CHE 122
HW CH#3
Ch#3 15, 17, 18, 19, 20, 23, 27, 28, 32, 36, 37, 38, 42, 46, 48, 49,67.
3-15
3-17
Many possible answers here, so I have provided several below
3-18
In ethane, each carbon is surrounded by four regions of electron density; bond angles are
109.5°. In ethylene, each carbon is surrounded by three regions of electron density; bond
angles are 120°.
3-19
3-20
The bond angles around the circled atoms are estimated using the VSEPR theory.
(a)
109.5o
(b)
OH
120o
109.5o
120o
(b)
Br
(d)
109.5o
180o
109.5o
Br
3-23 (Answers in back of your text)
3-27 (Answers in back of your text)
3-28
The structural feature that makes cis-trans isomerism possible in alkenes is restricted rotation about the
carbon-carbon double bond. In cycloalkanes, it is restricted rotation about the carbon-carbon bonds of
the ring. These two structural features have in common restricted rotation about carbon-carbon bonds.
3-32
The line-angle drawing of the all cis arachidonic acid:
COOH
Arachidonic acid
3-36
(a) Four alkenes with molecular formula C5H10 do not show cis-trans isomerism.
CH2=CHCH2CH2CH3
1-Pentene
CH3
CH2=CCH2CH3
2-Methyl-1-butene
CH3
CH2=CHCHCH3
3-Methyl-1-butene
CH3
CH3C=CHCH3
2-Methyl-2-butene
(b) Only one alkene with molecular formula C5H10 shows cis-trans isomerism.
H3 C
H3 C
H
C C
H
CH2CH3
trans-2-Pentene
CH2CH3
C C
H
H
cis-2-Pentene
(c) Four cycloalkanes with molecular formula C5H10 do not show cis-trans isomerism.
CH3
Cyclopentane
Methylcyclobutane
CH2CH3
H3C CH3
1,1-Dimethylcyclopropane
Ethylcyclopropane
(d) Only one cycloalkane with molecular formula C5H10 shows cis-trans isomerism.
CH3
CH3
cis-1,2-Dimethylcyclopropane
CH3
CH3
trans-1,2-Dimethylcyclopropane
3-37 (Answers in back of your text)
3-38
(a), (b), and (c): True
no false statements
3-42
Following are completed equations:
Cl
(a)
CH2CH3 + HCl
(b)
CH2CH3 + H2O
(c) CH3(CH2)5CH=CH2
+
CH2CH3
H2SO4
OH
CH2CH3
HI
I
CH3(CH2)5CHCH3
CH3
CCl
CH3
CH2
(d)
+ HCl
C
CH3
OH
OH
CH3CHCH2CH2CH3 + CH3CH2CHCH2CH3
H2SO4
(e) CH3CH=CHCH2CH3 + H2O
(f) CH2=CHCH2CH2CH3 + H2O
H2SO4
OH
CH3CHCH2CH2CH3
3-46
12.46 (a)
(b)
and
and
(c)
3-48
12.48 (a)
and
3-49 (Answers in back of your text)
3-63 (Answers in back of your text)
3-67 (Answers in back of your text)
(b)
(c)