Question 1

Which of the following statements is true?

Accepted Answer

A) Bond dissociation energies increase down a column of the periodic table. 
B) When DH° is positive, more energy is released in forming bonds than is needed to break bonds. 
C) When DH° is negative, more energy is needed to break bonds than is released in forming bonds. 
D) Bond dissociation energies decrease down a column of the periodic table. 
A) Bond dissociation energies increase down a column of the periodic table. 
B) When DH° is positive, more energy is released in forming bonds than is needed to break bonds. 
C) When DH° is negative, more energy is needed to break bonds than is released in forming bonds. 
D) Bond dissociation energies decrease down a column of the periodic table.

Question 2

Which of the following expressions summarizes the correct relationship between the free energy change, DG°, and the equilibrium constant, Keq?

Accepted Answer

A) Keq > 1 when DG° > 0 B) Keq > 1 when DG° eq eq < 1 when DG° = 0 A) Keq > 1 when DG° > 0 B) Keq > 1 when DG° eq eq < 1 when DG° = 0

Question 3

Which of the following statements is not true?

Accepted Answer

A) In polar reactions, a nucleophile reacts with an electrophile. 
B) Carbocations are electrophiles. 
C) Carbanions are nucleophiles. 
D) A half-headed curved arrow shows the movement of an electron pair. 
A) In polar reactions, a nucleophile reacts with an electrophile. 
B) Carbocations are electrophiles. 
C) Carbanions are nucleophiles. 
D) A half-headed curved arrow shows the movement of an electron pair.

Question 4

Which of the following statements about bond breaking is true?

Accepted Answer

A) Homolysis and heterolysis require energy. 
B) In homolysis, the electrons in the bond are divided unequally. 
C) In heterolysis, the electrons in the bond are divided equally. 
D) Homolysis generates charged intermediates. 
A) Homolysis and heterolysis require energy. 
B) In homolysis, the electrons in the bond are divided unequally. 
C) In heterolysis, the electrons in the bond are divided equally. 
D) Homolysis generates charged intermediates.

Question 5

Which of the following letters represents DH° for the forward reaction in the following energy diagram?

Accepted Answer

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

Question 6

For which of the following reactions is ∆S° a positive value?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 7

Which of the following statements about elimination reactions is true?

Accepted Answer

A) Two σ bonds are broken. 
B) Two σ bonds are formed. 
C) Two π bonds are broken. 
D) Two π bonds are formed. 
A) Two σ bonds are broken. 
B) Two σ bonds are formed. 
C) Two π bonds are broken. 
D) Two π bonds are formed.

Question 8

What kind of reaction does the conversion of A to B represent?

Accepted Answer

A) Addition reaction. 
B) Elimination reaction. 
C) Substitution reaction. 
D) Oxidation-reduction reaction. 
A) Addition reaction. 
B) Elimination reaction. 
C) Substitution reaction. 
D) Oxidation-reduction reaction.

Question 9

Which of the following statements is true?

Accepted Answer

A) Ionic intermediates are formed in radical reactions. 
B) Radicals are intermediates in polar reactions. 
C) Carbocations are electrophiles. 
D) Radicals are nucleophiles. 
A) Ionic intermediates are formed in radical reactions. 
B) Radicals are intermediates in polar reactions. 
C) Carbocations are electrophiles. 
D) Radicals are nucleophiles.

Question 10

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism:
 
If the concentration of -OCH3 were increased 5 times, what would happen to the rate of the reaction?

Accepted Answer

A) Rate would become one fifth 
B) Rate would increase 25 times 
C) Rate would increase 5 times 
D) Rate would remain unchanged 
A) Rate would become one fifth 
B) Rate would increase 25 times 
C) Rate would increase 5 times 
D) Rate would remain unchanged

Question 11

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism:
 
The conversion of acetyl chloride to methyl acetate would be classified as which of the following?

Accepted Answer

A) Addition 
B) Elimination 
C) Substitution 
D) None of these 
A) Addition 
B) Elimination 
C) Substitution 
D) None of these

Question 12

What kind of reaction does the conversion of A to B represent?

Accepted Answer

A) Acid-base reaction. 
B) Elimination reaction. 
C) Substitution reaction. 
D) Addition reaction. 
A) Acid-base reaction. 
B) Elimination reaction. 
C) Substitution reaction. 
D) Addition reaction.

Question 13

If the conversion of A to B is slow and B to C is fast, what is the rate equation for this reaction?

Accepted Answer

A) Rate = k[(CH3)2CHCl][H2O] 
B) Rate = k[(CH3)2CHCl] 
C) Rate = k[(CH3)2CH]+[H2O] 
D) Rate = k[(CH3)2CH]+ 
A) Rate = k[(CH3)2CHCl][H2O] 
B) Rate = k[(CH3)2CHCl] 
C) Rate = k[(CH3)2CH]+[H2O] 
D) Rate = k[(CH3)2CH]+

Question 14

The DG° (free energy change) for the conversion of A to B is predicted to be which of the following?

Accepted Answer

A) DG° = 0 
B) DG°  0 
D) Cannot be determined from the information provided 
A) DG° = 0 
B) DG°  0 
D) Cannot be determined from the information provided

Question 15

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism:
 
What is the rate equation for this reaction if the first step is rate determining?

