Question 1

Calculate Ea for the conversion of C B.

Accepted Answer

A) +3 kcal 
B) +7 kcal 
C) +9 kcal 
D) None of these 
A) +3 kcal 
B) +7 kcal 
C) +9 kcal 
D) None of these C

Question 2

Which reaction is slowest?

Accepted Answer

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

Question 3

Which of the following statements is not true?

Accepted Answer

A) Bond breaking is endothermic. 
B) The bond dissociation energy for bond breaking is always negative. 
C) Bond making is exothermic. 
D) The bond dissociation energy for bond formation is always negative. 
A) Bond breaking is endothermic. 
B) The bond dissociation energy for bond breaking is always negative. 
C) Bond making is exothermic. 
D) The bond dissociation energy for bond formation is always negative. B

Question 4

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

Accepted Answer

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

Question 5

Which of the following statements about a two-step reaction mechanism is true?

Accepted Answer

A) The transition states are located at energy minima. 
B) Each step is characterized by its own value of DH° and Ea. 
C) The rate-determining step has the lower energy transition state. 
D) The reactive intermediate is located at an energy maximum. 
A) The transition states are located at energy minima. 
B) Each step is characterized by its own value of DH° and Ea. 
C) The rate-determining step has the lower energy transition state. 
D) The reactive intermediate is located at an energy maximum.

Question 6

Which of the following reaction quantities will have an effect on reaction rate?

Accepted Answer

A) DG° 
B) DH° 
C) Keq 
D) Ea 
A) DG° 
B) DH° 
C) Keq 
D) Ea

Question 7

How many transition states and intermediates would the reaction profile have for the reaction shown below?

Accepted Answer

A) Three transition states and three intermediates 
B) Two transition states and two intermediates 
C) Three transition states and two intermediates 
D) Two transition states and three intermediates 
A) Three transition states and three intermediates 
B) Two transition states and two intermediates 
C) Three transition states and two intermediates 
D) Two transition states and three intermediates

Question 8

Which of the following statements about bond breaking is not true?

Accepted Answer

A) Homolysis generates uncharged reactive intermediates with unpaired electrons. 
B) Homolysis require energy but heterolysis does not require energy. 
C) Heterolysis generates charged intermediates. 
D) Heterolysis involves unequal sharing of bonding electrons by atoms. 
A) Homolysis generates uncharged reactive intermediates with unpaired electrons. 
B) Homolysis require energy but heterolysis does not require energy. 
C) Heterolysis generates charged intermediates. 
D) Heterolysis involves unequal sharing of bonding electrons by atoms.

Question 9

Which of the following statements about the equilibrium constant, Keq, is true?

Accepted Answer

A) When Keq > 1, the equilibrium favors the reactants. 
B) When Keq eq tells about the position of equilibrium. 
D) For a reaction to be useful, the equilibrium must favor the reactants. 
A) When Keq > 1, the equilibrium favors the reactants. 
B) When Keq eq tells about the position of equilibrium. 
D) For a reaction to be useful, the equilibrium must favor the reactants.

Question 10

Which of the following statements is true?

Accepted Answer

A) Fast reactions have small rate constants. 
B) Slow reactions have large rate constants. 
C) A rate equation contains concentration terms for all reactants involved in a one-step mechanism. 
D) A rate equation contains concentration terms for all the reactants involved in a multi-step reaction. 
A) Fast reactions have small rate constants. 
B) Slow reactions have large rate constants. 
C) A rate equation contains concentration terms for all reactants involved in a one-step mechanism. 
D) A rate equation contains concentration terms for all the reactants involved in a multi-step reaction.

Question 11

Which reaction has a positive DG°, assuming that entropy changes are negligible compared to enthalpy changes?

Accepted Answer

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

Question 12

Which compound would you predict to be highest in energy?

Accepted Answer

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

Question 13

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

Accepted Answer

A) +108 KJ/mol 
B) -130 KJ/mol 
C) -22 KJ/mol 
D) +22 KJ/mol 
A) +108 KJ/mol 
B) -130 KJ/mol 
C) -22 KJ/mol 
D) +22 KJ/mol

Question 14

Which of the following statements about substitution reactions is true?

