Question 1

Which of the following is true?

Accepted Answer

A)  If we know that a reaction is an elementary reaction, then we know its rate law.
B)  The rate-determining step of a reaction is the rate of the fastest elementary step of its mechanism.
C)  Since intermediate compounds can be formed, the chemical equations for the elementary reactions in a multistep mechanism do not always have to add to give the chemical equation of the overall process.
D)  In a reaction mechanism, an intermediate is identical to an activated complex.
E)  All of the above statements are true.F) None of the above
G) C) and D)

Question 2

A catalyst that is present in the same phase as the reacting molecules is called a __________ catalyst.

Accepted Answer

homogeneous

Question 3

The average rate of disappearance of I- between 1200.0 s and 1600.0 s is __________ M/s.

Accepted Answer

A)  1.8 × 10-5
B)  1.2 × 10-5
C)  2.0 × 10-5
D)  5.0 × 104
E)  1.6 × 10-4F) C) and D)
G) A) and E)

Question 4

The isomerization of methylisonitrile to acetonitrile CH3NC (g) → CH3CN (g) 
Is first order in CH3NC. The rate constant for the reaction is 9.45 × 10-5s-1 at 478 K. The half-life of the reaction when the initial [CH3NC] is 0.030 M is __________ s.

Accepted Answer

A)  1.06 × 104
B)  5.29 × 103
C)  3.53E × 105
D)  7.33 × 103
E)  1.36 × 10-4F) None of the above
G) A) and B)

Question 5

The rate constant for a particular second-order reaction is 0.47M-1s-1. If the initial concentration of reactant is 0.25 mol/L, it takes __________ s for the concentration to decrease to 0.080 mol/L.

Accepted Answer

A)  18
B)  1.4
C)  8.5
D)  4.0
E)  0.08F) B) and D)
G) A) and D)

Question 6

Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction: 2NO2 → 2NO + O2
In a particular experiment at 300 °C, [NO2] drops from 0.0100 to 0.00650 M in 100 s. The rate of disappearance of NO2 for this period is __________ M/s.

Accepted Answer

A)  0.35
B)  3.5 × 10-3
C)  3.5 × 10-5
D)  7.0 × 10-3
E)  1.8 × 10-3F) D) and E)
G) None of the above

Question 7

The enzyme nitrogenase converts __________ into __________.

Accepted Answer

A)  ammonia, urea
B)  CO and unburned hydrocarbons, H2O and CO2
C)  nitrogen, ammonia
D)  nitrogen oxides, N2 and O2
E)  nitroglycerine, nitric acid, and glycerineF) A) and E)
G) A) and B)

Question 8

The rate of disappearance of HBr in the gas phase reaction 2HBr (g) → H2 (g) + Br2 (g) 
Is 0.130 Ms-1 at 150°C. The rate of reaction is __________ Ms-1.

Accepted Answer

A)  3.85
B)  0.0650
C)  0.0169
D)  0.260
E)  0.0860F) A) and B)
G) B) and E)

Question 9

The half-life of this reaction is __________ s.

Accepted Answer

A)  0.97
B)  7.1
C)  5.0
D)  3.0
E)  0.14F) D) and E)
G) A) and B)

Question 10

A possible mechanism for the overall reaction Br2 (g) + 2NO (g) → 2NOBr (g) 
Is
NO (g) + Br2 (g)  2 (g) + 2NO (g) → 2NOBr (g)  Is NO (g) + Br2 (g)    NOBr2 (g) (fast)  NOBr2 (g) + NO (g)    2NOBr (slow)  The rate law for formation of NOBr based on this mechanism is rate = __________. A) k1[NO]1/2 B) k1[Br2]1/2 C) (k2k1/k-1) [NO]2[Br2] D) (k1/k-1) 2[NO]2 E) (k2k1/k-1) [NO]2[Br2]2" class="answers-bank-image d-inline" rel="preload" > NOBr2 (g) (fast) 
NOBr2 (g) + NO (g)  2 (g) + 2NO (g) → 2NOBr (g)  Is NO (g) + Br2 (g)    NOBr2 (g) (fast)  NOBr2 (g) + NO (g)    2NOBr (slow)  The rate law for formation of NOBr based on this mechanism is rate = __________. A) k1[NO]1/2 B) k1[Br2]1/2 C) (k2k1/k-1) [NO]2[Br2] D) (k1/k-1) 2[NO]2 E) (k2k1/k-1) [NO]2[Br2]2" class="answers-bank-image d-inline" rel="preload" > 2NOBr (slow) 
The rate law for formation of NOBr based on this mechanism is rate = __________.

Accepted Answer

A)  k1[NO]1/2
B)  k1[Br2]1/2
C)  (k2k1/k-1) [NO]2[Br2]
D)  (k1/k-1) 2[NO]2
E)  (k2k1/k-1) [NO]2[Br2]2F) A) and E)
G) A) and C) C

Question 11

What is the magnitude of the rate constant for the reaction?

