Question 1

Is a bimolecular reaction necessarily second-order? Is a second-order reaction necessarily bimolecular? Answer, with explanations and clarifications.

Accepted Answer

For elementary reactions, the order foll...

Question 2

A reaction has the following rate law: Rate = k[A][B]2 In experiment 1, the concentrations of A and B are both 0.10 mol L¯1; in experiment 2, the concentrations are both 0.30 mol L¯1. If the temperature stays constant, what is the value of the ratio, Rate(2) /Rate(1) ?

Accepted Answer

A)   3.0
B)   6.0
C)   9.0
D)   18
E)   27F) A) and E)
G) A) and C)

Question 3

According to the collision theory of reaction rates, what are the three requirements which must be met before an elementary reaction between two molecules can occur?

Accepted Answer

Molecules must collide with ea...

Question 4

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

Question 5

Briefly outline the key arguments in the collision theory of reaction rates for the elementary reaction  products. Show that this theory predicts a second-order rate law, and how it predicts the form of the rate constant k.

Accepted Answer

For reaction to occur, the molecules mus...

Question 6

The rate law for the reaction 3A  →\rightarrow→  C is Rate = 4.36 *10¯2 L mol¯1 hr¯1[A]2 What is the half-life for the reaction if the initial concentration of A is 0.250 M?

Accepted Answer

A)   0.0109 hr
B)   0.0629 hr
C)   15.9 hr
D)   23.9 hr
E)   91.7 hr F) A) and B)
G) A) and C)

Question 7

A transition state is a species (or state) corresponding to an energy maximum on a reaction energy diagram.

Accepted Answer

A) True 
 B)False

Question 8

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 *1020 molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

Accepted Answer

A)   1.00 * 104 molecules
B)   2.00 * 1019 molecules
C)   3.20 *1016 molecules
D)   5.00 * 1020 molecules
E)   None of these choices is correct.F) All of the above
G) A) and B)

Question 9

The radioactive isotope tritium decays with a first-order rate constant k of 0.056 year¯1. What fraction of the tritium initially in a sample is still present 30 years later?

Accepted Answer

A)   0.19
B)   0.60
C)   0.15
D)   2.8 *10¯38
E)   None of these choices is correct.F) A) and E)
G) A) and B)

Question 10

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¯1s¯1. What is the rate law for this reaction?

Accepted Answer

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

Question 11

For the reaction 2A + B + 2C →\rightarrow→  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 is 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 is correct. F) None of the above
G) A) and E)

Question 12

If the activation energy of a reaction decreases by 10.0 kJ/mol, from 100.0 to 90.0 kJ/mol, what effect will this have on the rate of reaction at 298K?

Accepted Answer

A)   The rate will increase, by a factor of more than 50.
B)   The rate will decrease, by a factor of more than 50.
C)   The rate will increase, by a factor of less than 50.
D)   The rate will decrease, by a factor of less than 50.
E)   The rate will not change unless temperature changes.F) A) and D)
G) A) and C)

Question 13

For each of the following terms/concepts, give a brief explanation or definition. Where possible, use examples.
A) order of a reaction
B) elementary reaction
C) reaction intermediate

Accepted Answer

a. Order refers to the power to which th...

Question 14

Dinitrogen tetraoxide, N2O4, decomposes to nitrogen dioxide, NO2, in a first-order process. If k = 2.5 * 103 s¯1 at -5 °\degree° C and k = 3.5 * 104 s¯1 at 25 °\degree° 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/mol F) None of the above
G) B) and D)

Question 15

An elementary reaction is a simple, one-step process.

Accepted Answer

A) True 
 B)False

Question 16

Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. 2O2][H+]2[Br¯] B)  Rate = k [H2O+     OH][Br¯] C)  Rate = k[H2O2][H+][Br¯] D)  Rate = k[HOBr][H+][Br¯][H2O2] E)  Rate = k[Br¯]" class="answers-bank-image d-inline" rel="preload" > Which of the following rate laws is consistent with the mechanism?

Accepted Answer

A)   Rate = k[H2O2][H+]2[Br¯]
B)   Rate = k [H2O+  2O2][H+]2[Br¯] 
B)   Rate = k [H2O+     OH][Br¯] 
C)   Rate = k[H2O2][H+][Br¯] 
D)   Rate = k[HOBr][H+][Br¯][H2O2] 
E)   Rate = k[Br¯]" class="answers-bank-image d-inline" rel="preload" > OH][Br¯]
C)   Rate = k[H2O2][H+][Br¯]
D)   Rate = k[HOBr][H+][Br¯][H2O2]
E)   Rate = k[Br¯]F) A) and E)
G) C) and E)

Question 17

A reaction is first-order with respect to the reactant R. Which of the following plots will produce a straight line?

