Chapter 20. Electrochemistry

Size: px
Start display at page:

Download "Chapter 20. Electrochemistry"

Transcription

1 Chapter 20. Electrochemistry Sample Exercise 20.1 (p. 845) The nickelcadmium (nicad) battery, a rechargeable dry cell used in batteryoperated devices, uses the following redox reaction to generate electricity: Cd (s) + NiO 2(s) + 2 H 2 O (l) Cd(OH) 2(s) + Ni(OH) 2(s) Identify the substances that are oxidized and reduced, and indicate which is the oxidizing agent and which is the reducing agent. Practice Exercise 20.1 Identify the oxidizing and reducing agents in the following oxidationreduction equation: 2 H 2 O (l) + Al (s) + MnO 4 (aq) Al(OH) 4 (aq) + MnO 2(s) 20.2 Balancing OxidationReduction Equations Practice: Write halfreactions for a reaction between Cu 2+ and Zn metal. Overall: Oxidation: Reduction: Balancing Equations by the Method of HalfReactions 1. Write the overall unbalanced reaction (if available). 2. (i) Identify oxidized and reduced substances (ii) Write down the two incomplete half reactions. 3. Balance each half reaction: (a) First, balance elements other than H and O. (b) Then balance O atoms by adding water on side deficient in O atoms. (c) Then balance H by adding H + for acidic solutions (or OH for alkaline solutions). (d) Finish by balancing charge by adding electrons. 4. Multiply each halfreaction by the appropriate factors so that the number of electrons gained equals electrons lost. 5. Now add the reactions and simplify. 1

2 Sample Exercise 20.2 (p. 849) Complete and balance the following equation by the method of halfreactions: Cr 2 O 7 2 (aq) + Cl (aq) Cr 3+ (aq) + Cl 2(g) (acidic solution) Practice Exercise 20.2 Complete and balance the following oxidationreduction equations using the method of halfreactions. Both reactions occur in acidic solution. a) Cu (s) + NO 3 (aq) Cu 2+ (aq) + NO 2(g) b) Mn 2+ (aq) + NaBiO 3(s) Bi 3+ (aq) + MnO 4 (aq) 2

3 Balancing Equations for Reactions Occurring in Basic Solution The same method as above is used, but OH is added to neutralize the H + used. The equation must again be simplified by canceling like terms on both sides of the equation. Sample Exercise 20.3 (p. 850) Complete and balance this equation for a redox reaction that takes place in basic solution: CN (aq) + MnO 4 (aq) CNO (aq) + MnO 2(s) (basic solution) Practice Exercise 20.3 Complete and balance the following equations for oxidationreduction reactions that occur in basic solution: a) NO 2 (aq) + Al (s) NH 3(aq) + Al(OH) 4 (aq) b) Cr(OH) 3(s) + ClO (aq) CrO 4 2 (aq) + Cl 2(g) 3

4 20.3 Voltaic (Galvanic) Cells Sample Exercise 20.4 (p. 853) The following oxidationreduction reaction is spontaneous: Cr 2 O 7 2 (aq) + 14 H + (aq) + 6 I (aq) 2 Cr 3+ (aq) + 3 I 2(s) + 7 H 2 O (l) A solution containing K 2 Cr 2 O 7 and H 2 SO 4 is poured into one beaker, and a solution of KI is poured into another. A salt bridge is used to join the beakers. A metallic conductor that will not react with either solution (such as platinum foil) is suspended in each solution, and the two conductors are connected with wires through a voltmeter or some other device to detect an electric current. The resultant voltaic cell generates an electric current. Indicate the reaction occurring at the anode, the reaction at the cathode, the direction of electron and ion migrations, and the signs of the electrodes. (Draw a diagram.) Practice Exercise 20.4 The two halfreactions in a voltaic cell are Zn (s) Zn 2+ (aq) + 2 e ClO 3 (aq) + 6 H + (aq) + 6 e Cl (aq) + 3 H 2 O (l) a) Indicate which reaction occurs at the anode and which at the cathode. b) Which electrode is consumed in the cell reaction? c) Which electrode is positive? 4

5 20.4 Cell EMF Sample Exercise 20.5 (p. 858) For the ZnCu 2+ voltaic cell shown in Figure 20.5, we have Zn (s) + Cu 2+ (aq, 1M) Zn 2+ (aq, 1M) + Cu (s) E o cell = 1.10 V Given that the standard reduction potential of Zn 2+ to Zn is 0.76 V, calculate the E o red for the reduction of Cu 2+ to Cu. Cu 2+ (aq, 1M) + 2 e Cu (s) (0.34 V) Practice Exercise 20.5 A voltaic cell is based on the following halfreactions: In + (aq) In 3+ (aq) + 2 e Br 2(l) + 2 e 2 Br (aq) The standard emf for this cell is 1.46 V. Using the data in Table 20.1 or your AP Chem packet, calculate E o red for the reduction of In 3+ to In +. (0.40 V) Sample Exercise 20.6 (p. 858) Using the standard reduction potentials listed in Table 20.1 or your AP Chem packet, calculate the standard emf for the voltaic cell described in Sample Exercise 20.4, which is based on the following reaction: Cr 2 O 7 2 (aq) + 14 H + (aq) + 6 I (aq) 2 Cr 3+ (aq) + 3 I 2(s) + 7 H 2 O (l) (0.79 V) Practice Exercise 20.6 Using the data in Table 20.1 or your AP Chem packet, calculate the standard emf for a cell that employs the following overall cell reaction: (+2.20 V) 2 Al (s) + 3 I 2(s) 2 Al 3+ (aq) + 6 I (aq) 5

6 Sample Exercise 20.7 (p. 859) A voltaic cell is based on the following two standard halfreactions: Cd 2+ (aq) + 2 e Sn 2+ (aq) + 2 e Cd (s) Sn (s) By using the data in Appendix E or your AP Chem packet, determine a) the halfreactions that occur at the cathode and the anode, and b) the standard cell potential (0.267 V) Practice Exercise 20.7 A voltaic cell is based on a Co 2+ /Co halfcell and an AgCl/Ag halfcell. a) What reaction occurs at the anode? b) What is the standard cell potential? (0.499 V) 6

