Chemistry

Chemistry: The Central Science | 13th Edition | ISBN: 9780321910417 | Authors: Theodore E. Brown; H. Eugene LeMay; Bruce E. Bursten; Catherine Murphy; Patrick Woodward; Matthew E. Stoltzfus
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Author: Theodore E. Brown; H. Eugene LeMay; Bruce E. Bursten; Catherine Murphy; Patrick Woodward; Matthew E. Stoltzfus
Publisher: Pearson
ISBN: 9780321910417
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Chapter Problems

Chapter: Problem: 1DE

Chemistry: The Central Science 13
The nuclear reaction that powers the radioisotope thermoelectric generator shown in the chapter-opening photograph is . The atomic masses of plutonium- 238 and uranium-234 are amu and amu, respectively. The mass of an alpha particle is . How much energy in is released when of plutoniu

Chapter: Problem: 1E

Chemistry: The Central Science 13
Positron emission from , occurs with release of per mole of " . What is the mass change per mole of in this nuclear reaction? The masses of and are and , respectively.

Chapter: Problem: 2E

Chemistry: The Central Science 13
Problem 2E Visualizing Concepts You may have heard that 'antioxidants" are good for your health. Based on what you have learned in this chapter, what do you deduce an 'antioxidant" is? [Sections]

Chapter: Problem: 3E

Chemistry: The Central Science 13
The diagram that follows represents a molecular view of a process occurring at an electrode in a voltaic cell. (a) Does the process represent oxidation or reduction? (b) Is the electrode the anode or cathode? (c) Why are the atoms in the electrode represented by larger spheres than the ions in

Chapter: Problem: 4E

Chemistry: The Central Science 13
Assume that you want to construct a voltaic cell that uses the following half-reactions: \(A^{2+}(a q)+2 e^{-} \rightarrow A(s)\) \(E_{r e d}^{0}=-0.10 V\) \(B^{2+}(a q)+2 e^{-} \rightarrow B(s)\) \(E_{r e d}^{0}=-1.10 V\) You begin with the incomplete cell pictured here in which the elec

Chapter: Problem: 5E

Chemistry: The Central Science 13
Visualizing Concepts Which of the following species (there may be more than one) is/are likely to have the structure shown here: (a) . (b) . (c) . (d) , (e) ? The colors do not reflect atom identities.) [Sections 22.3, 22.4. 22.6. and 22.10].

Chapter: Problem: 6E

Chemistry: The Central Science 13
Consider the following table of standard electrode potentials for a series of hypothetical reactions in aqueous solution: (a) Which substance is the strongest oxidizing agent? Which is weakest? (b) Which substance is the strongest reducing agent? Which is weakest? (c) Which substance(s) can o

Chapter: Problem: 7E

Chemistry: The Central Science 13
Problem 7E Visualizing Concepts Consider a redox reaction for which P is a negative number, (a) What is the sign of AG for the reaction? (b) Will the equilibrium constant for the reaction be larger or smaller than 1? (c) Can an electrochemical cell based on this reaction accomplish work on

Chapter: Problem: 8E

Chemistry: The Central Science 13
Consider the following voltaic cell: \(F e(s)\) \(A g(s)\) \(1 M F e^{2+}\) \(1 \mathrm{MAg}^{+}\) (a) Which electrode is the cathode? (b) What is the standard emf generated by this cell? (c) What is the change in the cell voltage when the ion concentrations in the cathode half-cell are increased

Chapter: Problem: 9E

Chemistry: The Central Science 13
Consider the half-reaction \(A g^{+}(a q)+e^{-} \rightarrow A g\) (a) Which of the lines in the following diagram indicates how the reduction potential varies with the concentration of \(A g^{+}\)? (b) What is the value of \(E_{\text {red }}^{0}\) when log \(\left[A g^{+}\right]=0\)? [Section 20.6]

Chapter: Problem: 10E

Chemistry: The Central Science 13
The electrodes in a silver oxide battery are silver oxide and zinc. (a) Which electrode acts as the anode? (b) Which battery do you think has an energy density most similar to the silver oxide battery: a Li-ion battery, a nickelcadmium battery, or a leadacid battery? [Section]

Chapter: Problem: 11E

Chemistry: The Central Science 13
Bars of iron are put into each of the three beakers as shown here. In which beakerA, B, or Cwould you expect the iron to show the most corrosion ? [Section 20.8]

Chapter: Problem: 12E

Chemistry: The Central Science 13
Magnesium is produced commercially by electrolysis from a molten salt using a cell similar to the one shown here. (a) What salt is used as the electrolyte? (b) Which electrode is the anode, and which one is the cathode? (c) Write the overall cell reaction and individual half-reactions. (d) What preca

Chapter: Problem: 13E

Chemistry: The Central Science 13
Problem 13E OxidationReduction Reactions (Section) (a) What is meant by the term oxidation? (b) On which side of an oxidation half-reaction do the electrons appear? (c) What is meant by the term oxidant? (d) What is meant by the termoxidizing agent?

Chapter: Problem: 14E

Chemistry: The Central Science 13
Oxidation-Reduction Reactions (Section) (a) What is meant by the term reduction? (b) On which side of a reduction half-reaction do the electrons appear? (c) What is meant by the term reductant? (d) What is meant by the term reducing agent?

Chapter: Problem: 15E

Chemistry: The Central Science 13
Problem 15E Oxidation-Reduction Reactions (Section) Indicate whether each of the following statements is true or false: (a) If something is oxidized, it is formally losing electrons, (b) For the reaction Fe3+(aq) + Co2+(ag)^Fe2+(ag) +Co3+(ag), Fe3+(ag) is the reducing agent and Co2+(ag) is the ox

Chapter: Problem: 16E

Chemistry: The Central Science 13
Oxidation-Reduction Reactions (Section) Indicate whether each of the following statements is true or false: (a) If something is reduced, it is formally losing electrons, (b) A reducing agent gets oxidized as it reacts, (c) An oxidizing agent is needed to convert into .

Chapter: Problem: 17E

Chemistry: The Central Science 13
Problem 17E OxidationReduction Reactions (Section) In each of the following balanced oxidationreduction equations, identify those elements that undergo changes in oxidation number and indicate the magnitude of the change in each case. (a) I2O5(s) + 5 CO(g)?I2(s) + 5 CO2(g) (b) 2 Hg2+(aq) + N2H4(aq)

Chapter: Problem: 18E

Chemistry: The Central Science 13
OxidationReduction Reactions (Section) In each of the following balanced oxidationreduction equations, identify those elements that undergo changes in oxidation number and indicate the magnitude of the change in each case. 1. 2. 3.

Chapter: Problem: 19E

Chemistry: The Central Science 13
OxidationReduction Reactions (Section) Indicate whether the following balanced equations involve oxidationreduction. If they do, identify the elements that undergo changes in oxidation number. (a) (b) (c)

Chapter: Problem: 20E

Chemistry: The Central Science 13
Problem 20E OxidationReduction Reactions (Section) Indicate whether the following balanced equations involve oxidationreduction. If they do, identify the elements that undergo changes in oxidation number. (a) 2 AgNO3(aq) + CoCl2(aq)?2 AgCl(s) +Co(NO3)2(aq) (b) 2 PbO2(s)?2 PbO1(s) + O2(g) (c) 2 H2SO

Chapter: Problem: 21E

Chemistry: The Central Science 13
Balancing Oxidation-Reduction Reactions (Section) At 900 C titanium tetrachloride vapor reacts with molten magnesium metal to form solid titanium metal and molten magnesium chloride, (a) Write a balanced equation for this reaction, (b) What is being oxidized, and what is being reduced? (c) Which subs

Chapter: Problem: 22E

Chemistry: The Central Science 13
Balancing Oxidation-Reduction Reactions (Section) Hydrazine and dinitrogen tetroxide form a self-igniting mixture that has been used as a rocket propellant. The reaction products are and . (a) Write a balanced chemical equation for this reaction, (b) What is being oxidized, and what is bei

Chapter: Problem: 23E

Chemistry: The Central Science 13
Problem 23E Balancing OxidationReduction Reactions (Section) Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction. (a) Sn2+(aq)?Sn4+(aq) (acidic solution) (b) TiO2(s)?Ti2+(aq) (acidic solution) (c) ClO3-(aq)?Cl-(aq) (acidi

Chapter: Problem: 24E

Chemistry: The Central Science 13
Problem 24E Balancing OxidationReduction Reactions (Section) Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction. (a) Mo3+(aq)?Mo(s) (acidic solution) (b) H2SO3(aq)?SO42-(aq) (acidic solution) (c) NO3-(aq)?NO(g) (acidic s

Chapter: Problem: 25E

Chemistry: The Central Science 13
Problem 25E Balancing OxidationReduction Reactions (Section) Complete and balance the following equations, and identify the oxidizing and reducing agents: (a) Cr2O72-(aq) + I-(aq)?Cr3+(aq) + IO3-(aq) (acidic solution) (b) MnO4-(aq) + CH3OH(aq) ?Mn2+(aq) +HCO2H(aq) (acidic solution) (c) I2(s) + OCl-

Chapter: Problem: 26E

Chemistry: The Central Science 13
Problem 26E Balancing OxidationReduction Reactions (Section) Complete and balance the following equations, and identify the oxidizing and reducing agents. (Recall that the O atoms in hydrogen peroxide, H2O2, have an atypical oxidation state.) (a) NO2-(aq) + Cr2O72-(aq)?Cr3+(aq) + NO3-(aq) (acidic s

Chapter: Problem: 27E

Chemistry: The Central Science 13
(a) What are the similarities and differences between Figure 20.3 and Figure 20.4? (b) Why are \(\mathrm{Na}^{+}\) ions drawn into the cathode half-cell as the voltaic cell shown in Figure 20.5 operates? Equation transcription: Text transcription: {Na}^{+}

Chapter: Problem: 28E

Chemistry: The Central Science 13
(a) What is the role of the porous glass disc shown in Figure 20.4? (b) Why do \(\mathrm{NO}_{3}^{-}\) ions migrate into the anode half-cell as the voltaic cell shown in Figure 20.5 operates? Equation transcription: Text transcription: {NO}_{3}^{-}

Chapter: Problem: 30E

Chemistry: The Central Science 13
A voltaic cell similar to that shown in Figure 20.5 is constructed. One half-cell consists of an aluminum strip placed in a solution of \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}\), and the other has a nickel strip placed in a solution of \(\mathrm{NiSO}_{4}\). The overall cell reaction is \(2

Chapter: Problem: 29E

Chemistry: The Central Science 13
A voltaic cell similar to that shown in Figure 20.5 is constructed. One electrode half-cell consists of a silver strip placed in a solution of \(\mathrm{AgNO}_{3}\), and the other has an iron strip placed in a solution of \(\mathrm{FeCl}_{2}\). The overall cell reaction is \(F e(s)+2 A g^{+}(a q) \

Chapter: Problem: 31E

Chemistry: The Central Science 13
Problem 31E Cell Potentials under Standard Conditions (Section) (a) What does the term electromotive force mean? (b) What is the definition of the volt? (c) What does the term cell potential mean?

