Chpt 20: Electrochemistry

Size: px
Start display at page:

Download "Chpt 20: Electrochemistry"

Transcription

1

2 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 change of the reaction n is the number of mole of electrons transferred in the reaction F is Faraday s constant E o is the standard cell potential Faraday s constant is the quantity of electrical charge on 1 mol of electrons 1 F = 96,500 C/mol e - 1 F = 96,500 J/Vmol e -

3 DG o from Cell emf I Example: For the reaction I 2 (s) + 5Cu 2+ (aq) 2IO 3- (aq) + 5Cu(s) + 12H + (aq) calculate the standard free energy change for the reaction. I 2 (s) 2IO 3- (aq) + 10e - The oxidation reaction is E o red = V The reduction reaction is 5Cu 2+ (aq) +10e - 5Cu(s) E o red = V E o = E o red(reduction) - E o red(oxidation) E o = V - ( V) E o = V from the half-reactions we see that 10 moles of electrons are transferred in the reaction n = 10

4 DG o from Cell emf II Example: For the reaction I 2 (s) + 5Cu 2+ (aq) 2IO 3- (aq) + 5Cu(s) + 12H + (aq) calculate the standard free energy change for the reaction. DG o = nfe o DG o =-(10 mole - )(96,500 J/Vmole - )( V) DG o = +828 kj Since DG o > 0, reaction is non-spontaneous (we could also note this since E o < 0) If reactants and products are not in their standard states, the more general relation can be applied DG = nfe

5 Example A 4 B 1, 2 C 2 D 2, 3 E 1, 4 Over time, you notice that the tin electrode seems to be disappearing while there are deposits forming on the silver electrode. Which of the following is a correct statement? 1. The silver electrode is the cathode and the tin electrode is the anode. 2. Electrons are flowing from the tin electrode to the silver electrode. 3. Nitrate ions are flowing through the salt bridge to the silver solution. 4. The half-reaction occurring at the tin electrode is: Sn e - Sn 2+.

6 Example Chlorine dioxide is used to treat municipal water supplies. 2 NaClO 2 (aq) + Cl 2 (g) 2 ClO 2 (g) + 2 NaCl (aq) Cl 2 + 2e - 2Cl - ClO 2 + e - ClO 2 - Calculate DG o for the reaction. A 78 kj B -39 kj C -78 kj D -156 kj E 39 kj E o red = 1.36 V E o red = V

7 The Nernst Equation I The cell emf will depend reactant/product concentration The dependence of cell emf on concentration can be derived from the dependence of the free energy change on concentration DG = DG o + RTlnQ R is the gas constant (8.314 J/Kmol) T is absolute temperature Q is the reaction quotient, which depends on reactant and product concentrations We can derive an expression for E by replacing DG o with nfe o and DG with nfe

8 The Nernst Equation II Following the substitution -nfe = -nfe o + RTlnQ E = E o - (RT/nF) lnq This relation is the Nernst Equation. The equation is typically expressed in base 10 logarithms log x = ln x E = E o - (2.303RT/nF) logq At standard temperature (T = 298 K) the quantity in parenthesis takes the form E = E o - (0.0592/n) 298 K The Nernst equation can be used in two ways to determine the cell emf under non-standard conditions to find [product] or [reactant] from E

9 Cell emf Under Non-Standard Conditions Example: Calculate the standard emf for a cell that employs the following reaction 2Al(s) + 3I 2 (s) 2Al 3+ (aq) + 6I - (aq) when [Al 3+ ] = 4.0x10-3 M and [I - ] = M from the the standard reduction potentials the cell potential is E o cell = V and n = 6 E = E o - (0.0592/n) logq Q = [Al 3+ ] 2 [I - ] 6 Q = (4.0x10-3 ) 2 (0.010) 6 Q = 1.6 x E = (+2.20V) - (0.0592/6) log (1.6x10-17 ) E = 2.36 V

