Chem 0310
Dennis P. Curran
January 30, 2012
Exam 1
Name:_________________________________
Signature:______________________________
Seat:__________________________________
Answer all questions on this exam. If you need more space than that provided,
use the back of any page.
1. ________________
(20 points) Structures and Names
2. ________________
(20 points) Short Answer Questions
3. ________________
(20 points) Isomers
4. ________________
(20 points) Conformations
5. ________________
(20 points) Radical Reactions
TOTAL ____________
(100 points)
The test has 7 pages (including this cover page) and 5 questions
Each question has several parts. Partial credit will be given.
Page 7 has tables of bond dissociation energies.
The exam ends at 10:55 am sharp.
Good Luck !!!
page 1
1) Structures and Names (20 points)
Provide IUPAC names for the following alkanes. (12 points)
a)
b)
Cl
(CH3)2CHCH2CH2CH2CH(CH3)2
Cl
c)
d)
F
F
Cl
Draw clear condensed or bond-line structures for compounds with the following names. (8 points)
c) sec-butyl iodide
e) 4-(1-methylethyl)nonane
d) 4-(tert-butyl)-4-methylheptane
h) 5-ethyl-3,5-dimethyloctane
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2) Short Answer Questions (20 points)
a) Define conformational isomers
b) Label one of each of the following items on 2,3,3-5-tetramethylhexane: i) an isopropyl
group, ii) a primary (1˚) hydrogen atom, iii) a quarternary (4˚) carbon atom, iv) a secondary (2˚)
carbon atom.
c) What is the strongest base that can exist in ammonia? What is the strongest acid that
can exist in ammonia? Ammonia is :NH3.
d) Write the complete equation for the acid-base reaction of ammonia with HCl. Label each
component as the stronger acid (SA), stronger base (SB), weaker acid (WA) or weaker base
(WB).
e) Write Lewis structures for the following formulas. Use lines for bonds. Include formal
charge for any atom that is not zero.
i) CH2NOH
b) [HOCH2CH2O]–1
-3-
3) Isomers (20 points)
a) What is the relationship between the following pairs of compounds. Are they:
1) the same, 2) constitutional isomers, or 3) neither? (16 points)
i)
(CH3)2CHCH2CH2CH(CH3)2
and
ii)
and
iii)
and
iv) CH3CH2CH2CH(CH(CH3)2)CH2CH3
and
b) Circle any structure that is NOT an isomer of octane. (4 points)
H2C
H2C
CH2
CH2
H2C
H2C
CH2
CH2
CH3CH2C(CH3)2CH2CH2CH3
CH3CH(CH2CH3)CH2CH(CH3)2
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4) Conformations (20 points)
a) On the structure below, show i) any one bond angle, and ii) any one dihedral angle.
H
H
C
C
H
H
H
H
b) Draw Newman projections of the CH2–CH3 bond of propane (CH3CH2CH3) in both eclipsed
and staggered conformations.
c) Draw a reaction coordinate diagram for the bond rotation in "b". Locate on your diagram the
eclipsed and staggered conformations and show the energy difference between them (in
kcal/mol).
d) Draw Newman projections for all the staggered isomers of the C2-C3 bond of 2methylhexane.
2
3
(CH3)2CHCH2CH2CH2CH3
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5) Answer the following questions regarding the bromination of propane.
(20 points)
Br
heat to
CH3CH2CH3 + Br2
130 ˚C
CH3CH2CH2Br + CH3CHCH3 + HBr
minor product
major product
a) Write the initiation step and one termination step for this reaction.
b) Write the propagation steps for one (not both) of the products. Use arrows to show electron
movement.
c) Using the tables of bond dissociation energies on the next page, calculate the ΔHo for both
of the products. Are the reactions exothermic or endothermic?
d) If propane is reacted with Cl2 in place of Br2, will the reaction to give CH3CH2CH2Cl and
CH3CH(Cl)CH3 be more selective or less selective than bromination? Explain in a few words.
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