Chemistry 2000 (Spring 2014) Problem Set #7: Redox Reactions and Electrochemistry Solutions

Size: px
Start display at page:

Download "Chemistry 2000 (Spring 2014) Problem Set #7: Redox Reactions and Electrochemistry Solutions"

Transcription

1 Chemistry 2000 (Spring 2014) Problem Set #7: Redox Reactions and Electrochemistry Solutions Answers to Questions in Silberberg (only those w/out answers at the back of the book) 192 An electrochemical process involves electron transfer from one particle to another This is, by definition, a redox reaction 194 ions do not exist in aqueous solution (If added to aqueous solution, would immediately react with H 2 to give two H - ions) 195 The two half-reactions are each multiplied by the appropriate coefficients so that the number of electrons on the product side of the oxidation half-reaction is the same as the number of electrons on the reactant side of the reduction half-reaction 199 (c) (d) (e) (f) True True False In an electrolytic cell, the surroundings do work on the system In a voltaic cell, the system does work on the surroundings True False The cell electrolyte provides a solution capable of conducting current Fe + Mn H + Mn + 5 Fe H 2 This reaction should look familiar You did this titration as part of the analysis in the green crystals lab! 1923 If the two compartments are not connected, there is no way for the electrons produced by the oxidation half-reaction to be consumed by the reduction half-reaction (so neither halfreaction will proceed) If the two compartments were physically connected, there would be no way for the voltaic cell to do work The energy generated by the overall reaction would instead be released as heat 1924 The salt bridge allows both half-cells to maintain a neutral charge (so that the overall reaction does not stop due to charge build-up) It does so by allowing spectator ions (eg Na +, N 3, etc) to travel between the two compartments while preventing the reactive ions from doing so 1935 See lecture notes or pp of text 1952 (a) A reaction is thermodynamically allowed when Q < K A reaction is thermodynamically allowed when ΔG < 0 and E cell > 0 Therefore, ΔG < 0 and E cell > 0 when Q < K If Q < K then Q/K < 1 As noted in part (a), when this is the case, E cell > 0 and the cell can do work

2 Additional Practice Problems 1 Determine the oxidation states for each atom in the following sulfur oxide anions (only one resonance structure is given) (a) peroxodisulfate: S 2 8 dithionite S 2 4 (c) thiosulfate S S S S S S 0 S +4 2 Balance the following redox reactions in acidic aqueous solution (a) 3 U 2 + Te + 4 H + 3 U 4+ + Te H 2 2 PbS H 2 Pb + Pb S H + (c) 4 AsH Ag H 2 As Ag + 24 H + (d) 2 Mn HCN + 5 I + 11 H + 2 Mn + 5 ICN + 8 H 2 (e) H 5 I I + 7 H + 4 I H 2 This is an example of a comproportionation reaction, a reaction in which the same species (I 2 ) is produced by both the oxidation and reduction half reactions (f) 3 U 2 + Cr H + 3 U Cr H 2 3 Balance the following redox reactions in basic aqueous solution (a) 3 Cl - + I - - I Cl - P H H - 2 HP PH 3 (c) 2 Co + 3 Cl + 3 H 2 2 Co(H) Cl (d) 2 As + 6 H 3 2 As H 2 (e) 4 Au + 8 CN H 2 4 [Au(CN) 2 ] + 4H - (Note: while gold is not oxidized by oxygen in aqueous solution, addition of cyanide makes this possible This reaction is heavily used in gold mining operations, especially if the gold concentration of the ores is low The cyanide ponds that are used for this extraction process are serious environmental hazards given the huge quantities of such a toxic substance!)

3 4 The cell described below develops a reversible emf of -097 V at 25 C (assume exact temperature so infinite sig fig) (a) + Pt s H 2g 1 bar H aq ph= 50 V aq mol/l V s The half-reactions are + H 2(g) 2H (aq) 2e - E 0 0V V (aq) 2e - 0 V (s) E V / V verall: H 2(g) V + (aq) 2H (aq) V (s) E 0 0 E V / V with e = 2 The emf generated by the cell under the given conditions is E = -097 V We can calculate E 0 using the Nernst equation: E E 0 RT e F lnq E 0 E RT RT lnq E e F e F ln a H + 2 a H2 a V 097V J K-1 mol K ln C/mol V Since E 0 0 E V, / V 0 E V / V 118 V For the overall reaction from part (a), r e FE C/mol 118 V 227 kj/mol However, we can also write r in terms of the standard free energies of formation of the reactants and products: r 2 f G 0 + H (aq) f G 0 V (s) f G 0 H 2(g) f G 0 V (aq) so f G 0 V (aq) f G 0 V (aq) 227 kj/mol