10 Product Concentration from Cell emf I Example: A voltaic cell is constructed that uses the following reaction and operates at 298 K 2Al(s) + 3Mn 2+ (aq) 2Al 3+ (aq) + 3Mn(s) What is [Al 3+ ] to produce a cell emf of V? Al(s) Al 3+ (aq) + 3e - E o red = V Mn 2+ (aq) + 2e - Mn(s) E o red = V E o = E o red(reduction) - E o red(oxidation) E o = -1.18V - (-1.66V) E o = V

11 Example A galvanic cell is constructed from the following two half reactions Ag + (aq) + e - Ag (s) E o red = 0.80 V H 2 O 2 (aq) + 2H + (aq) + 2e - 2H 2 O(l) E o red = 1.78 V In which scenario is E cell greater than E o cell? 1. [Ag + ] = 1.0 M, [H 2 O 2 ] = 2.0 M, [H + ] = 2.0 M 2. [Ag + ] = 2.0 M, [H 2 O 2 ] = 1.0 M, [H + ] = 1.0x10-7 M 3. [Ag + ]= 2.0 M, [H 2 O 2 ] = 0.25 M, [H + ] = 4.0 M A 1 B 2 C 3 D 2, 3 E 1, 3

12 Example A galvanic cell is constructed from the following two half reactions Cu 2+ (aq) + 2e - Cu (s) E o red = 0.34 Ag + + e - Ag (s) E o red = 0.80 The electrodes in this cell are Ag(s) and Cu(s). For which of the following scenarios does the cell potential decrease? 1. CuSO 4 (s) is added to the copper half-cell compartment (assume no volume change) 2. NH 3 (aq) is added to the copper half-cell compartment [Cu 2+ reacts with NH 3 to form Cu(NH 3 ) 4 2+ (aq)] 3. NaCl (s) is added to the silver half-cell compartment [Ag + reacts with Cl - to form AgCl(s)] 4. Water is added to both half-cells until the volumes are doubled A 1, 3 B 2, 3, 4 C 1,4 D 2, 4 E 1, 3, 4

13 Equilibrium Constants for Redox Reactions At equilibrium, DG = 0, Q = K and 0 = E o - (0.0592/n) logk logk = ne o / The above expression allows us to calculate the equilibrium constant for a redox reaction from the standard emf for the reaction Example: What is the equilibrium constant for reaction 2Al(s) + 3Mn 2+ (aq) 2Al 3+ (aq) + 3Mn(s) We have already that determined E o = 0.48V and n = 6 logk = (6)(0.48V)/ logk = K = 4.45 x

14 Corrosion Corrosion reactions are redox reactions in which a metal is attacked by some substance in its environment and converted to an unwanted compound Corrosion of iron (two-step process) I. 2Fe(s) + O 2 (g) + 4H + 2Fe 2+ (aq) + 2H 2 O( ) II. 4Fe 2+ (aq) + O 2 (g)+ 4H 2 O( ) 2Fe 2 O 3 (s) + 8H + (aq) The half reactions for the first step O 2 (g) + 4H + + 4e - 2H 2 O( ) E o red = 1.23 V Fe(s) Fe 2+ (aq) + 2e - E o red = V Salts enhance the corrosion as the ions serve as electrolytes to complete the electrical circuit

15 Corrosion Multiple ways to prevent corrosion. Paint or metal coating on metal alloying Cathodic protection Some metals form a protective oxide layer over its surface and prevent further oxidation Al Zn (coating a metal in zinc is referred to as galvanizing) Stainless steel, a steel alloy with Cr, also forms a protective oxide layer over its surface.