Accepted Answer

A)  1.15 × 104
B)  4.6
C)  230
D)  115
E)  713F) C) and E)
G) A) and E)

Question 12

Which substance in the reaction below either appears or disappears the fastest? 4NH3 + 7O2 → 4NO2 + 6H2O

Accepted Answer

A)  NH3
B)  O2
C)  NO2
D)  H2O
E)  The rates of appearance/disappearance are the same for all of these.F) B) and C)
G) All of the above

Question 13

Consider the following reaction: A → 2C
The average rate of appearance of C is given by Δ[C]/Δt. Comparing the rate of appearance of C and the rate of disappearance of A, we get Δ[C]/Δt = __________ × (-Δ[A]/Δt) .

Accepted Answer

A)  +2
B)  -1
C)  +1
D)  +1/2
E)  -1/2F) A) and B)
G) C) and D)

Question 14

The reaction below is first order in [H2O2]: 2H2O2 (l) → 2H2O (l) + O2 (g) 
A solution originally at 0.600 M H2O2 is found to be 0.075 M after 54 min. The half-life for this reaction is __________ min.

Accepted Answer

A)  6.8
B)  18
C)  14
D)  28
E)  54F) A) and B)
G) C) and D)

Question 15

The elementary reaction 2NO2 (g) → 2NO (g) + O2 (g) 
Is second order in NO2 and the rate constant at 501 K is 7.93 × 10-3M-1s-1. The reaction half-life at this temperature when [NO2]0= 0.45 M is __________ s.

Accepted Answer

A)  3.6 × 10-3
B)  0.011
C)  126
D)  87
E)  280F) A) and B)
G) A) and C)

Question 16

The average rate disappearance of A between 20 s and 30 s is __________ mol/s.

Accepted Answer

A)  5.0 × 10-4
B)  1.6 × 10-2
C)  1.5 × 10-3
D)  670
E)  0.15F) D) and E)
G) A) and B)

Question 17

The rate constant of a first-order process that has a half-life of 3.50 min is __________ s-1.

Accepted Answer

A)  0.693
B)  1.65 × 10-2
C)  1.98
D)  .198
E)  3.30 × 10-3F) All of the above
G) B) and C)

Question 18

At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN) : CH3NC (g) → CH3CN (g) 
The reaction is first order in methylisonitrile. The attached graph shows data for the reaction obtained at 198.9°C. 3NC) isomerizes to acetonitrile (CH3CN) : CH3NC (g) → CH3CN (g)  The reaction is first order in methylisonitrile. The attached graph shows data for the reaction obtained at 198.9°C.   The rate constant for the reaction is __________ s-1. A) -1.9 × 104 B) +1.9 × 104 C) -5.2 × 10-5 D) +5.2 × 10-5 E) +6.2" class="answers-bank-image d-inline" rel="preload" > The rate constant for the reaction is __________ s-1.

Accepted Answer

A)  -1.9 × 104
B)  +1.9 × 104
C)  -5.2 × 10-5
D)  +5.2 × 10-5
E)  +6.2F) B) and D)
G) A) and B) D

Question 19

If a rate law is second order (reactant), doubling the reactant __________ the reaction rate.

Accepted Answer

The answer of If a rate law is second order...

Question 20

Under constant conditions, the half-life of a first-order reaction __________.

Accepted Answer

A)  is the time necessary for the reactant concentration to drop to half its original value
B)  is constant
C)  can be calculated from the reaction rate constant
D)  does not depend on the initial reactant concentration
E)  All of the above are correct.F) A) and C)
G) B) and E)

Exam 14: Chemical Kinetics

Which of the following is true?

Correct AnswerverifiedShow Answer

A catalyst that is present in the same phase as the reacting molecules is called a __________ catalyst.

Correct Answerverifiedhomogeneous

The average rate of disappearance of I- between 1200.0 s and 1600.0 s is __________ M/s.

Correct AnswerverifiedShow Answer

The isomerization of methylisonitrile to acetonitrile CH3NC (g) → CH3CN (g) Is first order in CH3NC. The rate constant for the reaction is 9.45 × 10-5s-1 at 478 K. The half-life of the reaction when the initial [CH3NC] is 0.030 M is __________ s.

Correct AnswerverifiedShow Answer

The rate constant for a particular second-order reaction is 0.47M-1s-1. If the initial concentration of reactant is 0.25 mol/L, it takes __________ s for the concentration to decrease to 0.080 mol/L.

Correct AnswerverifiedShow Answer

Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction: 2NO2 → 2NO + O2 In a particular experiment at 300 °C, [NO2] drops from 0.0100 to 0.00650 M in 100 s. The rate of disappearance of NO2 for this period is __________ M/s.

Correct AnswerverifiedShow Answer

The enzyme nitrogenase converts __________ into __________.

Correct AnswerverifiedShow Answer

The rate of disappearance of HBr in the gas phase reaction 2HBr (g) → H2 (g) + Br2 (g) Is 0.130 Ms-1 at 150°C. The rate of reaction is __________ Ms-1.

Correct AnswerverifiedShow Answer

The half-life of this reaction is __________ s.

