Question 1

For a reaction with a second order rate constant, the correct unit is M ∙ time-1.

Accepted Answer

A) True 
 B)False

Question 2

Why is rate = k[HgCl2] 2[C2O42-] not the rate law for the following mechanism? 2HgCl2 + C2O42- → 2Cl- + 2CO2 + Hg2Cl2 (overall reaction)
HgCl2 + C2O42- ⇌ HgCl2C2O42- (Fast)
HgCl2C2O42- + C2O42- → Hg + 2C2O4Cl2- (Slow)
Hg + HgCl2 → Hg2Cl2 (Fast)
2C2O4Cl2- → C2O42- + 2Cl- + 2CO2 (Fast)

Accepted Answer

A)  The rate law is not based on the slow step of the proposed mechanism. 
B)  The steps do not add to the overall reaction. 
C)  The rate law does not agree with the overall reaction. 
D)  The exponents of HgCl2 and C2O42- are not equal. 
E)  The first step is not the slow step. 
A)  The rate law is not based on the slow step of the proposed mechanism. 
B)  The steps do not add to the overall reaction. 
C)  The rate law does not agree with the overall reaction. 
D)  The exponents of HgCl2 and C2O42- are not equal. 
E)  The first step is not the slow step.

Question 3

If the half-life of a reaction depends on the concentration of the reactant, then the reaction cannot be ________ order.

Accepted Answer

A)  second 
B)  zero 
C)  first 
D)  third 
A)  second 
B)  zero 
C)  first 
D)  third

Question 4

Data for the reaction A + B → C are given below. Find the rate constant for this system.

Accepted Answer

A)  2.8 × 10-2 M-1s-1 
B)  2.8 × 10-2 Ms-1 
C)  2.8 × 10-2 M2s-1 
D)  1.7 × 10-3 M-1s-1 
E)  1.7 × 10-3 Ms-1 
A)  2.8 × 10-2 M-1s-1 
B)  2.8 × 10-2 Ms-1 
C)  2.8 × 10-2 M2s-1 
D)  1.7 × 10-3 M-1s-1 
E)  1.7 × 10-3 Ms-1

Question 5

Temperature has no effect on reaction rate.

Accepted Answer

A) True 
 B)False

Question 6

Which of the following statements is correct?

Accepted Answer

A)  A zero order reaction depends on the concentration of reactants. 
B)  A reaction rate cannot be calculated from the collision frequency alone. 
C)  The activated complex is a chemical species that can be isolated and analysed. 
D)  The number of collisions has no effect on the rate constant. 
E)  The orientation of a collision does not affect the rate constant. 
A)  A zero order reaction depends on the concentration of reactants. 
B)  A reaction rate cannot be calculated from the collision frequency alone. 
C)  The activated complex is a chemical species that can be isolated and analysed. 
D)  The number of collisions has no effect on the rate constant. 
E)  The orientation of a collision does not affect the rate constant.

Question 7

The first order reaction A → products has t1/2 = 150 sec. What percent of the sample remains unreacted after 300 sec?

Accepted Answer

A)  25% 
B)  50% 
C)  12.5% 
D)  0.0% 
E)  100% 
A)  25% 
B)  50% 
C)  12.5% 
D)  0.0% 
E)  100%

Question 8

For the reaction: 2N2O5(g) → 4NO2(g) + O2(g) the rate law is:   = k[N2O5] At 300 K, the half-life is 2.50 × 104 seconds and the activation energy is 103.3 kJ/mol. What is the half-life at 310 K?

Accepted Answer

A)  2.49 × 104 s 
B)  9.51 × 104 s 
C)  9.51 × 106 s 
D)  6.57 × 103 s 
E)  1.87× 10-1 s 
A)  2.49 × 104 s 
B)  9.51 × 104 s 
C)  9.51 × 106 s 
D)  6.57 × 103 s 
E)  1.87× 10-1 s

Question 9

Define activation energy.

Accepted Answer

A)  the difference between the energy of the products and reactants 
B)  the energy difference between the maximum energy of reaction and the energy of the products 
C)  the minimum total kinetic energy that molecules must bring to their collisions for a chemical reaction to occur 
D)  the total kinetic energy of molecules in collisions 
E)  the total kinetic energy of molecules in a system 
A)  the difference between the energy of the products and reactants 
B)  the energy difference between the maximum energy of reaction and the energy of the products 
C)  the minimum total kinetic energy that molecules must bring to their collisions for a chemical reaction to occur 
D)  the total kinetic energy of molecules in collisions 
E)  the total kinetic energy of molecules in a system

Question 10

Which of the following lowers the activation energy of a reaction?