Chapter: Problem: 32E

Chemistry: The Central Science 13
Problem 32E Cell Potentials under Standard Conditions (Section) (a) Which electrode of a voltaic cell, the cathode or the anode, corresponds to the higher potential energy for the electrons? (b) What are the units for electrical potential? How does this unit relate to energy expressed in joules?

Chapter: Problem: 33E

Chemistry: The Central Science 13
Problem 33E Cell Potentials under Standard Conditions (Section) (a) Write the half-reaction that occurs at a hydrogen electrode in acidic aqueous solution when it serves as the cathode of a voltaic cell. (b) Write the half-reaction that occurs at a hydrogen electrode in acidic aqueous solution when

Chapter: Problem: 34E

Chemistry: The Central Science 13
Problem 34E Cell Potentials under Standard Conditions (Section) (a) What conditions must be met for a reduction potential to be a standard reduction potential? (b)What is the standard reduction potential of the standard hydrogen electrode? (c) Why is it impossible to measure the standard reduction

Chapter: Problem: 35E

Chemistry: The Central Science 13
Problem 35E Cell Potentials under Standard Conditions (Section) A voltaic cell that uses the reaction T13+(aq) + 2 Cr2+(aq)?T1+(aq) + 2 Cr3+(aq) has a measured standard cell potential of +1.19 V. (a) Write the two half-cell reactions. (b) By using data from Appendix E, determine Ered for the reduct

Chapter: Problem: 36E

Chemistry: The Central Science 13
Problem 36E Cell Potentials under Standard Conditions (Section) A voltaic cell that uses the reaction PdCl42-(aq) + Cd(s)?Pd(s) + 4 Cl-(aq) + Cd2+(aq) has a measured standard cell potential of +1.03 V.(a) Write the two half-cell reactions. (b) By using data from Appendix E, determine Ered for the r

Chapter: Problem: 37E

Chemistry: The Central Science 13
Problem 37E Cell Potentials under Standard Conditions (Section) Using standard reduction potentials (Appendix E), calculate the standard emf for each of the following reactions: (a) Cl2(g) + 2 I-(aq)?2 Cl-(aq) + I2(s) (b) Ni(s) + 2 Ce4+(aq)?Ni2+(aq) + 2 Ce3+(aq) (c) Fe(s) + 2 Fe3+(aq)?3 Fe2+(aq) (d

Chapter: Problem: 38E

Chemistry: The Central Science 13
Problem 38E Cell Potentials under Standard Conditions (Section) Using data in Appendix E, calculate the standard emf for each of the following reactions: (a) H2(g) + F2(g)?2 H+(aq) + 2 F-(aq) (b) Cu2+(aq) + Ca(s)?Cu(s) + Ca2+(aq) (c) 3 Fe2+(aq)?Fe(s) + 2 Fe3+(aq) (d) 2 ClO3-(aq) + 10 Br-(aq) + 12 H+(

Chapter: Problem: 39E

Chemistry: The Central Science 13
Problem 39E Cell Potentials under Standard Conditions (Section) The standard reduction potentials of the following half reactions are given in Appendix E: Ag+(aq) + e-?Ag(s) Cu2+(aq) + 2 e-?Cu(s) Ni2+(aq) + 2 e-?Ni(s) Cr3+(aq) + 3 e-?Cr(s) (a) Determine which combination of these half-cell reaction

Chapter: Problem: 40E

Chemistry: The Central Science 13
Problem 40E Cell Potentials under Standard Conditions (Section) Given the following half-reactions and associated standard reduction potentials: AuBr4-(aq) + 3 e-?Au(s) + 4 Br-(aq) Ered = -0.858 V Eu3+(aq) + e-?Eu2+(aq) Ered = -0.43 V IO-(aq) + H2O(l) + 2 e-?I-(aq) + 2 OH-(aq) Ered = +0.49 V (a) Wr

Chapter: Problem: 41E

Chemistry: The Central Science 13
Problem 41E Cell Potentials under Standard Conditions (Section) A 1 M solution of Cu(NO3)2 is placed in a beaker with a strip of Cu metal. A 1 M solution of SnSO4is placed in a second beaker with a strip of Sn metal. A salt bridge connects the two beakers, and wires to a voltmeter link the two meta

Chapter: Problem: 42E

Chemistry: The Central Science 13
Problem 42E Cell Potentials under Standard Conditions (Section) A voltaic cell consists of a strip of cadmium metal in a solution of Cd(NO3)2 in one beaker, and in the other beaker a platinum electrode is immersed in a NaCl solution, with Cl2 gas bubbled around the electrode. A salt bridge connects

Chapter: Problem: 43E

Chemistry: The Central Science 13
Problem 43E Strengths of Oxidizing and Reducing Agents (Section) From each of the following pairs of substances, use data in Appendix E to choose the one that is the stronger reducing agent: (a) Fe(s) or Mg(s) (b) Ca(s) or Al(s) (c) H2 (g, acidic solution) or H2S(g) (d) BrO3-(aq) or IO3-(aq)

Chapter: Problem: 44E

Chemistry: The Central Science 13
Problem 44E Strengths of Oxidizing and Reducing Agents (Section) From each of the following pairs of substances, use data in Appendix E to choose the one that is the stronger oxidizing agent: (a) Cl2(g) or Br2(l) (b) Zn2+(aq) or Cd2+(aq) (c) Cl-(aq) or ClO3-(aq) (d) H2O2(aq) or O3(g)

Chapter: Problem: 45E

Chemistry: The Central Science 13
Problem 45E Strengths of Oxidizing and Reducing Agents (Section) By using the data in Appendix E, determine whether each of the following substances is likely to serve as an oxidant or a reductant: (a) Cl2(g), (b) MnO4- (aq, acidic solution), (c) Ba(s), (d) Zn(s).

Chapter: Problem: 46E

Chemistry: The Central Science 13
Problem 46E Strengths of Oxidizing and Reducing Agents (Section) By using the data in Appendix E, determine whether each of the following substances is likely to serve as an oxidant or a reductant: (a) Ce3+(aq), (b) Ca(s) (c) ClO3-(aq), (d) N2O5(g)?

Chapter: Problem: 47E

Chemistry: The Central Science 13
Problem 47E Strengths of Oxidizing and Reducing Agents (Section) (a) Assuming standard conditions, arrange the following in order of increasing strength as oxidizing agents in acidic solution: Cr2O72-, H2O2, Cu2+, Cl2, O2. (b) Arrange the following in order of increasing strength as reducing agents

Chapter: Problem: 48E

Chemistry: The Central Science 13
Problem 48E Strengths of Oxidizing and Reducing Agents (Section) Based on the data in Appendix E, (a) which of the following is the strongest oxidizing agent and which is the weakest in acidic solution: Br2, H2O2, Zn, Cr2O7 2 - ? (b) Which of the following is the strongest reducing agent, and which

Chapter: Problem: 49E

Chemistry: The Central Science 13
Problem 49E Strengths of Oxidizing and Reducing Agents (Section) The standard reduction potential for the reduction of Eu3+(aq) to Eu2+(aq) is -0.43 V. Using Appendix E. which of the following substances is capable of reducing Eu3+(ag) to Eu2+(aq) under standard conditions: Al. Co. H202. N2H5 +.

Chapter: Problem: 50E

Chemistry: The Central Science 13
Problem 50E Strengths of Oxidizing and Reducing Agents (Section) The standard reduction potential for the reduction of Ru04 -(aq) to Ru04 2-(aq) is +0.59 V. By using Appendix E. which of the following substances can oxidize Ru04 2-(aq) to Ru04-(ag) under standard conditions: Br2(/), Br03-(ag).

Chapter: Problem: 51E

Chemistry: The Central Science 13
Problem 51E Free Energy and Redox Reactions (Section) Fe3+(aq) + e-? Fe2+(aq) Ered = +0.77 V S2O62- (aq) + 4 H+(aq) + 2 e-? 2 H2SO3(aq) Ered = +0.60 V N2O(g) + 2 H+(aq) + 2 e-? N2(g) + H2O(l) Ered = -1.77 V VO2+(aq) + 2 H+(aq) + e-.VO2+ + H2O(l) Ered = +1.00 V (a) Write balanced chemical equations

Chapter: Problem: 52E

Chemistry: The Central Science 13
Problem 52E Free Energy and Redox Reactions (Section) For each of the following reactions, write a balanced equation, calculate the standard emf, calculate ?G at 298 K, and calculate the equilibrium constant K at 298 K. (a) Aqueous iodide ion is oxidized to I2(s) by Hg22+(aq). (b) In acidic solutio

Chapter: Problem: 53E

Chemistry: The Central Science 13
Problem 53E Free Energy and Redox Reactions (Section) If the equilibrium constant for a two-electron redox reaction at 298 K is 1.5 10-4, calculate the corresponding ?G and Ered.

Chapter: Problem: 54E

Chemistry: The Central Science 13
Problem 54E Free Energy and Redox Reactions (Section) If the equilibrium constant for a one-electron redox reaction at 298 K is 8.7 104, calculate the corresponding ?G and Ered.

Chapter: Problem: 55E

Chemistry: The Central Science 13
Problem 55E Free Energy and Redox Reactions (Section) Using the standard reduction potentials listed in Appendix E, calculate the equilibrium constant for each of the following reactions at 298 K: (a) Fe(s) + Ni2+(aq)? Fe2+(aq) + Ni(s) (b) Co(s) + 2 H+(aq)? Co2+(aq) + H2(g) (c) 10 Br-(aq) + 2 MnO4-

Chapter: Problem: 56E

Chemistry: The Central Science 13
Problem 56E Free Energy and Redox Reactions (Section) Using the standard reduction potentiate listed in Appendix E. calculate the equilibrium constant for each of the following reactions at 298 K: (a) Cu(s) + 2 Ag+(eq)-. Cu2+(aq) + 2 Ag(s) (b) 3 Ce4+(ag) + Bits) + H20(/) 3 Ce3+(ag

Chapter: Problem: 57E

Chemistry: The Central Science 13
Problem 57E Free Energy and Redox Reactions (Section) A cell has a standard cell potential of +0.177 V at 298 K. What is the value of the equilibrium constant for the reaction (a) if n = 1? (b) if n = 2? (c) if n = 3?

Chapter: Problem: 58E

Chemistry: The Central Science 13
Problem 58E Free Energy and Redox Reactions (Section) At 298 K a cell reaction has a standard cell potential of +0.17 V. The equilibrium constant for the reaction is 5.5 105. What is the value of n for the reaction?

