Unit 10 Question Packet
Kinetics & Equilibrium
SKILLS
1. Identifying FACTORS THAT AFFECT REACTION RATE
2. Interpreting POTENTIAL ENERGY DIAGRAMS
3. Calculating HEAT OF REACTION & USING TABLE I
SKILL #1:
Name ………………………………………………
Period ………….
4. Understanding EQUILIBRIUM
5. Applying LECHATELIER’S PRINCIPLE
Identifying FACTORS THAT AFFECT REACTION RATE
- refer to your notes & RB p. 129-130
1. Which event must always occur for a chemical reaction to take place?
(1) formation of a precipitate
(3) effective collisions between reacting particles
(2) formation of a gas
(4) addition of a catalyst to the reaction system
2. Increasing the temperature increases the rate of a reaction by
(1) lowering the activation energy
(2) increasing the activation energy
(3) lowering the frequency of effective collisions between reacting molecules
(4) increasing the frequency of effective collisions between reacting molecules
3. A 5.0-gram sample of zinc and a 50.-milliliter sample of hydrochloric acid are used in a chemical
reaction. Which combination of these samples has the fastest reaction rate?
(1) a zinc strip and 1.0 M HCl(aq)
(3) zinc powder and 1.0 M HCl(aq)
(2) a zinc strip and 3.0 M HCl(aq)
(4) zinc powder and 3.0 M HCl(aq)
4. Given the balanced equation representing a reaction:
Zn(s) + 2HCl(aq)  H2(g) + ZnCl2(aq)
Which set of reaction conditions produces H2(g) at the fastest rate?
(1) a 1.0-g lump of Zn(s) in 50. mL of 0.5 M HCl(aq) at 20.oC
(2) a 1.0-g lump of Zn(s) in 50. mL of 0.5 M HCl(aq) at 30.•oC
(3) 1.0 g of powdered Zn(s) in 50. mL of 1.0 M HCl(aq) at 20.•oC
(4) 1.0 g of powdered Zn(s) in 50. mL of 1.0 M HCl(aq) at 30.•oC
5.
At 20.°C, a 1.2-gram sample of Mg ribbon reacts rapidly with 10.0 milliliters of 1.0 M HCl (aq). Which
change in conditions would have caused the reaction to proceed more slowly?
(1) increasing the initial temperature to 25°C
(3) using 1.2 g of powdered Mg
(2) decreasing the concentration of HCl (aq) to 0.1 M
(4) using 2.4 g of Mg ribbon
6. Given the balanced equation representing a reaction:
2HCl(aq) + Na2S2O3(aq)  S(s) + H2SO3(aq) + 2NaCl(aq)
Decreasing the concentration of Na2S2O3(aq) decreases the rate of reaction because the
(1) activation energy decreases
(3) frequency of effective collisions decreases
(2) activation energy increases
(4) frequency of effective collisions increases
7. At STP, which 4.0-gram zinc sample will react fastest with dilute hydrochloric acid?
(1) lump
(2) bar
(3) powdered
(4) sheet metal
8. In each of the four beakers below, a 2.0-centimeter strip of magnesium ribbon reacts with 100 mL of
HCl(aq) under the conditions shown.
In which beaker will the reaction occur
at the fastest rate?
(1) A
(2) B
(3) C
(4) D
9. A student conducts an experiment to determine how the temperature of water affects the rate at
which an antacid tablet dissolves in the water. The student has three antacid tablets of the same size
and composition. The student drops one tablet into each of three beakers containing 200. milliliters of
water at different temperatures and measures the time it takes for each tablet to completely dissolve.
The results are shown in the table below.
(a) Describe the effect of water temperature on the rate
of dissolving.
(b) Explain, in terms of collision theory, how water temperature influences the rate of dissolving.
high temperature more collisions dissolves faster
(c) What change, other than temperature, would affect the rate of dissolving?
crushing the table
stirring/shaking/agitating
10. State two methods to increase the rate of a chemical reaction and explain, in terms of particle
behavior, how each method increases the reaction rate.
Increasing the temperature of the reaction causes the reacting particles to move faster and
collide more frequently.
Increasing the concentration increases the number of particle collisions.
Increasing the surface area (solid reactant) allows a greater number of particles to collide.
Adding a catalyst provides an alternate way for the particles to react.
11. At room temperature, a reaction occurs when KIO3(aq) is mixed with NaHSO3(aq) that contains a small
amount of starch. The colorless reaction mixture turns dark blue after a period of time that depends
on the concentration of the reactants.