7 Strengths of Oxidizing and Reducing Agents Sample Exercise 20.8 (p. 861) Using Table 20.1 or your AP Chem packet, rank the following ions in order of increasing strength as oxidizing agents: NO 3 (aq), Ag + (aq), Cr 2 O 7 2 (aq). Practice Exercise 20.8 Using Table 20.1 or your AP Chem packet, rank the following species from the strongest to the weakest reducing agent: I (aq), Fe (s), Al (s) Free Energy and Redox Reactions For any electrochemical process E o = E o red(reduction process) E o red(oxidation process). Sample Exercise 20.9 (p. 862) Using standard reduction potentials (Table 20.1 or AP Chem packet), determine whether the following reactions are spontaneous under standard conditions: a) Cu (s) + 2 H + (aq) Cu 2+ (aq) + H 2(g) b) Cl 2(g) + 2 I (aq) 2 Cl (aq) + I 2(s) Practice Exercise 20.9 Using standard reduction potentials (Appendix E or AP Chem packet), determine whether the following reactions are spontaneous under standard conditions: a) I 2(s) + 5 Cu 2+ (aq) + 6 H 2 O (l) 2 IO 3 (aq) + 5 Cu (s) + H + (aq) b) Hg 2+ (aq) + 2 I (aq) Hg (l) + I 2(s) c) H 2 SO 3(aq) + 2 Mn (s) + 4 H + (aq) S (s) + 2 Mn 2+ (aq) + 3 H 2 O (l) 7

8 EMF and G Sample Exercise (p. 864) a) Use the standard reduction potentials listed in Table 20.1 or your AP Chem packet to calculate the standard freeenergy change, G o, and the equilibrium constant, K, at 298 K for the following reaction: 4 Ag (s) + O 2(g) + 4 H + (aq) 4 Ag + (aq) + 2 H 2 O (l) ( G o = 170 kj/mol, K = 9 x ) b) Suppose the reaction in part (a) were written as 2 Ag (s) + ½ O 2(g) + 2 H + (aq) 2 Ag + (aq) + H 2 O (l) What are the values of E o, G o and K when the reaction is written in this way? (E o = V, G o = 83 kj/mol, K = 4 x ) Practice Exercise For the reaction: 3 Ni 2+ (aq) + 2 Cr(OH) 3(s) + 10 OH (aq) 3 Ni (s) + 2 CrO 4 2 (aq) + 8 H 2 O (l) a) What is the value of n for this reaction? (6) b) Use the data in Appendix E or your AP Chem packet to calculate G o for this reaction. (+87 kj/mol) c) Calculate K at T = 298 K (6 x ) 20.6 Cell EMF Under Nonstandard Conditions Sample Exercise (p. 866) Calculate the emf at 298 K generated by the cell described in Sample Exercise 20.4 when [Cr 2 O 7 2 ] = 2.0 M, [H + ] = 1.0 M, [I ] = 1.0 M, and [Cr 3+ ] = 1.0 x 10 5 M. Cr 2 O 7 2 (aq) + 14 H + (aq) + 6 I (aq) 2 Cr 3+ (aq) + 3 I 2(s) + 7 H 2 O (l) (E = V) 8

9 Practice Exercise Calculate the emf generated by the cell described in the practice exercise accompanying Sample Exercise 20.6 when [Al 3+ ] = 4.0 x 10 3 M and [I ] = M. (E = V) Sample Exercise (p. 866) If the voltage of a ZnH + cell (like that in Figure 20.11) is 0.45 V at 25 o C when [Zn 2+ ] = 1.0 M and P H2 = 1.0 atm, what is the concentration of H +? ([H + ] = 5.8 x 10 6 M) Practice Exercise What is the ph of the solution in the cathode compartment of the cell pictured in Figure when P H2 = 1.0 atm, [Zn 2+ ] in the anode compartment is 0.10 M, and cell emf is V? (ph = 4.23) 9

10 Concentration Cells: A concentration cell is one whose emf is generated solely because of a concentration difference. Sample Exercise (p. 870) A voltaic cell is constructed with two hydrogen electrodes. Electrode 1 has P H2 = 1.00 atm and an unknown concentration of H + (aq). Electrode 2 is a standard hydrogen electrode ([H + ] = 1.00 M, P H2 = 1.00 atm). At 298 K the measured cell voltage is V, and the electrical current is observed to flow from electrode 1 through the external circuit to electrode 2. Calculate [H + ] for the solution at electrode 1. What is its ph? (ph = 3.57) Practice Exercise A concentration cell is constructed with two Zn (s) Zn 2+ (aq) halfcells. The first halfcell has [Zn 2+ ] = 1.35 M, and the second halfcell has [Zn 2+ ] = 3.75 x 10 4 M. a) Which halfcell is the anode of the cell? b) What is the emf of the cell? (0.105 V) Cell EMF and Chemical Equilibrium A system is at equilibrium when G = 0. From the Nernst equation, at equilibrium and 298 K (E = 0 V and Q = K eq ) = E log Keq n ne log Keq = Thus, if we know the cell emf, we can calculate the equilibrium constant. 10

11 20.9 Electrolysis Sample Exercise (p. 878) Calculate the number of grams of aluminum produced in 1.00 hr by the electrolysis of molten AlCl 3 if the electrical current is 10.0 A. (3.3.6 g Al) Practice Exercise a) The halfreaction for formation of magnesium metal upon electrolysis of molten MgCl 2 is Mg e Mg. Calculate the mass of magnesium formed upon passage of a current of 60.0 A for a period of 4.00 x 10 3 s. (30.2 g Mg) b) How many seconds would be required to produce 50.0 g of Mg from MgCl 2 if the current is A? (3.97 x 10 3 s) Electrical Work Sample Exercise (p. 880) Calculate the number of kilowatthours of electricity required to produce 1.0 x 10 3 kg of aluminum by electrolysis of Al 3+ if the applied emf is 4.50 V. (1.34 x 10 4 kwh) 11