16 Cathodic Protection To prevent corrosion, cathodic protection is sometimes employed. Protect a metal by ensuring it will act as the cathode in an electrochemical cell. A sacrificial anode, typically Zn, is attached to the cathode that is being protected. Compare the following half reactions Fe 2+ (aq) + 2e - Fe(s) E o red = V Zn 2+ (aq) + 2e - Zn(s) E o red = V Mg 2+ (aq) + 2e - Mg(s) E o red = V

17 Electrolysis Electrical energy can be used to induce non-spontaneous redox reactions to occur The electrolysis of water 2H 2 O( ) O 2 (g) + 2H 2 (g) Ox: 2H 2 O( ) O 2 (g) + 4H + + 4e - Red: 4H 2 O( ) + 4e - 2H 2 (g) + 4OH - The cell emf for this reaction is E o = E o red(reduction) - E o red(oxidation) E o = (+1.23 V) E o = 2.06 V Since E o is negative, the reaction in the forward direction is nonspontaneous If work is done on the system (in the form of electrical energy) the reaction can proceed

18 Electrochemical Cell A power supply can provide electrical energy to drive the electrochemical cell Oxidation occurs at the anode The anode is positive since e- are withdrawn from this electrode Reduction occurs at the cathode the cathode is negative since e- are supplied to this electrode

19 Electrolysis and Stoichiometry Example: What volume of H 2 (g) at STP is produced when 5.0 A is passed through a water electrolysis cell for 1 hour? 5 A = 5 C/s # Coulombs = (5 C/s)(1 hr)(3600 s/hr) = 18,000 C mol e - = (18,000 C)/(96,500 C/mol e - ) = mol e - 2H 2 O( ) O 2 (g) + 2H 2 (g) 2 mol H 2 (g) liberated for every 4 mol e - mol H 2 (g) = (0.186mol e - )(2mol H 2 )/(4mol e - ) = mol H 2 (g) V = nrt/p V = (0.093 mol)(0.082 Latm/molK)(298 K)/ (1 atm) = 2.28 L

20 Isolation of Al Aluminum is abundant on Earth (behind O 2 and Si) but until recently was incredibly expensive Aluminum is readily oxidized and is found in oxide compounds Al 3+ (aq) + 3e - Al(s) E o red = V Aluminum cannot be plated out of a solution of aqueous Al 3+ ions since the electrolysis of water would occur first 2 H 2 O + 2e - H 2 + 2OH - E o red = V

21 Isolation of Al Aluminum isolated electrochemically from Al 2 O 3. Cathode: AlF 6 3- (aq) + 3e - Al(s) + 6F - Reduction: 2Al 2 OF F - + C 4AlF CO 2 + 4e - Process consumes a few percent of the power produced in the US annually. CEM 152 SS2011

22 Electrolysis and Electrical Work The change in free energy for a chemical system provides a measure of the maximum useful work extracted from the reaction w max = DG = -nfe We should remember that work done on a system will result in w > 0 since electrolysis involves a non-spontaneous process, E < 0 and hence w > 0 Electrical work is typically expressed as a product of power times time energy (J) = power (J/s) time (s) The unit of electrical power is the watt 1 watt (W) = 1 J/s

23 Electrical Work Example Calculate the number of kwh of electricity required to produce 1 kg of Mg from electrolysis of MgCl 2 if applied emf = 5.0V mol Mg = (1x10 3 g Mg)/(24.3 g/mol) = 41.1 mol mol e - = (41.1 mol Mg)(2 mol e - )/(1 mol Mg) = 82.3 mol e - w = -nfe w = -(82.3 mol e - )(96,500 J/Vmol e - )(-5.0 V) w = 3.97 x 10 7 J 1 kwh = 3.6 x 10 6 J w = (3.97 x 10 7 J)/(3.6 x 10 6 J/kWh) w = 11.0 kwh This is assuming the electrolytic cell is 100 percent efficient

24 Electroplating Electrolytic processes which involve a metal electrode which participates in the cell reaction can be used to deposit the active metal onto another Oxidation at M (active metal) anode M(s) M e - ; E o red < 1.23 V Reduction of M at metallic cathode M e - M(s) ; E o red > The ions from the active metal which go into solution are plated on the cathode electrode (where the reduction occurs) For reference O 2 (g) + 4H + (aq) + 4e - H 2 O (l) E o red = V 2 H 2 O(l) 2e - H 2 (g) + 2OH - E o red = V

