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Problem 155b,c
The reaction of MnO4– with oxalic acid (H2C2O4) in acidic solution, yielding Mn2+ and CO2 gas, is widely used to determine the concentration of permanganate solutions. (b) Use the data in Appendix D to calculate E° for the reaction. (c) Show that the reaction goes to completion by calculating the values of ∆G° and K at 25 °C. (H2C2O4) in acidic solution, yielding Mn2+ and CO2 gas, is widely used to determine the concentration of permanganate solutions.
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
- What is the line notation for the galvanic cell?
Problem 5
(a)
(b) (c) (d) - 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) A
Problem 7
- Calculate E° for each of the following reactions, and determine which are spontaneous under standard-state conditions. (b)
Problem 9
- 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.)
Problem 10
(a) 8.0 (b) 4.5 (c) 2.2 (d) 3.0 - You are on your dream vacation at the beach when a major storm knocks out the power for days. Your cell phone is dead, and you want to make a battery to charge it. You find the following materials in the beach house: blue stone algaecide for pools, which can be used to make a 1.0 M Cu2+ solution; alum in the kitchen, which can be used to make a 1.0 M Al3+ solution; aluminum foil; copper wire; and bologna, which can be used as a salt bridge. (a) What are the half-reactions and overall reaction in the battery? (b) Draw a diagram using beakers, a voltmeter, and salt bridge to show how a battery can be constructed. Label the anode, cathode, and direction of electron flow.
Problem 12
- 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 14
- Chlorine can be prepared in the laboratory by the reaction of hydrochloric acid and potassium permanganate. (c) How many liters of Cl₂ at 1.0 atm and 25 °C will result from the reaction of 179 g KMnO₄ with an excess of HCl?
Problem 15
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>
- Consider a Daniell cell with 1.0 M ion concentrations:
Problem 37
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.
- Sketch a cell with inert electrodes suitable for electrolysis of aqueous CuBr2. (b) Indicate the direction of electron and ion flow.
Problem 38
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)