12 Practice Exercise Calculate the number of kilowatthours of electricity required to produce 1.00 kg of Mg by electrolysis of molten MgCl 2 if the applied emf is 5.00 V. Assume that the process is 100% efficient. (11.0 kwh) Electrochemistry Terminology Current = a flow of electrical charge through a conductor. The current at a particular crosssection is the rate of flow of the charge. The charge may be carried by electrons (in metals), ions (electrolyte solutions) or positive holes (semiconductors). Measured in amperes. Coulomb is the central unit for electrochemistry, enables us to maneuver amongst charge, voltage, current, watts, electrons and mass. The Faraday relates the charge to the number of electrons. 1 V = 1 J/C 1 A = 1 C/s 1 W = 1 J/s 1 F = 96,500 C/mol e Electrical work: energy units x time 1 watt = 1 J/s 1 watt = 1 V x 1 A # Watts = volts x amps or J x C C s Sample Integrative Exercise 20 (p. 880) The K sp at 298 K for iron (II) fluoride is 2.4 x a) Write a halfreaction that gives the likely products of the twoelectron reduction of FeF 2(s) in water. b) Use the K sp value and the standard reduction potential of Fe 2+ (aq) to calculate the standard reduction potential for the halfreaction in part (a). (0.606 V) c) Rationalize the difference in the reduction potential for the halfreaction in part (a) with that for Fe 2+ (aq). 12

Chapter 20. Electrochemistry

Chapter 20. Electrochemistry Chapter 20. Electrochemistry 20.1 OxidationReduction Reactions Oxidationreduction reactions = chemical reactions in which the oxidation state of one or more substance changes (redox reactions). Recall:

More information

Chapter 20. Electrochemistry

Chapter 20. Electrochemistry Chapter 20. Electrochemistry 20.1 Oxidation-Reduction Reactions Oxidation-reduction reactions = chemical reactions in which the oxidation state of one or more substance changes (redox reactions). Recall:

More information

Chapter 20. Electrochemistry Recommendation: Review Sec. 4.4 (oxidation-reduction reactions) in your textbook

Chapter 20. Electrochemistry Recommendation: Review Sec. 4.4 (oxidation-reduction reactions) in your textbook Chapter 20. Electrochemistry Recommendation: Review Sec. 4.4 (oxidation-reduction reactions) in your textbook 20.1 Oxidation-Reduction Reactions Oxidation-reduction reactions = chemical reactions in which

More information

Lecture Presentation. Chapter 20. Electrochemistry. James F. Kirby Quinnipiac University Hamden, CT Pearson Education

Lecture Presentation. Chapter 20. Electrochemistry. James F. Kirby Quinnipiac University Hamden, CT Pearson Education Lecture Presentation Chapter 20 James F. Kirby Quinnipiac University Hamden, CT is the study of the relationships between electricity and chemical reactions. It includes the study of both spontaneous and

More information

Oxidation-Reduction Review. Electrochemistry. Oxidation-Reduction Reactions. Oxidation-Reduction Reactions. Sample Problem.

Oxidation-Reduction Review. Electrochemistry. Oxidation-Reduction Reactions. Oxidation-Reduction Reactions. Sample Problem. 1 Electrochemistry Oxidation-Reduction Review Topics Covered Oxidation-reduction reactions Balancing oxidationreduction equations Voltaic cells Cell EMF Spontaneity of redox reactions Batteries Electrolysis

More information

Oxidation-reduction reactions = chemical reactions in which the oxidation state of one or more substance changes (redox reactions).

Oxidation-reduction reactions = chemical reactions in which the oxidation state of one or more substance changes (redox reactions). Chapter 20. Electrochemistry Common Student Misconceptions Students should be encouraged to review section 4.4. Students often think that oxidation must necessarily mean adding oxygen. Students often have

More information

Date Topics Problems Video(s) Due One Review tests, introduce red-ox, identify oxidizing and reducing agents

Date Topics Problems Video(s) Due One Review tests, introduce red-ox, identify oxidizing and reducing agents Chapter 20: Electrochemistry. Tentative Schedule Date Topics Problems Video(s) Due One Review tests, introduce redox, identify oxidizing and reducing agents Oxidation numbers / oxidizing and reducing agents

More information

Chapter 19 ElectroChemistry

Chapter 19 ElectroChemistry Chem 1046 General Chemistry by Ebbing and Gammon, 9th Edition George W.J. Kenney, Jr, Professor of Chemistry Last Update: 11July2009 Chapter 19 ElectroChemistry These Notes are to SUPPLIMENT the Text,

More information

ELECTROCHEMISTRY OXIDATION-REDUCTION

ELECTROCHEMISTRY OXIDATION-REDUCTION ELECTROCHEMISTRY Electrochemistry involves the relationship between electrical energy and chemical energy. OXIDATION-REDUCTION REACTIONS SPONTANEOUS REACTIONS Can extract electrical energy from these.

More information

CHEMISTRY 13 Electrochemistry Supplementary Problems

CHEMISTRY 13 Electrochemistry Supplementary Problems 1. When the redox equation CHEMISTRY 13 Electrochemistry Supplementary Problems MnO 4 (aq) + H + (aq) + H 3 AsO 3 (aq) Mn 2+ (aq) + H 3 AsO 4 (aq) + H 2 O(l) is properly balanced, the coefficients will

More information

Chapter 18. Electrochemistry

Chapter 18. Electrochemistry Chapter 18 Electrochemistry Section 17.1 Spontaneous Processes and Entropy Section 17.1 http://www.bozemanscience.com/ap-chemistry/ Spontaneous Processes and Entropy Section 17.1 Spontaneous Processes

More information

Redox reactions & electrochemistry

Redox reactions & electrochemistry Redox reactions & electrochemistry Electrochemistry Electrical energy ; Chemical energy oxidation/reduction = redox reactions Electrochemistry Zn + Cu 2+ º Zn 2+ + Cu Oxidation-reduction reactions always

More information

Chapter 17. Electrochemistry

Chapter 17. Electrochemistry Chapter 17 Electrochemistry Contents Galvanic cells Standard reduction potentials Cell potential, electrical work, and free energy Dependence of cell potential on concentration Batteries Corrosion Electrolysis

More information

REVIEW QUESTIONS Chapter 19

REVIEW QUESTIONS Chapter 19 Chemistry 10 ANSWER KEY REVIEW QUESTIONS Chapter 19 1. For each of the following unbalanced equations, (i) write the half-reactions for oxidation and reduction, and (ii) balance the overall equation in

