CHEMISTRY 104
Hour Exam I
Summer 2009
Page 1
Answer the following ten questions (1-10) true (A) or false (B) (1 point each).
Capsaicin is the active compound in chili peppers. A partial Lewis structure for capsaicin is:
O
H
k
CH 3
g
CH3
j
C
CH2
CH2
CH 2
CH2
CH 2
CH
CH
N
O
l
CH
i
CH 3
h
H
H
H
O
H
Complete the Lewis structure and answer the next seven questions.
1. Of all the indicated bond angles (g-1), bond angle j is the largest.
2. There are more atoms with sp2 hybridization than atoms with sp3 hybridization.
3. The bond angles marked g, i and k are all approximately 120o.
4. The nitrogen atom is sp2 hybridized.
5. Capsaicin is more soluble in an aqueous acidic solution than in pure water.
6. There are 4 lone pairs of electrons in the completed Lewis structure.
7. The  bonds in capsaicin are all formed from overlap of unhybridized p atomic orbitals.
----------------------------------------8. The stability of aromatic hydrocarbons is primarily due to the delocalized  electrons
found in benzene.
9. Addition polymerization can be initiated by using a peroxide, e.g., benzoyl peroxide.
10. Alkynes can exhibit cis/trans isomerism.
CHEMISTRY 104
Hour Exam I
Summer 2009
Page 2
MULTIPLE CHOICE (3 points each)
11.
The skeleton structure of TCNQ, C10N4O2, is given below. Complete the Lewis
structure and answer the next question.
O
N
C
C
C
C
N
C
C
N
C
N
C
C
C
O
How many  bonds are in the completed Lewis structure?
a) 6
12.
b) 8
c) 10
d) 12
e) 13
How many of the following compounds have free rotation about every bond in the
molecule?
I. cyclopropane
II. ethane
IV. ethyne
V. benzene
a) 1
b) 2
c) 3
III. ethene
d) 4
e) 5; All have free rotation about every bond.
13.
In class, the TA named a molecule 2-ethyl-4-tert-butylpentane. An alert student
pointed out that although the correct structure could be drawn, the name did not
follow IUPAC rules. What is the correct IUPAC name for the molecule?
a) 5-methyl-2-tert-butylhexane
b) 2-ethyl-4,5,5-trimethylhexane
c) 3,5,6,6-tetramethylheptane
d) 2,2,3,5-tetramethylheptane
e) 3-methyl-4-tert-butylhexane
CHEMISTRY 104
Hour Exam I
14.
Summer 2009
Page 3
Name the following compound:
CH3
H
a) trans-5-ethyl-5-methyl-2-octene
CH3
C
CH 3
CH 2
CH 2
C
C
CH2
b) trans-4 -ethyl-1,4-dimethyl-1-heptene
H
CH2
c) cis-3-methyl-3-propyl-6-hexene
d) trans-4-ethyl-4-methyl-6-octene
CH3
15.
How many different monochlorination products are formed in the reaction shown
below?
CH 3
CH 3
CH
CH
CH 3
light
+ Cl2
CH 3
a) 1
16.
b) 2
c) 3
d) 4
e) 5
How many of the following four types of hydrocarbons undergo addition reactions
easily?
I. alkanes
a) 0; None
II. alkenes
b) 1
c) 2
III. alkynes
d) 3
e) 4; All easily undergo addition reactions.
IV. aromatics
CHEMISTRY 104
Hour Exam I
17.
Summer 2009
Page 4
Which of the following statements about cyclohexane is false?
a) Its molecular formula is C6H12.
b) The chair conformation is more stable than the boat conformation.
c) It is a planar molecule.
d) All bond angles are about 109o.
e) It is a structural isomer of 2-hexene.
18.
Choose the correct order of reactants, intermediates and products for the acid
catalyzed hydration of the following alkene.
first
last
a) II,
III,
IV, I
b) II,
I,
IV, III
c) II,
IV,
III, I
d) III, I,
e) II,
+ H+/H2O
CH3
IV, II
IV, I,
III
H
H
O
H
I.
II.
+ H+
CH 3
CH 3
HO
H
IV.
III.
+
CH 3
H+
+ H 2O
CH3
CHEMISTRY 104
Hour Exam I
Summer 2009
Page 5
For the next two questions, refer to the compounds in Question 19.
19.
Which of the following compounds (I-VI) exhibit cis-trans isomerism?
Pair X:
CH 3
CH 3
CH 3
II
I
Pair Y:
CH 2
CHCH2 CH 2CH 3
CH 3CH
III
C 2H 5
CHCH2 CH 3
IV
Pair Z:
O
CH 2
CH
O
CH 2
CH3
V
VI
a) I, II, III, IV
20.
b) I, II, IV
d) pairs X and Z
-----------------
e) II and IV only
b) pairs X and Y
c) pairs Y and Z
e) pairs X, Y and Z
Consider the combustion reaction of 2-propynal. What is the coefficient in front of
O2 in the balanced combustion reaction assuming one mol of 2-propynal reacted?
a) 4.5
22.
d) III, IV, V
In which of the pairs (X, Y, and Z) is/are the compounds structural isomers of each
other?
a) pair Y only
21.
c) all of them
b) 4
c) 3.5
d) 3
e) 2.5
Which of the following compounds (a-d) cannot hydrogen bond with itself?
a) methyl amine
b) 2-pentanone
c) phenol
e) All the compounds (a-d) can H-bond with itself.
d) benzoic acid
CHEMISTRY 104
Hour Exam I
23.