Chapter: Problem: 59E

Chemistry: The Central Science 13
Problem 59E Free Energy and Redox Reactions (Section) A voltaic cell is based on the reaction Sn(s) + I2(s)? Sn2+(aq) + 2I-(aq) Under standard conditions, what is the maximum electrical work, in joules, that the cell can accomplish if 75.0 g of Sn is consumed?

Chapter: Problem: 60E

Chemistry: The Central Science 13
Consider the voltaic cell illustrated in Figure 20.5, which is based on the cell reaction \(Z n(s)+C u^{2+}(a q) \rightarrow Z n^{2+}(a q)+C u(s)\) Under standard conditions, what is the maximum electrical work, in joules, that the cell can accomplish if 50.0 g of copper is formed? Equation tra

Chapter: Problem: 61E

Chemistry: The Central Science 13
Problem 61E Cell EMF under Nonstandard Conditions (Section) (a) In the Nernst equation what is the numerical value of the reaction quotient, Q, under standard conditions? (b) Can the Nernst equation be used at temperatures other than room temperature?

Chapter: Problem: 62E

Chemistry: The Central Science 13
Problem 62E Cell EMF under Nonstandard Conditions (Section) (a) A voltaic cell is constructed with all reactants and products in their standard states. Will the concentration of the reactants increase, decrease, or remain the same as the cell operates? (b)What happens to the emf of a cell if the co

Chapter: Problem: 63E

Chemistry: The Central Science 13
What is the effect on the emf of the cell shown in Figure 20.9, which has the overall reaction \(Z n(s) 2 H^{+}(a q) \rightarrow Z n^{2+}(a q)+H_{2}(g)\) for each of the following changes? (a) The pressure of the \(H_{2}\) gas is increased in the cathode half-cell. (b) Zinc nitrate is added to the an

Chapter: Problem: 64E

Chemistry: The Central Science 13
Problem 64E Cell EMF under Nonstandard Conditions (Section) A voltaic cell utilizes the following reaction: Al(s) + 3 Ag+(aq2)? Al3+(aq) + 3 Ag(s) What is the effect on the cell emf of each of the following changes? (a) Water is added to the anode half-cell, diluting the solution. (b) The size of t

Chapter: Problem: 65E

Chemistry: The Central Science 13
Problem 65E Cell EMF under Nonstandard Conditions (Section) A voltaic cell is constructed that uses the following reaction and operates at 298 K: Zn(s) + Ni2+(aq)? Zn2+(aq) + Ni(s) (a) What is the emf of this cell under standard conditions? (b) What is the emf of this cell when [Ni2+] = 3.00 M? and [

Chapter: Problem: 66E

Chemistry: The Central Science 13
Problem 66E Cell EMF under Nonstandard Conditions (Section) A voltaic cell utilizes the following reaction and operates at 298 K: 3 Ce4+(aq) + Cr(s)? 3 Ce3+(aq) + Cr3+(aq) (a) What is the emf of this cell under standard conditions? (b) What is the emf of this cell when [Ce4+] = 3.0 M, [Ce3+] = 0.10 M

Chapter: Problem: 67E

Chemistry: The Central Science 13
Problem 67E Cell EMF under Nonstandard Conditions (Section) A voltaic cell utilizes the following reaction: 4 Fe2+(aq) + O2(g) + 4 H+(aq)? 4 Fe3+(aq) + 2 H2O(l) (a) What is the emf of this cell under standard conditions? (b) What is the emf of this cell when [Fe2+] = 1.3 M, [Fe3+] = 0.010 M, Po2 = 0.

Chapter: Problem: 68E

Chemistry: The Central Science 13
Problem 68E Cell EMF under Nonstandard Conditions (Section) A voltaic cell utilizes the following reaction: 2 Fe3+(aq) + H2(g)? 2 Fe2+(aq) + 2 H+(aq) (a) What is the emf of this cell under standard conditions? (b) What is the emf for this cell when [Fe3+] = 3.50 M, PH2 =0.95 atm, [Fe2+] = 0.0010 M, a

Chapter: Problem: 69E

Chemistry: The Central Science 13
Problem 69E Cell EMF under Nonstandard Conditions (Section) A voltaic cell is constructed with two Zn2+ - Zn electrodes. The two half-cells have [Zn2+] = 1.8 Mand [Zn2+] = 1.00 10-2 M, respectively. (a) Which electrode is the anode of the cell? (b) What is the standard emf of the cell? (c) What is

Chapter: Problem: 70E

Chemistry: The Central Science 13
Problem 70E Cell EMF under Nonstandard Conditions (Section) A voltaic cell is constructed with two silversilver chloride electrodes, each of which is based on the following half-reaction: AgCl(s) + e-? Ag(s) + Cl-(aq) The two half-cells have [Cl-] = 0.0150 M and [Cl-] = 2.55 M, respectively. (a) Wh

Chapter: Problem: 71E

Chemistry: The Central Science 13
The cell in Figure 20.9 could be used to provide a measure of the pH in the cathode half-cell. Calculate the pH of the cathode half-cell solution if the cell emf at 298 K is measured to be \(+0.684 V\) when \(\left[Z n^{2+}\right]=0.30 M\) and \(P_{H_{2}}=0.90 a t m\) Equation transcription:

Chapter: Problem: 72E

Chemistry: The Central Science 13
Problem 72E Cell EMF under Nonstandard Conditions (Section) A voltaic cell is constructed that is based on the following reaction: Sn2+(aq) + Pb(s)? Sn(s) + Pb2+(aq) (a) If the concentration of Sn2+ in the cathode half-cell is 1.00 M and the cell generates an emf of +0.22 V, what is the concentrati

Chapter: Problem: 73E

Chemistry: The Central Science 13
Problem 73E Batteries and Fuel Cells (Section) During a period of discharge of a leadacid battery, 402 g of Pb from the anode is converted into PbSO4(s). (a) What mass of PbO2(s) is reduced at the cathode during this same period? (b) How many coulombs of electrical charge are transferred from Pb to

Chapter: Problem: 74E

Chemistry: The Central Science 13
Problem 74E Batteries and Fuel Cells (Section) During the discharge of an alkaline battery, 4.50 g of Zn is consumed at the anode of the battery. (a) What mass of MnO2 is reduced at the cathode during this discharge? (b) How many coulombs of electrical charge are transferred from Zn to MnO2?

Chapter: Problem: 75E

Chemistry: The Central Science 13
Problem 75E Batteries and Fuel Cells (Section) Heart pacemakers are often powered by lithiumsilver chromate button batteries. The overall cell reaction is 2 Li(s) + Ag2CrO4(s)? Li2CrO4(s) + 2 Ag(s) (a) Lithium metal is the reactant at one of the electrodes of the battery. Is it the anode or the cat

Chapter: Problem: 76E

Chemistry: The Central Science 13
Problem 76E Batteries and Fuel Cells (Section) Mercuric oxide dry-cell batteries are often used where a flat discharge voltage and long life are required, such as in watches and cameras. The two half-cell reactions that occur in the battery are HgO(s) + H2O(l) + 2 e-? Hg(l) + 2 OH-(aq) Zn(s) + 2 OH

Chapter: Problem: 77E

Chemistry: The Central Science 13
Problem 77E Batteries and Fuel Cells (Section) (a) Suppose that an alkaline battery was manufactured using cadmium metal rather than zinc. What effect would this have on the cell emf? (b) What environmental advantage is provided by the use of nickelmetal hydride batteries over nickelcadmium batteri

Chapter: Problem: 78E

Chemistry: The Central Science 13
Problem 78E Batteries and Fuel Cells (Section) In some applications nickelcadmium batteries have been replaced by nickelzinc batteries. The overall cell reaction for this relatively new battery is: 2 H2O(l) + 2 NiO(OH)(s) + Zn(s)? 2 Ni(OH)2(s) + Zn(OH)2(s) (a)What is the cathode half-reaction? (b)W

Chapter: Problem: 79E

Chemistry: The Central Science 13
Problem 79E Batteries and Fuel Cells (Section) In a Li-ion battery the composition of the cathode is LiCoO2 when completely discharged. On charging approximately 50% of the Li+ ions can be extracted from the cathode and transported to the graphite anode where they intercalate between the layers. (a

Chapter: Problem: 80E

Chemistry: The Central Science 13
Problem 80E Batteries and Fuel Cells (Section) Li-ion batteries used in automobiles typically use a LiMn2O4 cathode in place of the LiCoO2cathode found in most Li-ion batteries. (a) Calculate the mass percent lithium in each electrode material? (b) Which material has a higher percentage of lithium?

Chapter: Problem: 81E

Chemistry: The Central Science 13
Problem 81E Batteries and Fuel Cells (Section) The hydrogenoxygen fuel cell has a standard emf of 1.23 V. What advantages and disadvantages are there to using this device as a source of power compared to a 1.55-V alkaline battery?

Chapter: Problem: 82E

Chemistry: The Central Science 13
Problem 82E Batteries and Fuel Cells (Section) (a) What is the difference between a battery and a fuel cell? (b) Can the fuel of a fuel cell be a solid? Explain.

Chapter: Problem: 83E

Chemistry: The Central Science 13
Problem 83E Corrosion (Section) (a) Write the anode and cathode reactions that cause the corrosion of iron metal to aqueous iron(II). (b) Write the balanced half-reactions involved in the air oxidation of Fe2+(aq) to Fe2O3 3 H2O.

Chapter: Problem: 84E

Chemistry: The Central Science 13
Problem 84E Corrosion (Section) (a) Based on standard reduction potentials, would you expect copper metal to oxidize under standard conditions in the presence of oxygen and hydrogen ions? (b) When the Statue of Liberty was refurbished, Teflon spacers were placed between the iron skeleton and the co

Chapter: Problem: 85E

Chemistry: The Central Science 13
Problem 85E Corrosion (Section) (a) Magnesium metal is used as a sacrificial anode to protect underground pipes from corrosion. Why is the magnesium referred to as a sacrificial anode? (b) Looking in Appendix E, suggest what metal the underground pipes could be made from in order for magnesium to b

Chapter: Problem: 86E

Chemistry: The Central Science 13
Problem 86E Corrosion (Section) An iron object is plated with a coating of cobalt to protect against corrosion. Does the cobalt protect iron by cathodic protection? Explain.

