Problem 27c
Complete and balance the following equations, and identify the oxidizing and reducing agents: MnO4-(aq) + Br-(aq) โ MnO2(s) + BrO3-(aq) (basic solution)
Problem 28
Complete and balance the following equations, and identify the oxidizing and reducing agents:
a. MnO4โ(๐๐)+CH3OH(๐๐)โถMn2+(๐๐)+HCOOH(๐๐)(acidic solution)
b. As2O3(๐ )+NO3โ(๐๐)โถH3AsO4(๐๐)+N2O3(๐๐)(acidic solution)
c. Pb(OH)42โ(๐๐)+ClOโ(๐๐)โถPbO2(๐ )+Clโ(๐๐)(basic solution)
Problem 28b
Complete and balance the following equations, and identify the oxidizing and reducing agents: As2O3(s) + NO3-(aq) โ H3AsO4(aq) + N2O3(aq) (acidic solution)
Problem 30c
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.) H2O21aq2 + ClO21aq2 ยก ClO2-1aq2 + O21g2 (basic solution)
Problem 33f
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 ยก Fe2+1aq2 + 2 Ag1s2 (f) In which directions do the cations and anions migrate through the solution?

Problem 35a
(a) What is the definition of the volt?
Problem 35b
(b) Do all voltaic cells produce a positive cell potential?
- (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?
Problem 36
Problem 37b
(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.
Problem 38c
(c) Why is it impossible to measure the standard reduction potential of a single half-reaction?
- A voltaic cell that uses the reaction Tl3+(aq) + 2 Cr2+(aq) โ Tl+(aq) + 2 Cr3+(aq) has a measured standard cell potential of +1.19 V. (c) Sketch the voltaic cell, label the anode and cathode, and indicate the direction of electron flow.
Problem 39
Problem 40c
A voltaic cell that uses the reaction PdCl42-(aq) + Cd(s) โ Pd(s) + 4 Cl-(aq) + Cd2+(aq) has a measured standard cell potential of +1.03 V. (c) Sketch the voltaic cell, label the anode and cathode, and indicate the direction of electron flow
Problem 41c
Using standard reduction potentials (Appendix E), calculate the standard emf for each of the following reactions: (c) Fe1s2 + 2 Fe3+1aq2 ยก 3 Fe2+1aq2
Problem 41d
Using standard reduction potentials (Appendix E), calculate the standard emf for each of the following reactions: (d) 2 NO3-1aq2 + 8 H+1aq2 + 3 Cu1s2 ยก 2 NO1g2 + 4 H2O1l2 + 3 Cu2+1aq2
- Using data in Appendix E, calculate the standard emf for each of the following reactions: (a) H2(g) + F2(g) โ 2 H+(aq) + 2 F-(aq) (b) Cu2+(aq) + Ca(s) โ Cu(s) + Ca2+(aq) (c) 3 Fe2+(aq) โ Fe(s) + 2 Fe3+(aq) (d) 2 ClO3-(aq) + 10 Br-(aq) + 12 H+(aq) โ Cl2(g) + 5 Br2(l) + 6 H2O(l)
Problem 42
Problem 43
The standard reduction potentials of the following halfreactions are given in Appendix E:
Ag+(aq) + e- โ Ag(s)
Cu2+(aq) + 2 e- โ Cu(s)
Ni2+(aq) + 2 e- โ Ni(s)
Cr3+(aq) + 3 e- โ Cr(s)
(a) Determine which combination of these half-cell reactions leads to the cell reaction with the largest positive cell potential and calculate the value.
(b) Determine which combination of these half-cell reactions leads to the cell reaction with the smallest positive cell potential and calculate the value.
- A 1 M solution of Cu(NO3)2 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 as the cathode? (b) Which electrode gains mass, and which loses mass as the cell reaction proceeds?
Problem 45
Problem 46
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 the two beakers. (a) Which electrode serves as the anode, and which as the cathode? (b) Does the Cd electrode gain or lose mass as the cell reaction proceeds? (c) Write the equation for the overall cell reaction.
Problem 47a,b,c
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)
- 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)
Problem 48
Problem 49a,b,c
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)
Problem 49d
By using the data in Appendix E, determine whether each of the following substances is likely to serve as an oxidant or a reductant: (d) Zn(s)
Problem 50
Is each of the following substances likely to serve as an oxidant or a reductant: (a) Ce3+(aq) (b) Ca(s) (c) ClO3-(aq) (d) N2O5(g)?
Problem 51a
(a) Assuming standard conditions, arrange the following in order of increasing strength as oxidizing agents in acidic solution: Cr2O72-, H2O2, Cu2+, Cl2, O2.
- 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, Cr2O72-?
Problem 52
- The standard reduction potential of Eu2+(aq) is -0.43 V. Using Appendix E, which of the following substances is capable of reducing Eu3+(aq) to Eu2+(aq) under standard conditions: Al, Co, H2O2, N2H5+, H2C2O4?
Problem 53
Problem 55a
Given the following reduction half-reactions:
Fe3+(aq) + e- โ Fe2+(aq) Eยฐred = +0.77 V
S2O62-(aq) + 4 H+(aq) + 2 e- โ 2 H2SO3(aq) Eยฐred = +0.60 V
N2O(g) + 2 H+(aq) + 2 e- โ N2(g) + H2O(l) Eยฐred = -1.77 V
VO2+(aq) + 2 H+(aq) + e- โ VO2+ + H2O(l) Eยฐred = +1.00 V
(a) Write balanced chemical equations for the oxidation of Fe2+(aq) by S2O62-(aq), by N2O(aq), and by VO2+(aq).
Problem 55b
Given the following reduction half-reactions:
Fe3+(aq) + e- โ Fe2+(aq) Eยฐred = +0.77 V
S2O62-(aq) + 4 H+(aq) + 2 e- โ 2 H2SO3(aq) Eยฐred = +0.60 V
N2O(g) + 2 H+(aq) + 2 e- โ N2(g) + H2O(l) Eยฐred = -1.77 V
VO2+(aq) + 2 H+(aq) + e- โ VO2+ + H2O(l) Eยฐred = +1.00 V
(b) Calculate โGยฐ for each reaction at 298 K.
Problem 56
Given the following reduction half-reactions:
Fe3+(aq) + e- โ Fe2+(aq) Eยฐred = +0.77 V
S2O62-(aq) + 4 H+(aq) + 2 e- โ 2 H2SO3(aq) Eยฐred = +0.60 V
N2O(g) + 2 H+(aq) + 2 e- โ N2(g) + H2O(l) Eยฐred = -1.77 V
VO2+(aq) + 2 H+(aq) + e- โ VO2+ + H2O(l) Eยฐred = +1.00 V
(c) Calculate the equilibrium constant K for each reaction at 298 K.
Problem 56a
For each of the following reactions, write a balanced equation, calculate the standard emf, calculate โGยฐ at 298 K, and calculate the equilibrium constant K at 298 K. (a) Aqueous iodide ion is oxidized to I21s2 by Hg22+1aq2.
Ch.20 - Electrochemistry