Accepted Answer

A) Substitution reactions involve π bonds. 
B) Substitution reactions involve σ bonds. 
C) One σ bond breaks and another forms at a different carbon atom. 
D) One π bond breaks and another forms at the same carbon atom. 
A) Substitution reactions involve π bonds. 
B) Substitution reactions involve σ bonds. 
C) One σ bond breaks and another forms at a different carbon atom. 
D) One π bond breaks and another forms at the same carbon atom.

Question 15

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism:
 
If the concentrations of both -OCH3 and acetyl chloride were increased 2 times, what would happen to the rate of the reaction?

Accepted Answer

A) Rate would become one-fourth 
B) Rate would increase 4 times 
C) Rate would increase 16 times 
D) Rate would increase 2 times 
A) Rate would become one-fourth 
B) Rate would increase 4 times 
C) Rate would increase 16 times 
D) Rate would increase 2 times

Question 16

Which of the following statements is true?

Accepted Answer

A) The product is favored in reaction in which DH° is a positive value. 
B) Entropy decreases when an acyclic compound forms a ring. 
C) In homolytic bond cleavage, entropy decreases and favors formation of products. 
D) The starting material is favored in a reaction in which DH° is a negative value. 
A) The product is favored in reaction in which DH° is a positive value. 
B) Entropy decreases when an acyclic compound forms a ring. 
C) In homolytic bond cleavage, entropy decreases and favors formation of products. 
D) The starting material is favored in a reaction in which DH° is a negative value.

Question 17

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

Accepted Answer

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

Question 18

Which of the following statements about a catalyst is true?

Accepted Answer

A) A catalyst accelerates a reaction by changing the amount of reactant and product at equilibrium. 
B) A catalyst accelerates a reaction by lowering the energy of activation. 
C) A catalyst accelerates a reaction by raising the energy of activation. 
D) A catalyst accelerates a reaction by lowering the equilibrium constant. 
A) A catalyst accelerates a reaction by changing the amount of reactant and product at equilibrium. 
B) A catalyst accelerates a reaction by lowering the energy of activation. 
C) A catalyst accelerates a reaction by raising the energy of activation. 
D) A catalyst accelerates a reaction by lowering the equilibrium constant.

Question 19

A decrease in which of the following results in an increase in the rate of a chemical reaction?

Accepted Answer

A) Energy of activation 
B) Concentration 
C) Temperature 
D) Kinetic energy 
A) Energy of activation 
B) Concentration 
C) Temperature 
D) Kinetic energy

Question 20

Which of the following statements about addition reactions is true?

Accepted Answer

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

Exam 6: Understanding Organic Reactions

Calculate Ea for the conversion of C B.

Which reaction is slowest?

Which of the following statements is not true?

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

Which of the following statements about a two-step reaction mechanism is true?

Which of the following reaction quantities will have an effect on reaction rate?

How many transition states and intermediates would the reaction profile have for the reaction shown below?

Which of the following statements about bond breaking is not true?

Which of the following statements about the equilibrium constant, Keq, is true?

Which of the following statements is true?

Which reaction has a positive DG°, assuming that entropy changes are negligible compared to enthalpy changes?

Which compound would you predict to be highest in energy?

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

Which of the following statements about substitution reactions is true?

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism: If the concentrations of both -OCH3 and acetyl chloride were increased 2 times, what would happen to the rate of the reaction?

Which of the following statements is true?

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

Which of the following statements about a catalyst is true?

A decrease in which of the following results in an increase in the rate of a chemical reaction?

Which of the following statements about addition reactions is true?

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

Calculate E_a for the conversion of C B.

Which of the following statements about the equilibrium constant, K_eq, is true?

The conversion of acetyl chloride to methyl acetate occurs via the following two-step mechanism: If the concentrations of both ^-OCH₃ and acetyl chloride were increased 2 times, what would happen to the rate of the reaction?