Chapter 6 Homework
SHORT ANSWER
Section 6-1
Classify each reaction below as a(n):
a.
b.
c.
d.
addition
elimination
substitution
rearrangement
Place the letter corresponding to the correct answer in the blank to the left of the reaction.
1.
_____
ANS:
c
2.
_____
ANS:
d
3.
_____
ANS:
a
1
An Overview of Organic Reactions
Section 6-2
Identify the functional groups present in each compound below and predict the direction of
polarity in each.
4.
mustard gas Cl−CH2CH2−S−CH2CH2−Cl
ANS:
5.
ANS:
Section 6-3
Classify each structure below as a nucleophile or electrophile and briefly explain your choice.
6.
ANS:
Azide is a nucleophile since it has a net negative charge (and lots of electron pairs!).
7.
ANS:
Hydronium ion is an electrophile since it has a positive charge.
2
Chapter 6
8.
ANS:
Phenol can be a nucleophile or an electrophile
Section 6-4
Identify the nucleophile and electrophile in each reaction below and label them.
9.
ANS:
10.
ANS:
3
An Overview of Organic Reactions
11.
ANS:
Section 6-5
Add curved arrows to the following reactions to indicate the flow of electrons in each.
12.
ANS:
13.
ANS:
14.
ANS:
4
Chapter 6
15.
Define a polar and a non-polar bond. See slides.
Section 6-6
MATCH each definition to one of the terms below. Place the letter of the term in the blank to the
left of the definition.
a.
b.
c.
d.
e.
polarization
addition reaction
homolytic bond breakage
electrophile
polar reaction
16.
f.
g.
h.
i.
j.
substitution
nucleophile
radical reaction
elimination reaction
heterolytic bond breakage
_____ A process involving symmetrical bond breaking and bond making.
ANS:
h
17.
_____ This occurs when both bonding electrons remain with one product fragment.
ANS:
j
18.
_____ A reaction where two reactants exchange parts to give two new products.
ANS:
f
19.
_____ A general term for species which have electron rich sites that can form a bond by
donating a pair of electrons to an electron poor site.
ANS:
g
Section 6-7
Consider this reaction when answering the following question(s):
20.
a.
Refer to Section 6-7. This reaction is an example of:
a substitution reaction.
5
An Overview of Organic Reactions
b.
c.
d.
a rearrangement reaction.
an addition reaction.
an elimination reaction.
ANS:
b
21.
Refer to Section 6-7.
a. The structures below show the step-wise bond making and bond breaking in this reaction.
Draw curved arrows to show the electron flow that has occurred in each step.
b. Calculate Keq for the reaction in part a.
c. Calculate ΔG° for the reaction in part a.
ANS:
a.
b. Keq = [products]/[reactants] = 76/24 = 3.17
c. ΔG°= –RT ln Keq = – 8.314 J/(K • mol)(298) ln 3.17 = –2.86 x 103 J/mol = –2.86 kJ/mol
22.
The original question has been combined with #21 as part b. This placeholder question is
here to maintain the integrity of the numbering system between the printed copy and
ExamView. Therefore, it has been marked "do not use on test" in ExamView's question
information dialog. As a result, this placeholder question is automatically prevented from
being chosen as a test question.
ANS:
Answer not provided.
6
Chapter 6
23.
Refer to Section 6-7. Draw a qualitative energy STEP1 for the reaction (assume that the first
step is slower than the second step). Label fully.
ANS:
Section 6-8
MATCH each definition to one of the terms below. Place the letter corresponding to the term in
the blank to the left of the definition.
a.
b.
c.
transition state
endergonic reaction
activation energy
24.
d.
e.
f.
standard Gibbs free energy change
exergonic reaction
reaction intermediate
_____ A species that lies at an energy minimum between steps on a reaction.
ANS:
f
25.
_____ The energy needed by reactants to reach the transition state.
ANS:
c
26.
_____ A reaction where ΔG° is negative.
ANS:
e
27.
_____ ΔG° = −RT ln Keq
ANS:
d
7
An Overview of Organic Reactions
Section 6-9
Use the reaction energy STEP1 below to answer the following question(s).
28.
a.
b.
c.
d.
Refer to Section 6-9. The reaction depicted in this reaction energy STEP1 can best be
described as:
a slow exothermic reaction
a fast exothermic reaction
a slow endothermic reaction
a fast endothermic reaction
ANS:
b
29.
Refer to Section 6-9. The transition state is found at point _____ on the STEP1.
ANS:
B
30.
Refer to Section 6-9. The products are found at point _____ on the STEP1.
ANS:
D
31.
Refer to Section 6-9. The free-energy change for the reaction is indicated at point _____ on
the STEP1.
ANS:
C
32.
ANS:
A
8
Refer to Section 6-9. The reactants are found at point _____ on the STEP1.
Chapter 6
Section 6-10
Consider the reaction of 2-bromo-2-methylpropane with water, shown below, to answer the
following question(s).
STEP1 1: The first step of this reaction is shown below.
STEP 2/3: The second and third steps of the reaction are shown below.
33.
a.
b.
c.
d.
Refer to Section 6-10. This reaction is an example of:
a substitution reaction.
a rearrangement reaction.
an elimination reaction.
an addition reaction.
ANS:
a
34.
a.
b.
c.
d.
Refer to Section 6-10. In STEP1 1, Species B is:
a carbene
a carbanion
a carbocation
a radical
ANS:
c
9
An Overview of Organic Reactions
35.
Refer to Section 6-10. In STEP1 1, add curved arrows to indicate electron flow.
ANS:
Refer to Section 6-10. In STEP2/3, label the nucleophile, Nu, and the electrophile, E+, in the
blanks provided under the structures.
36.
ANS:
37.
Refer to Section 6-10. In STEP1 2, draw arrows on the structures showing electron flow.
ANS:
38.
a.
b.
c.
d.
Refer to Section 6-10. The reaction in STEP1 2 is an example of:
a pericyclic reaction.
a radical reaction.
a concerted reaction.
a stepwise reaction.
ANS:
d
10