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

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

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

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

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

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

Chemistry 1011 TOPIC TEXT REFERENCE. Electrochemistry. Masterton and Hurley Chapter 18. Chemistry 1011 Slot 5 1

Chemistry 1011 TOPIC TEXT REFERENCE. Electrochemistry. Masterton and Hurley Chapter 18. Chemistry 1011 Slot 5 1 Chemistry 1011 TOPIC Electrochemistry TEXT REFERENCE Masterton and Hurley Chapter 18 Chemistry 1011 Slot 5 1 18.5 Electrolytic Cells YOU ARE EXPECTED TO BE ABLE TO: Construct a labelled diagram to show

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

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

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

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

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 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

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

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

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

Chapter 20. Electrochemistry

Chapter 20. Electrochemistry 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:

More information

Review: Balancing Redox Reactions. Review: Balancing Redox Reactions

Review: Balancing Redox Reactions. Review: Balancing Redox Reactions Review: Balancing Redox Reactions Determine which species is oxidized and which species is reduced Oxidation corresponds to an increase in the oxidation number of an element Reduction corresponds to a

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

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

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

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

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

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

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

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

Redox Reactions and Electrochemistry

Redox Reactions and Electrochemistry Redox Reactions and Electrochemistry Redox Reactions and Electrochemistry Redox Reactions (19.1) Galvanic Cells (19.2) Standard Reduction Potentials (19.3) Thermodynamics of Redox Reactions (19.4) The

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

Zn+2 (aq) + Cu (s) Oxidation: An atom, ion, or molecule releases electrons and is oxidized. The oxidation number of the atom oxidized increases.

Zn+2 (aq) + Cu (s) Oxidation: An atom, ion, or molecule releases electrons and is oxidized. The oxidation number of the atom oxidized increases. Oxidation-Reduction Page 1 The transfer of an electron from one compound to another results in the oxidation of the electron donor and the reduction of the electron acceptor. Loss of electrons (oxidation)

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

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

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

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

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

Dr. Anand Gupta

Dr. Anand Gupta By Dr Anand Gupta Mr. Mahesh Kapil Dr. Anand Gupta 09356511518 09888711209 anandu71@yahoo.com mkapil_foru@yahoo.com Electrochemistry Electrolysis Electric energy Chemical energy Galvanic cell 2 Electrochemistry

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

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

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

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

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

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

A + B C +D ΔG = ΔG + RTlnKp. Me n+ + ne - Me. Me n n

A + B C +D ΔG = ΔG + RTlnKp. Me n+ + ne - Me. Me n n A + B C +D ΔG = ΔG + RTlnKp Me n+ + ne - Me K p a a Me Me n a n e 1 mol madde 6.2 x 1 23 atom elektron yükü 1.62 x 1-19 C FARADAY SABİTİ: 6.2 x 1 23 x 1.62 x 1-19 = 96485 A.sn (= coulomb) 1 Faraday 965

More information

Oxidation & Reduction (Redox) Notes

Oxidation & Reduction (Redox) Notes Oxidation & Reduction (Redox) Notes Chemical Activity (or Chemical Reactivity) is the measure of the reactivity of elements. If an element has high activity, then it means that the element is willing to

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 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

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

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

General Chemistry I. Dr. PHAN TẠI HUÂN Faculty of Food Science and Technology Nong Lam University

General Chemistry I. Dr. PHAN TẠI HUÂN Faculty of Food Science and Technology Nong Lam University General Chemistry I Dr. PHAN TẠI HUÂN Faculty of Food Science and Technology Nong Lam University Module 7: Oxidation-reduction reactions and transformation of chemical energy Oxidation-reduction reactions

More information

CHEM Principles of Chemistry II. Chapter 17 - Electrochemistry

CHEM Principles of Chemistry II. Chapter 17 - Electrochemistry CHEM 1212 - Principles of Chemistry II Chapter 17 - Electrochemistry electrochemistry is best defined as the study of the interchange of chemical and electrical energy 17.1 Galvanic Cells an oxidation-reduction