More information

Electrochemistry Pearson Education, Inc. Mr. Matthew Totaro Legacy High School AP Chemistry

Electrochemistry Pearson Education, Inc. Mr. Matthew Totaro Legacy High School AP Chemistry 2012 Pearson Education, Inc. Mr. Matthew Totaro Legacy High School AP Chemistry Electricity from Chemistry Many chemical reactions involve the transfer of electrons between atoms or ions electron transfer

More information

Oxidation (oxidized): the loss of one or more electrons. Reduction (reduced): the gain of one or more electrons

Oxidation (oxidized): the loss of one or more electrons. Reduction (reduced): the gain of one or more electrons 1 of 13 interesting links: Battery Chemistry Tutorial at http://www.powerstream.com/batteryfaq.html Duracell Procell: Battery Chemistry at http://www.duracell.com/procell/chemistries /default.asp I. Oxidation

More information

Electrochemistry Pulling the Plug on the Power Grid

Electrochemistry Pulling the Plug on the Power Grid Electrochemistry 18.1 Pulling the Plug on the Power Grid 18.3 Voltaic (or Galvanic) Cells: Generating Electricity from Spontaneous Chemical Reactions 18.4 Standard Electrode Potentials 18.7 Batteries:

More information

Electrochemistry 1 1

Electrochemistry 1 1 Electrochemistry 1 1 Half-Reactions 1. Balancing Oxidation Reduction Reactions in Acidic and Basic Solutions Voltaic Cells 2. Construction of Voltaic Cells 3. Notation for Voltaic Cells 4. Cell Potential

More information

A voltaic cell using the following reaction is in operation: 2 Ag + (lm) + Cd(s) 2 Ag(s) + Cd 2+ (l M)

A voltaic cell using the following reaction is in operation: 2 Ag + (lm) + Cd(s) 2 Ag(s) + Cd 2+ (l M) 0. Cu (s) + 2Ag + Cu 2+ + 2Ag (s) If the equilibrium constant for the reaction above is 3.7x10 15, which of the following correctly describes the standard voltage, E o and the standard free energy change,

More information

AP Chemistry: Electrochemistry Multiple Choice Answers

AP Chemistry: Electrochemistry Multiple Choice Answers AP Chemistry: Electrochemistry Multiple Choice Answers 14. Questions 14-17 The spontaneous reaction that occurs when the cell in the picture operates is as follows: 2Ag + + Cd (s) à 2 Ag (s) + Cd 2+ (A)

More information

Chpt 20: Electrochemistry

Chpt 20: Electrochemistry Cell Potential and Free Energy When both reactants and products are in their standard states, and under constant pressure and temperature conditions where DG o = nfe o DG o is the standard free energy

More information

Ch 20 Electrochemistry: the study of the relationships between electricity and chemical reactions.

Ch 20 Electrochemistry: the study of the relationships between electricity and chemical reactions. Ch 20 Electrochemistry: the study of the relationships between electricity and chemical reactions. In electrochemical reactions, electrons are transferred from one species to another. Learning goals and

More information

Unit 12 Redox and Electrochemistry

Unit 12 Redox and Electrochemistry Unit 12 Redox and Electrochemistry Review of Terminology for Redox Reactions OXIDATION loss of electron(s) by a species; increase in oxidation number. REDUCTION gain of electron(s); decrease in oxidation

More information

Chapter 20 Electrochemistry

Chapter 20 Electrochemistry Chapter 20 Electrochemistry Learning goals and key skills: Identify oxidation, reduction, oxidizing agent, and reducing agent in a chemical equation Complete and balance redox equations using the method

More information

20.1 Consider the Brønsted-Lowry acid-base reaction and the redox reaction below. + A

20.1 Consider the Brønsted-Lowry acid-base reaction and the redox reaction below. + A 20 Electrochemistry Visualizing Concepts 20.1 Consider the Brønsted-Lowry acid-base reaction and the redox reaction below. HA + B BH + + A HA H + + A B + H + BH + X(red) + Y + (ox) X + (ox) + Y(red) X(red)

More information

Chemistry: The Central Science. Chapter 20: Electrochemistry

Chemistry: The Central Science. Chapter 20: Electrochemistry Chemistry: The Central Science Chapter 20: Electrochemistry Redox reaction power batteries Electrochemistry is the study of the relationships between electricity and chemical reactions o It includes the

More information

Electrochemistry. A. Na B. Ba C. S D. N E. Al. 2. What is the oxidation state of Xe in XeO 4? A +8 B +6 C +4 D +2 E 0

Electrochemistry. A. Na B. Ba C. S D. N E. Al. 2. What is the oxidation state of Xe in XeO 4? A +8 B +6 C +4 D +2 E 0 Electrochemistry 1. Element M reacts with oxygen to from an oxide with the formula MO. When MO is dissolved in water, the resulting solution is basic. Element M is most likely: A. Na B. Ba C. S D. N E.

More information

Part One: Introduction. a. Chemical reactions produced by electric current. (electrolysis)

Part One: Introduction. a. Chemical reactions produced by electric current. (electrolysis) CHAPTER 19: ELECTROCHEMISTRY Part One: Introduction A. Terminology. 1. Electrochemistry deals with: a. Chemical reactions produced by electric current. (electrolysis) b. Production of electric current

More information

Lecture Presentation. Chapter 18. Electrochemistry. Sherril Soman Grand Valley State University Pearson Education, Inc.

Lecture Presentation. Chapter 18. Electrochemistry. Sherril Soman Grand Valley State University Pearson Education, Inc. Lecture Presentation Chapter 18 Electrochemistry Sherril Soman Grand Valley State University Harnessing the Power in Nature The goal of scientific research is to understand nature. Once we understand the

More information

Practice Exam Topic 9: Oxidation & Reduction

Practice Exam Topic 9: Oxidation & Reduction Name Practice Exam Topic 9: Oxidation & Reduction 1. What are the oxidation numbers of the elements in sulfuric acid, H 2 SO 4? Hydrogen Sulfur Oxygen A. +1 +6 2 B. +1 +4 2 C. +2 +1 +4 D. +2 +6 8 2. Consider

More information

SHOCK TO THE SYSTEM! ELECTROCHEMISTRY

SHOCK TO THE SYSTEM! ELECTROCHEMISTRY SHOCK TO THE SYSTEM! ELECTROCHEMISTRY REVIEW I. Re: Balancing Redox Reactions. A. Every redox reaction requires a substance to be... 1. oxidized (loses electrons). a.k.a. reducing agent 2. reduced (gains

More information

Electrochemistry. Remember from CHM151 G E R L E O 6/24/2014. A redox reaction in one in which electrons are transferred.

