution of silver carbonate to which 0.20 mol of Na2CO3 has been added? The Ksp
of Ag2CO3 is 8.1 " 10#12 at 25%C.
6. Will a precipitate of PbSO4 form when 400.0 mL of 0.0050M MgSO4 is mixed with
600.0 mL of 0.0020M Pb(NO3)2? The Ksp of PbSO4 ! 6.3 " 10#7.
7. Will precipitation of CaCO3 occur when 500.0 mL of 4.2 " 10#3M CaCl2 is mixed
with 500.0 mL of 2.6 " 10#3M Na2CO3? The Ksp of CaCO3 is 4.5 " 10#9.
SECTION 18.4 ENTROPY AND FREE ENERGY
1. When gently warmed, the element iodine will sublime:
I2(s) → I2(g)
Is this process accompanied by an increase or decrease in entropy?
2. Does entropy increase or decrease when air is cooled and liquefied (changed
from a gas to a liquid)?
3. Is the degree of disorder increasing or decreasing in these reactions?
a. H2(g) $ Br2(l ) → 2HBr(g)
b. CuSO4 p 5H2O(s) → CuSO4(s) $ 5H2O(g)
c. 2XeO3(s) → 2Xe(g) $ 3O2(g)
4. Classify each of these systems as always spontaneous (A), never spontaneous
(N), or depends on the relative magnitude of the heat and entropy changes (D).
a. entropy decreases, heat is released
b. entropy decreases, heat is absorbed
c. entropy increases, heat is absorbed
d. entropy increases, heat is released
468
Core Teaching Resources
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8. Which of these compounds would not decrease the solubility of Mg(OH)2 when
added to a saturated solution of the compound?
NaOH, MgCl2, NaCl, KOH
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Name ___________________________
Date ___________________
Class __________________
SECTION 18.5 THE PROGRESS OF CHEMICAL REACTIONS
1. A first-order reaction has an initial reaction rate of 2.4 mol/(Lps). What is the
rate when one eighth the starting materials remain?
2. It has been experimentally determined that the rate law for the reaction
between mercury(II) chloride and sodium oxalate is third-order overall and
first-order with respect to HgCl2. Write the rate law for this reaction.
2HgCl2 ! Na2C2O4 → 2NaCl ! 2CO2 ! Hg2Cl2
3. A combination reaction gave the following data. What is the rate law for this
reaction?
J!K→Μ
Initial Rate
(mol/Lps)
Initial Concentration
(mol/L)
[J]
[K]
0.30
0.60
0.60
0.50
0.50
0.25
0.080
0.160
0.080
4. Iodide ion catalyzes the decomposition of hydrogen peroxide. The reaction is
first-order in H2O2. What is the value of the rate constant, k, if the initial rate is
0.00842 mol/(Lps)?
The initial concentration of H2O2 is 0.500 mol/L.
2H2O2 → 2H2O ! O2
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5. A proposed reaction mechanism has two intermediates. How many elementary
reactions are in this mechanism?
6. The reaction A ! B → C is first-order in A and B, second-order overall.
Complete the following table:
Initial Rate
(mol/Lps)
Initial Concentration
(mol/L)
[A]
[B]
0.50
0.50
0.50
0.25
1.0
0.020
0.040
7. The condensation of acetic acid (C2H4O2) with methanol (CH4O) to form methyl
acetate (C3H6O2) and water is catalyzed by HCl.
HCl
HCl
C2H4O2 ! CH4O 1 C3H8O3 1 C3H6O2 ! H2O
a. How many elementary reactions are there in this condensation?
b. Write the formula for the reaction intermediate(s).
c. Write the rate law for this condensation.
Chapter 18 Reaction Rates and Equilibrium
469