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

Chapter Objectives. Chapter 13 Electrochemistry. Corrosion. Chapter Objectives. Corrosion. Corrosion

Chapter Objectives. Chapter 13 Electrochemistry. Corrosion. Chapter Objectives. Corrosion. Corrosion Chapter Objectives Larry Brown Tom Holme Describe at least three types of corrosion and identify chemical reactions responsible for corrosion. www.cengage.com/chemistry/brown Chapter 13 Electrochemistry

More information

Electrochemistry. 1. For example, the reduction of cerium(iv) by iron(ii): Ce 4+ + Fe 2+ Ce 3+ + Fe 3+ a. The reduction half-reaction is given by...

Electrochemistry. 1. For example, the reduction of cerium(iv) by iron(ii): Ce 4+ + Fe 2+ Ce 3+ + Fe 3+ a. The reduction half-reaction is given by... Review: Electrochemistry Reduction: the gaining of electrons Oxidation: the loss of electrons Reducing agent (reductant): species that donates electrons to reduce another reagent. Oxidizing agent (oxidant):

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: 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

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

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

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

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

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

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

CH 223 Friday Sept. 08, 2017 L14B

CH 223 Friday Sept. 08, 2017 L14B CH 223 Friday Sept. 08, 2017 L14B Previously: Relationships between E cell, K, and ΔG Concentration and cell potential Nernst equation for non-standard conditions: E cell = E 0 cell - 0.0592 n log Q at

More information

Electrochem 1 Electrochemistry Some Key Topics Conduction metallic electrolytic Electrolysis effect and stoichiometry Galvanic cell Electrolytic cell Electromotive Force (potential in volts) Electrode

More information

General Chemistry 1412 Spring 2008 Instructor: Dr. Shawn Amorde Website:

General Chemistry 1412 Spring 2008 Instructor: Dr. Shawn Amorde Website: General Chemistry 1412 Spring 2008 Instructor: Dr. Shawn Amorde Website: www.austincc.edu/samorde Email: samorde@austincc.edu Lecture Notes Chapter 21 (21.1-21.25) Suggested Problems () Outline 1. Introduction

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

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

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

SCHOOL YEAR CH- 19 OXIDATION-REDUCTION REACTIONS SUBJECT: CHEMISTRY GRADE: 12

SCHOOL YEAR CH- 19 OXIDATION-REDUCTION REACTIONS SUBJECT: CHEMISTRY GRADE: 12 SCHOOL YEAR 2017-18 NAME: CH- 19 OXIDATION-REDUCTION REACTIONS SUBJECT: CHEMISTRY GRADE: 12 TEST A Choose the best answer from the options that follow each question. 1. During oxidation, one or more electrons

More information

I pledge, on my honor, that I have neither given nor received inappropriate aid on this examination

I pledge, on my honor, that I have neither given nor received inappropriate aid on this examination Chemistry 102b General Chemistry Exam #2 Name (Printed) I pledge, on my honor, that I have neither given nor received inappropriate aid on this examination Signature Circle the section in which you are

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

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

Electrochemical Cells II: Stoichiometry and Nernst Equation

Electrochemical Cells II: Stoichiometry and Nernst Equation CH302 LaBrake and Vanden Bout Electrochemical Cells II: Stoichiometry and Nernst Equation All the electrochemical cells on this worksheet are the same ones on the first Electrochemical Cells worksheet.

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

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

CHEM J-12 June 2013

CHEM J-12 June 2013 CHEM1101 2013-J-12 June 2013 In concentration cells no net chemical conversion occurs, however a measurable voltage is present between the two half-cells. Explain how the voltage is produced. 2 In concentration

More information

18.3 Electrolysis. Dr. Fred Omega Garces. Chemistry 201. Driving a non-spontaneous Oxidation-Reduction Reaction. Miramar College.