Chapter: Problem: 87E

Chemistry: The Central Science 13
Problem 87E Corrosion (Section) A plumbers handbook states that you should not connect a brass pipe directly to a galvanized steel pipe because electrochemical reactions between the two metals will cause corrosion. The handbook recommends you use instead an insulating fitting to connect them. Brass

Chapter: Problem: 88E

Chemistry: The Central Science 13
Problem 88E Corrosion (Section) A plumbers handbook states that you should not connect a copper pipe directly to a steel pipe because electrochemical reactions between the two metals will cause corrosion. The handbook recommends you use instead an insulating fitting to connect them. What spontaneou

Chapter: Problem: 89E

Chemistry: The Central Science 13
Problem 89E Corrosion (Section) (a) What is electrolysis? (b) Are electrolysis reactions thermodynamically spontaneous? Explain. (c) What process occurs at the anode in the electrolysis of molten NaCl? (d) Why is sodium metal not obtained when an aqueous solution of NaCl undergoes electrolysis?

Chapter: Problem: 90E

Chemistry: The Central Science 13
Problem 90E Corrosion (Section) (a) What is an electrolytic cell? (b) The negative terminal of a voltage source is connected to an electrode of an electrolytic cell. Is the electrode the anode or the cathode of the cell? Explain. (c)The electrolysis of water is often done with a small amount of sul

Chapter: Problem: 91E

Chemistry: The Central Science 13
Problem 91E Corrosion (Section) (a) A Cr3+(aq) solution is electrolyzed, using a current of 7.60 A. What mass of Cr(s) is plated out after 2.00 days? (b) What amperage is required to plate out 0.250 mol Cr from a Cr3+ solution in a period of 8.00 h?

Chapter: Problem: 92E

Chemistry: The Central Science 13
Problem 92E Corrosion (Section) Metallic magnesium can be made by the electrolysis of molten MgCl2. (a) What mass of Mg is formed by passing a current of 4.55 A through molten MgCl2, for 4.50 days? (b) How many minutes are needed to plate out 25.00 g Mg from molten MgCl2 using 3.50 A of current?

Chapter: Problem: 93E

Chemistry: The Central Science 13
Problem 93E Corrosion (Section) (a) Calculate the mass of Li formed by electrolysis of molten LiCl by a current of 7.5 104 A flowing for a period of 24 h. Assume the electrolytic cell is 85% efficient. (b) What is the minimum voltage required to drive the reaction?

Chapter: Problem: 94E

Chemistry: The Central Science 13
Problem 94E Corrosion (Section) Elemental calcium is produced by the electrolysis of molten CaCl2. (a) What mass of calcium can be produced by this process if a current of 7.5 103 A is applied for 48 h? Assume that the electrolytic cell is 68% efficient. (b) What is the minimum voltage needed to c

Chapter: Problem: 95E

Chemistry: The Central Science 13
Problem 95E Corrosion (Section) Metallic gold is collected from below the anode when crude copper metal is refined by electrolysis. Explain this behavior.

Chapter: Problem: 96E

Chemistry: The Central Science 13
Problem 96E Corrosion (Section) The crude copper that is subjected to electrorefining contains tellurium as an impurity. The standard reduction potential between tellurium and its lowest common oxidation state, Te4+, is Te4+(aq) + 4 e-? Te(s) Ered = 0.57 V Given this information, describe the proba

Chapter: Problem: 97AE

Chemistry: The Central Science 13
Problem 97AE A disproportionation reaction is an oxidationreduction reaction in which the same substance is oxidized and reduced. Complete and balance the following disproportionation reactions: (a) Ni+(aq)? Ni2+(aq) + Ni(s) (acidic solution) (b) MnO42-(aq)? MnO4-(aq) + MnO2(s) (acidic solution) (c

Chapter: Problem: 98AE

Chemistry: The Central Science 13
Problem 98AE A common shorthand way to represent a voltaic cell is anode | anode solution | | cathode solution | cathode A double vertical line represents a salt bridge or a porous barrier. A single vertical line represents a change in phase, such as from solid to solution. (a) Write the half-react

Chapter: Problem: 99AE

Chemistry: The Central Science 13
Problem 99AE Predict whether the following reactions will be spontaneous in acidic solution under standard conditions: (a) oxidation of Sn to Sn2+ by I2 (to form I-), (b) reduction of Ni2+ to Ni by I-(to form I2), (c) reduction of Ce4+ to Ce3+ by H2O2, (d) reduction of Cu2+ to Cu by Sn2+ (to form

Chapter: Problem: 100AE

Chemistry: The Central Science 13
Problem 100AE Gold exists in two common positive oxidation states, +1 and +3. The standard reduction potentials for these oxidation states are Au+(aq) + e-? Au(s) Ered = +1.69 V Au3+(aq) + 3 e-? Au(s) Ered = +1.50 V (a) Can you use these data to explain why gold does not tarnish in the air? (b) Sug

Chapter: Problem: 101AE

Chemistry: The Central Science 13
Problem 101AE A voltaic cell is constructed from an Ni2+(aq) Ni(s) half-cell and an Ag+(aq) - Ag(s) half-cell. The initial concentration of Ni2+(aq) in the Ni2+ - Ni half-cell is [Ni2+] = 0.0100 M. The initial cell voltage is +1.12 V. (a) By using data in Table, calculate the standard emf of this

Chapter: Problem: 102AE

Chemistry: The Central Science 13
Problem 102AE A voltaic cell is constructed that uses the following half-cell reactions: Cu+(aq) + e-? Cu(s) I2(s) + 2 e-? 2 I-(aq) The cell is operated at 298 K with [Cu+] = 0.25 M and [I-] = 3.5 M. (a) Determine E for the cell at these concentrations. (b) Which electrode is the anode of the cel

Chapter: Problem: 103AE

Chemistry: The Central Science 13
Problem 103AE Using data from Appendix E, calculate the equilibrium constant for the disproportionation of the copper(I) ion at room temperature: 2 Cu+(aq)? Cu2+(aq) + Cu(s)

Chapter: Problem: 104AE

Chemistry: The Central Science 13
Problem 104AE (a) Write the reactions for the discharge and charge of a nickelcadmium (nicad) rechargeable battery. (b) Given the following reduction potentials, calculate the standard emf of the cell: Cd(OH)2(s) + 2 e-? Cd(s) + 2 OH-(aq)Ered = -0.76 V NiO(OH)(s) + H2O(l) + e-? Ni(OH)2(s) + OH-(aq)

Chapter: Problem: 105AE

Chemistry: The Central Science 13
Problem 105AE The capacity of batteries such as the typical AA alkaline battery is expressed in units of milliamp-hours (mAh). An AA alkaline battery yields a nominal capacity of 2850 mAh. (a) What quantity of interest to the consumer is being expressed by the units of mAh? (b) The starting voltage

Chapter: Problem: 106AE

Chemistry: The Central Science 13
Problem 106AE If you were going to apply a small potential to a steel ship resting in the water as a means of inhibiting corrosion, would you apply a negative or a positive charge? Explain.

Chapter: Problem: 107AE

Chemistry: The Central Science 13
Problem 107AE (a) How many coulombs are required to plate a layer of chromium metal 0.25 mm thick on an auto bumper with a total area of 0.32 m2 from a solution containing CrO42-? The density of chromium metal is 7.20 g/cm3. (b) What current flow is required for this electroplating if the bumper is

Chapter: Problem: 108AE

Chemistry: The Central Science 13
Problem 108AE Magnesium is obtained by electrolysis of molten MgCl2. (a) Why is an aqueous solution of MgCl2not used in the electrolysis? (b) Several cells are connected in parallel by very large copper bars that convey current to the cells. Assuming that the cells are 96% efficient in producing th

Chapter: Problem: 109AE

Chemistry: The Central Science 13
Problem 109AE Calculate the number of kilowatt-hours of electricity required to produce 1.0 103 kg (1 metric ton) of aluminum by electrolysis of Al3+ if the applied voltage is 4.50 V and the process is 45% efficient.

Chapter: Problem: 110AE

Chemistry: The Central Science 13
Problem 110AE Some years ago a unique proposal was made to raise the Titanic. The plan involved placing pontoons within the ship using a surface-controlled submarine-type vessel. The pontoons would contain cathodes and would be filled with hydrogen gas formed by the electrolysis of water. It has be

Chapter: Problem: 111IE

Chemistry: The Central Science 13
Problem 111IE The Haber process is the principal industrial route for converting nitrogen into ammonia: N2(g) + 3 H2(g)? 2 NH3(g) (a) What is being oxidized, and what is being reduced? (b) Using the thermodynamic data in Appendix C, calculate the equilibrium constant for the process at room tempera

Chapter: Problem: 112IE

Chemistry: The Central Science 13
Problem 112IE In a galvanic cell the cathode is an Ag+(1.00 M)/Ag(s) halfcell. The anode is a standard hydrogen electrode immersed in a buffer solution containing 0.10 M benzoic acid (C6H5COOH) and 0.050 Msodium benzoate (C6H5COO-Na+). The measured cell voltage is 1.030 V. What is the pKa of benzoi

Chapter: Problem: 113IE

Chemistry: The Central Science 13
Problem 113IE Consider the general oxidation of a species A in solution: A? A+ + e-. The term oxidation potentialis sometimes used to describe the ease with which species A is oxidizedthe easier a species is to oxidize, the greater its oxidation potential. (a) What is the relationship between the

Chapter: Problem: 114IE

Chemistry: The Central Science 13
Problem 114IE A voltaic cell is based on Ag+(aq)/Ag(s) and Fe3+(aq)/Fe2+(aq) half-cells. (a) What is the standard emf of the cell? (b) Which reaction occurs at the cathode and which at the anode of the cell? (c)Use S values in Appendix C and the relationship between cell potential and free-energy

Chapter: Problem: 115IE

Chemistry: The Central Science 13
Problem 115IE Hydrogen gas has the potential for use as a clean fuel in reaction with oxygen. The relevant reaction is 2 H2(g) + O2(g)? 2 H2O(l) Consider two possible ways of utilizing this reaction as an electrical energy source: (i) Hydrogen and oxygen gases are combusted and used to drive a gene

Chapter: Problem: 116IE

Chemistry: The Central Science 13
Problem 116IE Cytochrome, a complicated molecule that we will represent as CyFe2+, reacts with the air we breathe to supply energy required to synthesize adenosine triphosphate (ATP). The body uses ATP as an energy source to drive other reactions. (Section) At pH 7.0 the following reduction potenti

Chapter: Problem: 117IE

Chemistry: The Central Science 13
Problem 117IE The standard potential for the reduction of AgSCN(s) is +0.0895 V. AgSCN(s) + e-.Ag(s) + SCN-(aq) Using this value and the electrode potential for Ag+(aq), calculate the Ksp for AgSCN.

