Electrochemistry Worksheets Donald Calbreath, Ph.D. Say Thanks to the Authors Click http://www.ck12.org/saythanks (No sign in required)
To access a customizable version of this book, as well as other interactive content, visit www.ck12.org AUTHOR Donald Calbreath, Ph.D. CK-12 Foundation is a non-profit organization with a mission to reduce the cost of textbook materials for the K-12 market both in the U.S. and worldwide. Using an open-source, collaborative, and web-based compilation model, CK-12 pioneers and promotes the creation and distribution of high-quality, adaptive online textbooks that can be mixed, modified and printed (i.e., the FlexBook textbooks). Copyright 2015 CK-12 Foundation, www.ck12.org The names CK-12 and CK12 and associated logos and the terms FlexBook and FlexBook Platform (collectively CK-12 Marks ) are trademarks and service marks of CK-12 Foundation and are protected by federal, state, and international laws. Any form of reproduction of this book in any format or medium, in whole or in sections must include the referral attribution link http://www.ck12.org/saythanks (placed in a visible location) in addition to the following terms. Except as otherwise noted, all CK-12 Content (including CK-12 Curriculum Material) is made available to Users in accordance with the Creative Commons Attribution-Non-Commercial 3.0 Unported (CC BY-NC 3.0) License (http://creativecommons.org/ licenses/by-nc/3.0/), as amended and updated by Creative Commons from time to time (the CC License ), which is incorporated herein by this reference. Complete terms can be found at http://www.ck12.org/about/ terms-of-use. Printed: June 8, 2015
www.ck12.org Chapter 1. Electrochemistry Worksheets CHAPTER 1 Electrochemistry Worksheets CHAPTER OUTLINE 1.1 Electrochemical Cells 1.2 Cell Potentials 1.3 Electrolysis 1
1.1. Electrochemical Cells www.ck12.org 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. 2 1. All of the following are applications of electrochemistry except 1. providing power to devices 2. removing electrons for storage 3. plate metals 4. nerve transmission 2. Nickel metal will oxidize when in a solution with cations 1. magnesium 2. barium 3. copper 4. potassium 3. Aluminum metal will not oxidize when in a solution of cations. 1. magnesium 2. mercury 3. iron 4. lead 4. The reaction involving zinc metal immersed in a solution of copper ions is called a reaction. 1. indirect 2. oscillating 3. direct 4. solution 5. True/False: Some chemical reactions can involve production of electricity. 6. True/False: Oxidation and reduction reactions occur sequentially. 7. True/False: Lithium will spontaneously oxidize in a solution of silver nitrate. 8. True/False: Iron will spontaneously oxidize in a solution of sodium chloride. 9. 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 Cu 2+ 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) + ZnCl 2 (aq)
www.ck12.org Chapter 1. Electrochemistry Worksheets 3. CuCl 2 (aq) + Ag(s) 4. K(s) +CaCl 2 (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. alternating current 2. fluctuating current 3. intermittent current 4. direct current 13. The cell notation for the zinc-copper cell is 1. Cu(s) Cu 2+ (1M) Zn 2+ (1M) Zn(s) 2. Zn(s) Zn 2+ (1M) Cu 2+ (1M) Cu(s) 3. Cu 2+ (1M) Cu(s) Zn 2+ (1M) Zn(s) 4. Zn 2+ (1M) Zn(s) Cu 2+ (1M) Cu(s) 14. All of the following are indicated in a voltaic cell except 1. salt bridge 2. anode 3. phase boundaries 4. salt bridge composition 15. True/False: A non-porous plug is used in the salt bridge. 16. True/False: A metal wire connects the two electrodes. 17. True/False: The anode is conventionally written on the right side of the notation. 18. Define the following terms 1. voltaic cell 2. half-cell 3. electrode 4. salt bridge 19. Write the shorthand notation for a galvanic cell that uses the reaction 20. Fe(s) + Sn 2+ (aq) Fe 2+ (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. dry cell 2. fuel cell 3. solar cell 4. lead storage battery 21. One of the following is not a component of the dry cell paste 1. MnO 2 2. ZnO 2 3. NH 4 Cl 4. ZnCl 2 22. The cathode in a lead storage battery is 1. PbO 2 3
1.1. Electrochemical Cells www.ck12.org 2. PbO 3. Pb 4. PbSO 4 23. True/False: The anode for a dry cell battery is the Zn container. 24. True/False: The dry cell battery uses a salt bridge. 25. True/False: In a fuel cell, hydrogen gas is oxidized to water. 26. 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. Write half-reactions for the recharging of a lead storage battery. 29. The inert electrolyte in the salt bridge is often potassium chloride (KCl) or sodium nitrate (NaNO 3 ). 30. Why would these two salts be considered to be inert electrolytes? 31. 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. 4
