Question 1

What is the name given to the reaction species that lies at an energy minimum between steps on a reaction energy diagram?

Accepted Answer

A) Transition state 
B) Activation energy 
C) Reactive intermediate 
D) Equilibrium product

Question 2

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.

Question 3

The equilibrium constant for the conversion of A to D is predicted to be which of the following?

Accepted Answer

A) Keq = 1 
B) Keq eq > 1 
D) Cannot be determined from the information provided

Question 4

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

Question 5

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

Question 6

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.

Question 7

Which of the Keq corresponds to the most negative value of DG°?

Accepted Answer

A) Keq = 1 
B) Keq = 101 
C) Keq = 102 
D) Keq = 103

Question 8

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.

Question 9

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.

Question 10

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

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

Question 12

Which reaction is fast and has Keq = 1?

Accepted Answer

A) A 
B) B 
C) C

Question 13

In which reaction is Keq > 1?

Accepted Answer

A) A 
B) B 
C) C

Question 14

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]+

Question 15

Which reaction is slowest?

Accepted Answer

A) A 
B) B 
C) C

Question 16

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

Question 17

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.

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.

Question 19

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.

Question 20

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

Exam 6: Understanding Organic Reactions

What is the name given to the reaction species that lies at an energy minimum between steps on a reaction energy diagram?

Which of the following statements about bond breaking is true?

The equilibrium constant for the conversion of A to D 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?

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 not true?

Which of the K_eq corresponds to the most negative value of DG°?

Which of the following statements about enzymes is true?

Which of the following statements is not true?

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

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?

Which reaction is fast and has K_eq= 1?

In which reaction is K_eq > 1?

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

Which reaction is slowest?

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

Which of the following statements is true?

Which of the following statements about a catalyst is true?

Which of the following statements about addition reactions is true?

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