Chapter: Problem: 118IE

Chemistry: The Central Science 13
Problem 118IE The Ksp value for PbS(s) is 8.0 10-28. By using this value together with an electrode potential from Appendix E, determine the value of the standard reduction potential for the reaction PbS(s) + 2 e-? Pb(s) + S2-(aq)

Chapter: Problem: 119IE

Chemistry: The Central Science 13
Problem 119IE A student designs an ammeter (a device that measures electrical current) that is based on the electrolysis of water into hydrogen and oxygen gases. When electrical current of unknown magnitude is run through the device for 2.00 min, 12.3 mL of water-saturated H2(g) is collected. The

Chapter: Problem: 20.1

Chemistry: The Central Science 13
In the BrnstedLowry concept of acids and bases, acidbase reactions are viewed as proton-transfer reactions. The stronger the acid, the weaker is its conjugate base. If we were to think of redox reactions in a similar way, what particle would be analogous to the proton? Would strong oxidizing agents b

Chapter: Problem: 20.2

Chemistry: The Central Science 13
You may have heard that antioxidants are good for your health. Based on what you have learned in this chapter, what do you deduce an antioxidant is? [Sections 20.1 and 20.2]

Chapter: Problem: 20.3

Chemistry: The Central Science 13
The diagram that follows represents a molecular view of a process occurring at an electrode in a voltaic cell. (a) Does the process represent oxidation or reduction? (b) Is the electrode the anode or cathode? (c) Why are the atoms in the electrode represented by larger spheres than the ions in the so

Chapter: Problem: 20.4

Chemistry: The Central Science 13
Assume that you want to construct a voltaic cell that uses the following half-reactions: A2+1aq2 + 2 e- A1s2 E red = -0.10 V B2+1aq2 + 2 e- B1s2 E red = -1.10 V You begin with the incomplete cell pictured here in which the electrodes are immersed in water (a) What additions must you make to the cell

Chapter: Problem: 20.5

Chemistry: The Central Science 13
For a spontaneous reaction A1aq2 + B1aq2 A-1aq2 + B+1aq2, answer the following questions: (a) If you made a voltaic cell out of this reaction, what halfreaction would be occurring at the cathode, and what halfreaction would be occurring at the anode? (b) Which half-reaction from (a) is higher in pote

Chapter: Problem: 20.6

Chemistry: The Central Science 13
Consider the following table of standard electrode potentials for a series of hypothetical reactions in aqueous solution: Reduction Half-Reaction E(V) A+1aq2 + e- A1s2 1.33 B2+1aq2 + 2 e- B1s2 0.87 C3+1aq2 + e- C2+1aq2 -0.12 D3+1aq2 + 3 e- D1s2 -1.59 (a) Which substance is the strongest oxidizing age

Chapter: Problem: 20.7

Chemistry: The Central Science 13
Consider a redox reaction for which E is a negative number. (a) What is the sign of G for the reaction? (b) Will the equilibrium constant for the reaction be larger or smaller than 1? (c) Can an electrochemical cell based on this reaction accomplish work on its surroundings? [Section 20.5]

Chapter: Problem: 20.8

Chemistry: The Central Science 13
Consider the following voltaic cell: e Fe(s) Ag(s) 1 M Fe2+ 1 M Ag+ Salt bridge Voltmeter (a) Which electrode is the cathode? (b) What is the standard emf generated by this cell? (c) What is the change in the cell voltage when the ion concentrations in the cathode half-cell are increased by a factor

Chapter: Problem: 20.9

Chemistry: The Central Science 13
Consider the half-reaction Ag+1aq2 + e- Ag1s2. (a) Which of the lines in the following diagram indicates how the reduction potential varies with the concentration of Ag+? (b) What is the value of E red when log3Ag+4 = 0? [Section 20.6] 1 2 3 log[Ag+]

Chapter: Problem: 20.10

Chemistry: The Central Science 13
The electrodes in a silver oxide battery are silver oxide 1Ag2O2 and zinc. (a) Which electrode acts as the anode? (b) Which battery do you think has an energy density most similar to the silver oxide battery: a Li-ion battery, a nickelcadmium battery, or a leadacid battery? [Section 20.7]

Chapter: Problem: 20.11

Chemistry: The Central Science 13
Bars of iron are put into each of the three beakers as shown here. In which beakerA, B, or Cwould you expect the iron to show the most corrosion ? [Section 20.8] Beaker A Pure water pH = 7.0 Beaker B Dilute HCl (aq) solution pH = 4.0 Beaker C Dilute NaOH solution pH = 10.0

Chapter: Problem: 20.12

Chemistry: The Central Science 13
Magnesium is produced commercially by electrolysis from a molten salt using a cell similar to the one shown here. (a) What salt is used as the electrolyte? (b) Which electrode is the anode, and which one is the cathode? (c) Write the overall cell reaction and individual half-reactions. (d) What preca

Chapter: Problem: 20.13

Chemistry: The Central Science 13
(a) What is meant by the term oxidation? (b) On which side of an oxidation half-reaction do the electrons appear? (c) What is meant by the term oxidant? (d) What is meant by the term oxidizing agent?

Chapter: Problem: 20.14

Chemistry: The Central Science 13
(a) What is meant by the term reduction? (b) On which side of a reduction half-reaction do the electrons appear? (c) What is meant by the term reductant? (d) What is meant by the term reducing agent?

Chapter: Problem: 20.15

Chemistry: The Central Science 13
Indicate whether each of the following statements is true or false: (a) If something is oxidized, it is formally losing electrons. (b) For the reaction Fe 3+1aq2 + Co2+1aq2 Fe 2+1aq2 + Co3+1aq2, Fe 3+1aq2 is the reducing agent and Co2+1aq2 is the oxidizing agent. (c) If there are no changes in the ox

Chapter: Problem: 20.16

Chemistry: The Central Science 13
Indicate whether each of the following statements is true or false: (a) If something is reduced, it is formally losing electrons. (b) A reducing agent gets oxidized as it reacts. (c) An oxidizing agent is needed to convert CO into CO2.

Chapter: Problem: 20.17

Chemistry: The Central Science 13
In each of the following balanced oxidationreduction equations, identify those elements that undergo changes in oxidation number and indicate the magnitude of the change in each case. (a) I2O51s2 + 5 CO1g2 I21s2 + 5 CO21g2 (b) 2 Hg2+1aq2 + N2H41aq22 Hg1l2 + N21g2 + 4 H+1aq2 (c) 3 H2S1aq2 + 2 H+1aq2 +

Chapter: Problem: 20.18

Chemistry: The Central Science 13
In each of the following balanced oxidationreduction equations, identify those elements that undergo changes in oxidation number and indicate the magnitude of the change in each case. (a) 2 MnO4 -1aq2 + 3 S2 - 1aq2 + 4 H2O1l2 3 S1s2 + 2 MnO21s2 + 8 OH-1aq2 (b) 4 H2O21aq2 +Cl2O71g2 + 2 OH-1aq22 ClO2 -

Chapter: Problem: 20.19

Chemistry: The Central Science 13
Indicate whether the following balanced equations involve oxidationreduction. If they do, identify the elements that undergo changes in oxidation number. (a) PBr31l2 + 3 H2O1l2 H3PO31aq2 + 3 HBr1aq2 (b) NaI1aq2 + 3 HOCl1aq2 NaIO31aq2 + 3 HCl1aq2 (c) 3 SO21g2 + 2 HNO31aq2 + 2 H2O1l2 3 H2SO41aq2 + 2 NO

Chapter: Problem: 20.20

Chemistry: The Central Science 13
Indicate whether the following balanced equations involve oxidationreduction. If they do, identify the elements that undergo changes in oxidation number. (a) 2 AgNO31aq2 + CoCl21aq2 2 AgCl1s2 + Co1NO3221aq2 (b) 2 PbO21s2 2 PbO1s2 + O21g2 (c) 2 H2SO41aq2 + 2 NaBr1s2 Br21l2 + SO21g2 + Na2SO41aq2 + 2 H2

Chapter: Problem: 20.21

Chemistry: The Central Science 13
At 900 C titanium tetrachloride vapor reacts with molten magnesium metal to form solid titanium metal and molten magnesium chloride. (a) Write a balanced equation for this reaction. (b) What is being oxidized, and what is being reduced? (c) Which substance is the reductant, and which is the oxidant?

Chapter: Problem: 20.22

Chemistry: The Central Science 13
Hydrazine 1N2H42 and dinitrogen tetroxide 1N2O42 form a self-igniting mixture that has been used as a rocket propellant. The reaction products are N2 and H2O. (a) Write a balanced chemical equation for this reaction. (b) What is being oxidized, and what is being reduced? (c) Which substance serves as

Chapter: Problem: 20.23

Chemistry: The Central Science 13
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction. (a) Sn2+1aq2 Sn4+1aq2 (acidic solution) (b) TiO21s2 Ti 2+1aq2 (acidic solution) (c) ClO3 -1aq2 Cl -1aq2 (acidic solution) (d) N21g2 NH4 +1aq2 (acidic solution) (e) OH- 1a

Chapter: Problem: 20.24

Chemistry: The Central Science 13
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction. (a) Mo3+1aq2 Mo1s2 (acidic solution) (b) H2SO31aq2 SO4 2-1aq2 (acidic solution) (c) NO3 -1aq2 NO1g2 (acidic solution) (d) O21g2 H2O1l2 (acidic solution) (e) O21g2 H2O1l2

Chapter: Problem: 20.25

Chemistry: The Central Science 13
Complete and balance the following equations, and identify the oxidizing and reducing agents: (a) Cr2O7 2-1aq2 + I-1aq2 Cr 3+1aq2 + IO3 -1aq2 (acidic solution) (b) MnO4 -1aq2 + CH3OH1aq2 Mn2+1aq2 + HCO2H1aq2 (acidic solution) (c) I21s2 + OCl -1aq2 IO3 -1aq2 + Cl -1aq2 (acidic solution) (d) As2O31s2 +

Chapter: Problem: 20.26

Chemistry: The Central Science 13
Complete and balance the following equations, and identify the oxidizing and reducing agents. (Recall that the O atoms in hydrogen peroxide, H2O2, have an atypical oxidation state.) (a) NO2 -1aq2 + Cr2O7 2-1aq2 Cr 3+1aq2 + NO3 -1aq2 (acidic solution) (b) S1s2 + HNO31aq2 H2SO31aq2 + N2O1g2 (acidic sol

Chapter: Problem: 20.27

Chemistry: The Central Science 13
(a) What are the similarities and differences between Figure 20.3 and Figure 20.4? (b) Why are Na + ions drawn into the cathode half-cell as the voltaic cell shown in Figure 20.5 operates?

Chapter: Problem: 20.28

Chemistry: The Central Science 13
(a) What is the role of the porous glass disc shown in Figure 20.4? (b) Why do NO3 - ions migrate into the anode half-cell as the voltaic cell shown in Figure 20.5 operates?

