Chemistry 321
50-Minute Examination #1
Friday, February 14, 2003
VERSION B.
Write your answers in the space provided on the Answer Sheet provided. Keep this examination;
turn in only the Answer Sheet.
1. Draw an acceptable Lewis dot structure for acetone, CH3COCH3. [8 points]
2. Draw the Lewis electron dot structure of formamidine, CH4N2. The carbon atom is bonded to
one hydrogen atom and the two nitrogen atoms. There is no nitrogen-nitrogen bond in
formamidine. [10 points]
c
3. What is the molecular formula of the molecule at right? [6 points]
a b
4. What type of molecular orbital is the lowest energy empty molecular
orbital in the compound at right? [4 points]
5. What is the hybridization of the indicated atoms on the structure at
right? [10 points]
d
CHO
N C
O
e
6. Acetophenone, C6H5COCH3 has a pKa of 26.5; ammonia has a pKa of 33.5.
(a) What will be the approximate equilibrium constant for the formation of acetophenone anion,
C6H5COCH2—, by the reaction between acetophenone and potassium amide (KNH2)? [6 points]
(b) Is amide ion a sufficiently strong base to convert most of the acetophenone to its conjugate
base? [2 points]
7. Name the following organic compounds. [18 points]
Br
Br
OH
(a)
Br
(b)
(c)
8. The name, 2,4-diethyl-3-methylpentane, is not correct, but it can be used to draw the structure
of the molecule. Draw the molecule and give its correct name. [8 points]
9. The conjugate acid of thiourea, CH5N2S+, has a structure in which a central carbon is bonded
to the two nitrogen atoms and the sulfur atom. There is one hydrogen-sulfur and no hydrogencarbon bond. Each nitrogen is bonded to two hydrogen atoms. Draw all the different possible
resonance contributors can be drawn for this cation. [12 points]
d
c
O
10. There are seven heteroatoms in the molecule at right. What is the
formal charge on each? [14 points]
b
C
O
N
N CH3
a
11. How many lone pairs are on the boron atom in B(CH3)3? [2 points]
O N
O
g
e
f
CHEMISTRY 321
50-MINUTE EXAMINATION #1 — Version B
FRIDAY, FEBRUARY 14, 2003
NAME (Print!):
1.
2.
H
C
H
H
3.
H
N
H C
N H
H
H
C
H
H
C12H17NO2
5. (a) sp
6. (a)
O
C
(b)
sp
(c)
sp2
107
7 (a)
5,6,6-tribromo-2-octene
7 (b)
4,8-diethyl-4,5-dimethylundecane
7 (c)
5,6,6-trimethyl-1-octanol
8 (a)
8 (b)
π∗
4.
3,4,5-trimethylheptane
(d)
(b)
sp2
yes
(e)
sp3
9.
H
10.
11.
N
H
S
C
H
N
H
H
H
N
H
S
C
H
N
H
H
H
N
H
(a)
-1
(b)
0
(c)
-1
(e)
+1
(f)
0
(g)
+1
0
S
C
H
N
H
H
(d)
0