In a laboratory, 12 drops of a 0.02 M NaHSO3(aq) solution containing starch were placed in each of
six test tubes. A different number of drops of 0.02 M KIO3(aq) and enough water to maintain a constant
volume were added to each test tube and the time for the dark-blue color to appear was measured.
The data were recorded in the table below.
(a) State how increasing the number of drops of 0.02 M KIO3(aq) used in the reaction affects the rate
of reaction.
The reaction occurs faster.
(b) Identify one factor, other than the concentration of the reactants, that would affect the rate of
this reaction.
Temperature, catalyst
12. Explain, in terms of collision theory, how increasing the concentration of reactants will increase the
rate of a reaction.
More reactant particles  more effective collisions  faster reaction
13. Explain, in terms of collision theory, how crushing a solid reactant will increase the rate at which it will
react.
More surface area  more effective collisions  faster reaction
SKILL #2:
interpreting POTENTIAL ENERGY DIAGRAMS
- refer to your notes and RB p. 131-135
Given the following potential energy diagrams, identify the following:
14.
15.
a. potential energy of reactants ____
a. potential energy of reactants ____
b. activation energy
b. activation energy
____
____
c. energy of activated complex ____
c. potential energy of products ____
d. heat of reaction
____
e. Is the reaction endothermic or
exothermic?
f. Is the heat of reaction (∆H) positive or
negative?
g. Draw in a dashed line to show what
happens to the activation energy if a
catalyst is added.
d. energy of activated complex ____
e. Draw in a vertical line to represent the
heat of reaction
f. Is the reaction endothermic or
exothermic?
g. Is the heat of reaction (∆H) positive or
negative?
h. Draw in a dashed line to show what
happens to the activation energy if a
catalyst is added.
16. Changes in activation energy during a chemical reaction are represented by a
(1) cooling curve
(3) ionization energy diagram
(2) heating curve
(4) potential energy diagram
17. Which information about a chemical reaction is provided by a potential energy diagram?
(1) the oxidation states of the reactants and products
(2) the average kinetic energy of the reactants and products
(3) the change in solubility of the reacting substances
(4) the energy released or absorbed during the reaction
18. The potential energy diagram for a chemical
reaction is shown below. Each interval on
the axis labeled “Potential Energy (kJ)”
represents 40 kilojoules.
(a) What is the activation energy for the
forward reaction? ____
(b) What is the activation energy for the
reverse reaction? ____
(c) What is the heat of reaction? ____
(d) On the potential energy diagram above,
label the following:
1. Potential energy of reactants
2. Potential energy of products
3. Heat of reaction
4. Activation energy of the forward
reaction
5. Activation energy of the reverse
reaction
(e) Is the reaction above endothermic or
exothermic?
20. A potential energy diagram for a chemical
reaction is shown below.
19. The potential energy diagram for a reaction
is shown below.
(a) potential energy of reactants ____
(b) potential energy of products ____
(c) activation energy of forward reaction
____
(d) activation energy of reverse reaction
____
(e) heat of reaction ____
(f) Is the heat of reaction (∆H) positive or
negative?
(g) Identify the information in the chemical
equation that indicates the reaction is
exothermic.
Heat term is on the right side of the
equation; heat is a product
21. Given the reaction:
2NO2(g) + 7H2(g)  2NH3(g) + 4H2O(g) + 1127kJ
On the diagram below, complete the potential
energy diagram for the forward reaction. Be sure
your drawing shows the activation energy and the
potential energy of the products.
(a) Label the following:
1. Potential energy of reactants
2. Potential energy of products
3. Heat of reaction
4. Activation energy of the forward
reaction
5. Activation energy of the reverse
reaction
(b) Is the reaction above endothermic or
exothermic?
22. Base your answers to the following questions
on the potential energy diagram below.
(a) What is the heat of reaction for the forward
reaction? +80 kJ or 80 kJ
(b) What is the activation energy for the
forward reaction with the catalyst?? +100
kJ or 100 kJ
(c) Explain, in terms of the function of a
catalyst, why the curves on the potential
energy diagram for the catalyzed and
uncatalyzed reactions are different. A
catalyst speeds up the reaction; lower
activation energy
24. Given the balanced equation:
2H2(g) + O2(g)  2H2O(l) + 571.6 kJ
(a) Identify the information in this equation that
indicates the reaction is exothermic.
Heat term is on the right side of the
equation; heat is a product
(b) On the axes below, draw a potential energy
diagram for the reaction represented by this
equation.
(c) Explain why the entropy of the system
decreases as the reaction proceeds.
Gases turn into a liquid
23. Given the reaction: A + B  C
(a) Does the diagram illustrate an exothermic
or an endothermic reaction? State one
reason, in terms of energy, to support your
answer.
endothermic, PE of product C is greater
than PE of reactants A and B
(b) On the diagram above, draw a dashed
line to indicate a potential energy curve
for the reaction if a catalyst is added.