4 5 Using the data appended to this problem, calculate the equilibrium constant for the reaction below at 25 C (exact temperature) Hg 2aq Hg l +Hg aq Which of the two aqueous ions will be more abundant at equilibrium? (Metallic mercury is insoluble in water, so it precipitates out if formed If necessary, assume that the aqueous layer is in direct contact with metallic mercury initially) Data: Hg aq +2e Hg l Hg 2aq +2e 2Hg l E 0 = +0851V E 0 = V If we turn the first half-reaction around, we have Hg l Hg aq +2e E 0 = 0851V Hg 2aq +2e 2Hg l E 0 = V The overall reaction is Hg 2(aq) Hg (l) Hg (aq) E V with e = 2 We can do the calculation in one or two steps I ll do it in one step here: K exp G 0 r m exp FE 0 e RT RT C/mol 0054 V exp J K -1 mol K 0015 This value of the equilibrium constant implies that the reaction is reactant-favored, ie there will be more Hg 2 than Hg at equilibrium

5 6 Mercury(II) sulfide is only sparingly soluble in water The sulfide ion is a stronger base than hydroxide, so the solubility equilibrium is: HgS (s) H 2 (l) Hg (aq) HS (aq) H (aq) The equilibrium constant for this reaction is at 25 C (exact temperature) (a) Let s start by setting up the equilibrium expression: K a Hg a HS - a H - Since the equilibrium constant is really tiny, this equilibrium will have a negligible effect on the hydroxide concentration in solution Therefore a H We will make one Hg 2= for each HS -, so the activities of these two ions will be equal Thus we have 2 K a a a Hg - Hg K a - H 210 H The concentration is proportional to the activity by a factor of 1 mol/l, so the solubility of HgS is mol/l In other words, in 10 L of water, we should have mol of the Hg and HS - ions But wait! That many moles is (110 3 mol)( mol -1 ) = 9 molecules! In other words, we only expect to find nine molecules of HgS dissolved in 1 L of water This equilibrium constant was clearly not measured by measuring a concentration of dissolved material! We might try something analogous to the AgCl solubility measurement We could make up an Hg HgS electrode (This is clearly not quite the same as an Ag,AgCl electrode since Hg is a liquid, but in principle we could make something like this) The likely half-cell reaction would be HgS (s) H 2 (l) 2e Hg (l) HS (aq) H (aq) Having made this electrode, we could mesure its half-cell potential and calculate the corresponding standard reduction potential Then, combining this standard reduction potential with the standard reduction potential of Hg to Hg (which is already available), we could calculate the equilibrium constant for the solubility equilibrium

6 7 Suppose that we operate an ethanol fuel cell in Lethbridge at 25 C (exact temperature) The partial pressure of 2 is 019 bar and the partial pressure of C 2 is about 0034 bar The fuel cell operates on liquid ethanol (a) The simplest way to do this problem is probably to work out the free energy change, then go from there to an emf We can t do anything without a balanced reaction, of course: C 2 H 5 H (l) 3 2(g) 2C 2(g) 3H 2 (l) r 2 f G 0 C 2(g) 3 f G 0 H 2 (l) f G 0 C 2 H 5 H (l) 2(3944) 3(2371) (1748) kj/mol = kj/mol r G m r G m 0 RT ln Q r RT ln a C 2 a kj/mol kj K -1 mol K ln kj/mol We re going to use the equation r G m = e FE to calculate E ur next problem is to figure out e There are three ways to do this: The hard way: Use the standard method for balancing redox reactions in solution to get the half-reactions We can then read e off from our balanced half-reactions The easier way: Look up the oxygen half-reaction from the table of standard reduction potentials at the back of the book In this case, it doesn t matter if we look up the reaction for acidic or basic reaction conditions because the aqueous intermediates cancel out anyway Note that there are 4 electrons for every 2 For our balanced reaction then, e = 3(4) = 12 The easiest way: In fuel cells that use oxygen as the oxidant, it s always 4 electrons per oxygen molecule, so just remember this ratio E r G m e F J/mol C/mol V If we wanted to make a 240V battery, assuming that the operating voltage is similar to the emf (which, remember, is measured under reversible conditions, and so is generally higher than the operating voltage), then we would need 240/11485 = 209 cells

