# Chapter 18 problems (with solutions)

Size: px
Start display at page:

Transcription

1 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 H = +1 d) H3PO4 H = +1 P = +5 O = -2 e) Cl2 Cl = 0 f) BrO4 - Br = +7 O = -2 g) KMnO4 K = +1 Mn = +7 O = -2 h) NaOH Na = +1 O = -2 H = +1 i) H2O2 H = +1 O = -1 j) H4P2O7 H = +1 P = +5 O = -2 2) Balance each redox reaction occurring in acid aqueous solution. In all cases we will use the procedure discussed in class. We will first find balanced half-cell oxidation and reduction half-reactions. We will multiply one or both reactions by an integer value so that the number of electrons transferred will cancel when the half-reactions are combined. Finally, we will combine the half-reactions and cancel any substances appearing as both reactants and products to obtain the final balanced cell reaction. a) I - (aq) + NO2 - (aq) I2(s) + NO(g) ox 2 I - (aq) I2(s) + 2 e - red NO2 - (aq) + 2 H + (aq) + e - NO(g) + H2O( ) x 2 2 I - (aq) + 2 NO2 - (aq) + 4 H + (aq) I2(s) + 2 NO(g) + 2 H2O( ) b) NO3 - (aq) + Sn 2+ (aq) Sn 4+ (aq) + NO(g) ox Sn 2+ (aq) Sn 4+ (aq) + 2 e - x 3 red NO3 - (aq) + 4 H + (aq) + 3 e - NO(g) + 2 H2O( ) x 2 3 Sn 2+ (aq) + 2 NO3 - (aq) 8 H + (aq) 3 Sn 4+ (aq) + 2 NO(g) + 4 H2O( ) c) S2O3 2- (aq) + I2(aq) S4O6 2- (aq) + I - (aq) ox 2 S2O3 2- (aq) S4O6 2- (aq) + 2 e - red I2(aq) + 2 e - 2 I - (aq) 2 S2O3 2- (aq) + I2(aq) S4O6 2- (aq) + 2 I - (aq) 1

2 3) Balance each redox reaction occurring in base aqueous solution. Balancing oxidation-reduction reactions for bas conditions is exactly the same as balancing the reactions for acid conditions except that there is one additional step where OH - ions are added, if necessary, to convert all H + ions into water molecules. a) MnO4 - (aq) + Br - (aq) MnO2(s) + BrO3 - (aq) ox Br - (aq) + 3 H2O( ) BrO3 - (aq) + 6 H + (aq) + 6 e - red MnO4 - (aq) + 4 H + (aq) + 3 e - MnO2(s) + 2 H2O( ) x 2 add OH - Br - (aq) + 2 MnO4 - (aq) + 2 H + (aq) BrO3 - (aq) + 2 MnO2(s) + H2O( ) 2 OH - (aq) 2 OH - (aq) Br - (aq) + 2 MnO4 - (aq) + H2O( ) BrO3 - (aq) + 2 MnO2(s) + 2 OH - (aq) b) NO2 - (aq) + Al(s) NH3(g) + AlO2 - (aq) ox Al(s) + 2 H2O( ) AlO2 - (aq) + 4 H + (aq) + 3 e - x 2 red NO2 - (aq) + 7 H + (aq) + 6 e - NH3(g) + 2 H2O( ) add OH - 2 Al(s) + NO2 - (aq) + 2 H2O( ) 2 AlO2 - (aq) + NH3(g) + H + (aq) OH - (aq) OH - (aq) 2 Al(s) + NO2 - (aq) + H2O( ) + OH - (aq) 2 AlO2 - (aq) + NH3(g) 4) Explain the difference between a voltaic (or galvanic) electrochemical cell and an electrolytic one. In a voltaic cell (also called a galvanic cell or a battery) a chemical reaction is used to generate a voltage. In an electrolytic cell an external voltage is used to force a chemical reaction to occur in a particular direction. 5) Explain the purpose of a salt bridge in an electrochemical cell. The salt bridge is used to complete the circuit. It provides a way in which charge can pass from one part of the cell to the other part without having the two parts of the cell directly react chemically. 2