25. Given the balanced equation:
N2(g) +O2(g) +182.6 kJ  2NO(g)
(a) Identify the information in the equation that
indicates the reaction is endothermic.
Heat term is on the left; heat is a reactant.
(b) On the labeled axes below, draw a
potential energy diagram for this reaction.
26. Given the reaction:
S(s) + O2(g)  SO2(g) + energy
27. According to Table I, which potential energy
diagram best represents the reaction that
forms H2O(l) from its elements?
Which diagram best represents the potential
energy changes for this reaction?
28. Which statement correctly describes an endothermic chemical reaction?
(1) The products have higher potential energy than the reactants, and the ΔH is negative.
(2) The products have higher potential energy than the reactants, and the ΔH is positive.
(3) The products have lower potential energy than the reactants, and the ΔH is negative.
(4) The products have lower potential energy than the reactants, and the ΔH is positive.
SKILL #3:
Calculating HEAT OF REACTION & USING TABLE I
29. Given the balanced equation representing a
reaction:
N2(g) + O2(g) + 82.6 kJ  2NO(g)
- refer to your notes & RB p. 131-133
30. Given the balanced equation representing a
reaction:
2H2(g) + O2(g)  2H2O(l) + 571.6 kJ
(a) How many kilojoules of heat are absorbed if
4 moles of NO (g) are produced?
82.6 = x
2
4
(a) How many kilojoules of heat are released if
1 mole of H2(g) is consumed?
571.6 = x
2
1
(b) How many kilojoules of heat are absorbed if
0.5 mole of N2 (g) is consumed?
(b) How many kilojoules of heat are released if
5 moles of H2O(l) is produced?
571.6 = x
2
5
82.6 = x
1
0.5
31. Given the balanced equation representing a reaction:
2NO2(g) + 7H2(g)  2NH3(g) + 4H2O(g) + 1127 kJ
(a) How much energy is released if 5 moles of H2O(g) are produced?
1127 = x
4
5
(b) How much energy is released if 2 moles of H2(g) are consumed?
1127 = x
7
2
32. In a chemical reaction, the difference between
the potential energy of the products and the
potential energy of the reactants is defined as
the
(1) activation energy
(2) ionization energy
(3) heat of reaction
(4) heat of vaporization
33. Which expression represents the ΔH for a
chemical reaction in terms of the potential
energy, PE, of its products and reactants?
(1) PE of products + PE of reactants
(2) PE of products – PE of reactants
(3) PE of products × PE of reactants
(4) PE of products ÷ PE of reactants
34. Which equation represents an exothermic
reaction at 298K?
35. Given the reaction:
2 H2(g) + O2(g)2 H2O(l) + 571.6 kJ
What is the approximate ∆H for the formation of 1
mole of H2O(l)?
(1) – 285.8 kJ
(3) – 571.6 kJ
(2) +285.8 kJ
(4) +571.6 kJ
36. Given the reaction:
CH4(g) + 2 O2(g)  2 H2O(g) + CO2(g)
What is the overall result when CH4(g) burns
according to this reaction?
(1) Energy is absorbed and ∆H is negative.
(2) Energy is absorbed and ∆H is positive.
(3) Energy is released and ∆H is negative.
(4) Energy is released and ∆H is positive.
37. Base your answers to the following questions on the potential energy diagram and the equation below.
(a) The letter B represents which chemical formula or formulas in the equation? ___________
(b) If 682.2 kilojoules are absorbed, how many moles of C2H2(g) are produced?
(c) Describe how the potential energy diagram will change if a catalyst is added.
SKILL #4:
Understanding EQUILIBRIUM
38. A chemical reaction is at equilibrium.
Compared to the rate of the forward reaction,
the rate of the reverse reaction is
(1) faster and more reactant is produced
(2) faster and more product is produced
(3) the same and the reaction has stopped
(4) the same and the reaction continues in
both directions
- refer to your notes & RB p. 137-138
44. Given the equation representing a phase
change at equilibrium:
39. Which balanced equation represents a phase
equilibrium?
40. Given the equation represents a reaction:
41. Which statement must be true when solution
equilibrium occurs?
(1) The solution is at STP.
(2) The solution is supersaturated.
(3) The concentration of the solution remains
constant.
(4) The masses of the dissolved solute and the
undissolved solute are equal.
42. Given the equation representing a system at
equilibrium:
H2O(s) H2O(l)
At which temperature does this equilibrium
exist at 101.3 kilopascals?