Chapter: Problem: 20.29

Chemistry: The Central Science 13
A voltaic cell similar to that shown in Figure 20.5 is constructed. One electrode half-cell consists of a silver strip placed in a solution of AgNO3, and the other has an iron strip placed in a solution of FeCl2. The overall cell reaction is Fe1s2 + 2 Ag+1aq2 Fe 2+1aq2 + 2 Ag1s2 (a) What is being oxi

Chapter: Problem: 20.30

Chemistry: The Central Science 13
A voltaic cell similar to that shown in Figure 20.5 is constructed. One half-cell consists of an aluminum strip placed in a solution of A11NO323, and the other has a nickel strip placed in a solution of NiSO4. The overall cell reaction is 2 Al1s2 + 3 Ni 2+1aq2 2 Al 3+1aq2 + 3 Ni1s2 (a) What is being

Chapter: Problem: 20.31

Chemistry: The Central Science 13
(a) What does the term electromotive force mean? (b) What is the definition of the volt? (c) What does the term cell potential mean

Chapter: Problem: 20.32

Chemistry: The Central Science 13
(a) Which electrode of a voltaic cell, the cathode or the anode, corresponds to the higher potential energy for the electrons? (b) What are the units for electrical potential? How does this unit relate to energy expressed in joules?

Chapter: Problem: 20.33

Chemistry: The Central Science 13
(a) Write the half-reaction that occurs at a hydrogen electrode in acidic aqueous solution when it serves as the cathode of a voltaic cell. (b) Write the half-reaction that occurs at a hydrogen electrode in acidic aqueous solution when it serves as the anode of a voltaic cell. (c) What is standard ab

Chapter: Problem: 20.34

Chemistry: The Central Science 13
(a) What conditions must be met for a reduction potential to be a standard reduction potential? (b) What is the standard reduction potential of a standard hydrogen electrode? (c) Why is it impossible to measure the standard reduction potential of a single half-reaction?

Chapter: Problem: 20.35

Chemistry: The Central Science 13
A voltaic cell that uses the reaction T1 3+1aq2 + 2 Cr 2+1aq2 T1 +1aq2 + 2 Cr 3+1aq2 has a measured standard cell potential of +1.19 V. (a) Write the two half-cell reactions. (b) By using data from Appendix E, determine E red for the reduction of T1 3+1aq2 to T1 +1aq2. (c) Sketch the voltaic cell, la

Chapter: Problem: 20.36

Chemistry: The Central Science 13
A voltaic cell that uses the reaction PdCl4 2-1aq2 + Cd1s2 Pd1s2 + 4 Cl -1aq2 + Cd2+1aq2 has a measured standard cell potential of +1.03 V. (a) Write the two half-cell reactions. (b) By using data from Appendix E, determine E red for the reaction involving Pd. (c) Sketch the voltaic cell, label the a

Chapter: Problem: 20.37

Chemistry: The Central Science 13
Using standard reduction potentials (Appendix E), calculate the standard emf for each of the following reactions: (a) Cl21g2 + 2 I -1aq2 2 Cl -1aq2 + I21s2 (b) Ni1s2 + 2 Ce 4+1aq2 Ni 2+1aq2 + 2 Ce 3+1aq2 (c) Fe1s2 + 2 Fe 3+1aq2 3 Fe 2+1aq2 (d) 2 NO3 -1aq2 + 8 H+1aq2 + 3 Cu1s2 2 NO1g2 + 4 H2O1l2 + 3 C

Chapter: Problem: 20.38

Chemistry: The Central Science 13
Using data in Appendix E, calculate the standard emf for each of the following reactions: (a) H21g2 + F21g2 2 H+1aq2 + 2 F-1aq2 (b) Cu2+1aq2 + Ca1s2 Cu1s2 + Ca 2+1aq2 (c) 3 Fe 2+1aq2 Fe1s2 + 2 Fe 3+1aq2 (d) 2 ClO3 -1aq2 + 10 Br -1aq2 + 12 H+1aq2 Cl21g2 + 5 Br21l2 + 6 H2O1l2

Chapter: Problem: 20.39

Chemistry: The Central Science 13
The standard reduction potentials of the following halfreactions are given in Appendix E: Ag+1aq2 + e- Ag1s2 Cu2+1aq2 + 2 e- Cu1s2 Ni 2+1aq2 + 2 e- Ni1s2 Cr 3+1aq2 + 3 e- Cr1s2 (a) Determine which combination of these half-cell reactions leads to the cell reaction with the largest positive cell poten

Chapter: Problem: 20.40

Chemistry: The Central Science 13
Given the following half-reactions and associated standard reduction potentials: AuBr4 -1aq2 + 3 e- Au1s2 + 4 Br -1aq2 E red = -0.858 V Eu3+1aq2 + e- Eu2+1aq2 E red = -0.43 V IO-1aq2 + H2O1l2 + 2 e- I -1aq2 + 2 OH-1aq2 E red = +0.49 V (a) Write the equation for the combination of these half-cell reac

Chapter: Problem: 20.41

Chemistry: The Central Science 13
A 1 M solution of Cu1NO322 is placed in a beaker with a strip of Cu metal. A 1 M solution of SnSO4 is placed in a second beaker with a strip of Sn metal. A salt bridge connects the two beakers, and wires to a voltmeter link the two metal electrodes. (a) Which electrode serves as the anode and which a

Chapter: Problem: 20.42

Chemistry: The Central Science 13
A voltaic cell consists of a strip of cadmium metal in a solution of Cd1NO322 in one beaker, and in the other beaker a platinum electrode is immersed in a NaCl solution, with Cl2 gas bubbled around the electrode. A salt bridge connects the two beakers. (a) Which electrode serves as the anode and whic

Chapter: Problem: 20.43

Chemistry: The Central Science 13
From each of the following pairs of substances, use data in Appendix E to choose the one that is the stronger reducing agent: (a) Fe(s) or Mg(s) (b) Ca(s) or Al(s) (c) H2 (g, acidic solution) or H2S1g2 (d) BrO3 -1aq2 or IO3 -1aq2

Chapter: Problem: 20.44

Chemistry: The Central Science 13
From each of the following pairs of substances, use data in Appendix E to choose the one that is the stronger oxidizing agent: (a) Cl21g2 or Br21l2 (b) Zn2+1aq2 or Cd2+1aq2 (c) Cl -1aq2 or ClO3 -1aq2 (d) H2O21aq2 or O31g

Chapter: Problem: 20.45

Chemistry: The Central Science 13
By using the data in Appendix E, determine whether each of the following substances is likely to serve as an oxidant or a reductant: (a) Cl21g2, (b) MnO4 - (aq, acidic solution), (c) Ba(s), (d) Zn(s).

Chapter: Problem: 20.46

Chemistry: The Central Science 13
Is each of the following substances likely to serve as an oxidant or a reductant: (a) Ce 3+1aq2, (b) Ca(s), (c) ClO3 -1aq2, (d) N2O51g2?

Chapter: Problem: 20.47

Chemistry: The Central Science 13
(a) Assuming standard conditions, arrange the following in order of increasing strength as oxidizing agents in acidic solution: Cr2O7 2-, H2O2, Cu2+, Cl2, O2. (b) Arrange the following in order of increasing strength as reducing agents in acidic solution: Zn, I -, Sn2+, H2O2, Al.

Chapter: Problem: 20.48

Chemistry: The Central Science 13
Based on the data in Appendix E, (a) which of the following is the strongest oxidizing agent and which is the weakest in acidic solution: Br2, H2O2, Zn, Cr2O7 2 - ? (b) Which of the following is the strongest reducing agent, and which is the weakest in acidic solution: F-, Zn, N2H5 +, I2, NO?

Chapter: Problem: 20.49

Chemistry: The Central Science 13
The standard reduction potential for the reduction of Eu3+1aq2 to Eu2+1aq2 is -0.43 V. Using Appendix E, which of the following substances is capable of reducing Eu3+1aq2 to Eu2+1aq2 under standard conditions: Al, Co, H2O2, N2H5 +, H2C2O4?

Chapter: Problem: 20.50

Chemistry: The Central Science 13
The standard reduction potential for the reduction of RuO4 -1aq2 to RuO4 2-1aq2 is +0.59 V. By using Appendix E, which of the following substances can oxidize RuO4 2-1aq2 to RuO4 -1aq2 under standard conditions: Br21l2, BrO3 -1aq2, Mn2+1aq2, O21g2, Sn2+1aq2?

Chapter: Problem: 20.51

Chemistry: The Central Science 13
Given the following reduction half-reactions: Fe 3+1aq2 + e- Fe 2+1aq2 E red = +0.77 V S2O6 2 - 1aq2 + 4 H+1aq2 + 2 e- 2 H2SO31aq2 E red = +0.60 V N2O1g2 + 2 H+1aq2 + 2 e- N21g2 + H2O1l2 E red = -1.77 V VO2 +1aq2 + 2 H+1aq2 + e- VO2+ + H2O1l2 E red = +1.00 V (a) Write balanced chemical equations for

Chapter: Problem: 20.52

Chemistry: The Central Science 13
For each of the following reactions, write a balanced equation, calculate the standard emf, calculate G at 298 K, and calculate the equilibrium constant K at 298 K. (a) Aqueous iodide ion is oxidized to I21s2 by Hg2 2+1aq2. (b) In acidic solution, copper(I) ion is oxidized to copper(II) ion by nitrat

Chapter: Problem: 20.53

Chemistry: The Central Science 13
If the equilibrium constant for a two-electron redox reaction at 298 K is 1.5 * 10-4 , calculate the corresponding G and E red.

Chapter: Problem: 20.54

Chemistry: The Central Science 13
If the equilibrium constant for a one-electron redox reaction at 298 K is 8.7 * 104 , calculate the corresponding G and E red

Chapter: Problem: 20.55

Chemistry: The Central Science 13
Using the standard reduction potentials listed in Appendix E, calculate the equilibrium constant for each of the following reactions at 298 K: (a) Fe1s2 + Ni 2+1aq2 Fe 2+1aq2 + Ni1s2 (b) Co1s2 + 2 H+1aq2 Co2+1aq2 + H21g2 (c) 10 Br -1aq2 + 2 MnO4 -1aq2 + 16 H+1aq2 2 Mn2+1aq2 + 8 H2O1l2 + 5 Br21l2

Chapter: Problem: 20.56

Chemistry: The Central Science 13
Using the standard reduction potentials listed in Appendix E, calculate the equilibrium constant for each of the following reactions at 298 K: (a) Cu1s2 + 2 Ag+1aq2 Cu2+1aq2 + 2 Ag1s2 (b) 3 Ce 4+1aq2 + Bi1s2 + H2O1l2 3 Ce 3+1aq2 + BiO+1aq2 + 2H+1aq2 (c) N2H5 +1aq2 + 4 Fe1CN26 3 - 1aq2 N21g2 + 5 H+1aq

Chapter: Problem: 20.57

Chemistry: The Central Science 13
A cell has a standard cell potential of +0.177 V at 298 K. What is the value of the equilibrium constant for the reaction (a) if n = 1? (b) if n = 2? (c) if n = 3?