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 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

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 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

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 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

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 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

Answer Key, Problem Set 9

Answer Key, Problem Set 9 Chemistry 122 Mines, Spring 2018 Answer Key, Problem Set 9 1. 19.44(c) (Also indicate the sign on each electrode, and show the flow of ions in the salt bridge.); 2. 19.46 (do this for all cells in 19.44);

More information

CHEM 10123/10125, Exam 3

CHEM 10123/10125, Exam 3 CHEM 10123/10125, Exam 3 April 4, 2012 (50 minutes) Name (please print) Please box your answers, and remember that significant figures, phases (for chemical equations), and units do count! 1. (18 points)

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 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

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

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

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. 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

Chemistry 2000 Lecture 15: Electrochemistry

Chemistry 2000 Lecture 15: Electrochemistry Chemistry 2000 Lecture 15: Electrochemistry Marc R. Roussel February 21, 2018 Marc R. Roussel Chemistry 2000 Lecture 15: Electrochemistry February 21, 2018 1 / 33 Electrochemical cells Electrochemical

More information

CHEM 112 Final Exam (New Material) Practice Test Solutions

CHEM 112 Final Exam (New Material) Practice Test Solutions CHEM 112 Final Exam (New Material) Practice Test Solutions 1D Another electrolysis problem. This time we re solving for mass, which almost always means solving for number of moles and then converting to

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

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

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

Electrochemistry. The study of the interchange of chemical and electrical energy.

Electrochemistry. The study of the interchange of chemical and electrical energy. Electrochemistry The study of the interchange of chemical and electrical energy. Oxidation-reduction (redox) reaction: involves a transfer of electrons from the reducing agent to the oxidizing agent. oxidation:

More information

Electron Transfer Reactions

Electron Transfer Reactions ELECTROCHEMISTRY 1 Electron Transfer Reactions 2 Electron transfer reactions are oxidation- reduction or redox reactions. Results in the generation of an electric current (electricity) or be caused by

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

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

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

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

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

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

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

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 20. Electrochemistry

Chapter 20. Electrochemistry Chemistry, The Central Science, 10th edition Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten Chapter 20 John D. Bookstaver St. Charles Community College St. Peters, MO 2006, Prentice Hall,

More information

Chem 321 Lecture 16 - Potentiometry 10/22/13

Chem 321 Lecture 16 - Potentiometry 10/22/13 Student Learning Objectives Chem 321 Lecture 16 - Potentiometry 10/22/13 In lab you will use an ion-selective electrode to determine the amount of fluoride in an unknown solution. In this approach, as

More information

Practice Test 1 Solutions - CHEM 112 Exam 3

Practice Test 1 Solutions - CHEM 112 Exam 3 Practice Test 1 Solutions - CHEM 112 Exam 3 1E This is a straight up solubility question with no real complications. The equation and ICE table we set up is: AgI 2 (s) Ag 2+ (aq) + 2I - (aq) I - 0 0 C

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

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

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

Half-Cell Potentials

Half-Cell Potentials Half-Cell Potentials! SHE reduction potential is defined to be exactly 0 v! half-reactions with a stronger tendency toward reduction than the SHE have a + value for E red! half-reactions with a stronger

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

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

Electrode Potentials and Their Measurement

Electrode Potentials and Their Measurement Electrochemistry Electrode Potentials and Their Measurement Cu(s) + 2Ag + (aq) Cu(s) + Zn 2+ (aq) Cu 2+ (aq) + 2 Ag(s) No reaction Zn(s) + Cu 2+ (aq) Cu(s) + Zn 2+ (aq) In this reaction: Zn (s) g Zn 2+

More information

AP Chemistry Unit #4. Types of Chemical Reactions & Solution Stoichiometry

AP Chemistry Unit #4. Types of Chemical Reactions & Solution Stoichiometry AP Chemistry Unit #4 Chapter 4 Zumdahl & Zumdahl Types of Chemical Reactions & Solution Stoichiometry Students should be able to: Predict to some extent whether a substance will be a strong electrolyte,

More information

CHEM J-14 June 2014

CHEM J-14 June 2014 CHEM1101 2014-J-14 June 2014 An electrochemical cell consists of an Fe 2+ /Fe half cell with unknown [Fe 2+ ] and a Sn 2+ /Sn half-cell with [Sn 2+ ] = 1.10 M. The electromotive force (electrical potential)

