9. What is the pH of a buffer prepared by adding 180 mL of 0.100
M
NaOH to 200 mL of
0.100
M
acetic acid?
(
K
a
for CH
3
COOH = 1.8 x 10
-5
)
a. 3.79
b. 4.34
c. 4.74
d. 5.04
e. 5.70
10. Consider the titration of 50.00 mL of 0.1000
M
HBr with 0.1000
M
KOH. Calculate
the pH after 49.00 mL of the base has been added to the 50.00 mL of HBr.
a. 2.0
b. 3.0
c. 4.0
d. 6.0
e. 7.0
11. An aqueous solution of a weak acid, HA, is titrated with NaOH solution. The pH at
the midpoint of the buffer region is 4.5. What is the
K
a
of the acid?
a. 3.2 x 10
-5
b. 3.2 x 10
-10
c. 1.8 x 10
-3
d. 7.0 x 10
-7
e. 4.5
Electrochemistry
1. Which of the following statements is incorrect?
a.
In an electrolytic cell, reduction occurs at the anode.
b.
Aluminum metal would form at the cathode during the electrolysis of molten
AlBr
3
.
c.
The cathode is labeled "+" in a voltaic cell.
d.
Oxidation occurs at the anode in a voltaic cell.
e.
Electrons flow from the anode to the cathode in all electrochemical cells.
2. Consider the following notation for an electrochemical cell
ZnlZn
2+
(1
M
)llFe
2+
(1
M
), Fe
3+
(1
M
)lPt
What is the balanced equation for the cell reaction?
a.
Zn(
s
) + 2Fe
3+
(
aq
)
→
2Fe
2+
(
aq
) + Zn
2+
(
aq
)
b.
Zn
2+
(
aq
) + 2Fe
2+
(
aq
)
→
Zn(
s
) + 2Fe
3+
(
aq
)
c.
Zn(
s
) + 2Fe
2+
(
aq
)
→
2Fe
3+
(
aq
) + Zn
2+
(
aq
)
d.
Zn(
s
) + Fe
3+
(
aq
)
→
Fe
2+
(
aq
) + Zn
2+
(
aq
)
e.
Zn(
s
) + Fe
2+
(
aq
)
→
Fe(
s
) + Zn
2+
(
aq
)