3 6) How can Table 18.1 be used to predict whether or not a metal will dissolve in HCl? In HNO3? Any metal below the H + /H 2 half-cell reduction potential, at 0.00 v, would be expected to dissolve in HCl (hydrochloric acid) for standard conditions. This is because when the half-cell oxidation potential for the metal (found by reversing the reaction and changing the sign of the potential) is combined with the half-cell reduction potential for H + /H2, a positive voltage will result, indicating a spontaneous reaction. The same reasoning applies for HNO3 (nitric acid) except that now there is a different reduction half-reaction to use, that for NO3 - /NO at 0.96 v. Metals lying below this half-cell reduction potential would be expected to dissolve in HNO3. So, for example, Ni (nickel) will dissolve in both HCl and HNO3, Cu (copper) will dissolve in HNO3 but not HCl, and Au (gold) will not dissolve in either acid. 7) Give the half cell oxidation reaction, the half cell reduction reaction, and the cell reaction for the following galvanic cells. a) Pb(s) Pb 2+ (aq) Cu 2+ (aq) Cu(s) ox Pb(s) Pb 2+ (aq) + 2 e - red Cu 2+ (aq) + 2 e - Cu(s) Pb(s) + Cu 2+ (aq) Pb 2+ (aq) + Cu(s) b) Pt, H2(g) H + (aq) Cl - (aq) AgCl(s), Ag(s) ox H2(g) 2 H + (aq) + 2 e - red AgCl(s) + e - Ag(s) + Cl - (aq) x 2 H2(g) + 2 AgCl(s) 2 H + (aq) + 2 Cl-(aq) + 2 Ag(s) 8) Calculate the standard cell potential for each of the following electrochemical cells. Also, represent each cell as a cell diagram using standard notation. a) Ni 2+ (aq) + Mg(s) Ni(s) + Mg 2+ (aq) Mg(s) Mg 2+ (aq) Ni 2+ (aq) Ni(s) ox Mg(s) Mg 2+ (aq) + 2 e - E = v red Ni 2+ (aq) + 2 e - Ni(s) E = v Ni 2+ (aq) + Mg(s) Ni(s) + Mg 2+ (aq) E = v 3

4 b) 2 H + (aq) + Fe(s) H2(g) + Fe 2+ (aq) Fe(s) Fe 2+ (aq) H + (aq) H2(g), Pt ox Fe(s) Fe 2+ (aq) + 2 e - E = v red 2 H + (aq) + 2 e- H2(g) E = 0.00 v 2 H + (aq) + Fe(s) H2(g) + Fe 2+ (aq) E = v c) 2 NO3 - (aq) + 8 H + (aq) + 3 Cu(s) 2 NO(g) + 4 H2O( ) + 3 Cu 2+ (aq) Cu(s) Cu 2+ (aq) NO3 - (aq) NO(g), Pt ox 3 Cu(s) 3 Cu 2+ (aq) + 6 e - E = v red 2 NO3 - (aq) + 8 H + (aq) + 6 e - 2 NO(g) + 4 H2O( ) E = v 2 NO3 - (aq) + 8 H + (aq) + 3 Cu(s) 2 NO(g) + 4 H2O( ) + 3 Cu 2+ (aq) E = v 9) Which of the redox reactions do you expect to occur spontaneously in the forward direction (for standard conditions)? a) Ni(s) + Zn 2+ (aq) Ni 2+ (aq) + Zn(s) b) Ni(s) + Pb 2+ (aq) Ni 2+ (aq) + Pb(s) c) Al(s) + 3 Ag + (aq) Al 3+ (aq) + 3 Ag(s) d) Pb(s) + Mn 2+ (aq) Pb 2+ (aq) + Mn(s) There are two ways in which we can do this sort of problem. We could calculate the cell potential, and then use the fact that for spontaneous processes the cell potential will be positive. Alternatively, we can use the position of the half-cell reactions in Table If the substance being reduced in the reaction is higher in Table 18.1 than the substance being oxidized then the reaction is spontaneous. In this problem I will use the second method, but I will also give the cell potential (although not the oxidation, reduction, and cell reactions). a) Zn 2+ /Zn is below Ni 2+ /Ni, and so not spontaneous. E = v b) Pb 2+ /Pb is above Ni 2+ /Ni, and so spontaneous. E = v c) Ag + /Ag is above Al 3+ /Al, and so spontaneous. E = v d) Mn 2+ /Mn is below Pb 2+ /Pb, and so not spontaneous. E = v 4

