Question 1

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 B)
G) A) and C)

Question 2

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) B) and D)
G) C) and E)

Question 3

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) D) and E)
G) B) and C)

Question 4

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) A) and D)
G) A) and B)

Question 5

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) A) and D)
G) B) and D)

Question 6

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) None of the above
G) A) and D)

Question 7

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) C) and D)
G) C) and E)

Question 8

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) None of the above
G) A) and B)

Question 9

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) B) and D)
F) A) and B)

Question 10

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) B) and C)
G) A) and E)

Question 11

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) A) and B)
G) A) and C)

Question 12

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) C) and E)
G) D) and E)

Question 13

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

Accepted Answer

A) True 
 B)False

Question 14

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) A) and D)

Question 15

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

Accepted Answer

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

Question 16

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) A) and E)
G) A) and D)

Question 17

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) B) and E)
G) B) and C)

Question 18

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) A) and E)
G) B) and E)

Question 19

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) C) and E)
G) A) and C)

Question 20

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

Accepted Answer

A)   rate = k[A]t
B)   t 
B)     
C)     
D)     
E)    " class="answers-bank-image d-inline" rel="preload" >
C)   t 
B)     
C)     
D)     
E)    " class="answers-bank-image d-inline" rel="preload" >
D)   t 
B)     
C)     
D)     
E)    " class="answers-bank-image d-inline" rel="preload" >
E)   t 
B)     
C)     
D)     
E)    " class="answers-bank-image d-inline" rel="preload" >F) A) and B)
G) B) and D)

Exam 14: Chemical Kinetics

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

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

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

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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

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 AnswerverifiedShow Answer

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

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

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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?

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Enzymes are ________ .

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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 AnswerverifiedShow Answer

What is the integrated rate law for a second-order 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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Consider the general gas-phase reaction of a molecular substance, A.

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

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

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

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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 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

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

Correct Answer
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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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Correct Answer
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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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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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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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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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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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Correct Answer
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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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Correct Answer
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