{1
C. fln,*^, F. Bernasconi Chemistryl08A
A
),
Winter2006
First Midterm Exam - Februarv 2.2006 This examconsists nine (9) questions atotal of 100points.Try to answorall questions. of for Write your answers a Blue Book. Put your nameand your TA's nameon the front pageof the in Blue Book. 1. (12 points) Give ItiPAC namesto the following compounds: H
(a)
CHi
\/ C:C ./\
H (b) CHCH"CH, l"r CH:
cH2cH3
CH3CH2C:CHz
I
7-t 7- +-w1#'u4- Y<n<
(c)
t- "&/- /- lo&n"
CH: CH:
(d)
cHl
-H
i, i, t{* /r;nt(d,r/-
lro, s - /, g -,{ nufr-uf rh pu,1^r.'n' q
2.
fuohh<*n<
(12 points) Draw as many resonance structures possiblefor the following species; as use curved alrows to show how the differentresonance structures into one can be converted another.
(a)
EV?
|
\-{
Au l-H
(b)
Po \ll
{_
CH3CH|-C_CHCH3
0
/f'
CI
D
c !1 * c H z -C = l l c H3 c
I
J,
(c)
d
J,
-'ocHr
/H C+ H
(d)
o' ) ll-o '/ c -.(] o
\\r /
o
I *#C"--D
\./
v
44c Hz + -,.?
\\
t/
Do2
? LVY
0
\\ t\.2 f
c-o-
i
a J.
(8 points) Consider the following acid-baseequilibrium:
,,O + C I2 CHC '\ OH
/7"
o -L
CH3C
Kto
o
cl^CHC' .\
+ cH3c\
,P
OH
o
pKu of aceticacidis pKu of dichloroacetic is 1.7,the approximate acid The approximate
4.7.
(a) (b)
Which sideof the equilibriumis favoredandhow largeis K? Is AGopositiveor negative this reaction? for
(a)
K=
gCtzc\ctx:4
lo
. " - t,7
Itl ' I t-/
,2
Kf,tsx""'t
lo - 1 . 7
iA,t rr'ttaus )s {^ru,"/
/fr"/&* r,"# {r",/ s,'4 (f"d^{
/
s,,4 )
(6)
rs n<q^A* /S',n'd Af , = -Rra K ) ^co
v\
o
(.10 points)When rotatingthe centralC-C bond of the following dicarboxylic acid HOOCCH"CH"COOH thereare four different conformations that are of particularinterest,two of them are eclipsedand two of them are staggered. Draw Newmanprojectionsof the four conformations and rank order them in termsof relativestability.
C-oult\
rl
CoDil
ir
\ J * f '1
\
rx
i\,,c)<>r"\
rr-Y"
l\
cut\
\ \. \' { /-n
Coot{
t*7b\n i{0"
11
l\
A
C
b
Le <b*r'Ahs
5.
A> c>
(8 poinrs) Calculate AH" for thefollowingreaction. CH3CH2BT HrO -+ CH2CH2OH+ FIBr + o Is thereaction favorable? Use therelevant Bond Dissociation Enersies from the attached tab leior yourcalculations.
cttrcurl -r Ho+ H S" 2(r '+11,,,,( #l/nd *at
---
r R' cQcr+zfor\ l+f
3t o "fiJ h,(
\-^r
r*..--.F
3U '6 Y,,',{
J
'"7s 3
'1+b
Ca
7W*-7835 71 frJl&
F";h'* ol"
6.
Wqus {l* rcr,/,rt k *(
S,u"w-K"
(8 points) Calculateformal charges the variousC, N, and O atomsin the following on (ions). molecules
7,
(a)
(b)
t _t l lll | /'.
\\\
\-/ N
f-l-/
td , : o :\//
7.
(10points)Which of the following species Br@nsted-Lowry are acids,Lewis acids,bases, both, or neither? (a) AlBr3 (b)
H2S04
(c)
NHz-
(d)
(e.)
Hzo
u) rw,ltu, ( e)
i, tl
(e) /n*,s a^'4 '$) $,*'fu/-hrnJ a^,/ ('c) 'fusu
Xrfl, R",rrb/* /u",7 a 6r/ ad/
6^**
l ,-
8.
(22points)Consider following reaction. the
+ HCI
(a)
Show the mechanism this reaction;be sureto indicatethe flow of the electrons of by means ofl'arrow pushing." Draw structures the transitionstates. of Explain the differencebetweenan intermediate and a transitionstate. Draw a free energyversus profile;identify AGI, AGt, AG?, reaction coordinate AGBu".ar, and AGfuerall the profile. ofl
(b) (c) (d)
@)
ft?Hrt
/ 51 .'
3*
F "1-sr ;
U
fr)
I
-1
; (\"
\l - *.,_ {cu
[c)
,matiwravu C6r5 a rzuck' A {<uus;f<^ sh{e is An 4yev11.-_A>o,t/1^"41 kl"6 An ,nt< r a
fnmimaw.,
"o{^{,
ls Qn
<n((3J
T Si
TSz
ee)
*
(a)
G
*
AG,
Loc"
G *H Q
*+
6ru1vl! =
L^,
R<^t /^,u
du'
Co oo/,n*L
ar av
/\c
L
(10 points)Propose structures meetthe following criteria: that (a) (b) (c) (d) An esterwith threecarbons A cyclic carboxylicacid with 6 carbons An aldehydewith one carbon A secondary aminewith four carbons
;1 u
(a)
c13c( o.n,
o
rr)
G)
!{
c. oH
,/,
ic)
C Hoc=
ck{zc113 cltsc{2N