5 10) Which metal cation is the best oxidizing agent? a) Pb 2+ b) Cr 3+ c) Fe 3+ d) Sn 2+ The best oxidizing agent will be the species that has the largest (most positive) reduction potential. Based on Table 18.1 Pb 2+ /Pb E = Cr 3+ /Cr E = v Fe 2+ /Fe E = v Sn 2+ /Sn E = v So Pb 2+ is the best oxidizing agent. 11) Which metal is the best reducing agent? a) Mn b) Al c) Ni d) Cr The best reducing agent will be the species that has the largest (most positive) oxidation potential. Note that to get the oxidation potential we have to reverse the reduction reaction, and so change the sign of the potential. Mn/Mn 2+ E = v Al/Al 3+ E = v Ni/Ni 2+ E = v Cr/Cr 3+ E = v So Al is the best reducing agent. 12) Use tabulated electrode potentials to calculate G rxn for each reaction at 25. C. Then calculate the equilibrium constant for each reaction. To find G rxn and K (the thermodynamic equilibrium constant) we will use the expression G rxn = - nfe cell lnk = nfe cell/rt Recall that (1 C) (1 v) = 1 J. Values for E are given in the Table a) O2(g) + 2 H2O( ) + 2 Cu(s) 4 OH - (aq) + 2 Cu 2+ (aq) ox 2 Cu(s) 2 Cu 2+ (aq) + 4 e - E = v red O2(g) + 2 H2O( ) + 4 e - 4 OH - (aq) E = v O2(g) + 2 H2O( ) + 2 Cu(s) 4 OH - (aq) + 2 Cu 2+ (aq) E = v n = 4 G rxn = - (4) (96485 C/mol) ( v) = kj/mol ln K = (4) (96485 C/mol) ( v) = 9.34 K = e 9.34 = 1.1 x 10 4 (8.314 J/mol. K) (298.2 K) 5

6 b) Br2( ) + 2 I - (aq) 2Br - (aq) + I2(s) ox 2 I - (aq) I2(s) + 2 e - E = v red Br2( ) + 2 e - 2 Br - (aq) E = v Br2( ) + 2 I - (aq) 2 Br - (aq) + I2(s) E = v n = 2 G rxn = - (2) (96485 C/mol) ( v) = kj/mol ln K = (2) (96485 C/mol) ( v) = K = e = 1.7 x (8.314 J/mol.K) (298.2 K) 13) A voltaic cell employs the redox reaction 2 Fe 3+ (aq) + 3 Mg(s) 2 Fe(s) + 3 Mg 2+ (aq) Calculate the cell potential at 25. C under each set of conditions a) Standard conditions. We first need to find E. ox 3 Mg(s) 3 Mg 2+ (aq) + 6 e - E = v red 2 Fe 3+ (aq) + 6 e - 2 Fe(s) E = v 2 Fe 3+ (aq) + 3 Mg(s) 2 Fe(s) + 3 Mg 2+ (aq) E = v Ecell = E cell - RT ln Q Q = [Mg 2+ ] 3 n = 6 nf [Fe 3+ ] 2 For standard conditions Ecell = E cell = v b) [Fe 3+ ] = 1.0 x 10-3 M; [Mg 2+ ] = 2.50 M Q = (2.50) 3 = 1.56 x 10 7 (1.0 x 10-3 ) 2 Ecell = v - (8.314 J/mol. K) (298.2 K) ln(1.56 x 10 7 ) = v (6) (96485 C/mol) c) [Fe 3+ ] = 2.00 M; [Mg 2+ ] = 1.5 x 10-3 M Q = (1.5 x 10-3 ) 3 = 8.44 x (2.00) 2 Ecell = v - (8.314 J/mol. K) (298.2 K) ln(8.44 x ) = v (6) (96485 C/mol) 6

