Electrochemistry
Practice Test
1.
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.
1.08 V
d.
0.40 V
2.
A chemical reaction generates electric energy spontaneously in ___________.
a.
corrosion
b.
spontaneous combustion
c.
a galvanic cell
d.
electrolysis
3.
What is the anode reaction when a NiCad battery is used to generate electric current?
a.
oxidation of cadmium in the presence of an acid
b.
oxidation or cadmium in the presence of a base
c.
reduction of cadmium in the presence of an acid
d.
reduction of cadmium in the presence of a base
4.
Using a table of standard reduction potentials, which of the following is the strongest oxidizing agent?
a.
F
-
b.
Al
c.
F
2
d.
Al
3+
5.
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.
H
2
+ 2OH
-
→ 2H
2
O + 2e
-
b.
Cl
2
+ 2e
-
→ 2Cl
-
c.
2Cl
-
→ Cl
2
+ 2e
-
d.
2H
2
O + 2e
-
→ H
2
+ 2OH
-
6.
How does paint protect steel surfaces from corrosion?
a.
Paint acts as a sacrificial anode.
b.
Paint prevents the oxidation-reduction reaction of corrosion from occurring.
c.
Paint corrodes leaving steel intact.
d.
Paint galvanizes steel.
7.
In any electrochemical cell, the cathode is the ________.
a.
negative electrode
b.
electrode at which some species gains electrons
c.
positive electrode
d.
electrode at which some species loses electrons
8.
Why is electrolysis needed to produce pure metals?
a.
Metals are easily reduced.
b.
Metals would rather be anions.
c.
Metals are always neutral.
d.
Metals would rather be cations.
9.
The pieces of metal that are placed on the outside of ships to help prevent corrosion are _________.
a.
galvanized metals
b.
sacrificial cathodes
c.
electrolyzed metals
d.
sacrificial anodes
10.
The use of electric energy to bring about a chemical reaction is ____________.
a.
electrolysis
b.
corrosion
c.
a galvanic cell
d.
spontaneous combustion
11.
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.
O
2
and H
+
are produced at one electrode, and H
2
and OH
-
are produced at the other.
c.
Al metal is produced at one electrode, and O
2
and H
+
are produced at the other.
d.
Al metal is produced at one electrode, and F
2
is produced at the other.
12.
Why are alkaline dry cell batteries smaller in size than zinc-carbon dry cells?
a.
No zinc is reduced in the alkaline batteries.
b.
Alkaline batteries do not require steel cases.
c.
Alkaline batteries do not need the carbon rod cathode.
d.
Zinc paste takes up less space than zinc powder.
13.
In a voltaic cell, the salt bridge __________.
a.
is not necessary for the cell to work
b.
acts as a mechanism to allow mechanical mixing of the solutions
c.
allows charge balance to be maintained in the cell
d.
drives electrons from one half-cell to another
14.
Which of the following must be true of a salt bridge?
a.
The tube of the salt bridge must remain open.
b.
The salt bridge must prevent the flow of charged particles.
c.
Ions can move through the salt bridge.
d.
The solutions joined by the salt bridge can mix freely.
15.
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 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.
b.
The cryolite raises the cell potential for the reduction of aluminum cations.
c.
The cryolite lowers the cell potential for the reduction of aluminum cations.
d.
The cryolite increases the conductivity of the mixture.
