Page 1
1.
Given the relative reactivities of various kinds of hydrogens, the major product
expected from mono-bromination of 2-methylbutane would be what?
A)
H3C C
CH3
H
CH2CH2Br
B)
H3C C
CH3
H
CHBr CH3
C)
H3C C
CH2Br
H
CH2CH3
D)
E)
H3C C
CH3
Br
CH2CH3
2.
Which of the following is a propagation step in the free-radical bromination of
methane?
A)
CH3• + Br• CH3Br
B)
Br2 2 Br•
h
C)
CH3• + Br2CH3Br + Br•
D)
CH3• + CH3• CH3CH3
E)
Br• + Br• Br2
Page 2
3.
Which of the reactions below would you expect to have the largest positive ?
A)
CH3• + Br• CH3Br
B)
Br2 2 Br•
h
C)
CH3• + Br2CH3Br + Br•
D)
CH3• + CH3• CH3CH3
E)
Br• + Br• Br2
4.
What reactant is needed to complete and balance the following reaction?
? + 3 O
2 3 CO + 3 H
2O
spark
A)
C3H8
B)
C2H6
C)
C3H4
D)
C3H6
E)
C6H12
5.
Which one of the reactions below will not proceed and accounts for why iodine added
to a free-radical chlorination or bromination will greatly slow or even stop the reaction?
A)
CH3• + I• CH3I
B)
h
I2 2 I•
C)
CH3I + I•CH3• + I2
D)
CH4 + I• CH3• + HI
E)
I• + I• I
2
6.
Which of the following is not true of free-radical halogenation reactions?
A)
Fluorine is more reactive than chlorine in these reactions.
B)
Bromine is more selective than chlorine.
C)
The reactions require either light or high temperatures to proceed.
D)
Brominations are faster than chlorinations.
E)
These reactions are irreversible.
Page 3
7.
Which of the following reaction types are typical of alkanes?
A)
addition
B)
elimination
C)
radical substitution
D)
reduction
E)
more than one of these is correct
8.
Alkanes are noted for their (choose one)
A)
high reactivity with acids.
B)
toxicity.
C)
intense odor.
D)
lack of reactivity.
E)
water-solubility.
9.
What is the major product of the following reaction?
+Br2?
light
A)
Br
B)
Br
C)
Br
D)
Br
Br
E)
no reaction occurs
Page 4
10.
Predict the major monofluorination product from the following reaction:
+?
h
F2
A)
F
B)
FF
C)
F
D)
F
E)
F
11.
In a carbon radical, the single unpaired electron resides in:
A)
sp2 orbital
B)
sp3 orbital
C)
s orbital
D)
p orbital
E)
None of the above.
12.
The order of radical stability is:
A)
3° > 2° > 1° > Me
B)
3° < 2° < 1° < Me
C)
all are about equal in stability
D)
Me > primary
E)
tertiary and methyl are equal in stability
Page 5
13.
Which of the following is true for an early transition state?
A)
The starting materials resemble the products.
B)
The reaction proceeds very slowly.
C)
The transition state resembles the reactants.
D)
The transition state resembles the products.
E)
both B and C
14.
Hyperconjugation is most useful for stabilizing which of the following?
A)
neopentyl radical
B)
tert-butyl radical
C)
isopropyl radical
D)
ethyl radical
E)
methyl radical
15.
In a carbon radical, the carbon possesses how many valence electrons?
A)
4
B)
5
C)
6
D)
7
E)
8
16.
Which, if any, of the following would you choose to accomplish the reaction shown
below in the best yield?
X
(X = halogen)
A)
F2, light
B)
Cl2, light
C)
Br2, light
D)
I2, light
E)
None of the above.
Page 6
17.
Predict the major product of the following reaction:
Br2 / light ?
A)
Br
B)
Br
C)
Br
D)
Br
E)
Br
18.
Predict the major product of the following reaction:
I2 / light ?
A)
I
B)
I
C)
I
D)
E)
no reaction
Page 7
19.
Free-radical fluorination demonstrates little regio-selectivity because
A)
fluorine is too small to have steric hinderance.
B)
free-radical reactions are never regio-selective.
C)
a late transition state is involved.
D)
an early transition state is involved.
E)
fluorine is too unreactive.
20.
Which of the carbon-carbon bonds indicated would be the weakest?
