Question 1

What is the energy of activation for the following reaction?

Accepted Answer

10 kJ/mol

Question 2

Given the following rate law, what is the order of the reaction with respect to sodium cyanide?

Accepted Answer

second

Question 3

Later in the course, we will compare the halogenation of differently substituted carbons, comparing reactions like the ones below. Which of the following reactions has a more exothermic heat of reaction (∆Ho)?

Accepted Answer

A)  Reaction I has a more exothermic heat of reaction (∆Ho) 
B)  Reaction II has a more exothermic heat of reaction (∆Ho) 
C)  Both reactions have the same heat of reaction (∆Ho) 
A)  Reaction I has a more exothermic heat of reaction (∆Ho) 
B)  Reaction II has a more exothermic heat of reaction (∆Ho) 
C)  Both reactions have the same heat of reaction (∆Ho) B

Question 4

Predict the sign of ∆G for an exothermic reaction with a decrease in entropy.

Accepted Answer

A)  positive 
B)  negative 
C)  no change 
D)  cannot predict without additional information 
A)  positive 
B)  negative 
C)  no change 
D)  cannot predict without additional information

Question 5

Does a reaction with a ∆H of 20 kJ/mol and a ∆S of 10 J/mol·K at 298 K favor reactants or products?

Accepted Answer

The answer of Does a reaction with a ∆H of...

Question 6

Which of the following energy diagrams shows a concerted endothermic reaction?

Accepted Answer

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

Question 7

For the following reaction step, indicate which pattern of arrow pushing it represents.

Accepted Answer

A)  proton transfer 
B)  loss of leaving group 
C)  nucleophilic attack 
D)  rearrangement 
A)  proton transfer 
B)  loss of leaving group 
C)  nucleophilic attack 
D)  rearrangement

Question 8

In a homolytic bond cleavage, ____ are formed.

Accepted Answer

A)  ions 
B)  radicals 
C)  only cations 
D)  only anions 
A)  ions 
B)  radicals 
C)  only cations 
D)  only anions

Question 9

Does a reaction with a Keq = 10 favor reactants or products?

Accepted Answer

Question 10

Using Table 6.1, estimate the enthalpy change of the following reaction under standard conditions.

Accepted Answer

The answer of Using Table 6.1, estimate the enthalpy change...

Question 11

Predict the sign of ∆S for the following reaction.

Accepted Answer

The answer of Predict the sign of ∆S for the...

Question 12

The following reaction has three mechanistic steps. Draw all curved arrows necessary to complete the mechanism.

Accepted Answer

The answer of The following reaction has three mechanistic steps....

Question 13

Why is the entropy change negative for ring closures?

Accepted Answer

A)  Closing a ring results in fewer molecules. 
B)  Closing a ring results in more molecules. 
C)  Closing a ring releases energy. 
D)  Closing a ring restricts the rotation around individual carbon-carbon bonds. 
A)  Closing a ring results in fewer molecules. 
B)  Closing a ring results in more molecules. 
C)  Closing a ring releases energy. 
D)  Closing a ring restricts the rotation around individual carbon-carbon bonds.

Question 14

Identify the nucleophilic centers in the following molecule.

Accepted Answer

The answer of Identify the nucleophilic centers in the following...

Question 15

Which of the following indicates a reaction with a negative ∆G?

Accepted Answer

A)  endergonic, spontaneous 
B)  endergonic, not spontaneous 
C)  exergonic, spontaneous 
D)  exergonic, not spontaneous 
A)  endergonic, spontaneous 
B)  endergonic, not spontaneous 
C)  exergonic, spontaneous 
D)  exergonic, not spontaneous

Question 16

What is a transition state?

Accepted Answer

A)  An isolable intermediate in a reaction. 
B)  The starting materials of the reaction. 
C)  A local maximum on the energy diagram. 
D)  A low-energy point between the starting materials and the product. 
A)  An isolable intermediate in a reaction. 
B)  The starting materials of the reaction. 
C)  A local maximum on the energy diagram. 
D)  A low-energy point between the starting materials and the product.

Question 17

Using Table 6.1, estimate the enthalpy change of the following reaction under standard conditions.

Accepted Answer

The answer of Using Table 6.1, estimate the enthalpy change...

Question 18

Identify the electrophilic site in the following molecule.

Accepted Answer

SHAPE \* M

Question 19

Draw curved arrows for the following mechanistic step.

Accepted Answer

@#IMG-DLM&_TB4454_00 6.10 Desc

Question 20

Identify the arrow in the following equation.

Accepted Answer

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

Exam 6: Chemical Reactivity and Mechanisms

What is the energy of activation for the following reaction?

Given the following rate law, what is the order of the reaction with respect to sodium cyanide?

Later in the course, we will compare the halogenation of differently substituted carbons, comparing reactions like the ones below. Which of the following reactions has a more exothermic heat of reaction (∆Ho)?

Predict the sign of ∆G for an exothermic reaction with a decrease in entropy.

Does a reaction with a ∆H of 20 kJ/mol and a ∆S of 10 J/mol·K at 298 K favor reactants or products?

Which of the following energy diagrams shows a concerted endothermic reaction?

For the following reaction step, indicate which pattern of arrow pushing it represents.

In a homolytic bond cleavage, ____ are formed.

Does a reaction with a Keq = 10 favor reactants or products?

Using Table 6.1, estimate the enthalpy change of the following reaction under standard conditions.

Predict the sign of ∆S for the following reaction.

The following reaction has three mechanistic steps. Draw all curved arrows necessary to complete the mechanism.

Why is the entropy change negative for ring closures?

Identify the nucleophilic centers in the following molecule.

Which of the following indicates a reaction with a negative ∆G?

What is a transition state?

Using Table 6.1, estimate the enthalpy change of the following reaction under standard conditions.

Identify the electrophilic site in the following molecule.

Draw curved arrows for the following mechanistic step.

Identify the arrow in the following equation.

A Review of General Chemistry: Electrons, Bonds, and Molecular Properties

Molecular Representations

Acids and Bases

Alkanes and Cycloalkanes

Stereoisomerism

Alkyl Halides: Nucleophilic Substitution and Elimination Reactions

Addition Reactions of Alkenes

Alkynes

Radical Reactions

Synthesis

Alcohols and Phenols

Ethers and Epoxides; Thiols and Sulfides

Infrared Spectroscopy and Mass Spectrometry

Nuclear Magnetic Resonance Spectroscopy

Conjugated Pi Systems and Pericyclic Reactions

Aromatic Compounds

Aromatic Substitution Reactions

Aldehydes and Ketones

Carboxylic Acids and Their Derivatives

Alpha Carbon Chemistry: Enols and Enolates

Amines

Introduction to Organometallic Compounds

Carbohydrates

Amino Acids, Peptides, and Proteins

Lipids

Synthetic Polymers

Filters

Later in the course, we will compare the halogenation of differently substituted carbons, comparing reactions like the ones below. Which of the following reactions has a more exothermic heat of reaction (∆H^o)?

Does a reaction with a K_eq = 10 favor reactants or products?