Correct AnswerverifiedShow Answer

A possible mechanism for the overall reaction Br2 (g) + 2NO (g) → 2NOBr (g) Is NO (g) + Br2 (g) NOBr2 (g) (fast) NOBr2 (g) + NO (g) 2NOBr (slow) The rate law for formation of NOBr based on this mechanism is rate = __________.

Correct AnswerverifiedC

What is the magnitude of the rate constant for the reaction?

Correct AnswerverifiedShow Answer

Which substance in the reaction below either appears or disappears the fastest? 4NH3 + 7O2 → 4NO2 + 6H2O

Correct AnswerverifiedShow Answer

Consider the following reaction: A → 2C The average rate of appearance of C is given by Δ[C]/Δt. Comparing the rate of appearance of C and the rate of disappearance of A, we get Δ[C]/Δt = __________ × (-Δ[A]/Δt) .

Correct AnswerverifiedShow Answer

The reaction below is first order in [H2O2]: 2H2O2 (l) → 2H2O (l) + O2 (g) A solution originally at 0.600 M H2O2 is found to be 0.075 M after 54 min. The half-life for this reaction is __________ min.

Correct AnswerverifiedShow Answer

The elementary reaction 2NO2 (g) → 2NO (g) + O2 (g) Is second order in NO2 and the rate constant at 501 K is 7.93 × 10-3M-1s-1. The reaction half-life at this temperature when [NO2]0= 0.45 M is __________ s.

Correct AnswerverifiedShow Answer

The average rate disappearance of A between 20 s and 30 s is __________ mol/s.

Correct AnswerverifiedShow Answer

The rate constant of a first-order process that has a half-life of 3.50 min is __________ s-1.

Correct AnswerverifiedShow Answer

At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN) : CH3NC (g) → CH3CN (g) The reaction is first order in methylisonitrile. The attached graph shows data for the reaction obtained at 198.9°C. The rate constant for the reaction is __________ s-1.

Correct AnswerverifiedD

If a rate law is second order (reactant), doubling the reactant __________ the reaction rate.

Correct AnswerverifiedShow Answer

Under constant conditions, the half-life of a first-order reaction __________.

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified
homogeneous

The average rate of disappearance of I^- between 1200.0 s and 1600.0 s is __________ M/s.

Correct Answer
verified

The isomerization of methylisonitrile to acetonitrile CH₃NC (g) → CH₃CN (g) Is first order in CH₃NC. The rate constant for the reaction is 9.45 × 10^-5s^-1 at 478 K. The half-life of the reaction when the initial [CH₃NC] is 0.030 M is __________ s.

Correct Answer
verified

The rate constant for a particular second-order reaction is 0.47M^-1s^-1. If the initial concentration of reactant is 0.25 mol/L, it takes __________ s for the concentration to decrease to 0.080 mol/L.

Correct Answer
verified

Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction: 2NO₂ → 2NO + O₂ In a particular experiment at 300 °C, [NO₂] drops from 0.0100 to 0.00650 M in 100 s. The rate of disappearance of NO₂ for this period is __________ M/s.

Correct Answer
verified

The enzyme nitrogenase converts into .

Correct Answer
verified

The rate of disappearance of HBr in the gas phase reaction 2HBr (g) → H₂ (g) + Br₂ (g) Is 0.130 Ms^-1 at 150°C. The rate of reaction is __________ Ms^-1.

Correct Answer
verified

Correct Answer
verified

A possible mechanism for the overall reaction Br₂ (g) + 2NO (g) → 2NOBr (g) Is NO (g) + Br₂ (g) NOBr₂ (g) (fast) NOBr₂ (g) + NO (g) 2NOBr (slow) The rate law for formation of NOBr based on this mechanism is rate = __________.

Correct Answer
verified
C

Correct Answer
verified

Which substance in the reaction below either appears or disappears the fastest? 4NH₃ + 7O₂ → 4NO₂ + 6H₂O

Correct Answer
verified

Correct Answer
verified

The reaction below is first order in [H₂O₂]: 2H₂O₂ (l) → 2H₂O (l) + O₂ (g) A solution originally at 0.600 M H₂O₂ is found to be 0.075 M after 54 min. The half-life for this reaction is __________ min.

Correct Answer
verified

The elementary reaction 2NO₂(g) → 2NO (g) + O₂ (g) Is second order in NO₂ and the rate constant at 501 K is 7.93 × 10^-³M^-1s^-1. The reaction half-life at this temperature when [NO₂]0= 0.45 M is __________ s.

Correct Answer
verified

Correct Answer
verified

The rate constant of a first-order process that has a half-life of 3.50 min is __________ s^-1.

Correct Answer
verified

At elevated temperatures, methylisonitrile (CH₃NC) isomerizes to acetonitrile (CH₃CN) : CH₃NC (g) → CH₃CN (g) The reaction is first order in methylisonitrile. The attached graph shows data for the reaction obtained at 198.9°C. The rate constant for the reaction is __________ s^-1.

Correct Answer
verified
D

Correct Answer
verified

Correct Answer
verified