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

EMA4303/5305 Electrochemical Engineering Lecture 02 Equilibrium Electrochemistry

EMA4303/5305 Electrochemical Engineering Lecture 02 Equilibrium Electrochemistry EMA4303/5305 Electrochemical Engineering Lecture 02 Equilibrium Electrochemistry Dr. Junheng Xing, Prof. Zhe Cheng Mechanical & Materials Engineering Florida International University 2 Equilibrium Electrochemistry

More information

CHEM 112 Final Exam. Practice Test Solutions

CHEM 112 Final Exam. Practice Test Solutions CHEM 112 Final Exam Practice Test Solutions 1B Since we re looking for the overall change in concentration over time, we can use the balanced equation to write the following: Δ [ N 2] ΔT = 1 Δ[ F 2 ] 3

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

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

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

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

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 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

Chemistry 2000 Lecture 11: Chemical equilibrium

Chemistry 2000 Lecture 11: Chemical equilibrium Chemistry 2000 Lecture 11: Chemical equilibrium Marc R. Roussel February 4, 2019 Marc R. Roussel Chemical equilibrium February 4, 2019 1 / 27 Equilibrium and free energy Thermodynamic criterion for equilibrium

More information

CHEM Pharmacy Week 9: Nernst Equation. Dr. Siegbert Schmid School of Chemistry, Rm 223 Phone:

CHEM Pharmacy Week 9: Nernst Equation. Dr. Siegbert Schmid School of Chemistry, Rm 223 Phone: CHEM1612 - Pharmacy Week 9: Nernst Equation Dr. Siegbert Schmid School of Chemistry, Rm 223 Phone: 9351 4196 E-mail: siegbert.schmid@sydney.edu.au Unless otherwise stated, all images in this file have

More information

Redox and Electrochemistry (BLB chapter 20, p.723)

Redox and Electrochemistry (BLB chapter 20, p.723) Redox and Electrochemistry (BLB chapter 20, p.723) Redox is short for reduction/oxidation Redox chemistry deals with changes in the oxidation states of atoms Oxidation States All atoms have an oxidation

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

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

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

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

The Nature of Redox. Both oxidation and reduction processes occur together. Each half of the full redox reaction is a. Oxidizing and Reducing Agents

The Nature of Redox. Both oxidation and reduction processes occur together. Each half of the full redox reaction is a. Oxidizing and Reducing Agents V. ELECTROCHEMISTRY V.1 INTRODUCTION TO OXIDATION AND REDUCTION Key Question: How are electrons gained or lost? ELECTROCHEMISTRY is the study of oxidation and reduction reactions in which chemical species

More information

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

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

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

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

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

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

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

Lecture 14. Thermodynamics of Galvanic (Voltaic) Cells.

Lecture 14. Thermodynamics of Galvanic (Voltaic) Cells. Lecture 14 Thermodynamics of Galvanic (Voltaic) Cells. 51 52 Ballard PEM Fuel Cell. 53 Electrochemistry Alessandro Volta, 1745-1827, Italian scientist and inventor. Luigi Galvani, 1737-1798, Italian scientist

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

AP* Electrochemistry Free Response Questions page 1

AP* Electrochemistry Free Response Questions page 1 Galvanic (Voltaic) Cells 1988 Average score = 5.02 a) two points Sn ---> Sn 2+ + 2e Ag + + e ---> Ag AP* Electrochemistry Free Response Questions page 1 b) two points 2 Ag + + Sn ---> 2 Ag + Sn 2+ E =

More information

Chapter 5. Chemical reactions

Chapter 5. Chemical reactions Chapter 5 Chemical reactions Chemical equations CaO(s) + CO 2 (g) CaCO 3 (s) + CO(g) Chemical equation - representation of a chemical reaction; uses the symbols of the elements and formulae of the compounds

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

CHEMISTRY - CLUTCH CH.18 - ELECTROCHEMISTRY.