7 14) Copper can be electroplated at the cathode of an electrolytic cell by the half reaction Cu 2+ (aq) + 2 e - Cu(s) How much time would it take for 325. mg of copper metal to be plated at a current of 5.6 A? MW(Cu) = g/mol t = 325. x 10-3 g Cu 1 mol Cu 2 mol e C 1 s = 176. s g Cu 1 mol Cu 1 mol e C 15) What mass of aluminum metal can be produced per hour in the electrolysis of molten aluminum salt (containing Al 3+ ion) by a current of 25. A? The reduction for aluminum (MW(Al) = g/mol) is Al 3+ Al g Al = 1 hr 3600 s 25 C 1 mol e - 1 mol Al g Al = 8.39 g Al 1 hr 1 s C 3 mol e - 1 mol Al 16) The Ksp of Zn(OH)2 is 1.8 x Find E cell for the half reaction Zn(OH)2(s) + 2 e - Zn(s) + 2 OH - (aq) The key to doing this problem is to find a combination of an oxidation and a reduction reaction that add up to the reaction of interest, which in this case is Zn(OH)2(s) Zn 2+ (aq) + 2 OH - (aq) The cell potential can be found using E cell = (RT/nF) ln K = (8.314 J/mol. K) (298.2 K) ln(1.8 x ) = v (2) (96485 C/mol) ox Zn(s) Zn 2+ (aq) + 2 e - E = v red Zn(OH)2(s) + 2 e - Zn(s) + 2 OH - (aq) E =? Zn(OH)2(s) Zn 2+ (aq) + 2 OH - (aq) E cell = v So the half-cell reduction potential for the reaction in question is 0.76 v + E = v ; E = v v = v 7

8 17) A metal forms from the fluoride compound MF3. Electrolysis of molten MF3 by a current of 3.86 A for 16.2 minutes deposits 1.25 g of metal. What is the molar mass of the metal? Based on the formula MF3 the reduction reaction for the metal is M e - M We know how many grams of metal are produced. To find the number of moles of metal we use mol M = 16.2 min 60 s 3.86 C 1 mol e - 1 mol M = x 10-2 mol M 1 min 1 s C 3 mol e - So the molecular mass is M = 1.25 g = 96.4 g/mol x 10-2 mol 18) (18.77) Calculate the emf of the following concentration cell at 25. C Cu(s) Cu 2+ (0.080 M) Cu 2+ (1.20 M) Cu ox Cu(s) Cu 2+ (aq) + 2 e - red Cu 2+ (aq) + 2 e - Cu(s) Cu(s) + Cu 2+ (aq) Cu(s) + Cu 2+ (aq) E cell = 0.00 v Since the oxidation and reduction reactions are the same reaction, we know the standard cell potential will be 0.00 v. However, since the two electrodes have a different concentration of Cu 2+ ion, a voltage can still be generated. Ecell = E cell - RT ln Q Q = [Cu 2+ ]left = 1.20 = 15 n = 2 nf [Cu 2+ ]right Ecell = 0.00 v - (8.314 J/mol K) (298.2 K) ln(15) = v (2) ( C/mol) 8

### 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

### 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

### 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.

### 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

### 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

### 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:

### 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

### 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

### 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

### 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);

### 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

### 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

### 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

### 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

### Study Guide for Module 17 Oxidation-Reduction Reactions and Electrochemistry

Chemistry 1020, Module 17 Name Study Guide for Module 17 Oxidation-Reduction Reactions and Electrochemistry Reading Assignment: Chapter 17 in Chemistry, 6th Edition by Zumdahl. Guide for Your Lecturer:

### 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

### 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

### The relevant half cell reactions and potentials are: Calculate the equilibrium constant, K, for the reaction at 25 C. lnk

CHEM1405 2004-J-3 June 2004 Calculate the initial cell potential for the following unbalanced reaction at 25 C from the standard electrode potentials. Assume the concentration of all species is initially

### 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.

### 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

### 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

### 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

### 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)

### 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

### 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,

### 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

### 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+

### 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

### 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)

### 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

### 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

### 1. The following reaction was studied at a certain temperature and the data below were collected. H 2 SeO 3 (aq) + 6I (aq) + 4H + (aq) Se(s) + 2I 3

1. The following reaction was studied at a certain temperature and the data below were collected. H 2 SeO 3 (aq) + 6I (aq) + 4H + (aq) Se(s) + 2I 3 (aq) + 3H2 O(l) [H 2 SeO 3 ] 0, [H + ] 0, [I ] 0, M Initial

### 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

### 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,

### 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.

### DO NOT USE A CALCULATOR.

Practice Test 20.1 (va pg 1 of 5) This is practice - Do NOT cheat yourself of finding out what you are capable of doing. Be sure you follow the testing conditions outlined below. DO NOT USE A CALCULATOR.

### 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

### 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:

### 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

### 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

### 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:

### 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

### ph = pk a + log 10{[base]/[acid]}

FORMULA SHEET (tear off) N A = 6.022 x 10 23 C = ( 5 / 9) ( F - 32) F = ( 9 / 5)( C) + 32 1 amu = 1.661 x 10-27 kg C = K - 273.15 K = C + 273.15 1 atm = 760 torr = 760 mm Hg 1 atm = 1.013 bar pv = nrt

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

### 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

### 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

### 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

### CHEMISTRY 123 FALL 2010 Midterm #2

CHEMISTRY 123 FALL 2010 Midterm #2 Test Booklet A - For Question 1 Your name: Your Student ID number: Your TA: This packet MUST be turned in following the exam There are multiple versions of the exam.

### 1022_3rd Exam_

1022_3rd Exam_1030521 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) For the following example, identify the following. H2O(l) H2O(g) A) a negative

### Regents review Electrochemistry(redox)

2011-2012 1. Chlorine has an oxidation state of +3 in the compound A) HClO B) HClO2 C) HClO3 D) HClO4 2. What is the oxidation number of iodine in KIO4? A) +1 B) 1 C) +7 D) 7 3. What is the oxidation number

### 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

### Wksht 4.2 Aqueous Equilibria II

Wksht 4.2 Aqueous Equilibria II Date: 10/16/17 1. Label the type of titration each graph represents and whether their equivalence point ph values would be greater than, equal to, or less than 7. WA being

### 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

### 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

### (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

### 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,

### Unit 8 Redox 8-1. At the end of this unit, you ll be able to

8-1 Unit 8 Redox At the end of this unit, you ll be able to Define and identify oxidation reactions Define and identify reduction reactions Assign oxidation numbers to elements in a compound Write and

### 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

### 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+

### ph = pk a + log 10{[base]/[acid]}

FORMULA SHEET (tear off) N A = 6.022 x 10 23 C = ( 5 / 9) ( F - 32) F = ( 9 / 5)( C) + 32 1 amu = 1.661 x 10-27 kg C = K - 273.15 K = C + 273.15 1 atm = 760 torr = 760 mm Hg 1 atm = 1.013 bar pv = nrt

### 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

### Oxidation-Reduction Reactions and Introduction to Electrochemistry

ADVANCED PLACEMENT CHEMISTRY Oxidation-Reduction Reactions and Introduction to Electrochemistry Students will be able to: identify oxidation and reduction of chemical species; identify oxidants and reductants