Accepted Answer

A)   [R] vs. 1/time
B)   1/[R] vs. time
C)   [R]2 vs. time
D)   1/[R]2 vs. time
E)   ln[R] vs. timeF) D) and E)
G) None of the above

Question 18

The compound RX3 decomposes according to the equation 3RX3  →\rightarrow→  R + R2X3 + 3X2
In an experiment the following data were collected for the decomposition at 100 °\degree° C. What is the average rate of reaction over the entire experiment? 3 decomposes according to the equation 3RX3  \rightarrow  R + R2X3 + 3X2 In an experiment the following data were collected for the decomposition at 100 \degree C. What is the average rate of reaction 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¯1 F) B) and E)
G) A) and B)

Question 19

(p. Various sections)  The gas-phase reaction 3NC]/ \Delta t = k[CH3NC]. Which one of the following actions is least likely to cause a change in the rate of the reaction? A)  lowering the temperature B)  adding a catalyst C)  using a larger initial amount of CH3NC in the same vessel D)  using a bigger vessel, but the same initial amount of CH3NC E)  continuously removing CH3CN as it is formed " class="answers-bank-image d-inline" rel="preload" > has been studied in a closed vessel, and the rate equation was found to be: Rate = - Δ\DeltaΔ [CH3NC]/ Δ\DeltaΔ t = k[CH3NC]. Which one of the following actions is least likely to cause a change in the rate of the reaction?

Accepted Answer

A)   lowering the temperature
B)   adding a catalyst
C)   using a larger initial amount of CH3NC in the same vessel
D)   using a bigger vessel, but the same initial amount of CH3NC
E)   continuously removing CH3CN as it is formed F) A) and C)
G) None of the above

Question 20

The rate law for the rearrangement of CH3NC to CH3CN at 800 K is Rate = (1300 s¯1) [CH3NC]. What is the half-life for this reaction?

Accepted Answer

A)   7.69 * 10¯4 s
B)   5.3* 10¯4 s
C)   1.9 * 10¯3 s
D)   520 s
E)   1920 sF) All of the above
G) A) and C)

Exam 16: Kinetics: Rates and Mechanisms of Chemical Reactions

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

Correct Answer
verified

An elementary reaction is a simple, one-step process.

Correct Answer
verified

A reaction has the following rate law: Rate = k[A][B]² In experiment 1, the concentrations of A and B are both 0.10 mol L^¯1; in experiment 2, the concentrations are both 0.30 mol L^¯1. If the temperature stays constant, what is the value of the ratio, Rate(2) /Rate(1) ?

Correct Answer
verified

A reaction is first-order with respect to the reactant R. Which of the following plots will produce a straight line?

Correct Answer
verified

For each of the following terms/concepts, give a brief explanation or definition. Where possible, use examples. A) order of a reaction B) elementary reaction C) reaction intermediate

Correct Answer
verified
a. Order refers to the power to which th...
View Answer

A transition state is a species (or state) corresponding to an energy maximum on a reaction energy diagram.

Correct Answer
verified

Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. Which of the following rate laws is consistent with the mechanism?

Correct Answer
verified

Is a bimolecular reaction necessarily second-order? Is a second-order reaction necessarily bimolecular? Answer, with explanations and clarifications.

Correct Answer
verified
For elementary reactions, the order foll...
View Answer

Correct Answer
verified

In an exothermic reaction,

Correct Answer
verified

Correct Answer
verified

Briefly outline the key arguments in the collision theory of reaction rates for the elementary reaction products. Show that this theory predicts a second-order rate law, and how it predicts the form of the rate constant k.

Correct Answer
verified
For reaction to occur, the molecules mus...
View Answer

If the activation energy of a reaction decreases by 10.0 kJ/mol, from 100.0 to 90.0 kJ/mol, what effect will this have on the rate of reaction at 298K?

Correct Answer
verified

The rate law for the reaction 3A $\rightarrow$ C is Rate = 4.36 *10¯² L mol¯¹ hr¯¹[A]² What is the half-life for the reaction if the initial concentration of A is 0.250 M?

Correct Answer
verified

According to the collision theory of reaction rates, what are the three requirements which must be met before an elementary reaction between two molecules can occur?

Correct Answer
verified
Molecules must collide with ea...
View Answer

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 *10²⁰ molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

Correct Answer
verified

The rate law for the rearrangement of CH₃NC to CH₃CN at 800 K is Rate = (1300 s¯¹) [CH₃NC]. What is the half-life for this reaction?

Correct Answer
verified

Correct Answer
verified

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¯¹s¯¹. What is the rate law for this reaction?

