Name ___________________
Chemistry 343
Summer 2006 Quiz 2
Instructor: Weaver
1. Hydriodic acid is dissolved in water. Write an equation for this process. Give the Keq
and Ka expressions corresponding to the equilibrium. Does the equilibrium lie to the
right or to the left? (7 points)
HI
+
H3O+
H2O
K a = K eq [ H 2 O] =
+
I-
[ H 3O + ][ I − ]
[ HI ]
HI is a strong acid with pKa of -10, therefore the equilibrium lies to the RIGHT
2. Acid A has a pKa value of 4.8 and Acid B has a pKa value of 8.2. Which acid’s conjugate
base is the strongest base? (2 points)
Stronger ACIDS have WEAKER CONJUGATE BASES, therefore Acid B will have the
STRONGEST CONJUGATE BASE
3. Rank the following acids from strongest to weakest (1 = Strongest, 4 = weakest). (4
points)
Cl
OH
OH
HNO3
H2CO3
O
3
2
O
1
4
4. Explain using acid strength factors the pKa difference between the two acids below. (2
points)
The RESONANCE stability afforded by
phenol (phenoxide anion to be exact)
makes it a much stronger acid than tertbutanol.
OH
pKa = 9.9
OH
pKa = 18
5. Classify the following compounds as polar (P) or nonpolar (NP). Circle any that are
capable of forming hydrogen bonds. (4 points)
CH3CH2OH
BCl3
CCl2Br2
Cl
Cl
B
Cl
H
Cl
O
Asymmetric
Net Dipole
POLAR
Trigonal Planar
Dipoles Cancel
NON POLAR
Br
Br
Cl
CAN HYDROGEN
BOND
Tetrahedral
Net Dipole
(Cl more Electronegative
than Br)
POLAR
6. Clearly label 5 functional groups present in the following compound. (3 points)
O
ESTER (LACTONE)
O
ALKENE
ALCOHOL
OH
AMINE
H2N
O
ALDEHYDE
ALKENE
OH
ALCOHOL
7. Provide a “curved arrow” mechanism for the following reaction: (3 points)
HCl
+
CH3CH2OH Æ
H
O
H
Cl
[CH3CH2OH2]+
+ ClH
O
H
+
Cl