CHEMISTRY - CLUTCH CH.18 - ELECTROCHEMISTRY. !! www.clutchprep.com CONCEPT: OXIDATION-REDUCTION REACTIONS Chemists use some important terminology to describe the movement of electrons. In reactions we have the movement of electrons from one reactant

More information

Electrochemical Reactions

Electrochemical Reactions 1 of 20 4/11/2016 1:00 PM Electrochemical Reactions Electrochemical Reactions Electrical Work From Spontaneous Oxidation- Reduction Reactions Predicting Spontaneous Redox Reactions from the Sign of E Line

More information

Solubility Equilibria

Solubility Equilibria Solubility Equilibria Heretofore, we have investigated gas pressure, solution, acidbase equilibriums. Another important equilibrium that is used in the chemistry lab is that of solubility equilibrium.

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

Solubility Rules See also Table 4.1 in text and Appendix G in Lab Manual

Solubility Rules See also Table 4.1 in text and Appendix G in Lab Manual Ch 4 Chemical Reactions Ionic Theory of Solutions - Ionic substances produce freely moving ions when dissolved in water, and the ions carry electric current. (S. Arrhenius, 1884) - An electrolyte is a

More information

2/18/2013. Spontaneity, Entropy & Free Energy Chapter 16. The Dependence of Free Energy on Pressure Sample Exercises

2/18/2013. Spontaneity, Entropy & Free Energy Chapter 16. The Dependence of Free Energy on Pressure Sample Exercises Spontaneity, Entropy & Free Energy Chapter 16 16.7 The Dependence of Free Energy on Pressure Why is free energy dependent on pressure? Isn t H, enthalpy independent of pressure at constant pressure? No

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

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

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

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

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

Chemical Equations. Chemical Reactions. The Hindenburg Reaction 5/25/11

Chemical Equations. Chemical Reactions. The Hindenburg Reaction 5/25/11 Chemical Reactions CHM 1032C Chemical Equations Chemical change involves a reorganization of the atoms in one or more substances. The Hindenburg Reaction Reactants are on left, products to the right. Arrow

More information

Chapter 7 Electrochemistry

Chapter 7 Electrochemistry Chapter 7 Electrochemistry Outside class reading Levine: pp. 417 14.4 Galvanic cells: pp. 423 14.5 types of reversible electrodes 7.6.1 Basic concepts of electrochemical apparatus (1) Electrochemical apparatus

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

Chapter 4 Reactions in Aqueous Solution

Chapter 4 Reactions in Aqueous Solution Chapter 4 Reactions in Aqueous Solution Homework Chapter 4 11, 15, 21, 23, 27, 29, 35, 41, 45, 47, 51, 55, 57, 61, 63, 73, 75, 81, 85 1 2 Chapter Objectives Solution To understand the nature of ionic substances

More information

CH 4 AP. Reactions in Aqueous Solutions

CH 4 AP. Reactions in Aqueous Solutions CH 4 AP Reactions in Aqueous Solutions Water Aqueous means dissolved in H 2 O Moderates the Earth s temperature because of high specific heat H-bonds cause strong cohesive and adhesive properties Polar,

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

Chemistry 223 Spring 2012 Oregon State University Exam 2 May 24, 2012 Drs. Nafshun, Watson, Richardson

Chemistry 223 Spring 2012 Oregon State University Exam 2 May 24, 2012 Drs. Nafshun, Watson, Richardson Chemistry 223 Spring 2012 Oregon State University Exam 2 May 24, 2012 Drs. Nafshun, Watson, Richardson Instructions: You should have with you several number two pencils, an eraser, your 3" x 5" note card,

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

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

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

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

CHM 2046 Test #4 Review: Chapter 17 & Chapter 18

CHM 2046 Test #4 Review: Chapter 17 & Chapter 18 1. Which of the following is true concerning a nonspontaneous reaction? a. It s impossible for the reaction to occur b. The reaction occurs, but very slowly c. It can be made spontaneous by adding a catalyst

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

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

lect 26:Electrolytic Cells

lect 26:Electrolytic Cells lect 26:Electrolytic Cells Voltaic cells are driven by a spontaneous chemical reaction that produces an electric current through an outside circuit. These cells are important because they are the basis

More information

Reactions in aqueous solutions Redox reactions

Reactions in aqueous solutions Redox reactions Reactions in aqueous solutions Redox reactions Redox reactions In precipitation reactions, cations and anions come together to form an insoluble ionic compound. In neutralization reactions, H + ions and

More information

RedOx Chemistry. with. Dr. Nick

RedOx Chemistry. with. Dr. Nick RedOx Chemistry with Dr. Nick What is RedOx Chemistry? The defining characteristic of a RedOx reaction is that electron(s) have completely moved from one atom / molecule to another. The molecule receiving

More information