Electrochemistry Worksheets
Donald Calbreath, Ph.D.
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Printed: June 8, 2015
AUTHOR
Donald Calbreath, Ph.D.
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Chapter 1. Electrochemistry Worksheets
C HAPTER
1
Electrochemistry
Worksheets
C HAPTER O UTLINE
1.1
Electrochemical Cells
1.2
Cell Potentials
1.3
Electrolysis
1
1.1. Electrochemical Cells
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1.1 Electrochemical Cells
Worksheet
Name _____________________ Class ______________________ Date ________________
Answer each of the questions below to show your achievement of the lesson objectives
Lesson Objective: Use the activity series to identify elements that are more easily oxidized than others, and
write oxidation and reduction half-reactions.
1. All of the following are applications of electrochemistry except
1.
2.
3.
4.
providing power to devices
removing electrons for storage
plate metals
nerve transmission
2. Nickel metal will oxidize when in a solution with ______ cations
1.
2.
3.
4.
magnesium
barium
copper
potassium
3. Aluminum metal will not oxidize when in a solution of ______ cations.
1.
2.
3.
4.
magnesium
mercury
iron
lead
4. The reaction involving zinc metal immersed in a solution of copper ions is called a ____ reaction.
1.
2.
3.
4.
5.
6.
7.
8.
9.
indirect
oscillating
direct
solution
True/False: Some chemical reactions can involve production of electricity.
True/False: Oxidation and reduction reactions occur sequentially.
True/False: Lithium will spontaneously oxidize in a solution of silver nitrate.
True/False: Iron will spontaneously oxidize in a solution of sodium chloride.
Define the following terms:
1. electrochemistry
2. electrochemical cell
10. The electrons that are transferred in the reaction go _______ from the Zn atoms on the ______of the strip to
the Cu2+ ions that are in the ________ adjacent to the zinc strip.
11. In each of the following combinations, indicate whether or not a reaction will occur.
1. NaCl(aq) + Ni(s)
2. Ca(s) + ZnCl2 (aq)
2
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Chapter 1. Electrochemistry Worksheets
3. CuCl2 (aq) + Ag(s)
4. K(s) +CaCl2 (aq)
Lesson Objective: Describe the parts of a voltaic cell and explain how redox reactions are used to generate an
electric current.
12. Volta constructed a cell that generated
1.
2.
3.
4.
alternating current
fluctuating current
intermittent current
direct current
13. The cell notation for the zinc-copper cell is
1.
2.
3.
4.
Cu(s)|Cu2+ (1M)kZn2+ (1M)|Zn(s)
Zn(s)|Zn2+ (1M)kCu2+ (1M)|Cu(s)
Cu2+ (1M)|Cu(s)kZn2+ (1M)|Zn(s)
Zn2+ (1M)|Zn(s)kCu2+ (1M)|Cu(s)
14. All of the following are indicated in a voltaic cell except
1.
2.
3.
4.
15.
16.
17.
18.
salt bridge
anode
phase boundaries
salt bridge composition
True/False: A non-porous plug is used in the salt bridge.
True/False: A metal wire connects the two electrodes.
True/False: The anode is conventionally written on the right side of the notation.
Define the following terms
1.
2.
3.
4.
voltaic cell
half-cell
electrode
salt bridge
19. Write the shorthand notation for a galvanic cell that uses the reaction
20. Fe(s) + Sn2+ (aq) → Fe2+ (aq) + Sn(s)
21. Assume any solutions to be 1.0 M
Lesson Objective: Describe the general features of a dry cell, a lead storage battery, and a fuel cell.
20. One of the following is not an example of a voltaic cell
1.
2.
3.
4.
dry cell
fuel cell
solar cell
lead storage battery
21. One of the following is not a component of the dry cell paste
1.
2.
3.
4.
MnO2
ZnO2
NH4 Cl
ZnCl2
22. The cathode in a lead storage battery is
1. PbO2
3
1.1. Electrochemical Cells
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2. PbO
3. Pb
4. PbSO4
23.
24.
25.
26.
True/False: The anode for a dry cell battery is the Zn container.
True/False: The dry cell battery uses a salt bridge.
True/False: In a fuel cell, hydrogen gas is oxidized to water.
Define the following terms
1. battery
2. fuel cell
27. Write the overall reactions for
a. a zinc dry cell battery
b. an alkaline battery
28.
29.
30.
31.
4
Write half-reactions for the recharging of a lead storage battery.
The inert electrolyte in the salt bridge is often potassium chloride (KCl) or sodium nitrate (NaNO3 ).