Electrochemistry. Remember from CHM151 G E R L E O 6/24/2014. A redox reaction in one in which electrons are transferred. Electrochemistry Remember from CHM151 A redox reaction in one in which electrons are transferred Reduction Oxidation For example: L E O ose lectrons xidation G E R ain lectrons eduction We can determine

More information

Electrochemistry objectives

Electrochemistry objectives Electrochemistry objectives 1) Understand how a voltaic and electrolytic cell work 2) Be able to tell which substance is being oxidized and reduced and where it is occuring the anode or cathode 3) Students

More information

25. A typical galvanic cell diagram is:

25. A typical galvanic cell diagram is: Unit VI(6)-III: Electrochemistry Chapter 17 Assigned Problems Answers Exercises Galvanic Cells, Cell Potentials, Standard Reduction Potentials, and Free Energy 25. A typical galvanic cell diagram is: The

More information

CHAPTER 12. Practice exercises

CHAPTER 12. Practice exercises CHAPTER 12 Practice exercises 12.1 2Al(s) + 3Cl 2 (g) 2AlCl 3 (aq) Aluminium is oxidised and is therefore the reducing agent. Chlorine is reduced and is therefore the oxidising agent. 12.3 First the oxidation

More information

AP CHEMISTRY NOTES 12-1 ELECTROCHEMISTRY: ELECTROCHEMICAL CELLS

AP CHEMISTRY NOTES 12-1 ELECTROCHEMISTRY: ELECTROCHEMICAL CELLS AP CHEMISTRY NOTES 12-1 ELECTROCHEMISTRY: ELECTROCHEMICAL CELLS Review: OXIDATION-REDUCTION REACTIONS the changes that occur when electrons are transferred between reactants (also known as a redox reaction)

More information

Lecture Presentation. Chapter 20. Electrochemistry. James F. Kirby Quinnipiac University Hamden, CT Pearson Education, Inc.

Lecture Presentation. Chapter 20. Electrochemistry. James F. Kirby Quinnipiac University Hamden, CT Pearson Education, Inc. Lecture Presentation Chapter 20 James F. Kirby Quinnipiac University Hamden, CT is the study of the relationships between electricity and chemical reactions. It includes the study of both spontaneous and

More information

Electrochemistry. Outline

Electrochemistry. Outline Electrochemistry Outline 1. Oxidation Numbers 2. Voltaic Cells 3. Calculating emf or Standard Cell Potential using Half-Reactions 4. Relationships to Thermo, Equilibrium, and Q 5. Stoichiometry 6. Balancing

More information

Redox and Electrochemistry

Redox and Electrochemistry Redox and Electrochemistry 1 Electrochemistry in Action! 2 Rules for Assigning Oxidation Numbers The oxidation number of any uncombined element is 0. The oxidation number of a monatomic ion equals the

More information

ELECTROCHEMISTRY. Oxidation/Reduction

ELECTROCHEMISTRY. Oxidation/Reduction ELECTROCHEMISTRY Electrochemistry involves the relationship between electrical energy and chemical energy. OXIDATION-REDUCTION REACTIONS SPONTANEOUS REACTIONS Examples: voltaic cells, batteries. NON-SPONTANEOUS

More information

Lecture Presentation. Chapter 20. Electrochemistry. James F. Kirby Quinnipiac University Hamden, CT Pearson Education

Lecture Presentation. Chapter 20. Electrochemistry. James F. Kirby Quinnipiac University Hamden, CT Pearson Education Lecture Presentation Chapter 20 James F. Kirby Quinnipiac University Hamden, CT is the study of the relationships between electricity and chemical reactions. It includes the study of both spontaneous and

More information

Chapter 20. Electrochemistry. Chapter 20 Problems. Electrochemistry 7/3/2012. Problems 15, 17, 19, 23, 27, 29, 33, 39, 59

Chapter 20. Electrochemistry. Chapter 20 Problems. Electrochemistry 7/3/2012. Problems 15, 17, 19, 23, 27, 29, 33, 39, 59 Chemistry, The Central Science, 11th edition Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten Chapter 20 John D. Bookstaver St. Charles Community College Cottleville, MO Chapter 20 Problems

More information

Chemistry 102 Chapter 19 OXIDATION-REDUCTION REACTIONS

Chemistry 102 Chapter 19 OXIDATION-REDUCTION REACTIONS OXIDATION-REDUCTION REACTIONS Some of the most important reaction in chemistry are oxidation-reduction (redox) reactions. In these reactions, electrons transfer from one reactant to the other. The rusting

More information

Electrochem: It s Got Potential!

Electrochem: It s Got Potential! Electrochem: It s Got Potential! Presented by: Denise DeMartino Westlake High School, Eanes ISD Pre-AP, AP, and Advanced Placement are registered trademarks of the College Board, which was not involved

More information

Electrochemistry. Review oxidation reactions and how to assign oxidation numbers (Ch 4 Chemical Reactions).

Electrochemistry. Review oxidation reactions and how to assign oxidation numbers (Ch 4 Chemical Reactions). Electrochemistry Oxidation-Reduction: Review oxidation reactions and how to assign oxidation numbers (Ch 4 Chemical Reactions). Half Reactions Method for Balancing Redox Equations: Acidic solutions: 1.

