Test Bank For Organic Chemistry 8th Edition By L. G. Wade

Test Bank For Organic Chemistry 8th Edition By L. G. Wade

Chapter 4 The Study of Chemical Reactions

1) ________ is the study of reaction rates.

Answer: Kinetics

Diff: 1

Section: 4.2

2) What is meant by the mechanism of a chemical reaction?

Answer: The mechanism of a reaction is the complete, step-by-step description of exactly which bonds break, which bonds form, and the order in which these events occur in the transformation of reactants into products.

Diff: 2

Section: 4.2

3) Which of the following species is not formed through a termination reaction in the chlorination of methane?

A) CH3Cl

B) HCl

C) H2

D) CH3CH3

Answer: C

Diff: 2

Section: 4.2

4) The chlorination of methane is characterized by a high quantum yield. Explain what this means.

Answer: Many molecules of product are formed for every photon of light which is absorbed by the reaction mixture.

Diff: 3

Section: 4.2

5) Within the visible spectrum, it has been experimentally determined that blue light is the most effective in initiating the chlorination of methane. What is the mechanistic significance of this observation?

Answer: Blue light is effectively absorbed by chlorine but not by methane. Thus the initiating step is most likely the production of two chlorine atoms from molecular chlorine.

Diff: 3

Section: 4.2

6) Explain how the termination step in a free-radical chain reaction stops the chain.

Answer: In order for a free-radical chain to propagate, each mechanistic step must yield a free-radical species as one of its products. A mechanistic step that does not yield a free-radical stops the chain. Such a step is known as a termination step.

Diff: 1

Section: 4.3

7) Species with unpaired electrons are called ________.

Answer: radicals or free radicals

Diff: 1

Section: 4.3

8) Which of the following is not a possible termination step in the free radical chlorination of methane?

A) ∙CH3  + Cl2  → CH3Cl + Cl∙

B) ∙CH3  + Cl∙ → CH3Cl

C) ∙CH3 + ∙CH3  → CH3CH3

D) ∙CH3 + wall → CH3-wall

E) Cl∙ + wall → Cl-wall

Answer: A

Diff: 2

Section: 4.3

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

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.

Answer: B

Diff: 2

Section: 4.3

10) In the reaction of Cl2 with ethane and UV light, which of the following reactions would be a chain termination event(s)?

I) Cl∙ + CH3-CH3 → CH3-CH2-Cl + H∙

II) Cl∙ + CH3-CH3  → CH3-H2C∙ + HCl

III) Cl∙ + CH3-H2C∙ → CH3-CH2-Cl

IV) Cl2 + CH3-H2C∙ → CH3-CH2-Cl + Cl∙

V) Cl2 + UV light → C l∙ + Cl∙

A) reaction V

B) reactions I and IV

C) reactions III and IV

D) reactions I and II

E) reaction III

Answer: E

Diff: 2

Section: 4.3