Why would these two salts be considered to be inert electrolytes?
Alessandro Volta tested the strength of the early electrochemical cells he developed by measuring the amount
of shock they produced. Discuss the pros and cons of this experimental approach.
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Chapter 1. Electrochemistry Worksheets
1.2 Cell Potentials
Worksheet
Name _____________________ Class ______________________ Date ________________
Answer each of the questions below to show your achievement of the lesson objectives
Lesson Objective: Describe how an electrical potential is generated in an electrochemical cell.
1. The electrical potential for a cell comes about as a result of competition for
1.
2.
3.
4.
protons
electrons
hydrogen ions
ions
2. Difference in electrical potential between two ______ produces voltage.
1.
2.
3.
4.
ions
electrodes
half-cells
anodes
3. True/False: The electrical potential of an isolated half-cell can be measured.
4. True/False: Spontaneous redox reactions produce electrical energy.
5. Define the following terms:
1. electrical potential
2. reduction potential
3. cell potential
Lesson Objective: Describe the standard hydrogen electrode and how it is used to determine the standard cell
potentials of other half-cells.
6. Determination of standard cell potential requires an electrochemical cell with aqueous components present at
____ concentration.
1.
2.
3.
4.
0.1 M
0.5 M
2.0 M
1.0 M
7. The standard potential for the hydrogen electrode is
1.
2.
3.
4.
0.00 V
0.10 V
0.01 mv
0.10 mv
8. A negative standard reduction potential means
1. it is easier to reduce the species
5
1.2. Cell Potentials
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2. it is easier to reduce hydrogen
3. it is easier to oxidize the species
4. hydrogen oxidizes less readily than the species
9.
10.
11.
12.
True/False: The standard hydrogen electrode is immersed in 1.0 M H+ .
True/False: The metal for the electrode is made of gold.
True/False: Hydrogen gas is formed in all applications of the hydrogen electrode.
Define the following terms:
1. standard cell potential
2. standard hydrogen electrode
13. Why is Pt used as the metal for the standard hydrogen electrode?
14. How can the SHE serve both as a cathode and an anode?
Lesson Objective: Calculate the standard cell potentials from a table of standard reduction potentials.
15. The half-cell with the higher reduction potential will
1.
2.
3.
4.
undergo reduction
undergo oxidation
cause the other cell to reduce
lose electrons
16. Co2+ will undergo reduction when paired with half-cells made of all of the following except
1.
2.
3.
4.
Cd2+
Sn2+
Ca2+
Cs+
17. The cell potential can be calculated using the formula
1.
2.
3.
4.
18.
19.
20.
21.
Eox − Ered
Eox ÷ Ered
Ered − Eox
Ered ÷ Eox
True/False: The cell potential must be negative for the redox reaction to be spontaneous.
True/False: In the voltaic cell using Zn|Zn2+ and Fe|Fe2+ , Fe2+ will be reduced.
True/False: Lithium ions reduce easily.
For the following cell combinations calculate the standard cell potential and write the overall cell reaction:
1. Co|Co2+ and Pb|Pb2+
2. Cu|Cu+ and Be|Be2+
3. Mg|Mg2+ and Sn|Sn4+
Lesson Objective: Predict the behavior of oxidizing and reducing agents based on their position in the table
of standard reduction potentials.
22. A strong oxidizing agent is one that can
1.
2.
3.
4.
pull electrons away from other species
donate electrons to other species
transfer electrons to other species
convert metallic ions to metals
23. Cr will reduce all of the following except
1. Ag+
6
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Chapter 1. Electrochemistry Worksheets
2. Br2
3. Mn2+
4. Pb2+
24.
25.
26.
27.
28.
True/False: Fluorine is the strongest oxidizing agent.
True/False: Metals will reduce metals listed below them in the standard reduction potential table.
Which of the following metals will react with HCl? Hg, Sn, Cr, Mg
Rank the following oxidizing agents with 1 as strongest and 4 as weakest: Cd2+ , Al3+ , Au3+ , Ni2+ .
The electrical potential of a cell results from a competition for electrons. In the zinc-copper voltaic cell
described in the previous lesson, the copper(II) ions were reduced to copper metal. That is because the Cu2+
ions have a greater attraction for electrons than the Zn2+ ions in the other half-cell. Instead, the zinc metal is
oxidized. A reduction potential measures the tendency of a given half-reaction to occur as a reduction in an
electrochemical cell. In a given voltaic cell, the half-cell that has the greater reduction potential is the one in
which reduction will occur.
