Question 1

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. 
A)  3.8 × 10-3 s. 
B)  6.9 × 10-3 s. 
C)  68 s. 
D)  120 s. 
E)  130 s.

Question 2

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-1 
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-1

Question 3

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. 
A)  Reaction A 
B)  Reaction B 
C)  Reaction C 
D)  All of the reactions have the same rate.

Question 4

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

Accepted Answer

A) True 
 B)False

Question 5

A study of the decomposition reaction 3RX2 → 3R + 6X yields the following initial rates.   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-1 
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

Question 6

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

Accepted Answer

a. Reactions 2 and 3 are elementary.
b.

Question 7

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 s 
A)  110 s 
B)  27 s 
C)  62 s 
D)  130 s 
E)  22 s

Question 8

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?

Accepted Answer

A)  0.019 s-1 
B)  0.046 s-1 
C)  0.067 s-1  
D)  15 s-1 
E)  17 s-1 
A)  0.019 s-1 
B)  0.046 s-1 
C)  0.067 s-1  
D)  15 s-1 
E)  17 s-1

Question 9

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-1 
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-1

Question 10

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

Accepted Answer

A)  rate = k[A]t 
B)    
C)    
D)    
E)    
A)  rate = k[A]t 
B)    
C)    
D)    
E)

Question 11

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 energy 
A)  Collision energy 
B)  Effective collision energy 
C)  Reaction energy 
D)  Activation energy 
E)  Rate energy

Question 12

Enzymes are ________ .

Accepted Answer

A)  large carbohydrate molecules 
B)  also called substrates 
C)  usually heterogeneous catalysts 
D)  insensitive to temperature 
E)  biological catalysts 
A)  large carbohydrate molecules 
B)  also called substrates 
C)  usually heterogeneous catalysts 
D)  insensitive to temperature 
E)  biological catalysts

Question 13

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. 
A)  Zero 
B)  First 
C)  Second 
D)  Third 
E)  More information is needed to determine the order.

Question 14

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)    
A)    
B)  rate = +Δ[B]/Δt 
C)  rate = -Δ[C]/Δt 
D)  rate = -Δ[A]/Δt 
E)

Question 15

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/k 
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/k

Question 16

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/s 
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/s

Question 17

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 × 102min 
A)  2.2 × 10-3 min 
B)  5.5 × 10-3 min 
C)  180 min 
D)  440 min 
E)  5.0 × 102min

Question 18

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.

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-1 
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

Question 19

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. 
A)  Zero 
B)  First 
C)  Second 
D)  Third 
E)  More information is needed to determine the overall order.

Question 20

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] 
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]

Exam 14: Chemical Kinetics

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

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?

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?

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

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

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

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?

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?

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)

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

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

Enzymes are ________ .

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?

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

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

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?

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?

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.

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?

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?

Chemistry: the Central Science

Atoms, Molecules, and Ions

Stoichiometry: Ratios of Combination

Reactions in Aqueous Solutions

Thermochemistry

Quantum Theory and the Electronic Structure of Atoms

Electron Configuration and the Periodic Table

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Molecular Geometry and Bonding Theories

Gases

Intermolecular Forces and the Physical Properties of Liquids and Solids

Modern Materials

Physical Properties of Solutions

Chemical Equilibrium

Acids and Bases

Acid-Base Equilibria and Solubility Equilibria

Entropy, Free Energy, and Equilibrium

Electrochemistry

Nuclear Chemistry

Environmental Chemistry

Coordination Chemistry

Metallurgy and the Chemistry of Metals

Nonmetallic Elements and Their Compounds

Organic Chemistry

Filters

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

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?

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

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)

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?

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?

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?

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.

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?

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?