More information

Chapter 12 Redox reactions and Electrochemistry

Chapter 12 Redox reactions and Electrochemistry Chapter 12 Redox reactions and Electrochemistry 11 Balancing Redox Equations 12 Electrochemical Cells 13 Stoichiometry in Electrochemical Cells 14 (Skip) Metals and Metallurgy 15 (Skip) Electrometallurgy

More information

Guide to Chapter 18. Electrochemistry

Guide to Chapter 18. Electrochemistry Guide to Chapter 18. Electrochemistry We will spend three lecture days on this chapter. During the first class meeting we will review oxidation and reduction. We will introduce balancing redox equations

More information

Chapter 19: Oxidation - Reduction Reactions

Chapter 19: Oxidation - Reduction Reactions Chapter 19: Oxidation - Reduction Reactions 19-1 Oxidation and Reduction I. Oxidation States A. The oxidation rules (as summarized by Mr. Allan) 1. In compounds, hydrogen has an oxidation # of +1. In compounds,

More information

Exercise 4 Oxidation-reduction (redox) reaction oxidimetry. Theoretical part

Exercise 4 Oxidation-reduction (redox) reaction oxidimetry. Theoretical part Exercise 4 Oxidation-reduction (redox) reaction oxidimetry. Theoretical part In oxidation-reduction (or redox) reactions, the key chemical event is the net movement of electrons from one reactant to the

More information

Oxidation Numbers, ox #

Oxidation Numbers, ox # Oxidation Numbers, ox # are or numbers assigned to each or assuming that the are transferred from the electronegative element to the electronegative element. now mimic systems. ox # are written followed

More information

Electrochemistry. Slide 1 / 144. Slide 2 / 144. Slide 3 / 144. Electrochemistry. Electrochemical Reactions

Electrochemistry. Slide 1 / 144. Slide 2 / 144. Slide 3 / 144. Electrochemistry. Electrochemical Reactions Slide 1 / 144 Electrochemistry Electrochemistry Slide 2 / 144 Electrochemistry deals with relationships between reactions and electricity In electrochemical reactions, electrons are transferred from one

More information

Chapter 19: Electrochemistry

Chapter 19: Electrochemistry Chapter 19: Electrochemistry Overview of the Chapter review oxidation-reduction chemistry basics galvanic cells spontaneous chemical reaction generates a voltage set-up of galvanic cell & identification

More information

Section A: Summary Notes

Section A: Summary Notes ELECTROCHEMICAL CELLS 25 AUGUST 2015 Section A: Summary Notes Important definitions: Oxidation: the loss of electrons by a substance during a chemical reaction Reduction: the gain of electrons by a substance

More information

Oxidation-reduction (redox) reactions

Oxidation-reduction (redox) reactions Oxidation-reduction (redox) reactions Reactions in which there are changes in oxidation state (oxidation number) between reactants and products 2 MnO 4- + 10 Br - + 16 H + 2 Mn 2+ + 5 Br 2 + 8 H 2 O One

More information

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. A.P. Chemistry Practice Test - Ch. 17: Electochemistry MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The gain of electrons by an element is called.

More information

http://redoxanswers.weebly.com REDOX LESSON LEARNING GOALS http://redoxanswers.weebly.com Lesson 1: Introduction to Redox Relate to examples of oxidation-reduction reactions in the real-world. Understand

More information

Chapter 20 Electrochemistry

Chapter 20 Electrochemistry Chapter 20 Electrochemistry 20.1 Oxidation States and Oxidation-Reduction Reactions An oxidation occurs when an atom or ion loses electrons. A reduction occurs when an atom or ion gains electrons. One

More information

Unit #8, Chapter 10 Outline Electrochemistry and Redox Reactions

Unit #8, Chapter 10 Outline Electrochemistry and Redox Reactions Unit #8, Chapter 10 Outline Electrochemistry and Redox Reactions Lesson Topics Covered Homework Questions and Assignments 1 Introduction to Electrochemistry definitions 1. Read pages 462 467 2. On page

More information

Chapter Nineteen. Electrochemistry

Chapter Nineteen. Electrochemistry Chapter Nineteen Electrochemistry 1 Electrochemistry The study of chemical reactions through electrical circuits. Monitor redox reactions by controlling electron transfer REDOX: Shorthand for REDuction-OXidation

More information

(for tutoring, homework help, or help with online classes)

(for tutoring, homework help, or help with online classes) www.tutor-homework.com (for tutoring, homework help, or help with online classes) 1. chem10b 20.4-3 In a voltaic cell electrons flow from the anode to the cathode. Value 2. chem10b 20.1-35 How many grams

More information

Redox Reactions and Electrochemistry

Redox Reactions and Electrochemistry Redox Reactions and Electrochemistry Problem Set Chapter 5: 2126, Chapter 21: 1517, 32, 34, 43, 53, 72, 74 R Oxidation/Reduction & Electrochemistry Oxidation a reaction in which a substance gains oxygen

More information

Electrochemistry. Galvanic Cell. Page 1. Applications of Redox

Electrochemistry. Galvanic Cell. Page 1. Applications of Redox Electrochemistry Applications of Redox Review Oxidation reduction reactions involve a transfer of electrons. OIL- RIG Oxidation Involves Loss Reduction Involves Gain LEO-GER Lose Electrons Oxidation Gain

More information

Name AP CHEM / / Collected Essays Chapter 17

Name AP CHEM / / Collected Essays Chapter 17 Name AP CHEM / / Collected Essays Chapter 17 1980 - #2 M(s) + Cu 2+ (aq) M 2+ (aq) + Cu(s) For the reaction above, E = 0.740 volt at 25 C. (a) Determine the standard electrode potential for the reaction

More information

1.In which of the following is the oxidation number of the underlined element given incorrectly? oxidation number

1.In which of the following is the oxidation number of the underlined element given incorrectly? oxidation number General Chemistry II Exam 4 Practice Problems 1 1.In which of the following is the oxidation number of the underlined element given incorrectly? oxidation number a. K 2 Cr 2 O 7 +6 b. NaAl(OH) 4 +3 c.

More information

Introduction Oxidation/reduction reactions involve the exchange of an electron between chemical species.

Introduction Oxidation/reduction reactions involve the exchange of an electron between chemical species. Introduction Oxidation/reduction reactions involve the exchange of an electron between chemical species. The species that loses the electron is oxidized. The species that gains the electron is reduced.

