Chapter 21:
Electrochemistry
Practice Test
1.
Electroplating is an example of __________.
a.
electrolysis
b.
a galvanic cell
c.
a fuel cell
d.
a primary battery
Hint
2.
What is the numerical value for the standard cell potential for the following reaction? 2Cr
3+
(aq) + 3Cu(s) → 2Cr(s) + 3Cu
2+
(aq)
a.
-0.40 V
b.
1.08 V
c.
0.40 V
d.
-1.08 V
Hint
3.
The electrolysis of an aqueous sodium chloride solution using inert electrodes produces gaseous chlorine at one electrode. At the other electrode, gaseous hydrogen is produced, and the solution around the electrode becomes basic. Which of the following equations is the correct equation for the cathode half-reaction in this electrolytic cell?
a.
2Cl
-
→ Cl
2
+ 2e
-
b.
H
2
+ 2OH
-
→ 2H
2
O + 2e
-
c.
2H
2
O + 2e
-
→ H
2
+ 2OH
-
d.
Cl
2
+ 2e
-
→ 2Cl
-
Hint
4.
The Hall?Héroult process, which is used to make aluminum metal, electrolyzes a molten mixture of aluminum oxide and cryolite (Na
3
AlF
6
) to reduce aluminum cations to aluminum metal. Why is the cryolite used in this mixture?
a.
The cryolite increases the conductivity of the mixture.
b.
The cryolite lowers the cell potential for the reduction of aluminum cations.
c.
The cryolite lowers the melting point of the mixture and thereby lowers the cost of manufacture by lowering the amount of heat energy needed to melt the mixture.
d.
The cryolite raises the cell potential for the reduction of aluminum cations.
Hint
5.
Using a table of standard reduction potentials, which of the following is the strongest oxidizing agent?
a.
Al
3+
b.
F
2
c.
Al
d.
F
-
Hint
6.
A chemical reaction generates electric energy spontaneously in ___________.
a.
corrosion
b.
spontaneous combustion
c.
electrolysis
d.
a galvanic cell
Hint
7.
Under standard conditions, what is the standard cell potential for the cell? Cd|Cd
2+
|| Cu
2+
|Cu?
a.
+0.06 V
b.
-0.74 V
c.
-0.06 V
d.
+0.74 V
Hint
8.
Under standard conditions, which of the following is the net reaction that occurs in the cell? Cd|Cd
2+
|| Cu
2+
|Cu
a.
Cu
2+
+ Cd → Cu + Cd
2+
b.
Cu
2+
+ Cd
2+
→ Cu + Cd
c.
Cu + Cd
2+
→ Cd + Cu
2+
d.
Cu + Cd → Cu
2+
+ Cd
2+
Hint
9.
The use of electric energy to bring about a chemical reaction is ____________.
a.
spontaneous combustion
b.
corrosion
c.
a galvanic cell
d.
electrolysis
Hint
10.
A redox reaction that is easily reversed, can produce electric energy, and can be recharged is a(n) __________.
a.
electrolytic cell
b.
primary battery
c.
fuel cell
d.
secondary battery
Hint
11.
A voltaic cell in which the reaction involves the combustion of one reactant with oxygen to produce electric energy is a(n) _____________.
a.
fuel cell
b.
electrolytic cell
c.
secondary battery
d.
primary battery
Hint
12.
Which of the following is not obtained from the electrolysis of an aqueous solution of sodium chloride?
a.
Cl
2
b.
NaOH
c.
H
2
d.
Na
Hint
13.
During the electrolysis of molten sodium iodide, sodium ions move ________.
a.
to the cathode, which is positively charged
b.
to the anode, which is negatively charged
c.
to the cathode, which is negatively charged
d.
to the anode, which is positively charged
Hint
14.
In a voltaic cell, the salt bridge __________.
a.
is not necessary for the cell to work
b.
allows charge balance to be maintained in the cell
c.
acts as a mechanism to allow mechanical mixing of the solutions
d.
drives electrons from one half-cell to another
Hint
15.
In an electrolytic cell, the electrode that acts as a source of electrons to the solution is called the __________; the chemical change that occurs at this electrode is called ________.
a.
cathode, oxidation
b.
anode, reduction
c.
anode, oxidation
d.
cathode, reduction
Hint
16.
The pieces of metal that are placed on the outside of ships to help prevent corrosion are _________.
a.
sacrificial anodes
b.
galvanized metals
c.
sacrificial cathodes
d.
electrolyzed metals
Hint
17.
A cell is constructed by immersing a strip of lead in a 1.0
M
Pb(NO
3
)
2
solution and a strip of silver in a 1.0M AgNO
3
solution. The circuit is completed by a wire and a salt bridge. As the cell operates, the strip of silver gains mass (only silver), the strip of lead loses mass, and the concentration of lead ions increases in the solution around the lead strip. Which of the following represents the reaction that occurs at the cathode in this cell?
a.
Pb
Pb
2+
+ 2e
-
b.
Pb
2+
+ 2e
-
Pb
c.
Ag → Ag
+
+ e
-
d.
Ag
+
+ e
-
→ Ag
Hint
18.
A voltaic cell consists of a standard hydrogen electrode connected by a salt bridge and a wire to an electrode consisting of a strip of Cd metal dipping into a 1
M
solution of Cd(NO
3
)
2
. When the cell produces a current, the electrons flow through the wire from the _________ electrode to the ________ electrode. In this cell, the _______ electrode acts as the cathode.
a.
H
2
, Cd, H
2
b.
Cd, H
2
, Cd
c.
H
2
, Cd, Cd
d.
Cd, H
2
, H
2
Hint
19.
A redox reaction that is not easily reversed is the source of electric energy in a(n) _______.
a.
primary battery
b.
electrolytic cell
c.
secondary battery
d.
fuel cell
Hint
20.
Which of the following is the weakest reducing agent?
a.
Al
3+
b.
F
2
c.
Al
d.
F
-
Hint
