Question 1

Explain the concepts of a mechanism and a rate-determining step in a chemical reaction.

Accepted Answer

A reaction mechanism is the exact molecular pathway that starting materials follow on their way to becoming products. The overall reaction is the sum of the elementary steps in the mechanism. The rate-determining step is the slowest step in the reaction mechanism. The overall reaction cannot go faster than the rate-determining step.

Question 2

The reaction of ozone with oxygen atoms to produce molecular oxygen has a rate constant of 4.8x106 1/M s at 25oC. A 20 degree increase in temperature results in a rate constant of 7.4x106 1/M s. What is the rate constant at 100oC?

Accepted Answer

1.9x10⁷ 1/M s

Question 3

Determine rate laws from concentration versus time data.

Accepted Answer

Rate laws must be determined from experimental data. The half-life of a first-order reaction is a constant. The half-life of a second-order reaction depends on the initial concentration.

Question 4

A proposed mechanism for the following reaction, A2 + B2 $\rightarrow$ 2AB, isA2   2AA + B2 $\rightarrow$AB + B slowB +A2 $\rightarrow$AB + ADetermine the rate law.

Accepted Answer

rate = k [A₂

Question 5

Nitrous oxide, N2O, decomposes on metal surfaces readily at high temperatures following first-order kinetics for the equation:
2 N2O (g)  $\rarr$  2 N2 (g) + O2 (g)
The following data are obtained for a reaction at 850°C:   What was the initial concentration of N2O (t = 0)?

Accepted Answer

A)  0.0885 M 
B)  0.0940 M 
C)  0.101 M 
D)  0.112 M 
E)  0.123 M 
A)  0.0885 M 
B)  0.0940 M 
C)  0.101 M 
D)  0.112 M 
E)  0.123 M

Question 6

The rate of a reaction

Accepted Answer

A)  increases with the concentration of reactants. 
B)  decreases with the concentration of reactants. 
C)  is independent of concentration. 
D)  is a function of reaction stoichiometry. 
E)  cannot be determined based on the balanced chemical reaction. 
A)  increases with the concentration of reactants. 
B)  decreases with the concentration of reactants. 
C)  is independent of concentration. 
D)  is a function of reaction stoichiometry. 
E)  cannot be determined based on the balanced chemical reaction.

Question 7

The following reaction takes place at 80.1°C:
Ru(NH3)5Cl2+ (aq) + H2O (l)  $\rarr$ Ru(NH3)5(H2O)3+ (aq) + Cl- (aq)
The following time and concentration data are collected:   Which of the following is the correct value of the rate constant?

Accepted Answer

A)  3.28 1/M•s 
B)  4.19 1/s 
C)  419 1/s 
D)  328 1/M•s 
E)  328 1/s 
A)  3.28 1/M•s 
B)  4.19 1/s 
C)  419 1/s 
D)  328 1/M•s 
E)  328 1/s

Question 8

Trioxane undergoes decomposition to formaldehyde at elevated temperatures.C3H6O3 (g) $\rightarrow$3 CH2O (g)The following data was collected for the gas phase reaction at 519ºK:   Determine the order of the decomposition in trioxane and the rate constant at 519ºK.

Accepted Answer

1st order

Question 9

You are running late for a basketball game on your campus and you are thinking about what will be the rate determining step for attending the basketball game? Which of the following will be your rate determining step?

Accepted Answer

A)  purchasing a ticket 
B)  locating a seat in the stands 
C)  walking/driving to the game 
D)  waiting for the players to arrive 
E)  giving your ticket to the doorman 
A)  purchasing a ticket 
B)  locating a seat in the stands 
C)  walking/driving to the game 
D)  waiting for the players to arrive 
E)  giving your ticket to the doorman

Question 10

The following are initial rate data for 2 NO + 2 H2 $\rightarrow$ N2 + 2 H2O   The rate law is determined to be: rate = k[NO]2[H2]. With this information determine k using the data from experiment 2.

Accepted Answer

k = 13.75

Question 11

Butadiene reacts to form its dimmer according to the following reaction:   Concentration versus time data were collected for this reaction and a plot of 1/[C4H6] resulted in a straight line with slope 6.14 x10-2 M s-1. The integrated for of the rate law is

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 12

The industrial production of 2-propanol involves the reaction of propene with sulphuric acid and then water. Write the second step of the mechanism if the following is the first step:

Accepted Answer

The answer of The industrial production of 2-propanol involves the...

