Question 1

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

Accepted Answer

A) True 
 B)False

Question 2

In order to obtain the activation energy of a reaction using a graphical method, __________ is plotted against __________, giving a straight line whose slope is equal to __________.

Accepted Answer

A)  k; T; −E a
B)  k; 1/T; −E a
C)  lnk; T; −E a/R
D)  k; 1/T; −E a/R
E)  lnk; 1/T; −E a/RF) A) and D)
G) A) and E)

Question 3

In going from room temperature (25.0°C)  to 10°C above room temperature, the rate of a reaction doubles. Calculate the activation energy for the reaction.

Accepted Answer

A)  157.2 kJ/mol
B)  103.8 kJ/mol
C)  52.9 kJ/mol
D)  6.4 kJ/mol
E)  <1 kJ/molF) All of the above
G) B) and C)

Question 4

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

Question 5

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

Accepted Answer

A)  s −1
B)  mol L −1s −1
C)  L mol −1s −1
D)  mol 2 L −2s −1
E)  L 2 mol −2s −1F) A) and E)
G) All of the above

Question 6

Reaction intermediates differ from activated complexes in that

Accepted Answer

A)  they are stable molecules with normal bonds and are frequently isolated.
B)  they are molecules with normal bonds rather than partial bonds and can occasionally be isolated.
C)  they are intermediate structures which have characteristics of both reactants and products.
D)  they are unstable and can never be isolated.
E)  all reactions involve reaction intermediates, but not all have activated complexes.F) A) and B)
G) All of the above

Question 7

2NOBr(g)  → 2NO(g)  + Br2(g)  2(g)    Based on the initial rate data above, what is the value of the rate constant? A) 0.0360 L mol −1s −1 B) 0.800 L mol −1s −1 C) 1.25 L mol −1s −1 D) 27.8 L mol −1s −1 E) 0.0360 s −1" class="answers-bank-image d-inline" rel="preload" > Based on the initial rate data above, what is the value of the rate constant?

Accepted Answer

A)  0.0360 L mol −1s −1
B)  0.800 L mol −1s −1
C)  1.25 L mol −1s −1
D)  27.8 L mol −1s −1
E)  0.0360 s −1F) B) and C)
G) C) and D)

Question 8

A boiled egg can be cooked at 100.0°C in exactly 5 minutes. At an altitude of around 2000 m where the boiling point of water is 93.0°C, it takes exactly 7.5 minutes to cook the egg to the same amount. What is the activation energy for the reaction involved when an egg is boiled?

Accepted Answer

A)  0.5 kJ/mol
B)  4.5 kJ/mol
C)  7.9 kJ/mol
D)  66 kJ/mol
E)  >100 kJ/molF) All of the above
G) A) and E)

Question 9

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

Accepted Answer

A) True 
 B)False

Question 10

The rate of a reaction is determined by the rate of the fastest step in the mechanism.

Accepted Answer

A) True 
 B)False

Question 11

For the reaction A(g)  + 2B(g)  → 2C(g)  + 2D(g) 
The following data were collected at constant temperature. Determine the correct rate law for this reaction.
2 [B] C) Rate = k[A] [B] 2 D) Rate = k[A] E) Rate = k[A] 3" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  Rate = k[A] [B]
B)  Rate = k[A] 2 [B]
C)  Rate = k[A] [B] 2
D)  Rate = k[A]
E)  Rate = k[A] 3F) A) and B)
G) B) and D)

Question 12

In an exothermic reaction,

Accepted Answer

A)  the forward reaction is slower than the reverse reaction.
B)  the reaction rate will speed up with time.
C)  the collision energy of the reactants will be greater than that of the products.
D)  the forward reaction will have a lower activation energy than the reverse reaction.
E)  the activation energy will change as the reaction progresses.F) C) and E)
G) A) and B)

Question 13

The compound RX3 decomposes according to the equation 3RX3 → R + R2X3 + 3X2
In an experiment the following data were collected for the decomposition at 100°C. What is the average rate at which RX3 is disappearing over the entire experiment?
3 decomposes according to the equation 3RX3 → R + R2X3 + 3X2 In an experiment the following data were collected for the decomposition at 100°C. What is the average rate at which RX3 is disappearing over the entire experiment?   A) 0.011 mol L −1s −1 B) 0.019 mol L −1s −1 C) 0.044 mol L −1s −1 D) 0.049 mol L −1s −1 E) 0.069 mol L −1s −1" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  0.011 mol L −1s −1
B)  0.019 mol L −1s −1
C)  0.044 mol L −1s −1
D)  0.049 mol L −1s −1
E)  0.069 mol L −1s −1F) A) and E)
G) None of the above

Question 14

All bimolecular reactions are second-order reactions.

Accepted Answer

A) True 
 B)False

Question 15

The decomposition of dinitrogen pentaoxide has an activation energy of 102 kJ/mol and ΔH°rxn = + 55 kJ/mol. What is the activation energy for the reverse reaction?

Accepted Answer

A)  27 kJ/mol
B)  47 kJ/mol
C)  55 kJ/mol
D)  102 kJ/mol
E)  More information is needed, since this is a Hess's law calculation.F) B) and E)
G) A) and E)

Question 16

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

Accepted Answer

A) True 
 B)False

Question 17

Dinitrogen tetraoxide, N2O4, decomposes to nitrogen dioxide, NO2, in a first-order process. If k = 2.5 × 103 s−1 at −5°C and k = 3.5 × 104 s−1 at 25°C, what is the activation energy for the decomposition?