Accepted Answer

A)  adding reactants 
B)  lowering the temperature 
C)  removing products 
D)  adding a catalyst 
E)  raising the temperature 
A)  adding reactants 
B)  lowering the temperature 
C)  removing products 
D)  adding a catalyst 
E)  raising the temperature

Question 11

Activation energy is:

Accepted Answer

A)  energy at the bottom of the reaction curve 
B)  the heat energy in Joules required to break the bonds in one reactant 
C)  an energy that a catalyst brings to the system to activate one of the reactants 
D)  the kinetic energy of solution stirring that brings the reaction to start 
E)  minimum kinetic energy that molecules must bring to their collisions for a chemical reaction to occur 
A)  energy at the bottom of the reaction curve 
B)  the heat energy in Joules required to break the bonds in one reactant 
C)  an energy that a catalyst brings to the system to activate one of the reactants 
D)  the kinetic energy of solution stirring that brings the reaction to start 
E)  minimum kinetic energy that molecules must bring to their collisions for a chemical reaction to occur

Question 12

For the reaction: 2N2O5(g) → 4NO2(g) + O2(g) at the time when N2O5 is being consumed at a rate of -1.2 × 10-4 M/s, what is the rate at which O2 is being formed?

Accepted Answer

A)  1.2 × 10-4 M/s 
B)  2.4 × 10-4 M/s 
C)  6.0 × 10-5 M/s 
D)  3.0 × 10-5 M/s 
E)  4.8 × 10-4 M/s 
A)  1.2 × 10-4 M/s 
B)  2.4 × 10-4 M/s 
C)  6.0 × 10-5 M/s 
D)  3.0 × 10-5 M/s 
E)  4.8 × 10-4 M/s

Question 13

In the Arrhenius equation, ln k = -Ea/RT + ln A, the symbol A is a constant that represents the frequency of collisions with the proper orientation and other steric conditions favorable for a reaction.

Accepted Answer

A) True 
 B)False

Question 14

A catalyst alters the rate of a chemical reaction by:

Accepted Answer

A)  always providing a surface on which molecules react 
B)  changing the products formed in the reaction 
C)  inducing an alternate pathway for the reaction with generally lower activation energy 
D)  changing the frequency of collisions between molecules 
E)  increasing the number of collisions of molecules 
A)  always providing a surface on which molecules react 
B)  changing the products formed in the reaction 
C)  inducing an alternate pathway for the reaction with generally lower activation energy 
D)  changing the frequency of collisions between molecules 
E)  increasing the number of collisions of molecules

Question 15

Which of the following statements is true about the reaction 2A → B + C which is first order in A and first order overall?

Accepted Answer

A)  The rate of the reaction will decrease at higher concentrations of B and C. 
B)  The time required for one half of A to react is directly proportional to the quantity of A. 
C)  The rate of formation of C is twice the rate of reaction of A. 
D)  The rate of formation of B is the same as the rate of reaction of A. 
E)  The initial rate doubles with doubling of initial concentration of A. 
A)  The rate of the reaction will decrease at higher concentrations of B and C. 
B)  The time required for one half of A to react is directly proportional to the quantity of A. 
C)  The rate of formation of C is twice the rate of reaction of A. 
D)  The rate of formation of B is the same as the rate of reaction of A. 
E)  The initial rate doubles with doubling of initial concentration of A.

Question 16

Energy of activation has no effect on reaction rate.

Accepted Answer

A) True 
 B)False

Question 17

If the half-life of a reactant is independent of its initial concentration, the reaction order is 0.

Accepted Answer

A) True 
 B)False

Question 18

Which of the following is FALSE for a second order reaction?

Accepted Answer

A)  1/[A]t - 1/[A]o = kt. 
B)  t1/2 = 1/k[A]o. 
C)  If 1/[A] versus time is a straight line, the reaction is second order. 
D)  Each successive half-life is 4 times as long as the previous. 
E)  The slope of 1/[A]t versus time is k. 
A)  1/[A]t - 1/[A]o = kt. 
B)  t1/2 = 1/k[A]o. 
C)  If 1/[A] versus time is a straight line, the reaction is second order. 
D)  Each successive half-life is 4 times as long as the previous. 
E)  The slope of 1/[A]t versus time is k.

