Question 1

The thermal decomposition of acetaldehyde, CH3CHO → CH4 + CO, is a second-order reaction. The following data were obtained at 518°C. 3CHO → CH4 + CO, is a second-order reaction. The following data were obtained at 518°C.   Calculate the rate constant for the decomposition of acetaldehyde from the above data. A)  2.2 × 10-3 s-1 B)  0.70 mmHg • s-1 C)  2.2 × 10-3 /mmHg • s-1 D)  6.7 × 10-6 /mmHg • s-1 E)  5.2 × 10-5 /mmHg • s-1" class="answers-bank-image d-inline" rel="preload" > Calculate the rate constant for the decomposition of acetaldehyde from the above data.

Accepted Answer

A)   2.2 × 10-3 s-1
B)   0.70 mmHg • s-1
C)   2.2 × 10-3 /mmHg • s-1
D)   6.7 × 10-6 /mmHg • s-1
E)   5.2 × 10-5 /mmHg • s-1F) C) and D)
G) A) and B)

Question 2

A first-order reaction has a rate constant of 7.5 × 10-3 s-1. The time required for the reaction to be 60% complete is

Accepted Answer

A)   3.8 × 10-3 s.
B)   6.9 × 10-3 s.
C)   68 s.
D)   120 s.
E)   130 s.F) A) and E)
G) B) and E)

Question 3

Consider the general gas-phase reaction of a molecular substance, A.

Accepted Answer

a. Reactions 2 and 3 are elementary.
b. ...

Question 4

What is the integrated rate law for a second-order reaction?

Accepted Answer

A)   rate = k[A]t
B)   t 
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D)   t 
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G) B) and E)

Question 5

The following diagram represents the first-order decomposition of A to form X according to the following balanced chemical equation: A → X. Each sphere represents 1.0 mmol of atoms, and the volume of the box is 1.0 L. -1 B)  0.046 s-1 C)  0.067 s-1  D)  15 s-1 E)  17 s-1" class="answers-bank-image d-inline" rel="preload" > What is the rate constant?

Accepted Answer

A)   0.019 s-1
B)   0.046 s-1
C)   0.067 s-1 
D)   15 s-1
E)   17 s-1F) A) and D)
G) B) and D)

Question 6

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

Accepted Answer

A) True 
 B)False

Question 7

Consider reactions A, B, and C, which have the potential energy profiles shown. Assuming that the reactions have roughly the same frequency factors, which reaction is the slowest?

Accepted Answer

A)   Reaction A
B)   Reaction B
C)   Reaction C
D)   All of the reactions have the same rate.E) A) and B)
F) A) and C)

Question 8

When the reaction A → B + C is studied, a plot of ln[A]t vs. time gives a straight line with a negative slope. What is the order of the reaction with respect to A?

Accepted Answer

A)   Zero
B)   First
C)   Second
D)   Third
E)   More information is needed to determine the order.F) B) and D)
G) A) and D)

Question 9

The rate constant for the reaction 3A → 4B is 6.00 × 10-3 L • mol-1 • min-1. How long will it take the concentration of A to drop from 0.75 M to 0.25 M?

Accepted Answer

A)   2.2 × 10-3 min
B)   5.5 × 10-3 min
C)   180 min
D)   440 min
E)   5.0 × 102minF) A) and E)
G) B) and C)

Question 10

What is the half-life for a first-order reaction?

Accepted Answer

A)   t1/2 = k
B)   t1/2 = 1/k[A]o
C)   t1/2 = 0.693/k[A]o
D)   t1/2 = [A]o/2k
E)   t1/2 = 0.693/kF) C) and E)
G) A) and B)

Question 11

Tetrafluoroethylene, C2F4, can be converted to octafluorocyclobutane, which can be used as a refrigerant or an aerosol propellant. A plot of 1/[C2F4] vs. time gives a straight line with a slope of 0.0448 L •mol-1 • s-1. What is the rate law for this reaction?