Question 13

The reaction of ozone with oxygen atoms to give oxygen has an activation energy of 17.1 kJ/mole with a rate constant at 298oK, k = 4.8 x 106 1/M•s. Calculate the rate constant for this reaction at 315oK.

Accepted Answer

Question 14

Consider the aqueous phase reaction between the dichromate anion and iron (II) cations:14 H3O+(aq) + Cr2O72- + 6Fe2+(aq)  $\rarr$ 2Cr3+(aq) + 21H2OWhat is the reaction rate expressed in terms of changing H3O+ concentration?

Accepted Answer

A)  Reaction rate =   
B)  Reaction rate = -   
C)  Reaction rate = -   
D)  Reaction rate =   
A)  Reaction rate =   
B)  Reaction rate = -   
C)  Reaction rate = -   
D)  Reaction rate =

Question 15

Determine the rate law, given the mechanism and knowledge of the relative rates of steps of a reaction.

Accepted Answer

A reaction rate depends on the

Question 16

Assume that the following first-order reaction has a rate constant k = 0.0137/min:
SO2Cl2 $\rightarrow$ SO2 + Cl2
Given the initial [SO2Cl2] = 0.42 M, how many minutes will it take for [SO2Cl2] = 0.19 M?

Accepted Answer

The answer of Assume that the following first-order reaction has...

Question 17

Consider the aqueous phase reaction between hydrogen gas and liquid bromine:H2(g) + Br2(g) $\rarr$ 2HBr(g)Which of the following expressions accurately express the rate of the above reaction?
I. Reaction rate =  
II. Reaction rate =  
III. Reaction rate =  
IV. Reaction rate =

Accepted Answer

A)  I and III 
B)  I and II 
C)  II and IV 
D)  III and IV 
E)  I only 
A)  I and III 
B)  I and II 
C)  II and IV 
D)  III and IV 
E)  I only

Question 18

The rate constant of the reaction, O (g) + N2 (g) $\rightarrow$NO (g) + N (g), is 9.7 x 10101/M•s at 800oK and has an activation energy of 315 kJ/mole. What is the value of the rate constant at 700oK?

Accepted Answer

k(70

Question 19

The following rate constants were obtained at the stated temperatures for the first-order reaction:A$\rightarrow$ B   Find the activation energy (in kJ/mole) for this reaction.

Accepted Answer

The answer of The following rate constants were obtained at...

Question 20

It has been suggested that the decomposition of NO2 occurs via the following mechanism:
NO2  $\rarr$  NO + O (Rxn I)
O + NO2  $\rarr$ 2NO + O2  (Rxn II)
Predict the rate determining step.

Accepted Answer

A)  Rxn II; this reaction is bimolecular, bimolecular reactions are always slower than unimolecular reactions. 
B)  Rxn I; unimolecular reactions are always slower than bimolecular reactions. 
C)  Rxn I; O is highly reactive and thus Rxn II will be very fast. 
D)  Rxn II; NO2 is highly reactive and thus Rxn I will be very fast. 
E)  Rxn I and II are both elementary reactions and will proceed at equal rates. 
A)  Rxn II; this reaction is bimolecular, bimolecular reactions are always slower than unimolecular reactions. 
B)  Rxn I; unimolecular reactions are always slower than bimolecular reactions. 
C)  Rxn I; O is highly reactive and thus Rxn II will be very fast. 
D)  Rxn II; NO2 is highly reactive and thus Rxn I will be very fast. 
E)  Rxn I and II are both elementary reactions and will proceed at equal rates.

Explain the concepts of a mechanism and a rate-determining step in a chemical reaction.

The reaction of ozone with oxygen atoms to produce molecular oxygen has a rate constant of 4.8x10⁶1/M s at 25^oC. A 20 degree increase in temperature results in a rate constant of 7.4x10⁶1/M s. What is the rate constant at 100^oC?

Determine rate laws from concentration versus time data.

The rate of a reaction

You are running late for a basketball game on your campus and you are thinking about what will be the rate determining step for attending the basketball game? Which of the following will be your rate determining step?