Correct Answer
verified

The radioactive isotope tritium decays with a first-order rate constant k of 0.056 year¯¹. What fraction of the tritium initially in a sample is still present 30 years later?

Correct Answer
verified

Exam 16: Kinetics: Rates and Mechanisms of Chemical Reactions

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

Correct AnswerverifiedShow Answer

An elementary reaction is a simple, one-step process.

Correct AnswerverifiedShow Answer

A reaction has the following rate law: Rate = k[A][B]2 In experiment 1, the concentrations of A and B are both 0.10 mol L¯1; in experiment 2, the concentrations are both 0.30 mol L¯1. If the temperature stays constant, what is the value of the ratio, Rate(2) /Rate(1) ?

Correct AnswerverifiedShow Answer

A reaction is first-order with respect to the reactant R. Which of the following plots will produce a straight line?

Correct AnswerverifiedShow Answer

For each of the following terms/concepts, give a brief explanation or definition. Where possible, use examples. A) order of a reaction B) elementary reaction C) reaction intermediate

Correct Answerverifieda. Order refers to the power to which th...View AnswerShow Answer

A transition state is a species (or state) corresponding to an energy maximum on a reaction energy diagram.

Correct AnswerverifiedShow Answer

Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. Which of the following rate laws is consistent with the mechanism?

Correct AnswerverifiedShow Answer

Is a bimolecular reaction necessarily second-order? Is a second-order reaction necessarily bimolecular? Answer, with explanations and clarifications.

Correct AnswerverifiedFor elementary reactions, the order foll...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

In an exothermic reaction,

Correct AnswerverifiedShow Answer

(p. Various sections) The gas-phase reaction has been studied in a closed vessel, and the rate equation was found to be: Rate = - Δ\DeltaΔ [CH3NC]/ Δ\DeltaΔ t = k[CH3NC]. Which one of the following actions is least likely to cause a change in the rate of the reaction?

Correct AnswerverifiedShow Answer

Briefly outline the key arguments in the collision theory of reaction rates for the elementary reaction products. Show that this theory predicts a second-order rate law, and how it predicts the form of the rate constant k.

Correct AnswerverifiedFor reaction to occur, the molecules mus...View AnswerShow Answer

If the activation energy of a reaction decreases by 10.0 kJ/mol, from 100.0 to 90.0 kJ/mol, what effect will this have on the rate of reaction at 298K?

Correct AnswerverifiedShow Answer

The rate law for the reaction 3A →\rightarrow→ C is Rate = 4.36 *10¯2 L mol¯1 hr¯1[A]2 What is the half-life for the reaction if the initial concentration of A is 0.250 M?

Correct AnswerverifiedShow Answer

According to the collision theory of reaction rates, what are the three requirements which must be met before an elementary reaction between two molecules can occur?

Correct AnswerverifiedMolecules must collide with ea...View AnswerShow Answer

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 *1020 molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

Correct AnswerverifiedShow Answer

The rate law for the rearrangement of CH3NC to CH3CN at 800 K is Rate = (1300 s¯1) [CH3NC]. What is the half-life for this reaction?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow 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¯1s¯1. What is the rate law for this reaction?

Correct AnswerverifiedShow Answer

The radioactive isotope tritium decays with a first-order rate constant k of 0.056 year¯1. What fraction of the tritium initially in a sample is still present 30 years later?

Correct AnswerverifiedShow Answer

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

Correct Answer
verified

Correct Answer
verified

A reaction has the following rate law: Rate = k[A][B]² In experiment 1, the concentrations of A and B are both 0.10 mol L^¯1; in experiment 2, the concentrations are both 0.30 mol L^¯1. If the temperature stays constant, what is the value of the ratio, Rate(2) /Rate(1) ?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
a. Order refers to the power to which th...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
For elementary reactions, the order foll...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
For reaction to occur, the molecules mus...
View Answer

Correct Answer
verified

The rate law for the reaction 3A $\rightarrow$ C is Rate = 4.36 *10¯² L mol¯¹ hr¯¹[A]² What is the half-life for the reaction if the initial concentration of A is 0.250 M?

Correct Answer
verified

Correct Answer
verified
Molecules must collide with ea...
View Answer

A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 *10²⁰ molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes?

Correct Answer
verified

The rate law for the rearrangement of CH₃NC to CH₃CN at 800 K is Rate = (1300 s¯¹) [CH₃NC]. What is the half-life for this reaction?

Correct Answer
verified

Correct Answer
verified

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¯¹s¯¹. What is the rate law for this reaction?

Correct Answer
verified

The radioactive isotope tritium decays with a first-order rate constant k of 0.056 year¯¹. What fraction of the tritium initially in a sample is still present 30 years later?

Correct Answer
verified