Question 1

Choose the INCORRECT statement.

Accepted Answer

A) The rate-determining step is always the first step. 
B) A unimolecular process is one in which a single molecule dissociates. 
C) A bimolecular process is one involving a collision of two molecules. 
D) A reaction mechanism is a step-by-step detailed description of a chemical reaction. 
E) An elementary process is a step in the mechanism. 
A) The rate-determining step is always the first step. 
B) A unimolecular process is one in which a single molecule dissociates. 
C) A bimolecular process is one involving a collision of two molecules. 
D) A reaction mechanism is a step-by-step detailed description of a chemical reaction. 
E) An elementary process is a step in the mechanism.

Question 2

The reaction that occurs in a Breathalyzer,a device used to determine the alcohol level in a person's bloodstream,is given below.If the rate of appearance of Cr2(SO4)3 is 1.64 mol min-1 at a particular moment,what is the rate of disappearance of C2H6O at that moment?
2 K2Cr2O7(aq)+ 8 H2SO4(aq)+ 3 C2H6O(aq)→ 2 Cr2(SO4)3(aq)+ 2 K2SO4(aq)+ 11 H2O(l)

Accepted Answer

A) 0.547 mol min-1 
B) 1.09 mol min-1 
C) 2.46 mol min-1 
D) 4.92 mol min-1 
A) 0.547 mol min-1 
B) 1.09 mol min-1 
C) 2.46 mol min-1 
D) 4.92 mol min-1

Question 3

The aquation of tris (1,10-phenanthroline)iron(II)in acid solution takes place according to the equation:
Fe(phen)32+ + 3 H3O+ + 3 H2O → Fe(H2O)62+ + 3 phenH+.
If the activation energy,Ea,is 126 kJ mol-1 and the rate constant at 30 °C is 9.8 × 10-3 min-1,what is the rate constant at 35 °C?

Accepted Answer

A) 4.4 × 10-3 min-1 
B) 2.2 × 10-2 min-1 
C) 4.5 × 101 min-1 
D) 2.3 × 102 min-1 
A) 4.4 × 10-3 min-1 
B) 2.2 × 10-2 min-1 
C) 4.5 × 101 min-1 
D) 2.3 × 102 min-1

Question 4

For the reaction: C2H4Br2 + 3 KI → C2H4 + 2 KBr + KI3,when the rate of appearance of C2H4 is 2.0 × 10-5 M/s,what is the rate of disappearance of C2H4Br2?

Accepted Answer

A) 0.67 × 10-5 M/s 
B) 2.0 × 10-5 M/s 
C) 4.0 × 10-5 M/s 
D) 6.0 × 10-5 M/s 
E) 1.0 × 10-5 M/s 
A) 0.67 × 10-5 M/s 
B) 2.0 × 10-5 M/s 
C) 4.0 × 10-5 M/s 
D) 6.0 × 10-5 M/s 
E) 1.0 × 10-5 M/s

Question 5

Which of the following situations involves a heterogeneous catalysis?

Accepted Answer

A) The catalyst is present in a different phase of matter than are the reactants and products. 
B) The catalyst is in two different phases of matter. 
C) The reactants and products are different phases of matter in a catalyzed reaction. 
D) The catalyst,reactants,and products are all different phases of matter. 
E) The catalyst changes phases during the reaction. 
A) The catalyst is present in a different phase of matter than are the reactants and products. 
B) The catalyst is in two different phases of matter. 
C) The reactants and products are different phases of matter in a catalyzed reaction. 
D) The catalyst,reactants,and products are all different phases of matter. 
E) The catalyst changes phases during the reaction.

Question 6

In the reaction C4H9Cl(aq)+ H2O(l)→ C4H9OH(aq)+ HCl(aq)the concentration of the reactant changes from 0.0562 M to 0.0431 M in 85 sec.What is the average rate of decomposition over this interval?

Accepted Answer

A) 1.54 × 10-4 M/s 
B) 1.54 × 10-4 moles 
C) 1.54 × 10-4 moles/s 
D) 0.0154 M 
E) 0.0154 M/s 
A) 1.54 × 10-4 M/s 
B) 1.54 × 10-4 moles 
C) 1.54 × 10-4 moles/s 
D) 0.0154 M 
E) 0.0154 M/s

Question 7

Carbon-14,which is present in all living tissue,radioactively decays via a first-order process.A one-gram sample of wood taken from a living tree gives a rate for carbon-14 decay of 13.6 counts per minute.If the half-life for carbon-14 is 5720 years,how old is a wood sample that gives a rate for carbon-14 decay of 11.9 counts per minute?

Accepted Answer

A) 5.3 × 102 yr 
B) 7.6 × 102 yr 
C) 1.1 × 103 yr 
D) 9.4 × 103 yr 
A) 5.3 × 102 yr 
B) 7.6 × 102 yr 
C) 1.1 × 103 yr 
D) 9.4 × 103 yr

Question 8

For the reaction: C2H4Br2 + 3 KI → C2H4 + 2 KBr + KI3,when the rate of disappearance of C2H4Br2 is 2.0 × 10-5 M/s,what is the rate of appearance of KBr?