(1) 0 K
(3) 32 K
(2) 0°C
(4) 273°C
43. The solid and liquid phases of water can exist
in a state of equilibrium at 1 atmosphere of
pressure and a temperature of
(1) 0°C
(3) 273°C
(2) 100°C
(4) 373°C
45. Which statement must be true for any
chemical reaction at equilibrium?
(1) The concentration of the products is
greater than the concentration of the
reactants.
(2) The concentration of the products is less
than the concentration of the reactants.
(3) The concentration of the products and the
concentration of the reactants are equal.
(4) The concentration of the products and the
concentration of the reactants are
constant.
46. Which factors must be equal in a reversible
chemical reaction at equilibrium?
(1) the activation energies of the forward and
reverse reactions
(2) the rates of the forward and reverse
reactions
(3) the concentrations of the reactants and
products
(4) the potential energies of the reactants and
products
47. A student adds solid KCl to water in a flask. The
flask is sealed with a stopper and thoroughly
shaken until no more solid KCl dissolves. Some
solid KCl is still visible in the flask. The solution in
the flask is
(1) saturated and is at equilibrium with the
solid KCl
(2) saturated and is not at equilibrium with the
solid KCl
(3) unsaturated and is at equilibrium with the
solid KCl
(4) unsaturated and is not at equilibrium with
the solid KCl
48. Which type or types of change, if any, can
reach equilibrium?
(1) a chemical change, only
(2) a physical change, only
(3) both a chemical and a physical change
(4) neither a chemical nor a physical change
49. Given the reaction at equilibrium:
H2(g) + Br2(g)  2 HBr(g)
The rate of the forward reaction is
(1) greater than the rate of the reverse
reaction
(2) less than the rate of the reverse reaction
(3) equal to the rate of the reverse reaction
(4) independent of the rate of the reverse
reaction
SKILL #5:
Applying LECHATELIER’S PRINCIPLE
50. A solution that is at equilibrium must be
(1) concentrated
(3) saturated
(2) dilute
(4) unsaturated
51. Given the reaction system in a closed
container at equilibrium and at a temperature
of 298 K:
N2O4(g) <==>2NO2(g)
The measurable quantities of the gases at
equilibrium must be
(1) decreasing
(3) equal
(2) increasing
(4) constant
52. Given the equation: H2O(s) <-->H2O(l) At which
temperature will equilibrium exist when the
atmospheric pressure is 1 atm?
(1) 0 K
(3) 273 K
(2) 100 K
(4) 373 K
- refer to your notes & RB p.139-141
53. For each of the following systems at equilibrium, identify which way the equilibrium position will shift (right
or left) and how the concentrations and rates will change (increase or decrease).
Chemical system:
2 SO3(g) + heat  2 SO2(g) + O2(g)
(a) Stress: increasing temperature
reaction will shift __________right
concentration of SO3 _____________ 
rate of forward reaction _____________↑
concentration of SO2 _____________↑
rate of reverse reaction _____________
concentration of O2
_____________ ↑
(b) Stress: increasing pressure
reaction will shift __________ left
concentration of SO3 _____________ ↑
rate of forward reaction _____________
concentration of SO2 _____________
rate of reverse reaction _____________↑
concentration of O2
_____________ 
(c) Stress: decreasing pressure
reaction will shift __________ right
concentration of SO3 _____________ 
rate of forward reaction _____________↑
concentration of SO2 _____________↑
rate of reverse reaction _____________
concentration of O2
_____________ ↑
Chemical system:
3 H2(g) + N2 (g)  2 NH3(g) + heat
(a) Stress: increasing temperature
reaction will shift __________
concentration of H2
_____________
rate of forward reaction _____________
concentration of N2
_____________
rate of reverse reaction _____________
concentration of NH3 _____________
(b) Stress: decreasing temperature
reaction will shift __________
concentration of H2
_____________
rate of forward reaction _____________
concentration of N2
_____________
rate of reverse reaction _____________
concentration of NH3 _____________
(c) Stress: adding NH3
reaction will shift __________
concentration of H2
_____________
rate of forward reaction _____________
concentration of N2
_____________
rate of reverse reaction _____________
concentration of NH3 _____________
(d) Stress: decreasing H2
reaction will shift __________
concentration of H2
_____________
rate of forward reaction _____________
concentration of N2
_____________
rate of reverse reaction _____________
concentration of NH3 _____________
Chemical system:
BaSO4 (s)  Ba2+(aq) + SO42-(aq)
(a) Stress: adding Ba(NO3)2 (s)
reaction will shift __________
concentration of Ba2+ ion _____________
rate of forward reaction _____________
concentration of SO42- ion _____________
rate of reverse reaction _____________
(b) Stress: removing SO42- ion
reaction will shift __________
concentration of Ba2+ ion _____________
rate of forward reaction _____________
concentration of SO42- ion _____________
rate of reverse reaction _____________
54. For the following systems at equilibrium, put a check mark next to the stressors that will cause the change
to the reaction.
