Name_____________________________________________________ Exam 1 R340 Fall 2014
This exam contains 104 points and will be scored out of a maximum of 100 points.
1. (4pts) Circle all pairs of molecules that are capable of hydrogen bonding with each other.
2. (4pts) Indicate all polar bonds with dipole arrows. Is this molecule polar or nonpolar overall? Explain.
3. (8 pts) When we say that the nucleic acid bases guanine and cytosine “base pair”, we are saying that
they recognize each other with complementary intermolecular forces, which hold them together, like a
magnet. Below are their structures , aligned in the proper orientation to each other. Using your
knowledge of resonance , redraw them in the more aromatic looking structures. Indicate partial charges
on the base pairing atoms to show how they align so strongly.
4. (6pts) Draw the products of these acid/base reaction.
5. (8pts) Write pKa values for the protons in bold. Label the most acidic compound by writing “most”
under it, and label the least acidic compound by writing “least” under it.
6. (12pts) Draw a full arrow mechanism for these reaction.
7. (12pts) Label both of these reactions as acid/base, electrophilic addition, elimination, or nucleophilic
substitution. Draw an energy diagram for each of these one-step reactions. Mark the starting material,
products, and transition state on your energy diagram. Label each reaction as exothermic (downhill) or
endothermic (uphill.)
8. (4pts) Predict the major products for the following addition reactions.
9. (12pts) Predict the products of these elimination reactions. One of them does not occur as written.
For that reaction, write “NO RXN” and explain why.
10. (4pts) Cirlce each of the following that would be acceptable substrates for a substitution reaction.
11. (16pts) Draw a mechanism for this elimination reaction. Include all arrows and intermediates.
Draw an energy diagram for this mechanism, assuming it is exothermic under these conditions. Indicate
the rate determining step.
Draw the transition state structure for the last step of the reaction mechanism.
Why is this reaction favorable even though a more unstable pi bond is formed?
12. (8pts) . Label the acid, base, conjugate acid, and conjugate base in this reaction. Using base stability
principles, indicate which base is more stable. In which direction does the equilibrium lie?
13. (6pts) Provide the reagents that will cause these transformations.
PERIODIC TABLE OF THE ELEMENTS
1
H
1.008
3
Li
6.941
11
Na
22.99
19
K
39.10
37
Rb
85.47
55
Cs
132.9
87
Fr
(223)
4
Be
9.012
12
Mg
24.31
20
Ca
40.08
38
Sr
87.62
56
Ba
137.3
88
Ra
(226)
Scratch work:
1
Atomic Number
H
Symbol
1.008 Atomic Weight
5
B
10.81
13
Al
26.98
21
22
23
24
25
26
27
28
29
30
31
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
44.96 47.88 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.39 69.72
39
40
41
42
43
44
45
46
47
48
49
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
88.91 91.22 92.91 95.94 (98) 101.1 102.9 106.4 107.9 112.4 114.8
57
72
73
74
75
76
77
78
79
80
81
La
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
138.9 178.5 180.9 183.9 186.2 190.2 192.2 195.1 197.0 200.6 204.4
89
Ac
(227)
6
C
12.01
14
Si
28.09
32
Ge
72.61
50
Sn
118.7
82
Pb
207.2
7
N
14.01
15
P
30.97
33
As
74.92
51
Sb
121.8
83
Bi
209.0
8
O
16.00
16
S
32.07
34
Se
78.96
52
Te
127.6
84
Po
(209)
58
Ce
140.1
90
Th
232.0
69
Tm
168.9
101
Md
70
Yb
173.0
102
No
71
Lu
175.0
103
Lr
59
Pr
140.9
91
Pa
(231)
60
Nd
144.2
92
U
238.0
61
Pm
(145)
93
Np
62
Sm
150.4
94
Pu
63
Eu
152.0
95
Am
64
Gd
157.3
96
Cm
65
Tb
158.9
97
Bk
66
Dy
162.5
98
Cf
67
Ho
164.9
99
Es
68
Er
167.3
100
Fm
9
F
19.00
17
Cl
35.45
35
Br
79.90
53
I
126.9
85
At
(210)
2
He
4.003
10
Ne
20.18
18
Ar
39.95
36
Kr
83.80
54
Xe
131.3
86
Rn
(222)