Accepted Answer

A) Rate = k [acetyl chloride] [-OCH3] 
B) Rate = k [acetyl chloride] 
C) Rate = k [-OCH3] 
D) Rate = k [acetyl chloride] [-OCH3]2 
A) Rate = k [acetyl chloride] [-OCH3] 
B) Rate = k [acetyl chloride] 
C) Rate = k [-OCH3] 
D) Rate = k [acetyl chloride] [-OCH3]2

Question 16

Which of the following statements about equilibrium is true?

Accepted Answer

A) Equilibrium favors the products when the energy of the products is higher than the energy of the reactants. 
B) Equilibrium favors the reactants when the energy of the product is lower than the energy of the reactants. 
C) Equilibrium favors the products when they are less stable than the starting material of a reaction. 
D) Equilibrium favors the products when they are more stable than the starting material of a reaction. 
A) Equilibrium favors the products when the energy of the products is higher than the energy of the reactants. 
B) Equilibrium favors the reactants when the energy of the product is lower than the energy of the reactants. 
C) Equilibrium favors the products when they are less stable than the starting material of a reaction. 
D) Equilibrium favors the products when they are more stable than the starting material of a reaction.

Question 17

Which reaction is fast and has Keq = 1?

Accepted Answer

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

Question 18

Which of the following statements is not true?

Accepted Answer

A) Two reactions can have identical values for DH° but very different Ea values. 
B) The larger the activation energy, the slower the reaction. 
C) DH° determines the height of the energy barrier. 
D) The lower the activation energy, the faster the reaction. 
A) Two reactions can have identical values for DH° but very different Ea values. 
B) The larger the activation energy, the slower the reaction. 
C) DH° determines the height of the energy barrier. 
D) The lower the activation energy, the faster the reaction.

Question 19

Which of the following statements about enzymes is true?

Accepted Answer

A) Enzymes increase the activation energy for a reaction. 
B) Enzymes decrease the equilibrium constant. 
C) Enzymes shift the equilibrium to favor the product. 
D) Enzymes lower the transition state for the rate-determining step. 
A) Enzymes increase the activation energy for a reaction. 
B) Enzymes decrease the equilibrium constant. 
C) Enzymes shift the equilibrium to favor the product. 
D) Enzymes lower the transition state for the rate-determining step.

Question 20

Using the bond dissociation energies given, calculate DH° for the following reaction.

Accepted Answer

A) +3 KJ/mol 
B) -3 KJ/mol 
C) -67 KJ/mol 
D) +70 KJ/mol 
A) +3 KJ/mol 
B) -3 KJ/mol 
C) -67 KJ/mol 
D) +70 KJ/mol

Exam 6: Understanding Organic Reactions

Which of the following statements is true?

Which of the following expressions summarizes the correct relationship between the free energy change, DG°, and the equilibrium constant, Keq?

Which of the following statements is not true?

Which of the following statements about bond breaking is true?

Which of the following letters represents DH° for the forward reaction in the following energy diagram?

For which of the following reactions is ∆S° a positive value?

Which of the following statements about elimination reactions is true?

What kind of reaction does the conversion of A to B represent?

Which of the following statements is true?

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism: If the concentration of -OCH3 were increased 5 times, what would happen to the rate of the reaction?

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism: The conversion of acetyl chloride to methyl acetate would be classified as which of the following?

What kind of reaction does the conversion of A to B represent?

If the conversion of A to B is slow and B to C is fast, what is the rate equation for this reaction?

The DG° (free energy change) for the conversion of A to B is predicted to be which of the following?

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism: What is the rate equation for this reaction if the first step is rate determining?

Which of the following statements about equilibrium is true?

Which reaction is fast and has Keq = 1?

Which of the following statements is not true?

Which of the following statements about enzymes is true?

Using the bond dissociation energies given, calculate DH° for the following reaction.

Structure and Bonding

Acids and Bases

Introduction to Organic Molecules and Functional Groups

Alkanes

Stereochemistry

Alkyl Halides and Nucleophilic Substitution

Alkyl Halides and Elimination Reactions

Alcohols, Ethers, and Related Compounds

Alkenes

Alkynes

Oxidation and Reduction

Mass Spectrometry and Infrared Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Radical Reactions

Conjugation, Resonance, and Dienes

Benzene and Aromatic Compounds

Reactions of Aromatic Compounds

Carboxylic Acids and the Acidity of the O-H Bond

Introduction to Carbonyl Chemistry;

Aldehydes and Ketones Nucleophilic Addition

Carboxylic Acids and Derivatives

Substitution Reactions of Carbonyl Compounds at the Alpha-Carbon

Carbonyl Condensation Reactions

Amines

Carbon-Carbon Bond Forming Reactions in Organic Synthesis

Pericyclic Reactions

Carbohydrates

Amino Acids and Proteins

Synthetic Polymers

Lipids

Filters

Which of the following expressions summarizes the correct relationship between the free energy change, DG°, and the equilibrium constant, K_eq?

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism: If the concentration of ^-OCH₃ were increased 5 times, what would happen to the rate of the reaction?

Which reaction is fast and has K_eq = 1?