Accepted Answer

A)   Rate = 0.0448 (L • mol-1 • s-1) [C2F4]
B)   Rate = 22.3 (mol • L-1 • s) [C2F4]
C)   Rate = 0.0448 (L • mol-1 • s-1) [C2F4]2
D)   Rate = 22.3 (mol • L-1 • s) [C2F4]2
E)   Rate = 0.0448 s-1 [C2F4]F) C) and D)
G) B) and E)

Question 12

Which equation best describes the average rate for the reaction shown? A(aq)  + B(aq)  → C(aq)  + D(aq)

Accepted Answer

A)   
B)   rate = +Δ[B]/Δt
C)   rate = -Δ[C]/Δt
D)   rate = -Δ[A]/Δt
E)   F) A) and B)
G) A) and C)

Question 13

For the reaction BrO3- + 5Br- + 6H+ → 3Br2 + 3H2O at a particular time, -Δ[BrO3-]/Δt = 1.5 × 10-2 M/s. What is -Δ[Br-]/Δt at the same instant?

Accepted Answer

A)   13 M/s
B)   7.5 × 10-2 M/s
C)   1.5 × 10-2 M/s
D)   3.0 × 10-3 M/s
E)   330 M/sF) None of the above
G) A) and B)

Question 14

What is defined as the minimum amount of energy required to initiate a chemical reaction?

Accepted Answer

A)   Collision energy
B)   Effective collision energy
C)   Reaction energy
D)   Activation energy
E)   Rate energyF) None of the above
G) B) and C)

Question 15

Consider the following reaction 8A(g)  + 5B(g)  → 8C(g)  + 6D(g) 
If [C] is increasing at the rate of 4.0 mol L-1 • s-1, at what rate is [B] changing?

Accepted Answer

A)   -0.40 mol L-1• s-1
B)   -2.5 mol L-1• s-1
C)   -4.0 mol L-1• s-1
D)   -5.0 mol L-1• s-1
E)   -6.4 mol L-1• s-1F) A) and E)
G) B) and C)

Question 16

Enzymes are ________ .

Accepted Answer

A)   large carbohydrate molecules
B)   also called substrates
C)   usually heterogeneous catalysts
D)   insensitive to temperature
E)   biological catalystsF) A) and E)
G) D) and E)

Question 17

A certain reaction A → products is second order in A. If this reaction is 85% complete in 12 minutes, how long would it take for the reaction to be 15% complete?

Accepted Answer

A)   110 s
B)   27 s
C)   62 s
D)   130 s
E)   22 sF) C) and E)
G) A) and E)

Question 18

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°C? (R = 8.314 J/mol• K)

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)   1.0 × 1029s-1F) C) and D)
G) A) and B)

Question 19

Sulfuryl chloride, SO2Cl2(g) , decomposes at high temperature to form SO2(g)  and Cl2(g) . The rate constant at a certain temperature is 4.68 × 10-5 s-1. 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 overall order.F) C) and D)
G) A) and D)

Question 20

A study of the decomposition reaction 3RX2 → 3R + 6X yields the following initial rates. 2 → 3R + 6X yields the following initial rates.   What is the rate constant for the reaction? A)  0.0103 L • mol-1 • s-1 B)  0.263 L • mol-1 • s-1 C)  0.571 L • mol-1 • s-1  D)  1.17 L • mol-1 • s-1 E)  1.75 L • mol-1 • s-1" class="answers-bank-image d-inline" rel="preload" > What is the rate constant for the reaction?

Accepted Answer

A)   0.0103 L • mol-1 • s-1
B)   0.263 L • mol-1 • s-1
C)   0.571 L • mol-1 • s-1 
D)   1.17 L • mol-1 • s-1
E)   1.75 L • mol-1 • s-1F) B) and C)
G) A) and E)

Exam 14: Chemical Kinetics

What is the half-life for a first-order reaction?

Correct AnswerverifiedShow Answer

Which equation best describes the average rate for the reaction shown? A(aq) + B(aq) → C(aq) + D(aq)

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For the reaction BrO3- + 5Br- + 6H+ → 3Br2 + 3H2O at a particular time, -Δ[BrO3-]/Δt = 1.5 × 10-2 M/s. What is -Δ[Br-]/Δt at the same instant?

Correct AnswerverifiedShow Answer

What is defined as the minimum amount of energy required to initiate a chemical reaction?

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A certain reaction A → products is second order in A. If this reaction is 85% complete in 12 minutes, how long would it take for the reaction to be 15% complete?

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Enzymes are ________ .

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Consider reactions A, B, and C, which have the potential energy profiles shown. Assuming that the reactions have roughly the same frequency factors, which reaction is the slowest?