Butadiene reacts to form its dimmer according to the following reaction: Concentration versus time data were collected for this reaction and a plot of 1/[C₄H₆] resulted in a straight line with slope 6.14 x10^-2 M s^-1. The integrated for of the rate law is

The industrial production of 2-propanol involves the reaction of propene with sulphuric acid and then water. Write the second step of the mechanism if the following is the first step:

The reaction of ozone with oxygen atoms to give oxygen has an activation energy of 17.1 kJ/mole with a rate constant at 298^oK, k = 4.8 x 10⁶ 1/M•s. Calculate the rate constant for this reaction at 315^oK.

Consider the aqueous phase reaction between the dichromate anion and iron (II) cations:14 H₃O⁺(aq) + Cr₂O₇^2-+ 6Fe²⁺(aq) $\rarr$ 2Cr³⁺(aq) + 21H₂OWhat is the reaction rate expressed in terms of changing H₃O⁺concentration?

Determine the rate law, given the mechanism and knowledge of the relative rates of steps of a reaction.

Assume that the following first-order reaction has a rate constant k = 0.0137/min: SO₂Cl₂ $\rightarrow$ SO₂ + Cl₂ Given the initial [SO₂Cl₂] = 0.42 M, how many minutes will it take for [SO₂Cl₂] = 0.19 M?

The rate constant of the reaction, O (g) + N₂ (g) $\rightarrow$ NO (g) + N (g), is 9.7 x 10¹⁰1/M•s at 800^oK and has an activation energy of 315 kJ/mole. What is the value of the rate constant at 700^oK?

It has been suggested that the decomposition of NO₂ occurs via the following mechanism: NO₂ $\rarr$ NO + O (Rxn I) O + NO₂ $\rarr$ 2NO + O₂(Rxn II) Predict the rate determining step.

Fundamental Concepts of Chemistry

The Behaviour of Gases

Energy and Its Conservation

Atoms and Light

Atomic Energies and Periodicity

Fundamentals of Chemical Bonding

Theories of Chemical Bonding

Effects of Intermolecular Forces

Properties of Solutions

Organic Chemistrystructure

Organic Chemistryreactions

Spontaneity of Chemical Processes

Principles of Chemical Equilibrium

Aqueous Acidbase Equilibria

Applications of Aqueous Equilibria

Electron Transfer Reactions

Macromolecules

The Transition Metals

The Main Group Elements

Nuclear Chemistry and Radiochemistry

Filters

Exam 13: Kinetics: Mechanisms and Rates of Reactions

Explain the concepts of a mechanism and a rate-determining step in a chemical reaction.

The reaction of ozone with oxygen atoms to produce molecular oxygen has a rate constant of 4.8x106 1/M s at 25oC. A 20 degree increase in temperature results in a rate constant of 7.4x106 1/M s. What is the rate constant at 100oC?

Determine rate laws from concentration versus time data.

A proposed mechanism for the following reaction, A2 + B2 →\rightarrow→ 2AB, isA2 2AA + B2 →\rightarrow→ AB + B slowB +A2 →\rightarrow→ AB + ADetermine the rate law.

Nitrous oxide, N2O, decomposes on metal surfaces readily at high temperatures following first-order kinetics for the equation: 2 N2O (g) →\rarr→ 2 N2 (g) + O2 (g) The following data are obtained for a reaction at 850°C: What was the initial concentration of N2O (t = 0)?

The rate of a reaction

The following reaction takes place at 80.1°C: Ru(NH3)5Cl2+ (aq) + H2O (l) →\rarr→ Ru(NH3)5(H2O)3+ (aq) + Cl- (aq) The following time and concentration data are collected: Which of the following is the correct value of the rate constant?

Trioxane undergoes decomposition to formaldehyde at elevated temperatures.C3H6O3 (g) →\rightarrow→ 3 CH2O (g)The following data was collected for the gas phase reaction at 519ºK: Determine the order of the decomposition in trioxane and the rate constant at 519ºK.

You are running late for a basketball game on your campus and you are thinking about what will be the rate determining step for attending the basketball game? Which of the following will be your rate determining step?

The following are initial rate data for 2 NO + 2 H2 →\rightarrow→ N2 + 2 H2O The rate law is determined to be: rate = k[NO]2[H2]. With this information determine k using the data from experiment 2.

