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Problem 1
Which of the following unbalanced half-reactions is correctly labeled as an oxidation or reduction? (a) NO3- (aq) → NO(g); reduction (b) Zn(s) → Zn2+(aq); reduction (c) ClO3-(aq) → Cl2(g); oxidation (d) Br-(aq) → Br2(l); reduction
Problem 2
What is the coefficient on Sn2+ when the following reaction is balanced in acidic solution?
(a) 2 (b) 4 (c) 5 (d) 7
Problem 3
Balance the redox reaction in basic solution. What is the coefficient on the hydroxide ion, and on which side of the equation does it appear? (a) 2 OH- in reactants (b) 4 OH- in products (c) 4 OH- in reactants (d) 3 OH- in reactants
Problem 5
What is the line notation for the galvanic cell?
(a)
(b) (c) (d) Problem 7
Consider the following table of standard reduction potentials:. Which substance(s) can be reduced by C-? (a) D and B (b) A- (c) D3+ and B2+ (d) AProblem 10
What is the pH of the solution in the cathode compartment of the following cell if the measured cell potential at 25 °C is 0.58 V? (Refer to Appendix B for standard reduction potentials.)(a) 8.0 (b) 4.5 (c) 2.2 (d) 3.0 Problem 14
What are the products of the overall reaction in the elec-trolysis of an aqueous solution of sodium hydroxide? (Refer to Table 19.1 for standard reduction potentials.) (a) Na(s) and O2(g) (b) H2(g) and O2(g) (c) Na(s) and H2(g) (d) Na(s) and H2O2(aq)Problem 19.67
How are standard reduction potentials defined?
Problem 19.68
The silver oxide–zinc battery used in watches delivers a voltage of 1.60 V. Calculate the free-energy change (in kilo-joules) for the cell reaction
Problem 19.88
Calculate the standard cell potential and the standard free-energy change (in kilojoules) for the reaction below. (See Appendix D for standard reduction potentials.) <QUESTION REFERENCES APPENDIX D>
Problem 37
Consider a Daniell cell with 1.0 M ion concentrations:
Does the cell voltage increase, decrease, or remain the same when each of the following changes is made? Explain. (a) Write a balanced equation for each cell reaction.
Problem 38
Sketch a cell with inert electrodes suitable for electrolysis of aqueous CuBr2. (b) Indicate the direction of electron and ion flow.Problem 40a
Porous pellets of TiO2 can be reduced to titanium metal at the cathode of an electrochemical cell containing molten CaCl2 as the electrolyte. When the TiO2 is reduced, the O2-ions dis-solve in the CaCl2 and are subsequently oxidized to O2 gas at the anode. This approach may be the basis for a less expensive process than the one currently used for producing titanium.
(a) Label the anode and cathode, and indicate the signs of the electrodes.
Problem 40c
Porous pellets of TiO2 can be reduced to titanium metal at the cathode of an electrochemical cell containing molten CaCl2 as the electrolyte. When the TiO2 is reduced, the O2-ions dis-solve in the CaCl2 and are subsequently oxidized to O2 gas at the anode. This approach may be the basis for a less expensive process than the one currently used for producing titanium.
(c) Write balanced equations for the anode, cathode, and overall cell reactions.
Problem 42b
Classify each of the following unbalanced half-reactions as either an oxidation or a reduction. (b) Pt2+ (aq) → Pt(s)
Problem 42c
Classify each of the following unbalanced half-reactions as either an oxidation or a reduction. (c) Cr(s) → Cr3+ (aq)
Problem 43a
Classify each of the following unbalanced half-reactions as either an oxidation or a reduction. (a) O2(g) → OH-(aq)
Problem 43b
Classify each of the following unbalanced half-reactions as either an oxidation or a reduction. (b) H2O2(aq) → O2(g)
Problem 43c
Classify each of the following unbalanced half-reactions as either an oxidation or a reduction. (c) MnO4-(aq) → MnO42-(aq)
Problem 43d
Classify each of the following unbalanced half-reactions as either an oxidation or a reduction. (d) CH3O→H(aq) CH2O(aq)
Problem 44
Balance the half-reactions in Problem 19.42, assuming that they occur in acidic solution.
Problem 45
Balance the half-reactions in Problem 19.43, assuming that they occur in basic solution.
Problem 46a
Write unbalanced oxidation and reduction half-reactions for the following processes. . (a) Te(s) + NO3-(aq) → TeO2(s) + NO(g)
Problem 46b
Write unbalanced oxidation and reduction half-reactions for the following processes. . (b) H2O2(aq) + Fe2+(aq) → Fe3+(aq) + H2O(l)
Problem 47a
Write unbalanced oxidation and reduction half-reactions for the following processes. (a) Mn(s) + NO3-(aq) → Mn2+(aq) + NO2(g)
Problem 47b
Write unbalanced oxidation and reduction half-reactions for the following processes. (b) Mn3+(aq) → MnO2(s) + Mn2+(aq)
Problem 48a
Balance the following half-reactions. (a) (acidic) Cr2O72-(aq) → Cr3+(aq)
Problem 48b
Balance the following half-reactions. (b) (basic) CrO42-(aq) → Cr(OH)4-(aq)
Problem 48c
Balance the following half-reactions. (c) (basic) Br3+(aq) → BiO3-(aq)
Problem 48d
Balance the following half-reactions. (d) (basic) ClO-(aq) → Cl-(aq)