18.3 Electrolysis. Dr. Fred Omega Garces. Chemistry 201. Driving a non-spontaneous Oxidation-Reduction Reaction. Miramar College. 18.3 Electrolysis Driving a non-spontaneous Oxidation-Reduction Reaction Dr. Fred Omega Garces Chemistry 201 Miramar College 1 Electrolysis Voltaic Vs. Electrolytic Cells Voltaic Cell Energy is released

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

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

Electrolytes non electrolytes. Types of Electrolytes

Electrolytes non electrolytes. Types of Electrolytes Electrochemistry Chemical reactions where electrons are transferred between molecules are called oxidation/reduction (redox) reactions. In general, electrochemistry deals with situations where oxidation

More information

Introduction to electrochemistry

Introduction to electrochemistry Introduction to electrochemistry Oxidation reduction reactions involve energy changes. Because these reactions involve electronic transfer, the net release or net absorption of energy can occur in the

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

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

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

Reducing Agent = a substance which "gives" electrons to another substance causing that substance to be reduced; a reducing agent is itself oxidized.

Reducing Agent = a substance which gives electrons to another substance causing that substance to be reduced; a reducing agent is itself oxidized. Oxidation = a loss of electrons; an element which loses electrons is said to be oxidized. Reduction = a gain of electrons; an element which gains electrons is said to be reduced. Oxidizing Agent = a substance

More information

We can use chemistry to generate electricity... this is termed a Voltaic (or sometimes) Galvanic Cell

We can use chemistry to generate electricity... this is termed a Voltaic (or sometimes) Galvanic Cell Unit 6 Electrochemistry Chemistry 020, R. R. Martin Electrochemistry Electrochemistry is the study of the interconversion of electrical and chemical energy. We can use chemistry to generate electricity...

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

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

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

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

Electrolysis. Electrolysis is the process of using electrical energy to break a compound apart or to reduced an metal ion to an element.

Electrolysis. Electrolysis is the process of using electrical energy to break a compound apart or to reduced an metal ion to an element. Electrolysis Electrolysis is the process of using electrical energy to break a compound apart or to reduced an metal ion to an element. Electrolysis is done in an electrolytic cell. Electrolytic cells

More information

Q1. Why does the conductivity of a solution decrease with dilution?

Q1. Why does the conductivity of a solution decrease with dilution? Q1. Why does the conductivity of a solution decrease with dilution? A1. Conductivity of a solution is the conductance of ions present in a unit volume of the solution. On dilution the number of ions per

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

ELECTROCHEMISTRY Chapter 19, 4.9

ELECTROCHEMISTRY Chapter 19, 4.9 ELECTROCHEMISTRY Chapter 19, 4.9 Overview of an Electrochemical Process at Constant T and P ΔG = ΔG o + RT ln Q = welec (maximum) Note: I below stands for current measured in amperes = qecell = ItEcell

More information

ELECTROCHEMISTRY Chapter 14

ELECTROCHEMISTRY Chapter 14 ELECTROCHEMISTRY Chapter 14 Basic Concepts: Overview of Electrochemical Process at Constant T, P (14-1) ΔG = ΔG o + RT ln Q = w elec (maximum) = qe = ItE (exp) (E intensive parameter, q extensive) = nfe

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

CHAPTER 5 REVIEW. C. CO 2 D. Fe 2 O 3. A. Fe B. CO

CHAPTER 5 REVIEW. C. CO 2 D. Fe 2 O 3. A. Fe B. CO CHAPTER 5 REVIEW 1. The following represents the process used to produce iron from iron III oxide: Fe 2 O 3 + 3CO 2Fe + 3CO 2 What is the reducing agent in this process? A. Fe B. CO C. CO 2 D. Fe 2 O 3

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

Review. Chapter 17 Electrochemistry. Outline. Voltaic Cells. Electrochemistry. Mnemonic

Review. Chapter 17 Electrochemistry. Outline. Voltaic Cells. Electrochemistry. Mnemonic Review William L Masterton Cecile N. Hurley Edward J. Neth cengage.com/chemistry/masterton Chapter 17 Electrochemistry Oxidation Loss of electrons Occurs at electrode called the anode Reduction Gain of

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

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