29. Is there any advantage to using the term reduction potential or would oxidation potential be just as useful?
30. Lead in water supplies is a serious problem in many parts of the world. Your local chemistry genius is
proposing to bubble fluorine gas into water supplies to precipitate the lead. Do you think this is a good idea.
Explain your answer.
7
1.3. Electrolysis
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1.3 Electrolysis
Worksheet
Name _____________________ Class ______________________ Date ________________
Answer each of the questions below to show your achievement of the lesson objectives
Lesson Objective: Distinguish between voltaic and electrolytic cells.
1. All of the following are true statements except
1.
2.
3.
4.
voltaic cells use spontaneous reactions to generate electric current
nonspontaneous reactions are driven by an external electrical current
products are favored over reactants in a nonspontaneous reaction
half cells are involved in both voltaic and electrolytic processes
2. In an electrolytic process involving Zn and Cu
1.
2.
3.
4.
the Zn electrode is the anode
the Cu electrode is the anode
Zn is oxidized
Cu is reduced
3. True/False: Electrolysis is used to plate silver on jewelry.
4. True/False: A voltaic cell uses an electric current to initiate a spontaneous reaction.
5. Define the following terms:
1. electrolysis
2. electrolytic cell
Lesson Objective: Describe a Down’s cell, and identify the products of the electrolysis of molten sodium
chloride.
6. In the Down’s cell
1.
2.
3.
4.
molten NaCl reacts at the cathode to form metallic sodium
molten NaCl reacts at the anode to form metallic sodium
chlorine ions are reduced to form chlorine gas
chlorine ions are converted to chlorine gas at the cathode
7. The overall Down’s cell requires over_____ volts for the reaction to occur
1.
2.
3.
4.
8.
9.
10.
11.
8
2.5
3.4
1.8
4.1
True/False: The Down’s cell is a minor producer of sodium metal.
True/False: Chlorine is used as a disinfectant.
Write the half-reactions and the overall reaction for the Down’s process.
Would you expect the melted Na to be more or less dense than melted NaCl? Explain your answer.
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Chapter 1. Electrochemistry Worksheets
12. Solid NaCl is a poor conductor of electricity. Why would melted NaCl conduct electricity well?
Lesson Objective: Describe the reactions that occur during the electrolysis of water.
13. All of the following are components of the apparatus for electrolysis of water except
1.
2.
3.
4.
sulfuric acid
platinum electrode
power supply
gold electrode
14. Oxygen is formed at the
1.
2.
3.
4.
15.
16.
17.
18.
anode
cathode
electrode
electrical interface
True/False: Pure water will effectively conduct an electric current
True/False: Water is simultaneously oxidized and reduced.
Write the half-reactions and the overall reaction for the electrolysis of water.
Describe the Hoffman apparatus for the electrolysis of water. Include a diagram.
Lesson Objective: Identify the products that would be generated during the electrolysis of an aqueous solution
of sodium chloride.
19. One of the following is not a product of brine electrolysis
1.
2.
3.
4.
Cl2
Na
H2
O2
20. The reduction potential for water is
1.
2.
3.
4.
21.
22.
23.
24.
-0.70 V
-0.80 V
-0.83 V
-0.89 V
True/False: Chlorine gas is produced at the cathode
True/False: NaOH can be obtained by evaporating the water.
Write the half-reactions and the overall reaction for the electrolysis of brine.
Could you use a standard apparatus for electrolysis of water to carry out the electrolysis of brine? Explain
your answer.
Lesson Objective: Describe the process of electroplating.
25. All of the following are true statements about electroplating except
1.
2.
3.
4.
silver is both oxidized and reduced
a silver strip serves as the anode
silver nitrate solution is used in the process
silver metal is oxidized to provide Ag+ for plating
26. In electroplating, silver metal is deposited on a
1. stainless steel spoon
9
1.3. Electrolysis
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2. silver fork
3. platinum rod
4. aluminum foil
27.
28.
29.
30.
31.
True/False: The spoon serves as the cathode in the process.
True/False: The Ag+ concentration gradually changes.
Define electroplating.
If the silver nitrate solution provides the ions for electroplating, why is the silver strip needed?
A nonspontaneous reaction is one in which the reactants are favored over the products under a given set of
reaction conditions. However, if a chemical system is supplied with energy from an external source, it is
possible to drive a reaction in the nonspontaneous direction.
32. Why would a nonspontaneous reaction be needed?
33. How would you electroplate copper (hint: look at the table in lesson 23-2)?
10