Question 1

The half-life of a first-order reaction does not depend on the initial concentration of reactant.

Accepted Answer

A) True 
 B)False

Question 2

Which one of the following sets of units is appropriate for a third-order rate constant?

Accepted Answer

A)   s¯1
B)   mol L¯1 s¯1
C)   L mol¯1 s¯1
D)   L2 mol¯2 s¯1
E)   L3 mol¯3 s¯1F) A) and E)
G) B) and C)

Question 3

Ammonia will react with oxygen in the presence of a copper catalyst to form nitrogen and water. From 164.5  °\degree° C to 179.0  °\degree° C, the rate constant increases by a factor of 4.27. What is the activation energy of this oxidation reaction?

Accepted Answer

A)   24.5 kJ/mol
B)   165 kJ/mol
C)   242 kJ/mol
D)   1630 kJ/mol
E)   > 104 kJ/mol F) A) and E)
G) D) and E)

Question 4

You are required to determine the energy of activation (Ea) of a reaction. Briefly describe the experimental measurements you would make and how you would obtain the activation energy from a suitable linear plot of the experimental data.

Accepted Answer

Rate constants k over a suitab...

Question 5

A chemical reaction of the general type A $\rightarrow$2B is first-order, with a rate constant of 1.52 *10¯4 s¯1.
A) Calculate the half-life of A.
B) Assuming the initial concentration of A is 0.067 mol L¯1, calculate the time needed for the concentration to fall to 0.010 mol L¯1.

Accepted Answer

a. t_½ = 4.5...

Question 6

A reaction intermediate is a species corresponding to a local energy maximum on a reaction energy diagram.

Accepted Answer

A) True 
 B)False

Question 7

The rate law cannot be predicted from the stoichiometry of a reaction.

Accepted Answer

A) True 
 B)False

Question 8

The active ingredient in an over-the-counter pain killer analgesic decomposes with a rate constant, k = 9.05 x 10¯4 day¯1. How many days does it take for 15% of the original ingredient to decompose?

Accepted Answer

A)   730 days
B)   414 days
C)   365 days
D)   180 days
E)   78 daysF) None of the above
G) A) and E)

Question 9

A catalyst lowers the activation energy but does not affect the mechanism of a reaction.

Accepted Answer

A) True 
 B)False

Question 10

What is the molecularity of the following elementary reaction?

Accepted Answer

A)   unimolecular
B)   bimolecular
C)   termolecular
D)   tetramolecular
E)   Need to know the reaction order before molecularity can be determined.F) A) and C)
G) B) and E)

Question 11

Cyclopropane is converted to propene in a first-order process. The rate constant is 5.4 * 10¯2 hr¯1. If the initial concentration of cyclopropane is 0.150 M, what will its concentration be after 22.0 hours?

Accepted Answer

A)   0.0457 M
B)   0.105 M
C)   0.127 M
D)   0.492 M
E)   None of these choices is correct.F) A) and D)
G) B) and D)

Question 12

A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 *¯4 mol L¯1 and the rate constant k = 1.08 *10¯6 s¯1, what concentration of R remains after 25 days?

Accepted Answer

A)   1.0 * 10¯3 mol L¯1
B)   1.0 *10¯4 mol L¯1
C)   9.6 * 10¯5 mol L¯1
D)   4.3 * 10¯5 mol L¯1
E)   9.7 *10¯6 mol L¯1F) A) and D)
G) None of the above

Question 13

The reaction CH3NC(g)   →\rightarrow→  CH3CN(g)  is first-order with respect to methyl isocyanide, CH3NC. If it takes 10.3 minutes for exactly one quarter of the initial amount of methyl isocyanide to react, what is the rate constant in units of min¯1?

Accepted Answer

A)   -0.135 min¯1
B)   0.0279 min¯1
C)   0.089 min¯1
D)   0.135 min¯1
E)   35.8 min¯1 F) A) and E)
G) B) and C)

Question 14

A rate constant obeys the Arrhenius equation, the factor A being 2.2 *1013 s¯1 and the activation energy being 150. kJ mol¯1. What is the value of the rate constant at 227 °\degree° C, in s¯1?