Summer 2009
Page 6
Which of the following compounds will have the lowest boiling point?
CH 3
b)
a)
CH 3CH2 CH 2 CH 2CH 3
CH 3
C
c)
CH 3
O
CH 3CH2 CH 2
CH
CH 3
O
d)
e)
CH 3CH2 CH 2 CH 2CH 2CH3
CH 3CH2 CCH 3
24.
The following molecule contains which functional groups?
O
C
H
N
C
CH2
C
C
C
CH
C
H 2N
OCH 3
H
a)
b)
c)
d)
e)
25.
O
alcohol, aldehyde, amine, ketone
aldehyde, amide, amine, ether
amide, amine, ether, ketone
amine, ester, ether, ketone
aldehyde, amine, ether, ketone
An unknown organic compound is isolated. The unknown compound can be oxidized
to a ketone but it does not decolorize a brown bromine (Br2) solution. Which of the
following (a-d) is a possible structure for the unknown compound?
CH 2
CH
O
OH
CH 3CH2 CH2 C
H
b)
a)
OH
O
C
c)
OH
d)
CH3 CCH2 CH2 CH 3
CH 2CH 3
e)
None of the above could be the unknown organic compound.
CHEMISTRY 104
Hour Exam I
26.
Summer 2009
Page 7
Which of the following typifies the amino acid linkage in proteins?
a)
c)
b)
R
C
R
R
O
27.
R
O
R
O
C
N
O
H
R
R
large molecular weight, branched chains, syndiotactic
large molecular weight, linear chains, atactic
large molecular weight, linear chains, isotactic
small molecular weight, branched chains. syndiotactic
small molecular weight, linear chains, atactic
You are asked to create a synthetic fiber for use in mountain-climbing robes. Which
functional group, when incorporated into the fiber at position X, will product the
strongest rope?
X
a) ether
X
b) ketone
X
X
c) chloride
n
d) alcohol
e) aldehyde
----------------------------------------29.
Estradiol is a female hormone with the following structure. What is the molecular
formula of estradiol?
H 3C
OH
a)
b)
c)
d)
e)
C18H24O2
C17H22O2
C18H28O2
C17H20O2
C18H20O2
HO
30.
O
You are asked to find a new polymeric material for a proposed space station. It must
have high tensile strength. Which properties would you look for in the polymer?
a)
b)
c)
d)
e)
28.
C
d)
How many chiral carbons does estradiol (the compound in question 29) have?
a) 1
b) 2
c) 3
-----------------------------------------
d) 4
e) 5
R
CHEMISTRY 104
Hour Exam I
Summer 2009
Page 8
FREE RESPONSE QUESTIONS – Points as indicated.
31.
The amino acid ValineH+ has the following structure with pK a1 = 2.3 and pK a 2 = 9.7.
CH 3
15 pts.
H
H
HC
CH 3
N
C
C
H
H
O
O
H
a) What is the R group that differentiates valine from the other approximately 20
amino acids present in the body?
b) Most amino acids are optically active. In the structure above, place a box around
the optically active atom(s) [the chiral atom(s)].
c) Consider the titration of 50.0 mL of 0.10 M ValineH+ with 0.10 M NaOH.
Sketch the titration curve (pH vs. volume of NaOH added). On your sketch,
show the pH of the solution at 25.0 mL, 50.0 mL and 75.0 mL of NaOH added.
CHEMISTRY 104
Hour Exam I
Summer 2009
Page 9
d) Valine has the three different charged forms (shown below) depending on the pH
of the solution. Each dominates (is the only major amino acid species present) at
specific volumes of NaOH added. At what volume of NaOH added does each
form dominate?
CH 3
CH 3
CH
H 2N
CH
CH 3
COO
Volume NaOH added =
CH 3
CH
Volume NaOH added =
H 3N
CH
CH 3
COOH
CH 3
Volume NaOH added =
CH
H3N
CH
COO
e) Circle the form(s) above which is/are the major amino acid species present at the
isoelectric point.
CHEMISTRY 104
Hour Exam I
32.
Summer 2009
Page 10
Name and write the structural formula for the major organic product in each of the
following chemical reactions.
12 pts.
O
H+
a)
CH 3OH + HOCCH 2CH3
b)
C 6 H6
Cl2
FeCl3
O
33.
6 pts.
O
LiAlH4 (excess)
c)
H
d)
HC
C
CH 2
C
CH
C
CH3
CH2
HBr (excess)
When HCl is reacted with 1-methyl-1-cyclopentene, two products are obtained.
Propose a detailed mechanism for the major product formed from this reaction.
Explain why the major product is preferred over the minor product.
CHEMISTRY 104
Hour Exam I
34.
Summer 2009
Page 11
Alcohols are very useful starting materials for the production of a variety of different
compounds. Consider the following conversions, all starting with 1-butanol. What
reagents (including catalysts) are necessary to convert 1-butanol into the desired
product? Some many require more than one step. If more than one step is required,
draw the structural formula for the major organic product in each step (this means to
include the hydrogens).
15 pts.
a) 1-butanol