H3C
A
BC
D
E
A)
A
B)
B
C)
C
D)
D
E)
E
21.
Which alkane below would you expect to have the lowest heat of combustion?
A)
B)
C)
D)
E)
All would be the same.
22.
Which of the following would you not expect to be formed in even small amounts
during the free-radical chlorination of methane?
A)
CH2Cl2
B)
CH3CH3
C)
CHCl3
D)
CCl4
E)
Some of all of these would be formed.
Page 8
23.
Given the relative reactivities of various kinds of hydrogens, the major product
expected from mono-chlorination of 2-methylbutane would be what?
A)
H3C C
CH3
H
CH2CH2Cl
B)
H3C C
CH3
H
CHCl CH3
C)
H3C C
CH2Cl
H
CH2CH3
D)
CH3C
CH3
Cl
CH2CH3
E)
There is no way to predict this.
Page 9
24.
Which of the following hydrocarbons would yield only a single mono-chloro derivative
under free radical chlorination conditions? (Cl2/h)
A)
B)
C)
D)
CH3
E)
25.
Give the relative reactivity in decreasing order for free radical halogenation of
(CH3)3CH.
A)
F > Cl >Br
B)
Cl > Br > F
C)
Br > F > Cl
D)
Br > Cl > F
E)
I > F > Cl
26.
Which is most true about the function of a catalyst?
A)
Catalysts speed up the reaction by lowering the transition state of a reaction.
B)
Catalysts usually need higher temperatures to promote reactions.
C)
Catalysts lower the energies of the reactants.
D)
Catalysts lower the energies of the products.
E)
Catalysts increase the yield of the reaction.
Page 10
27.
In a free radical termination step:
A)
an initiator starts a chain reaction.
B)
free radicals recombine with one another.
C)
a radical reacts to form another radical.
D)
the activation energy is high.
E)
a reactive intermediate is formed.
28.
Rank the following radicals in decreasing order of stability.
CH3(CH3)3CCH2CH2CH CH2
1 2 34
A)
3 > 4 > 2 > 1
B)
3 > 2 > 4 > 1
C)
2 > 3 > 4 > 1
D)
2 > 4 > 3 > 1
E)
1 > 2 > 3 > 4
29.
Carbon dioxide is an essential greenhouse gas that insulates the planet and maintains a
surface temperature that allows life to flourish. Human activities have resulted in a
dramatic increase in the greenhouse gases in the atmosphere. Which of the following
reactions produce the most carbon dioxide per mole of carbon-containing starting
material? (Note that these equations are not balanced.)
A)
C8H18 + O2
major component
of gasoline
CO2 + H2O
B)
CH4 + O2
major component
of natural gas
CO2 + H2O
C)
C12H22O11+ O2
sugar
CO2 + H2O
D)
All produce the same amount of carbon dioxide.
E)
None of these reactions produce carbon dioxide.
Page 11
30.
Chemists have determined that chlorofluorocarbons are contributing to destruction of
the protective ozone layer. Upon irradiation of chlorofluorcarbons, chlorine radicals are
produced and react with the ozone via the chemical process shown below. Which of the
following statement(s) are true based upon these equations?
A)
Termination steps in the equations above are contributing to ozone depletion.
B)
A single chlorine radical is capable of destroying many molecules of ozone since it
is regenerated.
C)
Chlorine radicals are the result of a heterolytic cleavage of the C-Cl bond of the
chlorofluorocarbon.
D)
A, B and C are correct.
E)
B and C are correct.
31.
What reactant is needed to complete and balance the following reaction?
?+spark + +
5 O23 CO24 H2O
A)
C3H8
B)
C2H6
C)
C3H4
D)
C3H6
E)
C6H12
32.
How many constitutional isomers can be formed from the monochlorination of the
hydrocarbon shown below?
C
CH3
H3C C C
CH3
CH3
CH3
H
HH
hv
Cl2
+
A)
1
B)
2
C)
3
D)
4
E)
5
Page 12
33.
The following reaction represents what type of process?
A)
Propagation
B)
Termination
C)
Initiation
D)
Nucleophilic addition
E)
None of the above.
34.
How many different products will result if radical monobromination of the following
compound only occurs at 3° carbons.
CH3
H3C
CH(CH3)2
Br2
h
A)
0
B)
1
C)
2
D)
3
E)
4
Page 13
Answer Key