More information

Electrochemical System

Electrochemical System Electrochemical System Topic Outcomes Week Topic Topic Outcomes 8-10 Electrochemical systems It is expected that students are able to: Electrochemical system and its thermodynamics Chemical reactions in

More information

CHAPTER 17: ELECTROCHEMISTRY. Big Idea 3

CHAPTER 17: ELECTROCHEMISTRY. Big Idea 3 CHAPTER 17: ELECTROCHEMISTRY Big Idea 3 Electrochemistry Conversion of chemical to electrical energy (discharge). And its reverse (electrolysis). Both subject to entropic caution: Convert reversibly to

More information

Name Period Date. Ch. 19: Oxidation-Reduction Reactions Homework

Name Period Date. Ch. 19: Oxidation-Reduction Reactions Homework Name Period Date Ch. 19: OxidationReduction Reactions Homework Answer each of the following questions in as much detail as you can. Be sure to show all your work for any calculations and follow all rules

More information

Chapter 18 problems (with solutions)

Chapter 18 problems (with solutions) Chapter 18 problems (with solutions) 1) Assign oxidation numbers for the following species (for review see section 9.4) a) H2SO3 H = +1 S = +4 O = -2 b) Ca(ClO3)2 Ca = +2 Cl = +5 O = -2 c) C2H4 C = -2

More information

Oxidation number. The charge the atom would have in a molecule (or an ionic compound) if electrons were completely transferred.

Oxidation number. The charge the atom would have in a molecule (or an ionic compound) if electrons were completely transferred. Oxidation number The charge the atom would have in a molecule (or an ionic compound) if electrons were completely transferred. 1. Free elements (uncombined state) have an oxidation number of zero. Na,

More information

Electrochemistry. (Hebden Unit 5 ) Electrochemistry Hebden Unit 5

Electrochemistry. (Hebden Unit 5 ) Electrochemistry Hebden Unit 5 (Hebden Unit 5 ) is the study of the interchange of chemical energy and electrical energy. 2 1 We will cover the following topics: Review oxidation states and assigning oxidation numbers Redox Half-reactions

More information

mccord (pmccord) HW11 Electrochemistry I mccord (51520) 1

mccord (pmccord) HW11 Electrochemistry I mccord (51520) 1 mccord (pmccord) HW11 Electrochemistry I mccord (51520) 1 This print-out should have 27 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001

More information

Homework 11. Electrochemical Potential, Free Energy, and Applications

Homework 11. Electrochemical Potential, Free Energy, and Applications HW11 Electrochemical Poten!al, Free Energy, and Applica!ons Homework 11 Electrochemical Potential, Free Energy, and Applications Question 1 What is the E for Zn(s) Zn (aq) Ce (aq) Ce (aq) + cell + 4+ 3+

More information

Chapter 18 Electrochemistry

Chapter 18 Electrochemistry Chapter 18 Electrochemistry Definition The study of the interchange of chemical and electrical energy in oxidation-reduction (redox) reactions This interchange can occur in both directions: 1. Conversion

More information

Section Electrochemistry represents the interconversion of chemical energy and electrical energy.

Section Electrochemistry represents the interconversion of chemical energy and electrical energy. Chapter 21 Electrochemistry Section 21.1. Electrochemistry represents the interconversion of chemical energy and electrical energy. Electrochemistry involves redox (reduction-oxidation) reactions because

More information

Chapter 18 Electrochemistry. Electrochemical Cells

Chapter 18 Electrochemistry. Electrochemical Cells Chapter 18 Electrochemistry Chapter 18 1 Electrochemical Cells Electrochemical Cells are of two basic types: Galvanic Cells a spontaneous chemical reaction generates an electric current Electrolytic Cells

More information

Chapter 12 Redox reactions and Electrochemistry

Chapter 12 Redox reactions and Electrochemistry Chapter 12 Redox reactions and Electrochemistry 11 Balancing Redox Equations 12 Electrochemical Cells 13 Stoichiometry in Electrochemical Cells 14 Metals and Metallurgy 15 Electrometallurgy Note: See course

More information

Electrochemistry. Chapter 18. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Electrochemistry. Chapter 18. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Electrochemistry Chapter 18 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Electrochemical processes are oxidation-reduction reactions in which: the energy

More information

Chapter 18. Electrochemistry

Chapter 18. Electrochemistry Chapter 18 Electrochemistry Oxidation-Reduction Reactions Review of Terms Oxidation-reduction (redox) reactions always involve a transfer of electrons from one species to another. Oxidation number - the

More information

Lecture #15. Chapter 18 - Electrochemistry

Lecture #15. Chapter 18 - Electrochemistry Lecture #15 Chapter 18 - Electrochemistry Chapter 18 - Electrochemistry the branch of chemistry that examines the transformations between chemical and electrical energy Redox Chemistry Revisited A Spontaneous

More information

Chemistry 30 Review Test 3 Redox and Electrochemistry /55

Chemistry 30 Review Test 3 Redox and Electrochemistry /55 Chemistry 30 Review Test 3 Redox and Electrochemistry /55 Part I Multiple choice / Numerical Response Answer the following multiple choice questions on the scantron sheet. Answer the numerical response

More information

Chapter 19 - Electrochemistry. the branch of chemistry that examines the transformations between chemical and electrical energy

Chapter 19 - Electrochemistry. the branch of chemistry that examines the transformations between chemical and electrical energy Chapter 19 - Electrochemistry the branch of chemistry that examines the transformations between chemical and electrical energy 19.1 Redox Chemistry Revisited A Spontaneous Redox Reaction Znº(s) + Cu 2+

More information

CHAPTER 17 ELECTROCHEMISTRY

CHAPTER 17 ELECTROCHEMISTRY Advanced Chemistry Approximate Timeline Students are expected to keep up with class work when absent. CHAPTER 17 ELECTROCHEMISTRY Day Plans for the day Assignment(s) for the day 17.1 Galvanic Cells Assignment

More information

Ch 11 Practice Problems

Ch 11 Practice Problems Ch 11 Practice Problems 1. How many electrons are transferred in the following reaction? 2Cr 2O 7 2- + 14H + + 6Cl 2Cr 3+ + 3Cl 2 + 7H 2O A) 2 B) 4 C) 6 D) 8 2. Which metal, Al or Ni, could reduce Zn 2+

More information

12.05 Galvanic Cells. Zn(s) + 2 Ag + (aq) Zn 2+ (aq) + 2 Ag(s) Ni(s) + Pb 2+ (aq) «Ni 2+ (aq) + Pb(s)

12.05 Galvanic Cells. Zn(s) + 2 Ag + (aq) Zn 2+ (aq) + 2 Ag(s) Ni(s) + Pb 2+ (aq) «Ni 2+ (aq) + Pb(s) 12.05 Galvanic Cells 1. In an operating voltaic cell, reduction occurs A) at the anode B) at the cathode C) in the salt bridge D) in the wire 2. Which process occurs in an operating voltaic cell? A) Electrical

More information

CHEM N-12 November In the electrolytic production of Al, what mass of Al can be deposited in 2.00 hours by a current of 1.8 A?

