Download Exam 1 Key

Name: _________KEY__________
Chemistry 343: Summer 2006
Hour Exam I
Instructor: Weaver
1. Draw the best Lewis structure for nitrate ion (NO3¯). Include all lone pairs and
formal charges for each atom. (6 points)
O
-1
+1
N
O
-1
O
2. Draw the two best Lewis structures for acetonitrile oxide (CH3CNO). Show how
electron pushing arrows can be used to interconvert these Lewis structures. (6
points)
H
H
C
H
C
N
O
H
H
C
C
N
O
H
3. Indicate the number of valence electrons expected for the following atoms or ions. (6
points)
Potassium Ion: ___0____
Bromine Atom: ____7___
Hydride Anion: __-1___
Carbon Atom: ____4___
Sulfur Atom:
Iodide Ion:
____6___
____8___
Name: ___________________________
Student ID#: ______________________
4. Consider the structure of Cortisone in answering the following (7 points):
What
is
formula?
cortisone’s
O
molecular
OH
O
C21H28O5
OH
H
How many sp3 hybridized carbons are
in cortisone?
H
16
How many sp2 hybridized carbons are
in cortisone?
H
O
Cortisone
5
5. Give an example of a compound whose carbon-carbon sigma bonds involve sp2
hybridized orbitals. (5 Points)
Ethene, acetone, acetaldehyde, benzene, etc.
Page 1
________/16
Page 2
________/12
Page 3
________/14
Page 4
________/21
Page 5
________/17
Page 6
________/20
Total
________/100
Name: ___________________________
Student ID#: ______________________
6. Classify the following halides and alcohols as primary (1º), secondary (2º) or tertiary
(3º). (4 points)
OH
O
Br
HO
Cl
Primary
Secondary
Secondary
Tertiary
7. Provide valid IUPAC (systematic) names for the following compounds (10 points):
F
Br
OH
Cl
Name: ___________________________
Student ID#: ______________________
8. An unknown compound has molecular formula C8H8O. The IR spectrum contains
an intense absorption at 1686 cm-1 and additional absorptions are observed at 3006
and 2967 cm-1. Calculate the unsaturation number for this compound. What
functional groups/atom types are indicated by the IR absorptions? Finally, propose
a structure for this unknown. (12 points)
r + p = 8 - 8/2 + 1 = 5 (indicates possible benzene ring)
O
1686 cm-1
Carbonyl (ketone)
2967 cm-1
sp3 C-H Stretching
C
O
CH3
Alkyl (CH3??)
3006 cm-1 sp2 C-H Stretching
(Consistent w/ Benzene Ring)
C8C8O
(also accepted aldehyde variant)
9. Draw the most stable chair conformation and its chair flipped form for the
cyclohexane derivative shown below. Clearly indicate which is the most stable (9
points).
Me
Et
Me
t
Bu
Me
Et
t
Bu
Me
Most Stable
t
Bu Equatorial
t
Bu
Et
Me
Me
Name: ___________________________
Student ID#: ______________________
10. Consider the following acids. Rank these in order of decreasing acidity (1 = most
acidic, 4 = least acidic). (4 points)
OH
OH
OH
Cl
Br
3
1
2
4
Alcohol
Resonance
Inductive
Effect
Alkyl
11. Rank the following in order of decreasing basicity (1 = most basic, 4 = least basic).
(4 points)
NH3
CH3CH2
HCO3
NaNH2
3
1
4
2
12. Give the hybridization of the central atom for each compounds below. Are the
molecules polar or non polar? (9 points)
Compound
Central Atom Hybridization
Polar? (Y/N)
BF3
sp2
NO
CO32-
sp2
NO
CH2Br2
sp3
YES
Name: ___________________________
Student ID#: ______________________
13. Give a curved arrow mechanism for the following reaction, which is a sequence of
acid/base reactions. (12 points)
Br
OH
HBr
+
OH
Ph
-
H
-Br
Br
H 2O
OH2
Ph
-H2O
Br
Br
Ph
14. Clearly identify and label 6 DIFFERENT functional groups present in the following
molecule. (8 points)
Ketone (Carbonyl -1)
O
Alcohol
OH
Lactam
(amide -1)
N
Alkene
O
NH2
Amine
O
Aldehyde (Carbonyl -1)
Ether
OCH2CH3