Accepted Answer

A) 0.67 × 10-5 M/s 
B) 2.0 × 10-5 M/s 
C) 4.0 × 10-5 M/s 
D) 6.0 × 10-5 M/s 
E) 1.0 × 10-5 M/s 
A) 0.67 × 10-5 M/s 
B) 2.0 × 10-5 M/s 
C) 4.0 × 10-5 M/s 
D) 6.0 × 10-5 M/s 
E) 1.0 × 10-5 M/s

Question 9

For a reaction with a second order rate constant,what is the correct unit?

Accepted Answer

A) M time-1  
B) M-1 time-1  
C) time-1 
D) M-2 time 
E) M time-2  
A) M time-1  
B) M-1 time-1  
C) time-1 
D) M-2 time 
E) M time-2

Question 10

The decomposition of     In solution in carbon tetrachloride proceeds via the reaction 
 
The reaction is first order and has a rate constant of 4.82 ×     
At 64 °C.If the reaction is initiated with 0.058 mol in a 1.00 L vessel,how many moles remain after 151 s?

Accepted Answer

A) 0.055 mol L-1 
B) 0.060 mol L-1 
C) 0.028 mol L-1 
D) 12 mol L-1 
E) 2.0 ×   mol L-1 
A) 0.055 mol L-1 
B) 0.060 mol L-1 
C) 0.028 mol L-1 
D) 12 mol L-1 
E) 2.0 ×   mol L-1

Question 11

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 12

The following reaction is first order,C2H6 → 2 CH3.If the rate constant is equal to 5.5 × 10-4 s-1 at 1000 K,how long will it take for 0.35 mol of C2H6 in a 1.00 L container to decrease to 0.20 mol in the same container?

Accepted Answer

A) 4.5 min 
B) 17 min 
C) 53 min 
D) 65 min 
A) 4.5 min 
B) 17 min 
C) 53 min 
D) 65 min

Question 13

Adding a catalyst lowers the activation energy of a reaction.

Accepted Answer

A) True 
 B)False

Question 14

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 15

In the first-order,reaction A → products,[A] = 0.400 M initially and 0.250 M after 15.0 min,at what time will [A] = 0.200 M?

Accepted Answer

A) 63.9 min 
B) 22.1 min 
C) 9.62 min 
D) 51.0 min 
E) 15.0 min 
A) 63.9 min 
B) 22.1 min 
C) 9.62 min 
D) 51.0 min 
E) 15.0 min

Question 16

Choose the INCORRECT statement.

Accepted Answer

A) A reaction intermediate is produced and used up during the reaction. 
B) A transition state and a reaction intermediate are the same. 
C) An activated complex has partially formed bonds. 
D) A reaction intermediates have fully formed bonds. 
E) The rate-determining step is the slow-step. 
A) A reaction intermediate is produced and used up during the reaction. 
B) A transition state and a reaction intermediate are the same. 
C) An activated complex has partially formed bonds. 
D) A reaction intermediates have fully formed bonds. 
E) The rate-determining step is the slow-step.

Question 17

Hydrogen iodide decomposes at 800 K via a second-order process to produce hydrogen and iodine according to the following chemical equation:
2 HI(g)→ H2(g)+ I2(g)
At 800 K it takes 142 seconds for the initial concentration of HI to decrease from 6.75 × 10-2 mol L-1 to 3.50 × 10-2 mol L-1.What is the rate constant for the reaction at this temperature?

Accepted Answer

A) 5.12 × 10-4 L mol-1 s-1 
B) 9.69 × 10-2 L mol-1 s-1 
C) 10.3 L mol-1 s-1 
D) 1.95 × 103 L mol-1 s-1 
A) 5.12 × 10-4 L mol-1 s-1 
B) 9.69 × 10-2 L mol-1 s-1 
C) 10.3 L mol-1 s-1 
D) 1.95 × 103 L mol-1 s-1

Question 18

Which of the following statements is INCORRECT?

Accepted Answer

A) Radioactive decay is a first order reaction. 
B) Half-life in a first order reaction is constant. 
C) For a first order reaction ln [A]t/[A]o = kt. 
D) In gaseous reactions [A] can be expressed as concentration or as pressure. 
E) In a zero order reaction the rate remains constant throughout the reaction. 
A) Radioactive decay is a first order reaction. 
B) Half-life in a first order reaction is constant. 
C) For a first order reaction ln [A]t/[A]o = kt. 
D) In gaseous reactions [A] can be expressed as concentration or as pressure. 
E) In a zero order reaction the rate remains constant throughout the reaction.

Question 19

For the second order reaction A → products,the following data are obtained:
[A] = 1.512 M,t = 0 min
[A] = 1.490 M,t = 1.0 min
[A] = 1.469 M,t = 2.0 min
What is the concentration of [A] in the experiment after 4.0 min for the reaction?