Accepted Answer

A)   2.1 *1013 s¯1
B)   6.7 * 10¯22 s¯1
C)   1.5 * 1011 s¯1
D)   4.7 *10¯3 s¯1
E)   None of these choices is correct. F) B) and D)
G) C) and D)

Question 15

All bimolecular reactions are second-order reactions.

Accepted Answer

A) True 
 B)False

Question 16

In the lock and key model of enzyme action, the active site on the enzyme provides an exact fit for the substrate.

Accepted Answer

A) True 
 B)False

Question 17

When the reaction A →\rightarrow→  B + C is studied, a plot 1/[A]t vs. time gives a straight line with a positive slope. What is the order of the reaction?

Accepted Answer

A)   zero
B)   first
C)   second
D)   third
E)   More information is needed to determine the order. F) C) and D)
G) B) and E)

Question 18

Which of the following sets of units could be appropriate for a zero-order rate constant?

Accepted Answer

A)   s¯1
B)   L mol¯1 s¯1
C)   L2 mol¯2 s¯1
D)   L3 mol¯3 s¯1
E)   mol L¯1 s¯1F) A) and B)
G) B) and E)

Question 19

The decomposition of hydrogen peroxide is a first-order process with a rate constant of 1.06 *10¯3 min¯1. How long will it take for the concentration of H2O2 to drop from 0.0200 M to 0.0120 M?

Accepted Answer

A)   
B)   7.55 min
C)   481 min
D)   4550 min
E)   31,400 minF) C) and E)
G) A) and D)

Question 20

Butadiene, C4H6 (used to make synthetic rubber and latex paints)  reacts to C8H12 with a rate law of rate = 0.014 L/(mol·s)  [C4H6]2. What will be the concentration of C4H6 after 3.0 hours if the initial concentration is 0.025 M?

Accepted Answer

A)   0.0052 M
B)   0.024 M
C)   43 M
D)   190 M
E)   0.0000 MF) None of the above
G) A) and C)

Exam 16: Kinetics: Rates and Mechanisms of Chemical Reactions

All bimolecular reactions are second-order reactions.

Correct AnswerverifiedShow Answer

The half-life of a first-order reaction does not depend on the initial concentration of reactant.

Correct AnswerverifiedShow Answer

What is the molecularity of the following elementary reaction?

Correct AnswerverifiedShow Answer

You are required to determine the energy of activation (Ea) of a reaction. Briefly describe the experimental measurements you would make and how you would obtain the activation energy from a suitable linear plot of the experimental data.

Correct AnswerverifiedRate constants k over a suitab...View AnswerShow Answer

When the reaction A →\rightarrow→ B + C is studied, a plot 1/[A]t vs. time gives a straight line with a positive slope. What is the order of the reaction?

Correct AnswerverifiedShow Answer

In the lock and key model of enzyme action, the active site on the enzyme provides an exact fit for the substrate.

Correct AnswerverifiedShow Answer

Which of the following sets of units could be appropriate for a zero-order rate constant?

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Which one of the following sets of units is appropriate for a third-order rate constant?

Correct AnswerverifiedShow Answer

The rate law cannot be predicted from the stoichiometry of a reaction.

Correct AnswerverifiedShow Answer

A catalyst lowers the activation energy but does not affect the mechanism of a reaction.

Correct AnswerverifiedShow Answer

A rate constant obeys the Arrhenius equation, the factor A being 2.2 *1013 s¯1 and the activation energy being 150. kJ mol¯1. What is the value of the rate constant at 227 °\degree° C, in s¯1?

Correct AnswerverifiedShow Answer

The decomposition of hydrogen peroxide is a first-order process with a rate constant of 1.06 *10¯3 min¯1. How long will it take for the concentration of H2O2 to drop from 0.0200 M to 0.0120 M?

Correct AnswerverifiedShow Answer

Ammonia will react with oxygen in the presence of a copper catalyst to form nitrogen and water. From 164.5 °\degree° C to 179.0 °\degree° C, the rate constant increases by a factor of 4.27. What is the activation energy of this oxidation reaction?

Correct AnswerverifiedShow Answer

A chemical reaction of the general type A →\rightarrow→ 2B is first-order, with a rate constant of 1.52 *10¯4 s¯1. A) Calculate the half-life of A. B) Assuming the initial concentration of A is 0.067 mol L¯1, calculate the time needed for the concentration to fall to 0.010 mol L¯1.