Butadiene reacts to form its dimmer according to the following reaction: Concentration versus time data were collected for this reaction and a plot of 1/[C4H6] resulted in a straight line with slope 6.14 x10-2 M s-1. The integrated for of the rate law is

The industrial production of 2-propanol involves the reaction of propene with sulphuric acid and then water. Write the second step of the mechanism if the following is the first step:

The reaction of ozone with oxygen atoms to give oxygen has an activation energy of 17.1 kJ/mole with a rate constant at 298oK, k = 4.8 x 106 1/M•s. Calculate the rate constant for this reaction at 315oK.

Consider the aqueous phase reaction between the dichromate anion and iron (II) cations:14 H3O+(aq) + Cr2O72- + 6Fe2+(aq) →\rarr→ 2Cr3+(aq) + 21H2OWhat is the reaction rate expressed in terms of changing H3O+ concentration?

Determine the rate law, given the mechanism and knowledge of the relative rates of steps of a reaction.

Assume that the following first-order reaction has a rate constant k = 0.0137/min: SO2Cl2 →\rightarrow→ SO2 + Cl2 Given the initial [SO2Cl2] = 0.42 M, how many minutes will it take for [SO2Cl2] = 0.19 M?

Consider the aqueous phase reaction between hydrogen gas and liquid bromine:H2(g) + Br2(g) →\rarr→ 2HBr(g)Which of the following expressions accurately express the rate of the above reaction? I. Reaction rate = II. Reaction rate = III. Reaction rate = IV. Reaction rate =

The rate constant of the reaction, O (g) + N2 (g) →\rightarrow→ NO (g) + N (g), is 9.7 x 10101/M•s at 800oK and has an activation energy of 315 kJ/mole. What is the value of the rate constant at 700oK?

The following rate constants were obtained at the stated temperatures for the first-order reaction:A →\rightarrow→ B Find the activation energy (in kJ/mole) for this reaction.

It has been suggested that the decomposition of NO2 occurs via the following mechanism: NO2 →\rarr→ NO + O (Rxn I) O + NO2 →\rarr→ 2NO + O2 (Rxn II) Predict the rate determining step.

Fundamental Concepts of Chemistry

The Behaviour of Gases

Energy and Its Conservation

Atoms and Light

Atomic Energies and Periodicity

Fundamentals of Chemical Bonding

Theories of Chemical Bonding

Effects of Intermolecular Forces

Properties of Solutions

Organic Chemistrystructure

Organic Chemistryreactions

Spontaneity of Chemical Processes

Principles of Chemical Equilibrium

Aqueous Acidbase Equilibria

Applications of Aqueous Equilibria

Electron Transfer Reactions

Macromolecules

The Transition Metals

The Main Group Elements

Nuclear Chemistry and Radiochemistry

Filters

The reaction of ozone with oxygen atoms to produce molecular oxygen has a rate constant of 4.8x10⁶1/M s at 25^oC. A 20 degree increase in temperature results in a rate constant of 7.4x10⁶1/M s. What is the rate constant at 100^oC?

Butadiene reacts to form its dimmer according to the following reaction: Concentration versus time data were collected for this reaction and a plot of 1/[C₄H₆] resulted in a straight line with slope 6.14 x10^-2 M s^-1. The integrated for of the rate law is

The reaction of ozone with oxygen atoms to give oxygen has an activation energy of 17.1 kJ/mole with a rate constant at 298^oK, k = 4.8 x 10⁶ 1/M•s. Calculate the rate constant for this reaction at 315^oK.

Consider the aqueous phase reaction between the dichromate anion and iron (II) cations:14 H₃O⁺(aq) + Cr₂O₇^2-+ 6Fe²⁺(aq) $\rarr$ 2Cr³⁺(aq) + 21H₂OWhat is the reaction rate expressed in terms of changing H₃O⁺concentration?

Assume that the following first-order reaction has a rate constant k = 0.0137/min: SO₂Cl₂ $\rightarrow$ SO₂ + Cl₂ Given the initial [SO₂Cl₂] = 0.42 M, how many minutes will it take for [SO₂Cl₂] = 0.19 M?

The rate constant of the reaction, O (g) + N₂ (g) $\rightarrow$ NO (g) + N (g), is 9.7 x 10¹⁰1/M•s at 800^oK and has an activation energy of 315 kJ/mole. What is the value of the rate constant at 700^oK?

It has been suggested that the decomposition of NO₂ occurs via the following mechanism: NO₂ $\rarr$ NO + O (Rxn I) O + NO₂ $\rarr$ 2NO + O₂(Rxn II) Predict the rate determining step.