CHEM N-12 November In the electrolytic production of Al, what mass of Al can be deposited in 2.00 hours by a current of 1.8 A? CHEM161 014-N-1 November 014 In the electrolytic production of Al, what mass of Al can be deposited in.00 hours by a current of 1.8 A? What products would you expect at the anode and the cathode on electrolysis

More information

Electrochemical Cells

Electrochemical Cells Electrochemistry Electrochemical Cells The Voltaic Cell Electrochemical Cell = device that generates electricity through redox rxns 1 Voltaic (Galvanic) Cell An electrochemical cell that produces an electrical

More information

Spontaneous Redox Between Zinc Metal and Copper(II) Ions. Zn 2+ Zn + 2e- Cu 2+ NO 3

Spontaneous Redox Between Zinc Metal and Copper(II) Ions. Zn 2+ Zn + 2e- Cu 2+ NO 3 Spontaneous Redox Between Zinc Metal and Copper(II) Ions Zn 2+ Cu 2+ NO 3 _ Zn + 2e- Cu Zn 0 + Cu 2+ º Zn 2+ + Cu 0 spontaneous red 1 ox 2 ox 1 red 2 Spontaneous Redox Between Copper Metal and Silver Ions

More information

Oxidation refers to any process in which the oxidation number of an atom becomes more positive

Oxidation refers to any process in which the oxidation number of an atom becomes more positive Lecture Notes 3 rd Series: Electrochemistry Oxidation number or states When atoms gain or lose electrons they are said to change their oxidation number or oxidation state. If an element has gained electrons

More information

Chemistry 112 Name Exam III Form A Section April 2,

Chemistry 112 Name Exam III Form A Section April 2, Chemistry 112 Name Exam III Form A Section April 2, 2013 email IMPORTANT: On the scantron (answer sheet), you MUST clearly fill your name, your student number, section number, and test form (white cover

More information

Ch. 13 Fundamentals of Electrochemistry

Ch. 13 Fundamentals of Electrochemistry Ch. 13 Fundamentals of Electrochemistry 13.1 13-1. Basic Concepts of electrochemistry redox reaction : reactions with electron transfer oxidized : loses electrons reduced : gains electrons Fe 3+ + V 2+

More information

17.1 Redox Chemistry Revisited

17.1 Redox Chemistry Revisited Chapter Outline 17.1 Redox Chemistry Revisited 17.2 Electrochemical Cells 17.3 Standard Potentials 17.4 Chemical Energy and Electrical Work 17.5 A Reference Point: The Standard Hydrogen Electrode 17.6

More information

Ch 18 Electrochemistry OIL-RIG Reactions

Ch 18 Electrochemistry OIL-RIG Reactions Ch 18 Electrochemistry OIL-RIG Reactions Alessandro Volta s Invention Modified by Dr. Cheng-Yu Lai Daily Electrochemistry Appliactions Electrochemistry: The area of chemistry that examines the transformations

More information

Electrochemistry (Galvanic and Electrolytic Cells) Exchange of energy in chemical cells

Electrochemistry (Galvanic and Electrolytic Cells) Exchange of energy in chemical cells Electrochemistry (Galvanic and Electrolytic Cells) Exchange of energy in chemical cells Oxidation loss of electrons (oxidation number increases) OIL RIG Reduction gain of electrons (oxidation number decreases)

More information

Electrochemistry. 1. Determine the oxidation states of each element in the following compounds. (Reference: Ex. 4:16) a. N 2 N: b.

Electrochemistry. 1. Determine the oxidation states of each element in the following compounds. (Reference: Ex. 4:16) a. N 2 N: b. Name: Electrochemistry Two of the most common types of chemical reactions are acid-base reactions in which protons are transferred between two reactants and oxidation-reduction reactions in which electrons

More information

17.1 Redox Reactions. Oxidation Numbers. Assigning Oxidation Numbers. Redox Reactions. Ch. 17: Electrochemistry 12/14/2017. Creative Commons License

17.1 Redox Reactions. Oxidation Numbers. Assigning Oxidation Numbers. Redox Reactions. Ch. 17: Electrochemistry 12/14/2017. Creative Commons License Ch. 17: Electrochemistry Electric vehicles contain batteries that can be recharged, thereby using electric energy to bring about a chemical change and vice versa. (credit: modification of work by Robert

More information

Oxidation-Reduction (Redox)

Oxidation-Reduction (Redox) Oxidation-Reduction (Redox) Electrochemistry involves the study of the conversions between chemical and electrical energy. Voltaic (galvanic) cells use chemical reactions to produce an electric current.

More information

Name (Print) Section # or TA. 1. You may use a crib sheet which you prepared in your own handwriting. This may be

Name (Print) Section # or TA. 1. You may use a crib sheet which you prepared in your own handwriting. This may be Name (Print) Section # or TA 1. You may use a crib sheet which you prepared in your own handwriting. This may be one 8-1/2 by 11 inch sheet of paper with handwriting only on one side. 2. You may use a

More information

ELECTROCHEMISTRY. Electrons are transferred from Al to Cu 2+. We can re write this equation as two separate half reactions:

ELECTROCHEMISTRY. Electrons are transferred from Al to Cu 2+. We can re write this equation as two separate half reactions: ELECTROCHEMISTRY A. INTRODUCTION 1. Electrochemistry is the branch of chemistry which is concerned with the conversion of chemical energy to electrical energy, and vice versa. Electrochemical reactions

More information

Chapter 17 Electrochemistry

Chapter 17 Electrochemistry Chapter 17 Electrochemistry 17.1 Galvanic Cells A. Oxidation-Reduction Reactions (Redox Rxns) 1. Oxidation = loss of electrons a. the substance oxidized is the reducing agent 2. Reduction = gain of electrons

More information