CHE231 SSCC – Exam 1
Organic Chemistry
Monday, October 16th, 2006
Name _____________________________
Multiple choice (20pts-2pts each). Please circle your answers.
1. The compound below is an adrenocortical hormone called cortisone. Which functional group is
not present in cortisone?
A)
B)
C)
D)
E)
1 alcohol
2 alcohol
3 alcohol
Ketone
Alkene
2. Based on VSEPR theory, which of the following would have a trigonal planar shape?
A)
B)
C)
D)
E)
(CH3)3N
HCN
NH4+
CH3CH3+
3. The orbital picture for acetylene (C2H2) is shown. The arrow points to
A)
B)
C)
D)
an sp-sp sigma bond
an sp-s sigma bond
an sp2-sp2 sigma bond
a pi () bond
4. The C-O-C bond in diethyl ether (CH3CH2 -O- CH2CH3) is predicted to be approximately:
A)
B)
C)
D)
E)
90
105
110
120
180
5. Which point on the potential energy diagram below represents the most stable state for the
hydrogen molecule?
A)
B)
C)
D)
E)
I
II
III
IV
V
6. Which of the following molecules has a nitrogen with a formal charge of –1?
A)
N
B) H
H
N
H
C) H
D) H3C
H
H
H
N CH3
N
CH3
H
7. Which of these Lewis dot structures is correct for the nitrite ion, NO2- ?
O N
O N O
O
O N O
IV
I
II
III
IV
V
III
II
I
A)
B)
C)
D)
E)
O N
O
N O
V
O
E) CH3C
N
8. Which compound has the shortest carbon-carbon bond?
A) CH3CH3
B) CH2
C) CH
CH2
CH
D) CH3CH2CH3
E) All carbon-carbon bonds are the same length
9. Which compound is not an isomer of the others?
CH3CH
CHCH
OH
O
I
A)
B)
C)
D)
E)
OH
II
I
II
III
IV
All of the above.
10. Which compound is a tertiary alcohol?
A)
B)
C)
D)
E)
I
II
III
IV
V
O
III
IV
Short answer section (30pts).
1. (7pts) Write structural formulas for each of the following:
a. Four primary alkyl halides with the formula: C5H11Br
Br
Br
Br
Br
O
O
b. Three aldehydes with the formula: C5H10O
O
O
H
H
2. The skeleton structure of urea is:
H2N
H
H
O
C
NH2
a. (4pts) Draw the Lewis dot structure of urea including all lone pairs and bonding electrons.
O
H
C
H
N
N
H
H
b. (3pts) What are the hybridizations for C, N, and O in the Lewis dot structure you drew in
Part A?
C is sp2, N is sp3, O is sp2
c. (4pts) Estimate the following bond angles in urea:
N-C-N
N-C-O
H-N-C
H-N-H
120
120
107
107
d. (3pts) Does the molecule have a dipole moment? If so, indicate the direction of the net
dipole.
O
H
C
H
N
N
H
H
net
e. (5pts) Show as many resonance structures for urea as you can. Include any formal
charges.
O
H
O
O
C
H
N
N
H
H
H
C
H
H
C
H
N
N
N
N
H
H
H
H
f. (4pts) The molar mass of acetamide, CH3-CO-NH2 is 59 while that of urea is 60.
Acetamide boils at 221C. Would the boiling point of urea be expected to be higher,
lower, or about the same as that of acetamide? Explain.
O
H3C
O
NH2
acetamide
H2N
NH2
urea
The boiling point of urea will be higher than acetamide because it has more hydrogen
bonding than acetamide, which can only hydrogen bond in one place.