Question 19

If increasing the concentration of A in a chemical reaction causes no increase in the rate of the reaction, then we may say:

Accepted Answer

A)  A is a catalyst 
B)  the reaction rate is zero order in A 
C)  the reaction rate is zero order in [A] 
D)  the reaction rate is first order in [A] 
E)  A is not involved in the reaction 
A)  A is a catalyst 
B)  the reaction rate is zero order in A 
C)  the reaction rate is zero order in [A] 
D)  the reaction rate is first order in [A] 
E)  A is not involved in the reaction

Question 20

A catalyst: 
I. lowers activation energy
II. provides an alternate reaction pathway
III. is consumed in the reaction and therefore does not appear
In the chemical equation of each mechanism
IV. speeds a reaction
V. is heterogeneous if it is in a different phase than the reactants

Accepted Answer

A)  I, III, and IV 
B)  I, IV, and V 
C)  II, III, and IV 
D)  II and IV 
E)  I, II, IV, and V 
A)  I, III, and IV 
B)  I, IV, and V 
C)  II, III, and IV 
D)  II and IV 
E)  I, II, IV, and V

Exam 14: Chemical Kinetics

For a reaction with a second order rate constant, the correct unit is M ∙ time-1.

Why is rate = k[HgCl2] 2[C2O42-] not the rate law for the following mechanism? 2HgCl2 + C2O42- → 2Cl- + 2CO2 + Hg2Cl2 (overall reaction) HgCl2 + C2O42- ⇌ HgCl2C2O42- (Fast) HgCl2C2O42- + C2O42- → Hg + 2C2O4Cl2- (Slow) Hg + HgCl2 → Hg2Cl2 (Fast) 2C2O4Cl2- → C2O42- + 2Cl- + 2CO2 (Fast)

If the half-life of a reaction depends on the concentration of the reactant, then the reaction cannot be ________ order.

Data for the reaction A + B → C are given below. Find the rate constant for this system.

Temperature has no effect on reaction rate.

Which of the following statements is correct?

The first order reaction A → products has t1/2 = 150 sec. What percent of the sample remains unreacted after 300 sec?

For the reaction: 2N2O5(g) → 4NO2(g) + O2(g) the rate law is: = k[N2O5] At 300 K, the half-life is 2.50 × 104 seconds and the activation energy is 103.3 kJ/mol. What is the half-life at 310 K?

Define activation energy.

Which of the following lowers the activation energy of a reaction?

Activation energy is:

For the reaction: 2N2O5(g) → 4NO2(g) + O2(g) at the time when N2O5 is being consumed at a rate of -1.2 × 10-4 M/s, what is the rate at which O2 is being formed?

In the Arrhenius equation, ln k = -Ea/RT + ln A, the symbol A is a constant that represents the frequency of collisions with the proper orientation and other steric conditions favorable for a reaction.

A catalyst alters the rate of a chemical reaction by:

Which of the following statements is true about the reaction 2A → B + C which is first order in A and first order overall?

Energy of activation has no effect on reaction rate.

If the half-life of a reactant is independent of its initial concentration, the reaction order is 0.

Which of the following is FALSE for a second order reaction?

If increasing the concentration of A in a chemical reaction causes no increase in the rate of the reaction, then we may say:

A catalyst: I. lowers activation energy II. provides an alternate reaction pathway III. is consumed in the reaction and therefore does not appear In the chemical equation of each mechanism IV. speeds a reaction V. is heterogeneous if it is in a different phase than the reactants

Matter - Its Properties and Measurement

Atoms and the Atomic Theory

Chemical Compounds

Chemical Reactions

Introduction to Reactions in Aqueous Solutions

Gases

Thermochemistry

Electrons in Atoms

The Periodic Table and Some Atomic Properties

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Additional Aspects

Intermolecular Forces: Liquids and Solids

Solutions and Their Physical Properties

Principles of Chemical Equilibrium

Acids and Bases

Additional Aspects of Acid-Base Equilibria

Solubility and Complex-Ion Equilibria

Spontaneous Change: Entropy and Free Energy

Electrochemistry

Main Group Elements I: Groups 1, 2, 13, and 14

Main Group Elements II: Groups 18, 17, 16, 15, and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry 1-41

Structures of Organic Compounds

Reactions of Organic Compounds

Chemistry of the Living State

Filters

For the reaction: 2N₂O₅(g) → 4NO₂(g) + O₂(g) the rate law is: = k[N₂O₅] At 300 K, the half-life is 2.50 × 10⁴ seconds and the activation energy is 103.3 kJ/mol. What is the half-life at 310 K?

For the reaction: 2N₂O₅(g) → 4NO₂(g) + O₂(g) at the time when N₂O₅ is being consumed at a rate of -1.2 × 10^-4M/s, what is the rate at which O₂ is being formed?