www.ck12.org 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. protons 2. electrons 3. hydrogen ions 4. ions 2. Difference in electrical potential between two produces voltage. 1. ions 2. electrodes 3. half-cells 4. 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. 0.1 M 2. 0.5 M 3. 2.0 M 4. 1.0 M 7. The standard potential for the hydrogen electrode is 1. 0.00 V 2. 0.10 V 3. 0.01 mv 4. 0.10 mv 8. A negative standard reduction potential means 1. it is easier to reduce the species 5
1.2. Cell Potentials www.ck12.org 2. it is easier to reduce hydrogen 3. it is easier to oxidize the species 4. hydrogen oxidizes less readily than the species 9. True/False: The standard hydrogen electrode is immersed in 1.0 M H +. 10. True/False: The metal for the electrode is made of gold. 11. True/False: Hydrogen gas is formed in all applications of the hydrogen electrode. 12. 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. undergo reduction 2. undergo oxidation 3. cause the other cell to reduce 4. lose electrons 16. Co 2+ will undergo reduction when paired with half-cells made of all of the following except 1. Cd 2+ 2. Sn 2+ 3. Ca 2+ 4. Cs + 17. The cell potential can be calculated using the formula 1. E ox E red 2. E ox E red 3. E red E ox 4. E red E ox 18. True/False: The cell potential must be negative for the redox reaction to be spontaneous. 19. True/False: In the voltaic cell using Zn Zn 2+ and Fe Fe 2+, Fe 2+ will be reduced. 20. True/False: Lithium ions reduce easily. 21. For the following cell combinations calculate the standard cell potential and write the overall cell reaction: 1. Co Co 2+ and Pb Pb 2+ 2. Cu Cu + and Be Be 2+ 3. Mg Mg 2+ and Sn Sn 4+ Lesson Objective: Predict the behavior of oxidizing and reducing agents based on their position in the table of standard reduction potentials. 6 22. A strong oxidizing agent is one that can 1. pull electrons away from other species 2. donate electrons to other species 3. transfer electrons to other species 4. convert metallic ions to metals 23. Cr will reduce all of the following except 1. Ag +
www.ck12.org Chapter 1. Electrochemistry Worksheets 2. Br 2 3. Mn 2+ 4. Pb 2+ 24. True/False: Fluorine is the strongest oxidizing agent. 25. True/False: Metals will reduce metals listed below them in the standard reduction potential table. 26. Which of the following metals will react with HCl? Hg, Sn, Cr, Mg 27. Rank the following oxidizing agents with 1 as strongest and 4 as weakest: Cd 2+, Al 3+, Au 3+, Ni 2+. 28. 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 Cu 2+ ions have a greater attraction for electrons than the Zn 2+ 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 www.ck12.org 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. voltaic cells use spontaneous reactions to generate electric current 2. nonspontaneous reactions are driven by an external electrical current 3. products are favored over reactants in a nonspontaneous reaction 4. half cells are involved in both voltaic and electrolytic processes 2. In an electrolytic process involving Zn and Cu 1. the Zn electrode is the anode 2. the Cu electrode is the anode 3. Zn is oxidized 4. 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. 8 6. In the Down s cell 1. molten NaCl reacts at the cathode to form metallic sodium 2. molten NaCl reacts at the anode to form metallic sodium 3. chlorine ions are reduced to form chlorine gas 4. 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. 2.5 2. 3.4 3. 1.8 4. 4.1 8. True/False: The Down s cell is a minor producer of sodium metal. 9. True/False: Chlorine is used as a disinfectant. 10. Write the half-reactions and the overall reaction for the Down s process. 11. Would you expect the melted Na to be more or less dense than melted NaCl? Explain your answer.
www.ck12.org 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. sulfuric acid 2. platinum electrode 3. power supply 4. gold electrode 14. Oxygen is formed at the 1. anode 2. cathode 3. electrode 4. electrical interface 15. True/False: Pure water will effectively conduct an electric current 16. True/False: Water is simultaneously oxidized and reduced. 17. Write the half-reactions and the overall reaction for the electrolysis of water. 18. 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. Cl 2 2. Na 3. H 2 4. O 2 20. The reduction potential for water is 1. -0.70 V 2. -0.80 V 3. -0.83 V 4. -0.89 V 21. True/False: Chlorine gas is produced at the cathode 22. True/False: NaOH can be obtained by evaporating the water. 23. Write the half-reactions and the overall reaction for the electrolysis of brine. 24. 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. silver is both oxidized and reduced 2. a silver strip serves as the anode 3. silver nitrate solution is used in the process 4. 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 www.ck12.org 2. silver fork 3. platinum rod 4. aluminum foil 27. True/False: The spoon serves as the cathode in the process. 28. True/False: The Ag + concentration gradually changes. 29. Define electroplating. 30. If the silver nitrate solution provides the ions for electroplating, why is the silver strip needed? 31. 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