Accepted Answer

A) 1.43 M 
B) 1.35 M 
C) 1.61 M 
D) 1.39 M 
E) 1.37 M 
A) 1.43 M 
B) 1.35 M 
C) 1.61 M 
D) 1.39 M 
E) 1.37 M

Question 20

For the second-order reaction A → products,the following data are obtained:
[A] = 3.024 M,t = 0 min
[A] = 2.935 M,t = 1.0 min
[A] = 2.852 M,t = 2.0 min
What is the initial rate of the reaction?

Accepted Answer

A) 1.0 × 10-4 M min-1  
B) 0.091 M min-1  
C) 11.2 M min-1  
D) 0.010 M min-1  
E) 0.030 M min-1  
A) 1.0 × 10-4 M min-1  
B) 0.091 M min-1  
C) 11.2 M min-1  
D) 0.010 M min-1  
E) 0.030 M min-1

Exam 20: Chemical Kinetics

Choose the INCORRECT statement.

The aquation of tris (1,10-phenanthroline)iron(II)in acid solution takes place according to the equation: Fe(phen)32+ + 3 H3O+ + 3 H2O → Fe(H2O)62+ + 3 phenH+. If the activation energy,Ea,is 126 kJ mol-1 and the rate constant at 30 °C is 9.8 × 10-3 min-1,what is the rate constant at 35 °C?

For the reaction: C2H4Br2 + 3 KI → C2H4 + 2 KBr + KI3,when the rate of appearance of C2H4 is 2.0 × 10-5 M/s,what is the rate of disappearance of C2H4Br2?

Which of the following situations involves a heterogeneous catalysis?

In the reaction C4H9Cl(aq)+ H2O(l)→ C4H9OH(aq)+ HCl(aq)the concentration of the reactant changes from 0.0562 M to 0.0431 M in 85 sec.What is the average rate of decomposition over this interval?

For the reaction: C2H4Br2 + 3 KI → C2H4 + 2 KBr + KI3,when the rate of disappearance of C2H4Br2 is 2.0 × 10-5 M/s,what is the rate of appearance of KBr?

For a reaction with a second order rate constant,what is the correct unit?

The decomposition of In solution in carbon tetrachloride proceeds via the reaction The reaction is first order and has a rate constant of 4.82 × At 64 °C.If the reaction is initiated with 0.058 mol in a 1.00 L vessel,how many moles remain after 151 s?

A catalyst alters the rate of a chemical reaction by:

The following reaction is first order,C2H6 → 2 CH3.If the rate constant is equal to 5.5 × 10-4 s-1 at 1000 K,how long will it take for 0.35 mol of C2H6 in a 1.00 L container to decrease to 0.20 mol in the same container?

Adding a catalyst lowers the activation energy of a reaction.

Activation energy is:

In the first-order,reaction A → products,[A] = 0.400 M initially and 0.250 M after 15.0 min,at what time will [A] = 0.200 M?

Choose the INCORRECT statement.

Which of the following statements is INCORRECT?

For the second order reaction A → products,the following data are obtained: [A] = 1.512 M,t = 0 min [A] = 1.490 M,t = 1.0 min [A] = 1.469 M,t = 2.0 min What is the concentration of [A] in the experiment after 4.0 min for the reaction?

For the second-order reaction A → products,the following data are obtained: [A] = 3.024 M,t = 0 min [A] = 2.935 M,t = 1.0 min [A] = 2.852 M,t = 2.0 min What is the initial rate of the reaction?

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: Valence Bond and Molecular Orbital Theories

Intermolecular Forces: Liquids and Solids

Spontaneous Change: Entropy and Gibbs Energy

Solutions and Their Physical Properties

Principles of Chemical Equilibrium

Acids and Bases

Additional Aspects of Acidbase Equilibria

Solubility and Complex-Ion Equilibria

Electrochemistry

Chemistry of the Main-Group Elements I: Groups 1,2,13,and 14

Chemistry of the Main-Group Elements Ii: Groups 18,17,16,15,and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry

Structures of Organic Compounds

Reactions of Organic Compounds

Chemistry of the Living State

Filters

For the reaction: C₂H₄Br₂ + 3 KI → C₂H₄+ 2 KBr + KI₃,when the rate of appearance of C₂H₄ is 2.0 × 10^-5 M/s,what is the rate of disappearance of C₂H₄Br₂?

In the reaction C₄H₉Cl(aq)+ H₂O(l)→ C₄H₉OH(aq)+ HCl(aq)the concentration of the reactant changes from 0.0562 M to 0.0431 M in 85 sec.What is the average rate of decomposition over this interval?

For the reaction: C₂H₄Br₂ + 3 KI → C₂H₄+ 2 KBr + KI₃,when the rate of disappearance of C₂H₄Br₂ is 2.0 × 10^-5 M/s,what is the rate of appearance of KBr?

The following reaction is first order,C₂H₆ → 2 CH₃.If the rate constant is equal to 5.5 × 10^-4 s^-1 at 1000 K,how long will it take for 0.35 mol of C₂H₆ in a 1.00 L container to decrease to 0.20 mol in the same container?