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A first-order reaction has a rate constant of 7.5 × 10-3 s-1. The time required for the reaction to be 60% complete is

Correct AnswerverifiedShow Answer

The thermal decomposition of acetaldehyde, CH3CHO → CH4 + CO, is a second-order reaction. The following data were obtained at 518°C. Calculate the rate constant for the decomposition of acetaldehyde from the above data.

Correct AnswerverifiedShow Answer

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L-1 • s-1, at what rate is [B] changing?

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

Correct AnswerverifiedShow Answer

Sulfuryl chloride, SO2Cl2(g) , decomposes at high temperature to form SO2(g) and Cl2(g) . The rate constant at a certain temperature is 4.68 × 10-5 s-1. What is the order of the reaction?

Correct AnswerverifiedShow Answer

The following diagram represents the first-order decomposition of A to form X according to the following balanced chemical equation: A → X. Each sphere represents 1.0 mmol of atoms, and the volume of the box is 1.0 L. What is the rate constant?

Correct AnswerverifiedShow Answer

The rate constant for the reaction 3A → 4B is 6.00 × 10-3 L • mol-1 • min-1. How long will it take the concentration of A to drop from 0.75 M to 0.25 M?

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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°C? (R = 8.314 J/mol• K)

Correct AnswerverifiedShow Answer

What is the integrated rate law for a second-order reaction?

Correct AnswerverifiedShow Answer

Consider the general gas-phase reaction of a molecular substance, A.

Correct Answerverifieda. Reactions 2 and 3 are elementary.b. ...View AnswerShow Answer

Tetrafluoroethylene, C2F4, can be converted to octafluorocyclobutane, which can be used as a refrigerant or an aerosol propellant. A plot of 1/[C2F4] vs. time gives a straight line with a slope of 0.0448 L •mol-1 • s-1. What is the rate law for this reaction?

Correct AnswerverifiedShow Answer

When the reaction A → B + C is studied, a plot of ln[A]t vs. time gives a straight line with a negative slope. What is the order of the reaction with respect to A?

Correct AnswerverifiedShow Answer

A study of the decomposition reaction 3RX2 → 3R + 6X yields the following initial rates. What is the rate constant for the reaction?

Correct AnswerverifiedShow Answer

Correct Answer
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For the reaction BrO₃^-+ 5Br^-+ 6H⁺→ 3Br₂ + 3H₂O at a particular time, -Δ[BrO₃^-]/Δt = 1.5 × 10^-2^M/s. What is -Δ[Br^-]/Δt at the same instant?

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Correct Answer
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Correct Answer
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Correct Answer
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A first-order reaction has a rate constant of 7.5 × 10^-3s^-1. The time required for the reaction to be 60% complete is

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The thermal decomposition of acetaldehyde, CH₃CHO → CH₄ + CO, is a second-order reaction. The following data were obtained at 518°C. Calculate the rate constant for the decomposition of acetaldehyde from the above data.

Correct Answer
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Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L^-1 • s^-1, at what rate is [B] changing?

Correct Answer
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Correct Answer
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Sulfuryl chloride, SO₂Cl₂(g) , decomposes at high temperature to form SO₂(g) and Cl₂(g) . The rate constant at a certain temperature is 4.68 × 10^-5s^-1. What is the order of the reaction?

Correct Answer
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Correct Answer
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The rate constant for the reaction 3A → 4B is 6.00 × 10^-3 L• mol^-1• min^-1. How long will it take the concentration of A to drop from 0.75 M to 0.25 M?

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°C? (R = 8.314 J/mol• K)

Correct Answer
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Correct Answer
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Correct Answer
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a. Reactions 2 and 3 are elementary.
b. ...
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Tetrafluoroethylene, C₂F₄, can be converted to octafluorocyclobutane, which can be used as a refrigerant or an aerosol propellant. A plot of 1/[C₂F₄] vs. time gives a straight line with a slope of 0.0448 L •mol^-1• s^-1. What is the rate law for this reaction?

Correct Answer
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When the reaction A → B + C is studied, a plot of ln[A]_t vs. time gives a straight line with a negative slope. What is the order of the reaction with respect to A?

Correct Answer
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A study of the decomposition reaction 3RX₂ → 3R + 6X yields the following initial rates. What is the rate constant for the reaction?

Correct Answer
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