CHM235
Spring 2005
Exam 1-Retake
February 18, 2005
131 points
1. (20 pts) Methyl lithium, CH3Li, can be written as an ionic or a covalent structure.
Write methyl lithium as a covalent compound: (Correct Lewis Structure)
Write methyl lithium as an ionic compound. (Correct Lewis Structure)
Methyl lithium reacts violently with water. Write the reaction of methyl with water:
Given that the pKa of sp3C-H = 50 and H2O = 16.
What is the direction of the reaction?
2. (25 pts) Structure and reactivity:
Which of the following have bond angles based on tetrahedral angles? (does not mean
exactly tetrahedral).
-+
BF3
:CH3
CH3
H2O
H3O+
H2S
NH3
In the blanks above put the hybridization of the non-hydrogen atom for each molecule above.
In the blanks put the oxidation number for the non-hydrogen atom for each molecule above.
Which of the molecules above is the most acidic?
Which of the molecules above is the most basic?
3. (16 pts) Polarity
Which molecule is more polar? Why?
Cl
Cl
Cl
Cl
Show the dipole vector in the more polar molecule.
Which molecule is soluble in water?
CH3OCH3
CH3CH2OH
CH3CH2Cl
CH3CH2CH2CH2CHO
CH3CH2CH2CH2CH2CO2H
Which of the following would have the highest boiling point?
CH3CH2OCH2CH2OCH2CH3
CH3OCH2CH2CH2OCH3
CH3OCH2CH2CH2OCH2OH
HOCH2CH2CH2OCH2CH2OH
CH3OCH2C(OH)HCH2OCH3
4. (16 pts) Draw good Lewis Structures for the following – Show LP and formal charges.
(a) dicyanogen NCCN
(b) imine H2CNH
(c) carbon monoxide CO
(d) BH4-
5. (16 pts) Provide products of the acid base reactions below.
Predict direction and estimate Keq.
Given these pKa values:
CH4 = 50
NH3 = 35
RC CH = 25 ROH = 16 NH4+ = 9
RCO2H = 5
O
+
H3C
H3C
O
-
OH
+
Direction?
Keq =
+
NH3
Direction?
+
CH3—O-
Keq =
6. (12 pts) Draw major resonance structures for the molecules below:
CH3
+
H2C
O
H3C
O
CH3
7. (12 pts) Draw these alkanes:
2.2.5-trimethylhexane
trans-1,2-diethylcyclobutane
4-isopropylheptane
8. (12 pts) Name these alkanes with proper names.
H3C
CH3
CH3
H3C
CH3
H3C
CH3
CH3
CH3
H3C
CH3
CH3
CH3
9. (12 pts) Identify functional groups in the molecules below.
H3C
NH
O
CH3
CH3
O
N
OH
O
N
diruretic
H3C
analgesic
CH3
O
CH3
HO
O
CH3
O
Anti-inflammatory
O
O
H
H
O
H
H3C