Correct Answerverifieda. t½ = 4.5...View AnswerShow Answer

A reaction intermediate is a species corresponding to a local energy maximum on a reaction energy diagram.

Correct AnswerverifiedShow Answer

A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 *¯4 mol L¯1 and the rate constant k = 1.08 *10¯6 s¯1, what concentration of R remains after 25 days?

Correct AnswerverifiedShow Answer

The reaction CH3NC(g) →\rightarrow→ CH3CN(g) is first-order with respect to methyl isocyanide, CH3NC. If it takes 10.3 minutes for exactly one quarter of the initial amount of methyl isocyanide to react, what is the rate constant in units of min¯1?

Correct AnswerverifiedShow Answer

Cyclopropane is converted to propene in a first-order process. The rate constant is 5.4 * 10¯2 hr¯1. If the initial concentration of cyclopropane is 0.150 M, what will its concentration be after 22.0 hours?

Correct AnswerverifiedShow Answer

Butadiene, C4H6 (used to make synthetic rubber and latex paints) reacts to C8H12 with a rate law of rate = 0.014 L/(mol·s) [C4H6]2. What will be the concentration of C4H6 after 3.0 hours if the initial concentration is 0.025 M?

Correct AnswerverifiedShow Answer

The active ingredient in an over-the-counter pain killer analgesic decomposes with a rate constant, k = 9.05 x 10¯4 day¯1. How many days does it take for 15% of the original ingredient to decompose?

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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You are required to determine the energy of activation (E_a) of a reaction. Briefly describe the experimental measurements you would make and how you would obtain the activation energy from a suitable linear plot of the experimental data.

Correct Answer
verified
Rate constants k over a suitab...
View Answer

When the reaction A $\rightarrow$ B + C is studied, a plot 1/[A]_t vs. time gives a straight line with a positive slope. What is the order of the reaction?

Correct Answer
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Correct Answer
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Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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A rate constant obeys the Arrhenius equation, the factor A being 2.2 *10¹³ s¯¹ and the activation energy being 150. kJ mol¯¹. What is the value of the rate constant at 227 $\degree$ C, in s¯¹?

Correct Answer
verified

The decomposition of hydrogen peroxide is a first-order process with a rate constant of 1.06 *10¯³ min¯¹. How long will it take for the concentration of H₂O₂ to drop from 0.0200 M to 0.0120 M?

Correct Answer
verified

Ammonia will react with oxygen in the presence of a copper catalyst to form nitrogen and water. From 164.5 $\degree$ C to 179.0 $\degree$ C, the rate constant increases by a factor of 4.27. What is the activation energy of this oxidation reaction?

Correct Answer
verified

A chemical reaction of the general type A $\rightarrow$ 2B is first-order, with a rate constant of 1.52 *10¯⁴ s¯¹. A) Calculate the half-life of A. B) Assuming the initial concentration of A is 0.067 mol L¯¹, calculate the time needed for the concentration to fall to 0.010 mol L¯¹.

Correct Answer
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a. t_½ = 4.5...
View Answer

Correct Answer
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A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 ¯⁴ mol L¯¹ and the rate constant k = 1.08 10¯⁶ s¯¹, what concentration of R remains after 25 days?

Correct Answer
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The reaction CH₃NC(g) $\rightarrow$ CH₃CN(g) is first-order with respect to methyl isocyanide, CH₃NC. If it takes 10.3 minutes for exactly one quarter of the initial amount of methyl isocyanide to react, what is the rate constant in units of min¯¹?

Correct Answer
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Cyclopropane is converted to propene in a first-order process. The rate constant is 5.4 * 10¯² hr¯¹. If the initial concentration of cyclopropane is 0.150 M, what will its concentration be after 22.0 hours?

Correct Answer
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Butadiene, C₄H₆ (used to make synthetic rubber and latex paints) reacts to C₈H₁₂ with a rate law of rate = 0.014 L/(mol·s) [C₄H₆]². What will be the concentration of C₄H₆ after 3.0 hours if the initial concentration is 0.025 M?

Correct Answer
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The active ingredient in an over-the-counter pain killer analgesic decomposes with a rate constant, k = 9.05 x 10¯⁴ day¯¹. How many days does it take for 15% of the original ingredient to decompose?

Correct Answer
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