Chapter 21:
Electrochemistry
Practice Test
1.
A voltaic cell in which the reaction involves the combustion of one reactant with oxygen to produce electric energy is a(n) _____________.
a.
electrolytic cell
b.
fuel cell
c.
secondary battery
d.
primary battery
Hint
2.
The pieces of metal that are placed on the outside of ships to help prevent corrosion are _________.
a.
sacrificial anodes
b.
galvanized metals
c.
electrolyzed metals
d.
sacrificial cathodes
Hint
3.
Why is electrolysis needed to produce pure metals?
a.
Metals would rather be cations.
b.
Metals are easily reduced.
c.
Metals are always neutral
d.
Metals would rather be anions.
Hint
4.
In any electrochemical cell, the cathode is the ________.
a.
positive electrode
b.
negative electrode
c.
electrode at which some species loses electrons
d.
electrode at which some species gains electrons
Hint
5.
Consider the electrolysis of an aqueous solution of aluminum fluoride. Which one of the following statements describes what will be observed?
a.
Al metal is produced at one electrode, and O
2
and H
are produced at the other.
b.
Al metal is produced at one electrode, and F
2
is produced at the other.
c.
O
2
and H
+
are produced at one electrode, and H
2
and OH
-
are produced at the other.
d.
Al metal is produced at one electrode, and O
2
and H
+
are produced at the other.
Hint
6.
A redox reaction that is easily reversed, can produce electric energy, and can be recharged is a(n) __________.
a.
primary battery
b.
electrolytic cell
c.
fuel cell
d.
secondary battery
Hint
7.
Electroplating is an example of __________.
a.
electrolysis
b.
a galvanic cell
c.
a primary battery
d.
a fuel cell
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 + Cd
2+
→ Cd + Cu
2+
b.
Cu
2+
+ Cd → Cu + Cd
2+
c.
Cu + Cd → Cu
2+
+ Cd
2+
d.
Cu
2+
+ Cd
2+
→ Cu + Cd
Hint
9.
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.
Cd, H
2
, H
2
b.
Cd, H
2
, Cd
c.
H
2
, Cd, H
2
d.
H
2
, Cd, Cd
Hint
10.
How many moles of electrons have been transferred between the species in the following reaction? 2Cr
3+
(aq) + 3Cu(s) → 2Cr(s) + 3Cu
2+
(aq)
a.
4
b.
3
c.
2
d.
6
Hint
11.
Which of the following is the weakest reducing agent?
a.
Al
b.
Al
3+
c.
F
-
d.
F
2
Hint
12.
Which of the following is not obtained from the electrolysis of an aqueous solution of sodium chloride?
a.
H
2
b.
Cl
2
c.
Na
d.
NaOH
Hint
13.
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.
2H
2
O + 2e
-
→ H
2
+ 2OH
-
b.
Cl
2
+ 2e
-
→ 2Cl
-
c.
H
2
+ 2OH
-
→ 2H
2
O + 2e
-
d.
2Cl
-
→ Cl
2
+ 2e
-
Hint
14.
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
2+
+ 2e
-
Pb
b.
Ag → Ag
+
+ e
-
c.
Pb
Pb
2+
+ 2e
-
d.
Ag
+
+ e
-
→ Ag
Hint
15.
During the electrolysis of molten sodium iodide, sodium ions move ________.
a.
to the anode, which is negatively charged
b.
to the cathode, which is positively charged
c.
to the anode, which is positively charged
d.
to the cathode, which is negatively charged
Hint
16.
In a voltaic cell, the salt bridge __________.
a.
acts as a mechanism to allow mechanical mixing of the solutions
b.
drives electrons from one half-cell to another
c.
is not necessary for the cell to work
d.
allows charge balance to be maintained in the cell
Hint
17.
Under standard conditions, which one of the following statements about the half-cell process is true for the cell?
a.
Cu
2+
is reduced at the anode
b.
Cd
2+
is reduced at the anode
c.
Cu
2+
is reduced at the cathode
d.
Cd
2+
is reduced at the cathode
Hint
18.
A redox reaction that is not easily reversed is the source of electric energy in a(n) _______.
a.
fuel cell
b.
electrolytic cell
c.
primary battery
d.
secondary battery
Hint
19.
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 raises the cell potential for the reduction of aluminum cations.
b.
The cryolite increases the conductivity of the mixture.
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 lowers the cell potential for the reduction of aluminum cations.
Hint
20.
Using a table of standard reduction potentials, which of the following is the strongest oxidizing agent?
a.
F
2
b.
Al
3+
c.
F
-
d.
Al
Hint