Chapter: Problem: 20.58

Chemistry: The Central Science 13
At 298 K a cell reaction has a standard cell potential of +0.17 V. The equilibrium constant for the reaction is 5.5 * 105 . What is the value of n for the reaction?

Chapter: Problem: 20.59

Chemistry: The Central Science 13
A voltaic cell is based on the reaction Sn1s2 + I21s2 Sn2+1aq2 + 2I -1aq2 Under standard conditions, what is the maximum electrical work, in joules, that the cell can accomplish if 75.0 g of Sn is consumed?

Chapter: Problem: 20.60

Chemistry: The Central Science 13
Consider the voltaic cell illustrated in Figure 20.5, which is based on the cell reaction Zn1s2 + Cu2+1aq2 Zn2+1aq2 + Cu1s2 Under standard conditions, what is the maximum electrical work, in joules, that the cell can accomplish if 50.0 g of copper is formed?

Chapter: Problem: 20.61

Chemistry: The Central Science 13
(a) In the Nernst equation what is the numerical value of the reaction quotient, Q, under standard conditions? (b) Can the Nernst equation be used at temperatures other than room temperature?

Chapter: Problem: 20.62

Chemistry: The Central Science 13
(a) A voltaic cell is constructed with all reactants and products in their standard states. Will the concentration of the reactants increase, decrease, or remain the same as the cell operates? (b) What happens to the emf of a cell if the concentrations of the products are increased?

Chapter: Problem: 20.63

Chemistry: The Central Science 13
What is the effect on the emf of the cell shown in Figure 20.9, which has the overall reaction Zn1s2 + 2 H+1aq2 Zn2+1aq2 + H21g2, for each of the following changes? (a) The pressure of the H2 gas is increased in the cathode halfcell. (b) Zinc nitrate is added to the anode half-cell. (c) Sodium hydrox

Chapter: Problem: 20.64

Chemistry: The Central Science 13
A voltaic cell utilizes the following reaction: Al1s2 + 3 Ag+1aq2 Al 3+1aq2 + 3 Ag1s2 What is the effect on the cell emf of each of the following changes? (a) Water is added to the anode half-cell, diluting the solution. (b) The size of the aluminum electrode is increased. (c) A solution of AgNO3 is

Chapter: Problem: 20.65

Chemistry: The Central Science 13
A voltaic cell is constructed that uses the following reaction and operates at 298 K: Zn1s2 + Ni 2+1aq2 Zn2+1aq2 + Ni1s2 (a) What is the emf of this cell under standard conditions? (b) What is the emf of this cell when 3Ni 2+4 = 3.00 M? and 3Zn2+4 = 0.100 M? (c) What is the emf of the cell when 3Ni 2

Chapter: Problem: 20.66

Chemistry: The Central Science 13
A voltaic cell utilizes the following reaction and operates at 298 K: 3 Ce 4+1aq2 + Cr1s2 3 Ce 3+1aq2 + Cr 3+1aq2 (a) What is the emf of this cell under standard conditions? (b) What is the emf of this cell when 3Ce 4+4 = 3.0 M, 3Ce 3+4 = 0.10 M, and 3Cr 3+4 = 0.010 M? (c) What is the emf of the cell

Chapter: Problem: 20.67

Chemistry: The Central Science 13
A voltaic cell utilizes the following reaction: 4 Fe 2+1aq2 + O21g2 + 4 H+1aq2 4 Fe 3+1aq2 + 2 H2O1l2 (a) What is the emf of this cell under standard conditions? (b) What is the emf of this cell when 3Fe 2+4 = 1.3 M, 3Fe 3+4 = 0.010 M, Po2 = 0.50 atm, and the pH of the solution in the cathode half-ce

Chapter: Problem: 20.68

Chemistry: The Central Science 13
A voltaic cell utilizes the following reaction: 2 Fe 3+1aq2 + H21g2 2 Fe 2+1aq2 + 2 H+1aq2 (a) What is the emf of this cell under standard conditions? (b) What is the emf for this cell when 3Fe 3+4 = 3.50 M, PH2 = 0.95 atm, 3Fe 2+4 = 0.0010 M, and the pH in both half-cells is 4.00?

Chapter: Problem: 20.69

Chemistry: The Central Science 13
A voltaic cell is constructed with two Zn2+ - Zn electrodes. The two half-cells have 3Zn2+4 = 1.8 M and 3Zn2+4 = 1.00 * 10-2 M, respectively. (a) Which electrode is the anode of the cell? (b) What is the standard emf of the cell? (c) What is the cell emf for the concentrations given? (d) For each ele

Chapter: Problem: 20.70

Chemistry: The Central Science 13
A voltaic cell is constructed with two silversilver chloride electrodes, each of which is based on the following half-reaction: AgCl1s2 + e- Ag1s2 + Cl -1aq2 The two half-cells have 3Cl -4 = 0.0150 M and 3Cl -4 = 2.55 M, respectively. (a) Which electrode is the cathode of the cell? (b) What is the st

Chapter: Problem: 20.71

Chemistry: The Central Science 13
The cell in Figure 20.9 could be used to provide a measure of the pH in the cathode half-cell. Calculate the pH of the cathode half-cell solution if the cell emf at 298 K is measured to be +0.684 V when 3Zn2+4 = 0.30 M and PH2 = 0.90 atm.

Chapter: Problem: 20.72

Chemistry: The Central Science 13
A voltaic cell is constructed that is based on the following reaction: Sn2+1aq2 + Pb1s2 Sn1s2 + Pb2+1aq2 (a) If the concentration of Sn2+ in the cathode half-cell is 1.00 M and the cell generates an emf of +0.22 V, what is the concentration of Pb2+ in the anode half-cell? (b) If the anode half-cell c

Chapter: Problem: 20.73

Chemistry: The Central Science 13
During a period of discharge of a leadacid battery, 402 g of Pb from the anode is converted into PbSO41s2. (a) What mass of PbO21s2 is reduced at the cathode during this same period? (b) How many coulombs of electrical charge are transferred from Pb to PbO2?

Chapter: Problem: 20.74

Chemistry: The Central Science 13
During the discharge of an alkaline battery, 4.50 g of Zn is consumed at the anode of the battery. (a) What mass of MnO2 is reduced at the cathode during this discharge? (b) How many coulombs of electrical charge are transferred from Zn to MnO2?

Chapter: Problem: 20.75

Chemistry: The Central Science 13
Heart pacemakers are often powered by lithiumsilver chromate button batteries. The overall cell reaction is 2 Li1s2 + Ag2CrO41s2 Li2CrO41s2 + 2 Ag1s2 (a) Lithium metal is the reactant at one of the electrodes of the battery. Is it the anode or the cathode? (b) Choose the two half-reactions from Appen

Chapter: Problem: 20.76

Chemistry: The Central Science 13
Mercuric oxide dry-cell batteries are often used where a flat discharge voltage and long life are required, such as in watches and cameras. The two half-cell reactions that occur in the battery are HgO1s2 + H2O1l2 + 2 e- Hg1l2 + 2 OH-1aq2 Zn1s2 + 2 OH-1aq2 ZnO1s2 + H2O1l2 + 2 e- (a) Write the overall

Chapter: Problem: 20.77

Chemistry: The Central Science 13
(a) Suppose that an alkaline battery was manufactured using cadmium metal rather than zinc. What effect would this have on the cell emf? (b) What environmental advantage is provided by the use of nickelmetal hydride batteries over nickelcadmium batteries?

Chapter: Problem: 20.78

Chemistry: The Central Science 13
In some applications nickelcadmium batteries have been replaced by nickelzinc batteries.The overall cell reaction for this relatively new battery is: 2 H2O1l2 + 2 NiO1OH21s2 + Zn1s2 2 Ni1OH221s2 + Zn1OH221s2 (a)What is the cathode half-reaction? (b)What is the anode half-reaction? (c) A single nickel

Chapter: Problem: 20.79

Chemistry: The Central Science 13
In a Li-ion battery the composition of the cathode is LiCoO2 when completely discharged. On charging approximately 50% of the Li + ions can be extracted from the cathode and transported to the graphite anode where they intercalate between the layers. (a) What is the composition of the cathode when th

Chapter: Problem: 20.80

Chemistry: The Central Science 13
Li-ion batteries used in automobiles typically use a LiMn2O4 cathode in place of the LiCoO2 cathode found in most Li-ion batteries. (a) Calculate the mass percent lithium in each electrode material? (b) Which material has a higher percentage of lithium? Does this help to explain why batteries made wi

Chapter: Problem: 20.81

Chemistry: The Central Science 13
The hydrogenoxygen fuel cell has a standard emf of 1.23 V. What advantages and disadvantages are there to using this device as a source of power compared to a 1.55-V alkaline battery?

Chapter: Problem: 20.82

Chemistry: The Central Science 13
(a) What is the difference between a battery and a fuel cell? (b) Can the fuel of a fuel cell be a solid? Explain.

Chapter: Problem: 20.83

Chemistry: The Central Science 13
(a) Write the anode and cathode reactions that cause the corrosion of iron metal to aqueous iron(II). (b) Write the balanced half-reactions involved in the air oxidation of Fe 2+1aq2 to Fe2O3 # 3 H2O.

Chapter: Problem: 20.84

Chemistry: The Central Science 13
(a) Based on standard reduction potentials, would you expect copper metal to oxidize under standard conditions in the presence of oxygen and hydrogen ions? (b) When the Statue of Liberty was refurbished, Teflon spacers were placed between the iron skeleton and the copper metal on the surface of the s

Chapter: Problem: 20.85

Chemistry: The Central Science 13
(a) Magnesium metal is used as a sacrificial anode to protect underground pipes from corrosion. Why is the magnesium referred to as a sacrificial anode? (b) Looking in Appendix E, suggest what metal the underground pipes could be made from in order for magnesium to be successful as a sacrificial anod

Chapter: Problem: 20.86

Chemistry: The Central Science 13
An iron object is plated with a coating of cobalt to protect against corrosion. Does the cobalt protect iron by cathodic protection? Explain.

Chapter: Problem: 20.87

Chemistry: The Central Science 13
A plumbers handbook states that you should not connect a brass pipe directly to a galvanized steel pipe because electrochemical reactions between the two metals will cause corrosion. The handbook recommends you use instead an insulating fitting to connect them. Brass is a mixture of copper and zinc.