Accepted Answer

A)  0.73 kJ/mol
B)  58 kJ/mol
C)  140 kJ/mol
D)  580 kJ/mol
E)  > 1000 kJ/molF) C) and D)
G) B) and E)

Question 18

For the reaction 2A + B + 2C → D + E
The following initial rate data were collected at constant temperature. Determine the correct rate law for this reaction. All units are arbitrary.
2[B][C] C) Rate = k[A] 2[B][C] −1 D) Rate = k[A][B] 2[C]  −1 E) None of these choices are correct." class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  Rate = k[A][B][C]
B)  Rate = k[A] 2[B][C]
C)  Rate = k[A] 2[B][C] −1
D)  Rate = k[A][B] 2[C]  −1
E)  None of these choices are correct.F) B) and E)
G) A) and E)

Question 19

The reaction X → Y is first-order overall and first-order with respect to the reactant X. The result of doubling the initial concentration of X will be to

Accepted Answer

A)  shorten the half-life of the reaction.
B)  increase the rate constant of the reaction.
C)  decrease the rate constant of the reaction.
D)  shorten the time taken to reach equilibrium.
E)  double the initial rate.F) A) and B)
G) B) and C)

Question 20

Consider the reaction 2NH3(g)  → N2(g)  + 3H2(g) 
If the rate Δ[H2]/Δt is 0.030 mol L−1s−1, then Δ[NH3 ]/Δt is

Accepted Answer

A)  −0.045 mol L −1 s −1
B)  −0.030 mol L −1 s −1
C)  −0.020 mol L −1 s −1
D)  −0.010 mol L −1 s −1
E)  None of these choices are correct.F) C) and D)
G) B) and D)

Exam 16: Kinetics: Rates and Mechanisms of Chemical Reactions

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

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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?

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

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For the reaction 2A + B + 2C → D + E The following initial rate data were collected at constant temperature. Determine the correct rate law for this reaction. All units are arbitrary.

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The decomposition of dinitrogen pentaoxide has an activation energy of 102 kJ/mol and ΔH°rxn = + 55 kJ/mol. What is the activation energy for the reverse reaction?

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Reaction intermediates differ from activated complexes in that

Correct AnswerverifiedShow Answer

All bimolecular reactions are second-order reactions.

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Dinitrogen tetraoxide, N2O4, decomposes to nitrogen dioxide, NO2, in a first-order process. If k = 2.5 × 103 s−1 at −5°C and k = 3.5 × 104 s−1 at 25°C, what is the activation energy for the decomposition?

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A boiled egg can be cooked at 100.0°C in exactly 5 minutes. At an altitude of around 2000 m where the boiling point of water is 93.0°C, it takes exactly 7.5 minutes to cook the egg to the same amount. What is the activation energy for the reaction involved when an egg is boiled?

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

Correct AnswerverifiedShow Answer

The rate of a reaction is determined by the rate of the fastest step in the mechanism.

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In order to obtain the activation energy of a reaction using a graphical method, __________ is plotted against __________, giving a straight line whose slope is equal to __________.

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For the reaction A(g) + 2B(g) → 2C(g) + 2D(g) The following data were collected at constant temperature. Determine the correct rate law for this reaction.

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

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Consider the reaction 2NH3(g) → N2(g) + 3H2(g) If the rate Δ[H2]/Δt is 0.030 mol L−1s−1, then Δ[NH3 ]/Δt is

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In going from room temperature (25.0°C) to 10°C above room temperature, the rate of a reaction doubles. Calculate the activation energy for the reaction.

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The reaction X → Y is first-order overall and first-order with respect to the reactant X. The result of doubling the initial concentration of X will be to

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In an exothermic reaction,

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The compound RX3 decomposes according to the equation 3RX3 → R + R2X3 + 3X2 In an experiment the following data were collected for the decomposition at 100°C. What is the average rate at which RX3 is disappearing over the entire experiment?

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2NOBr(g) → 2NO(g) + Br2(g) Based on the initial rate data above, what is the value of the rate constant?

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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 decomposition of dinitrogen pentaoxide has an activation energy of 102 kJ/mol and ΔH°_rxn = + 55 kJ/mol. What is the activation energy for the reverse reaction?

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Dinitrogen tetraoxide, N₂O₄, decomposes to nitrogen dioxide, NO₂, in a first-order process. If k = 2.5 × 10³s⁻¹ at −5°C and k = 3.5 × 10⁴s⁻¹ at 25°C, what is the activation energy for the decomposition?

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In order to obtain the activation energy of a reaction using a graphical method, is plotted against , giving a straight line whose slope is equal to __.

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Consider the reaction 2NH₃(g) → N₂(g) + 3H₂(g) If the rate Δ[H₂]/Δt is 0.030 mol L⁻¹s⁻¹, then Δ[NH₃ ]/Δt is

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The compound RX₃ decomposes according to the equation 3RX₃ → R + R₂X₃+ 3X₂ In an experiment the following data were collected for the decomposition at 100°C. What is the average rate at which RX₃ is disappearing over the entire experiment?

Correct Answer
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2NOBr(g) → 2NO(g) + Br₂(g) Based on the initial rate data above, what is the value of the rate constant?

Correct Answer
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