Question 1

In the first propagation step of the free radical chlorination of methane, which of the following occurs?

Accepted Answer

A)  Cl2 dissociates. 
B)  A chlorine radical abstracts a hydrogen. 
C)  A carbon radical reacts with Cl2. 
D)  A carbon radical reacts with a chlorine radical. 
E)  Two chlorine radicals combine. 
A)  Cl2 dissociates. 
B)  A chlorine radical abstracts a hydrogen. 
C)  A carbon radical reacts with Cl2. 
D)  A carbon radical reacts with a chlorine radical. 
E)  Two chlorine radicals combine.

Question 2

The hydrogenation of acetylene to produce ethane is shown below. Is ΔS° for this reaction positive, negative, or impossible to predict? Explain your reasoning.
C2H2 (g) + 2H2 (g) → C2H6 (g)

Accepted Answer

ΔS° < 0. The three reactant mo

Question 3

Provide the structure of the carbene that results when diazomethane (shown below) decomposes.

Accepted Answer

The answer of Provide the structure of the carbene that...

Question 4

Predict the major monobromination product in the following reaction.

Accepted Answer

The answer of Predict the major monobromination product in the...

Question 5

Which of the following statements correctly describes the contribution of ΔS° to ΔG°?

Accepted Answer

A)  The entropy term makes a greater contribution to ΔG° at low temperatures. 
B)  The entropy term makes a greater contribution to ΔG° at high temperatures. 
C)  The entropy term makes a greater contribution to ΔG° in exothermic reactions. 
D)  The entropy term makes a greater contribution to ΔG° in endothermic reactions. 
E)  The entropy term always makes a more significant contribution to ΔG° than does the enthalpy term. 
A)  The entropy term makes a greater contribution to ΔG° at low temperatures. 
B)  The entropy term makes a greater contribution to ΔG° at high temperatures. 
C)  The entropy term makes a greater contribution to ΔG° in exothermic reactions. 
D)  The entropy term makes a greater contribution to ΔG° in endothermic reactions. 
E)  The entropy term always makes a more significant contribution to ΔG° than does the enthalpy term.

Question 6

Consider the bond dissociation energies listed below in kcal/mol.   
These data show that the carbon-bromine bond is weakest when bromine is bound to a ________.

Accepted Answer

A)  methyl carbon 
B)  primary carbon 
C)  secondary carbon 
D)  tertiary carbon 
E)  quaternary carbon 
A)  methyl carbon 
B)  primary carbon 
C)  secondary carbon 
D)  tertiary carbon 
E)  quaternary carbon

Question 7

If stronger bonds are formed and weaker bonds are broken, then the reaction is ________.

Accepted Answer

The answer of If stronger bonds are formed and weaker...

Question 8

Describe the hybridization of the cationic center and predict the CCC bond angle in (CH3)3C+.

Accepted Answer

Cationic center is s

Question 9

Free radical bromination of pentane results in poor yields of 1-bromopentane, while cyclopentane can be readily brominated under similar conditions to yield bromocyclopentane. Offer an explanation.

Accepted Answer

In the bromination of pentane, the lowes

Question 10

How many distinct dichlorination products can result when isobutane is subjected to free radical chlorination?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  6 
A)  1 
B)  2 
C)  3 
D)  4 
E)  6

Question 11

________ is the study of reaction rates.

Accepted Answer

The answer of ________ is the study of reaction rates....

Question 12

Which of the following is true for the initiation step of a free radical chlorination reaction?

Accepted Answer

A) ΔH° > 0 and ΔS° > 0 B) ΔH° > 0 and ΔS° 0 D) ΔH° < 0 and ΔS° < 0 E) ΔH° = 0 and ΔS° = 0 A) ΔH° > 0 and ΔS° > 0 B) ΔH° > 0 and ΔS° 0 D) ΔH° < 0 and ΔS° < 0 E) ΔH° = 0 and ΔS° = 0

Question 13

Given the chlorination of acetone shown below, choose the correct rate law. CH3COCH3 + Cl2  → CH3COCH2Cl + HCl

Accepted Answer

A)  rate = [CH3COCH3] 
B)  rate = [Cl2] 
C)  rate = [CH3COCH3][Cl2] 
D)  rate = [CH3COCH3][Cl2]1/2 
E)  cannot be determined from stoichiometry; must be determined experimentally 
A)  rate = [CH3COCH3] 
B)  rate = [Cl2] 
C)  rate = [CH3COCH3][Cl2] 
D)  rate = [CH3COCH3][Cl2]1/2 
E)  cannot be determined from stoichiometry; must be determined experimentally

Question 14

What is the CCC bond angle in (CH3)3C:-?

Accepted Answer

slightly l

Question 15

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is -0.5 kcal/mol, the Keq is ________ and the % conversion is ________.

Accepted Answer

A)  0.18, 15% 
B)  0.43, 30% 
C)  1.0, 50% 
D)  2.3, 70% 
E)  5.4, 84% 
A)  0.18, 15% 
B)  0.43, 30% 
C)  1.0, 50% 
D)  2.3, 70% 
E)  5.4, 84%

Question 16

________ is the minimum kinetic energy reacting molecules must possess to overcome the repulsions between their electron clouds when they collide.