Chapter: Problem: 20.88

Chemistry: The Central Science 13
A plumbers handbook states that you should not connect a copper pipe directly to a steel pipe because electrochemical reactions between the two metals will cause corrosion. The handbook recommends you use instead an insulating fitting to connect them. What spontaneous redox reaction(s) might cause th

Chapter: Problem: 20.89

Chemistry: The Central Science 13
(a) What is electrolysis? (b) Are electrolysis reactions thermodynamically spontaneous? Explain. (c) What process occurs at the anode in the electrolysis of molten NaCl? (d) Why is sodium metal not obtained when an aqueous solution of NaCl undergoes electrolysis?

Chapter: Problem: 20.90

Chemistry: The Central Science 13
(a) What is an electrolytic cell? (b) The negative terminal of a voltage source is connected to an electrode of an electrolytic cell. Is the electrode the anode or the cathode of the cell? Explain. (c) The electrolysis of water is often done with a small amount of sulfuric acid added to the water. Wh

Chapter: Problem: 20.91

Chemistry: The Central Science 13
(a) A Cr 3+1aq2 solution is electrolyzed, using a current of 7.60 A. What mass of Cr(s) is plated out after 2.00 days? (b) What amperage is required to plate out 0.250 mol Cr from a Cr 3+ solution in a period of 8.00 h?

Chapter: Problem: 20.92

Chemistry: The Central Science 13
Metallic magnesium can be made by the electrolysis of molten MgCl2. (a) What mass of Mg is formed by passing a current of 4.55 A through molten MgCl2, for 4.50 days? (b) How many minutes are needed to plate out 25.00 g Mg from molten MgCl2 using 3.50 A of current?

Chapter: Problem: 20.93

Chemistry: The Central Science 13
(a) Calculate the mass of Li formed by electrolysis of molten LiCl by a current of 7.5 * 104 A flowing for a period of 24 h. Assume the electrolytic cell is 85% efficient. (b) What is the minimum voltage required to drive the reaction?

Chapter: Problem: 20.94

Chemistry: The Central Science 13
Elemental calcium is produced by the electrolysis of molten CaCl2. (a) What mass of calcium can be produced by this process if a current of 7.5 * 103 A is applied for 48 h? Assume that the electrolytic cell is 68% efficient. (b) What is the minimum voltage needed to cause the electrolysis?

Chapter: Problem: 20.95

Chemistry: The Central Science 13
Metallic gold is collected from below the anode when crude copper metal is refined by electrolysis. Explain this behavior

Chapter: Problem: 20.96

Chemistry: The Central Science 13
The crude copper that is subjected to electrorefining contains tellurium as an impurity. The standard reduction potential between tellurium and its lowest common oxidation state, Te 4+, is Te 4+1aq2 + 4 e- Te1s2 E red = 0.57 V Given this information, describe the probable fate of tellurium impurities

Chapter: Problem: 20.97

Chemistry: The Central Science 13
A disproportionation reaction is an oxidationreduction reaction in which the same substance is oxidized and reduced. Complete and balance the following disproportionation reactions: (a) Ni +1aq2 Ni 2+1aq2 + Ni1s2 (acidic solution) (b) MnO4 2-1aq2 MnO4 -1aq2 + MnO21s2 (acidic solution) (c) H2SO31aq2 S

Chapter: Problem: 20.98

Chemistry: The Central Science 13
A common shorthand way to represent a voltaic cell is anode? anode solution ? ? cathode solution ?cathode A double vertical line represents a salt bridge or a porous barrier. A single vertical line represents a change in phase, such as from solid to solution. (a) Write the half-reactions and overall

Chapter: Problem: 20.99

Chemistry: The Central Science 13
Predict whether the following reactions will be spontaneous in acidic solution under standard conditions: (a) oxidation of Sn to Sn2+ by I2 (to form I -), (b) reduction of Ni 2+ to Ni by I - (to form I2), (c) reduction of Ce 4+ to Ce 3+ by H2O2, (d) reduction of Cu2+ to Cu by Sn2+ (to form Sn4+).

Chapter: Problem: 20.100

Chemistry: The Central Science 13
Gold exists in two common positive oxidation states, +1 and +3. The standard reduction potentials for these oxidation states are Au+1aq2 + e- Au1s2 E red = +1.69 V Au3+1aq2 + 3 e- Au1s2 E red = +1.50 V (a) Can you use these data to explain why gold does not tarnish in the air? (b) Suggest several sub

Chapter: Problem: 20.101

Chemistry: The Central Science 13
A voltaic cell is constructed from an Ni 2+1aq2 - Ni1s2 half-cell and an Ag+1aq2 - Ag1s2 half-cell. The initial concentration of Ni 2+1aq2 in the Ni 2+ - Ni half-cell is 3Ni 2+4 = 0.0100 M. The initial cell voltage is +1.12 V. (a) By using data in Table 20.1, calculate the standard emf of this voltai

Chapter: Problem: 20.102

Chemistry: The Central Science 13
A voltaic cell is constructed that uses the following half-cell reactions: Cu+1aq2 + e- Cu1s2 I21s2 + 2 e- 2 I -1aq2 The cell is operated at 298 K with 3Cu+4 = 0.25 M and 3I -4 = 3.5 M. (a) Determine E for the cell at these concentrations. (b) Which electrode is the anode of the cell? (c) Is the answ

Chapter: Problem: 20.103

Chemistry: The Central Science 13
Using data from Appendix E, calculate the equilibrium constant for the disproportionation of the copper(I) ion at room temperature: 2 Cu+1aq2 Cu2+1aq2 + Cu1s2.

Chapter: Problem: 20.104

Chemistry: The Central Science 13
(a) Write the reactions for the discharge and charge of a nickelcadmium (nicad) rechargeable battery. (b) Given the following reduction potentials, calculate the standard emf of the cell: Cd1OH221s2 + 2 e- Cd1s2 + 2 OH-1aq2 E red = -0.76 V NiO1OH21s2 + H2O1l2 + e- Ni1OH221s2 + OH-1aq2 E red = +0.49 V

Chapter: Problem: 20.105

Chemistry: The Central Science 13
The capacity of batteries such as the typical AA alkaline battery is expressed in units of milliamp- hours (mAh). An AA alkaline battery yields a nominal capacity of 2850 mAh. (a) What quantity of interest to the consumer is being expressed by the units of mAh? (b) The starting voltage of a fresh alk

Chapter: Problem: 20.106

Chemistry: The Central Science 13
If you were going to apply a small potential to a steel ship resting in the water as a means of inhibiting corrosion, would you apply a negative or a positive charge? Explain.

Chapter: Problem: 20.107

Chemistry: The Central Science 13
(a) How many coulombs are required to plate a layer of chromium metal 0.25 mm thick on an auto bumper with a total area of 0.32 m2 from a solution containing CrO4 2-? The density of chromium metal is 7.20 g>cm3 . (b) What current flow is required for this electroplating if the bumper is to be plated

Chapter: Problem: 20.108

Chemistry: The Central Science 13
Magnesium is obtained by electrolysis of molten MgCl2. (a) Why is an aqueous solution of MgCl2 not used in the electrolysis? (b) Several cells are connected in parallel by very large copper bars that convey current to the cells. Assuming that the cells are 96% efficient in producing the desired produ

Chapter: Problem: 20.109

Chemistry: The Central Science 13
Calculate the number of kilowatt-hours of electricity required to produce 1.0 * 103 kg (1 metric ton) of aluminum by electrolysis of Al 3+ if the applied voltage is 4.50 V and the process is 45% efficient.

Chapter: Problem: 20.110

Chemistry: The Central Science 13
Some years ago a unique proposal was made to raise the Titanic. The plan involved placing pontoons within the ship using a surface-controlled submarine-type vessel. The pontoons would contain cathodes and would be filled with hydrogen gas formed by the electrolysis of water. It has been estimated tha

Chapter: Problem: 20.111

Chemistry: The Central Science 13
The Haber process is the principal industrial route for converting nitrogen into ammonia: N21g2 + 3 H21g2 2 NH31g2 (a) What is being oxidized, and what is being reduced? (b) Using the thermodynamic data in Appendix C, calculate the equilibrium constant for the process at room temperature. (c) Calcula

Chapter: Problem: 20.112

Chemistry: The Central Science 13
In a galvanic cell the cathode is an Ag+11.00 M2>Ag1s2 halfcell. The anode is a standard hydrogen electrode immersed in a buffer solution containing 0.10 M benzoic acid 1C6H5COOH2 and 0.050 M sodium benzoate 1C6H5COO-Na +2. The measured cell voltage is 1.030 V. What is the pKa of benzoic acid?

Chapter: Problem: 20.113

Chemistry: The Central Science 13
Consider the general oxidation of a species A in solution: A A+ + e-. The term oxidation potential is sometimes used to describe the ease with which species A is oxidized the easier a species is to oxidize, the greater its oxidation potential. (a) What is the relationship between the standard oxidati

Chapter: Problem: 20.114

Chemistry: The Central Science 13
A voltaic cell is based on Ag+1aq2>Ag1s2 and Fe 3+1aq2> Fe 2+1aq2 half-cells. (a) What is the standard emf of the cell? (b) Which reaction occurs at the cathode and which at the anode of the cell? (c) Use S values in Appendix C and the relationship between cell potential and free-energy change to pre

Chapter: Problem: 20.115

Chemistry: The Central Science 13
Hydrogen gas has the potential for use as a clean fuel in reaction with oxygen. The relevant reaction is 2 H21g2 + O21g2 2 H2O1l2 Consider two possible ways of utilizing this reaction as an electrical energy source: (i) Hydrogen and oxygen gases are combusted and used to drive a generator, much as co

Chapter: Problem: 20.116

Chemistry: The Central Science 13
Cytochrome, a complicated molecule that we will represent as CyFe 2+, reacts with the air we breathe to supply energy required to synthesize adenosine triphosphate (ATP). The body uses ATP as an energy source to drive other reactions. (Section 19.7) At pH 7.0 the following reduction potentials pertai

Chapter: Problem: 20.117

Chemistry: The Central Science 13
The standard potential for the reduction of AgSCN(s) is +0.0895 V. AgSCN1s2 + e- Ag1s2 + SCN- 1aq2 Using this value and the electrode potential for Ag+1aq2, calculate the Ksp for AgSCN.

Chapter: Problem: 20.118

Chemistry: The Central Science 13
The Ksp value for PbS(s) is 8.0 * 10-28 . By using this value together with an electrode potential from Appendix E, determine the value of the standard reduction potential for the reaction PbS1s2 + 2 e- Pb1s2 + S2-1aq2

Chapter: Problem: 20.119

Chemistry: The Central Science 13
A student designs an ammeter (a device that measures electrical current) that is based on the electrolysis of water into hydrogen and oxygen gases. When electrical current of unknown magnitude is run through the device for 2.00 min, 12.3 mL of water-saturated H21g2 is collected. The temperature of th

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