1-butene
b) 1-butanol

butane
c) 1-butanol

2-butanol
d) 1-butanol

2-butanone
e) 1-butanol

butanoic acid
CHEMISTRY 104
Hour Exam I
35.
Summer 2009
Page 12
Isoprene is the monomer in natural rubber. The structure of isoprene is
6 pts.
CH 3
CH 2
C
CH
CH 2
a) What is the IUPAC name for isoprene?
b) When isoprene polymerizes, two polymers form, the cis configuration and the
trans configuration. Draw the cis configuration showing two repeating units and
the configuration about the carbon-carbon double bonds.
36.
7 pts.
Fiberglass is a condensation polymer formed from the following monomers:
HOCH2CH2OH and HO2CCH=CHCO2H
a) Draw the structure of this fiberglass polymer showing two repeating units.
b) What types of intermolecular forces are exhibited between individual fiberglass
polymer chains?
c) Fiberglass is a highly crosslinked polymer. What compound can be added to
crosslink individual fiberglass polymer chains? Explain how the crosslinks form.
CHEMISTRY 104
Hour Exam I
37.
Summer 2009
Page 13
For the following, what monomer(s) are needed to form the polymer? Label each as
either an addition polymer or a condensation polymer.
8 pts
a)
CH
CH 2
CH
CH 2
CH
CH 2
CH
CH2
n
O
O
b)
NH
NHCCH 2CNH
O
O
NHCCH2 C
n
38.
a) How many alcohols have the formula C4H10O?
6 pts.
b) How many ethers have the formula C4H10O?
c) How many alkenes have the formula C4H10?