Accepted Answer

The activa

Question 17

Given that the theoretical reaction below was found to be second order and bimolecular, provide a rate equation for the reaction.
A-B + C-D → A-C + B-D

Accepted Answer

The answer of Given that the theoretical reaction below was...

Question 18

Which of the following statements is the best statement of the Hammond Postulate?

Accepted Answer

A)  In an endothermic reaction, the transition state is closer to the reactants in structure. 
B)  In an exothermic reaction, the transition state is closer in energy to the products. 
C)  Related species that are similar in energy are also similar in structure. 
D)  The structure of the transition state in an organic reaction is always modeled on the structure of the reactants leading to that transition state. 
E)  Transition states are molecular species of finite lifetime whose properties can be probed through free radical reactions. 
A)  In an endothermic reaction, the transition state is closer to the reactants in structure. 
B)  In an exothermic reaction, the transition state is closer in energy to the products. 
C)  Related species that are similar in energy are also similar in structure. 
D)  The structure of the transition state in an organic reaction is always modeled on the structure of the reactants leading to that transition state. 
E)  Transition states are molecular species of finite lifetime whose properties can be probed through free radical reactions.

Question 19

In the hydrocarbon shown below, how many tertiary hydrogens are present?

Accepted Answer

A)  0 
B)  1 
C)  2 
D)  3 
E)  4 
A)  0 
B)  1 
C)  2 
D)  3 
E)  4

Question 20

Provide the two propagation steps in the free-radical chlorination of ethane.

Accepted Answer

CH₃CH₃ +

Exam 4: The Study of Chemical Reactions

In the first propagation step of the free radical chlorination of methane, which of the following occurs?

The hydrogenation of acetylene to produce ethane is shown below. Is ΔS° for this reaction positive, negative, or impossible to predict? Explain your reasoning. C2H2 (g) + 2H2 (g) → C2H6 (g)

Provide the structure of the carbene that results when diazomethane (shown below) decomposes.

Predict the major monobromination product in the following reaction.

Which of the following statements correctly describes the contribution of ΔS° to ΔG°?

Consider the bond dissociation energies listed below in kcal/mol. These data show that the carbon-bromine bond is weakest when bromine is bound to a ________.

If stronger bonds are formed and weaker bonds are broken, then the reaction is ________.

Describe the hybridization of the cationic center and predict the CCC bond angle in (CH3)3C+.

Free radical bromination of pentane results in poor yields of 1-bromopentane, while cyclopentane can be readily brominated under similar conditions to yield bromocyclopentane. Offer an explanation.

How many distinct dichlorination products can result when isobutane is subjected to free radical chlorination?

________ is the study of reaction rates.

Which of the following is true for the initiation step of a free radical chlorination reaction?

Given the chlorination of acetone shown below, choose the correct rate law. CH3COCH3 + Cl2 → CH3COCH2Cl + HCl

What is the CCC bond angle in (CH3)3C:-?

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is -0.5 kcal/mol, the Keq is ________ and the % conversion is ________.

________ is the minimum kinetic energy reacting molecules must possess to overcome the repulsions between their electron clouds when they collide.

Given that the theoretical reaction below was found to be second order and bimolecular, provide a rate equation for the reaction. A-B + C-D → A-C + B-D

Which of the following statements is the best statement of the Hammond Postulate?

In the hydrocarbon shown below, how many tertiary hydrogens are present?

Provide the two propagation steps in the free-radical chlorination of ethane.

Introduction and Review

Structure and Properties of Organic Molecules

Structure and Stereochemistry of Alkanes

Stereochemistry

Alkyl Halides: Nucleophilic Substitution and Elimination

Structure and Synthesis of Alkenes

Reactions of Alkenes

Alkynes

Structure and Synthesis of Alcohols

Reactions of Alcohols

Infrared Spectroscopy and Mass Spectrometry

Nuclear Magnetic Resonance Spectroscopy

Ethers, Epoxides, and Thioethers

Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy

Aromatic Compounds

Reactions of Aromatic Compounds

Ketones and Aldehydes

Amines

Carboxylic Acids

Carboxylic Acid Derivatives

Condensations and Alpha Substitutions of Carboxyl Compounds

Carbohydrates and Nucleic Acids

Amino Acids, Peptides, and Proteins

Lipids

Synthetic Polymers

Filters

The hydrogenation of acetylene to produce ethane is shown below. Is ΔS° for this reaction positive, negative, or impossible to predict? Explain your reasoning. C₂H₂ (g) + 2H₂ (g) → C₂H₆ (g)

Describe the hybridization of the cationic center and predict the CCC bond angle in (CH₃)₃C⁺.

Given the chlorination of acetone shown below, choose the correct rate law. CH₃COCH₃ + Cl₂ → CH₃COCH₂Cl + HCl

What is the CCC bond angle in (CH₃)₃C:^-?

Consider the reaction of A being converted into B at 25°C. If the ΔG° of this reaction is -0.5 kcal/mol, the K_eq is and the % conversion is .