### 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

### ELECTROCHEMICAL CELLS

ELECTROCHEMICAL CELLS Electrochemistry 1. Redox reactions involve the transfer of electrons from one reactant to another 2. Electric current is a flow of electrons in a circuit Many reduction-oxidation

### Oxidation State Short Cuts

Oxidation State Short Cuts The oxidation state of an atom in its elemental state is zero The sum of atomic oxidation states = total charge on an ion or molecule The oxidation state of F is always -1 (except

### 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

### 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)

### 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

### 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

### 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)

### 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

### 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

### 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

### 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+

### REDOX test practice. 2 Cr(s) + 3 Sn 2+ (aq) 2 Cr 3+ (aq) + 3 Sn(s)

1. Which polyatomic ion has a charge of 3? A) chromate ion B) oxalate ion C) phosphate ion D) thiocyanate ion 2. What is the oxidation state of nitrogen in NaNO2? A) +1 B) +2 C) +3 D) +4 3. What are the

### ph = pk a + log 10 {[base]/[acid]}

FORMULA SHEET (tear off) N A = 6.022 x 10 23 C = ( 5 / 9 ) ( F - 32) F = ( 9 / 5 )( C) + 32 1 amu = 1.661 x 10-27 kg C = K - 273.15 K = C + 273.15 1 atm = 760 torr = 760 mm Hg 1 atm = 1.013 bar pv = nrt

### 2. Balance the following reaction. How many electrons would be transferred?

JASPERSE CHEM 210 Ch. 19 Electrochemistry PRACTICE TEST 4 VERSION 3 Ch. 20 Nuclear Chemistry 1 Formulas: E cell =E reduction + E oxidation G = nfe cell (for kj, use F = 96.5) E cell = E [0.0592/n]log Q

### 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.

### 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

### Chem II. Zn(s) + CuSO4(aq)

Redox Review Chem II 1. What is the sum of the oxidation numbers of the atoms in the compound CO2? A) 0 B) 2 C) 4 D) +4 2. In which substance does phosphorus have a +3 oxidation state? A) P4O10 B) PCl5

### Standard reduction potentials are established by comparison to the potential of which half reaction?

HW10 Electrochemical Poten al, Free Energy, and Applica ons This is a preview of the draft version of the quiz Started: Nov 8 at 5:51pm Quiz Instruc ons Question 1 What is the E for cell + 4+ 3+ Zn(s)

### 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

### 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

### 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

### 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

### Practice Final CH142, Spring 2012

Practice Final CH142, Spring 2012 First here are a group of practice problems on Latimer Diagrams: 1. The Latimer diagram for nitrogen oxides in given below. Is NO stable with respect to disproportionation

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

Exam of General Chemistry :ch.18-19 Name ID MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) When the following half-reaction is balanced, the number

### BCIT Winter Chem Final Exam

BCIT Winter 2017 Chem 0012 Final Exam Name: Attempt all questions in this exam. Read each question carefully and give a complete answer in the space provided. Part marks given for wrong answers with partially

### 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

### 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

### 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

### 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

### 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

### CHEMISTRY 102 EXAM 4 FORM 4D

CHEMISTRY 102 EXAM 4 SECTIONS 529-537 Dr. Joy Heising Directions: FORM 4D April 22, 2002 1. This examination consists of two parts: 12 multiple choice questions (5 points each) in Part 1 and 3 free response

### Redox and Voltaic Cells

Name: Redox and Voltaic Cells Period: 1. Which half-reaction equation represents the reduction of an iron(ii) ion? 1) Fe 2+ Fe 3+ + e 2) Fe 2+ + 2e Fe 1) 1 to +2 2) 1 to 2 3) Fe 3+ + e Fe 2+ 4) Fe Fe 2+

### 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

### CHM152 Exam Pts Spring 2017 Name: Due Friday May 5 th at the beginning of class.

CHM152 Exam 4 100 Pts Spring 2017 Name: Due Friday May 5 th at the beginning of class. Show all work. You are to work alone on this exam, but may see me for questions. 1. Arrange these compounds in order

### 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