3 H2(g) + N2 (g)  2 NH3(g) + heat
(a) Which stressors will cause the forward reaction to be favored?





increasing [H2]
increasing [N2]
increasing [NH3]
increasing heat
increasing pressure





decreasing [H2]




decreasing [N2]
decreasing [N2]
decreasing [NH3]
decreasing heat
decreasing pressure
(b) Which stressors will cause the amount of H2 to increase?




increasing [N2]
increasing [NH3]
increasing heat
increasing pressure
decreasing [NH3]
decreasing heat
decreasing pressure
2 SO3(g) + heat  2 SO2(g) + O2(g)
(a) Which changes will favor the reverse reaction?





increasing [SO3]
increasing [SO2]
increasing [O2]
increasing heat
increasing pressure





decreasing [SO3]




decreasing [SO3]
decreasing [SO2]
decreasing [O2]
decreasing heat
decreasing pressure
(b) Which stressors will increase the concentration of O2?




increasing [SO3]
increasing [SO2]
increasing heat
increasing pressure
55. Given the reaction at equilibrium:
decreasing [SO2]
decreasing heat
decreasing pressure
N2(g) + 3H2(g)  2NH3(g) + 91.8 kJ
What occurs when the concentration of H2(g) is increased?
(1) The rate of the forward reaction increases and the concentration of N2(g) decreases.
(2) The rate of the forward reaction decreases and the concentration of N2(g) increases.
(3) The rate of the forward reaction and the concentration of N2(g) both increase.
(4) The rate of the forward reaction and the concentration of N2(g) both decrease.
56. Given the equation representing a reaction at equilibrium:
Which change favors the reverse reaction?
(1) decreasing the concentration of HI (g)
(2) decreasing the temperature
(3) increasing the concentration of I 2(g)
(4) increasing the pressure
H2(g) + I2(g) + heat  2HI(g)
57. Given the system at equilibrium:
2POCl3(g) + energy  2PCl3(g) + O2(g)
Which changes occur when O2(g) is added tothis system?
(1) The equilibrium shifts to the right and the concentration of PCl 3(g)increases.
(2) The equilibrium shifts to the right and the concentration of PCl3(g)decreases.
(3) The equilibrium shifts to the left and the concentration of PCl 3(g)increases.
(4) The equilibrium shifts to the left and the concentration of PCl 3(g)decreases.
58. Given the equilibrium reaction in a closed system:
H2(g) + I2(g) + heat  2 HI(g)
What will be the result of an increase in temperature?
(1) The equilibrium will shift to the left and [H2] will increase.
(2) The equilibrium will shift to the left and [H2] will decrease.
(3) The equilibrium will shift to the right and [HI] will increase.
(4) The equilibrium will shift to the right and [HI] will decrease.
59. Given the reaction at equilibrium:
N2(g)+ 3 H2(g)
2 NH3(g) + 92.05 kJ
(a) State the effect on the number of moles of N2(g) if the temperature of the system is increased.
number of moles of N2(g) increases or more N2(g) is made
(b) State the effect on the number of moles of H2(g) if the pressure on the system is increased.
number of moles of H2(g) decreases, less H2(g) is made, or more H2(g) is consumed
(c) State the effect on the number of moles of NH3(g) if a catalyst is introduced into the reaction
system. Explain why this occurs. Remains the same;A catalyst does not affect the concentrations
of reactants or products.
60. Nitrogen gas, hydrogen gas, and ammonia gas are in equilibrium in a closed container at constant
temperature and pressure. The equation below represents this equilibrium.
N2(g) + 3H2(g)  2NH3(g)
The graph below shows the initial concentration of each gas, the changes that occur as a result of
adding H2(g) to the system, and the final concentrations when equilibrium is reestablished.
(a) What information on the graph indicates that the
system was initially at equilibrium?
Concentrations stay the same.
(b) Explain, in terms of LeChatelier’s principle, why the
final concentration of NH3(g) is greater than the
initial concentration of NH3 (g). The reaction shifts
to the right to relieve the stress.
(c) Explain, in terms of collision theory, why the concentration of H 2 (g) begins to decrease
immediately after more H2(g) is added to the system.
More collisions between H2 and N2 produce NH3, so more H2 is used up.