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Problem 101b
When suspected drunk drivers are tested with a Breathalyzer, the alcohol (ethanol) in the exhaled breath is oxidized to acetic acid with an acidic solution of potassium dichromate: The color of the solution changes because some of the orange Cr2O72- is converted to the green Cr3+ The Breathalyzer measures the color change and produces a meter reading calibrated in blood alcohol content. (b) What is the value of E for the reaction when the concentrations of ethanol, acetic acid, Cr2O7 are 1.0 M and the pH is 4.00?
- What is the reduction potential at 25 °C for the hydrogen electrode in each of the following solutions? The half-reaction is
Problem 102
. (c) Pure water. - At one time on Earth, iron was present mostly as iron(II). Later, once plants had produced a significant quantity of oxygen in the atmosphere, the iron became oxidized to iron(III). Show that Fe2+(aq) can be spontaneously oxidized to Fe3+(aq) by O2(g) at 25°C assuming the following reasonable environmental conditions:
Problem 103
- Standard reduction potentials for the Pb2+/Pb and Cd2+/Cd half-reactions are -0.13 V and -0.40 V, respectively. At what relative concentrations of Pb2+ and Cd2+ will these half-reactions have the same reduction potential?
Problem 104
- Copper reduces dilute nitric acid to nitric oxide (NO) but reduces concentrated nitric acid to nitrogen dioxide (NO2): Assuming that [Cu2+] = 0.10 M and that the partial pressures of NO and NO2 are 1.0 * 10-3 atm, calculate the potential (E) for reactions (1) and (2) at 25 °C and show which reaction has the greater thermodynamic tendency to occur when the concentration of HNO3 is (a) 1.0 M
Problem 105
- What is the pH of the solution in the cathode compartment of the following cell if the measured cell potential at 25 °C is 0.17 V?
Problem 107
- Beginning with the equations that relate E°, ∆G°, and K, show that ∆G° is negative and K 7 1 for a reaction that has a positive value of E°
Problem 108
- If a reaction has an equilibrium constant K 6 1, is E° posi-tive or negative? What is the value of K when E° = 0 V?
Problem 109
- Calculate the equilibrium constant at 25 °C for the reaction
Problem 112
- Calculate the equilibrium constant at 25 °C for the reaction
Problem 113
- Calculate the equilibrium constant at 25 °C for the reaction
Problem 114
. See Appendix D for standard reduction potentials. - The following galvanic cell has a potential of 1.214 V at 25 °C: Calculate the value of Ksp for Hg2Br2 at 25°C
Problem 116
- For the following half-reaction, E° = 1.103 V: Calculate the formation constant Kf for Cu(CN)2-.
Problem 117
- Write a balanced equation for the overall cell reaction when a lead storage battery is being charged. Refer to Section 19.10.
Problem 118
- Write a balanced equation for the overall cell reaction when a lead storage battery is being charged. Refer to Section 19.10.
Problem 119
Problem 120b
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. (b) What voltage can be generated?
Problem 120d
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. (d) An iPhone requires 5.0 V for charging. Can this battery charge the phone? Explain.
Problem 121a
A storm has knocked out power to your beach house, and you would like to build a battery from household items to charge your iPhone. You have the following materials. alum in the kitchen, which can be used to make a 1.0 M Al3+ solution bleach, which is a solution that is approximately a 1.0 M in ClO-aluminum foil, a platinum necklace and bologna, which can be used as a salt bridge (a) What are the half-reactions and overall reaction in the battery?
Problem 121b
A storm has knocked out power to your beach house, and you would like to build a battery from household items to charge your iPhone. You have the following materials. alum in the kitchen, which can be used to make a 1.0 M Al3+ solution bleach, which is a solution that is approximately a 1.0 M in ClO-aluminum foil, a platinum necklace and bologna, which can be used as a salt bridge (b) What voltage can be generated?
Problem 121d
A storm has knocked out power to your beach house, and you would like to build a battery from household items to charge your iPhone. You have the following materials. alum in the kitchen, which can be used to make a 1.0 M Al3+ solution bleach, which is a solution that is approximately a 1.0 M in ClO-aluminum foil, a platinum necklace and bologna, which can be used as a salt bridge (d) An iPhone requires 5.0 V for charging. Can this battery charge the phone? Explain.
- For a lead storage battery: (a) Sketch one cell that shows the anode, cathode, electrolyte, direction of electron and ion flow, and sign of the electrodes. (b) Write the anode, cathode, and overall cell reactions. (c) Calculate the equilibrium constant for the cell reaction (E° = 1.924 V). (d) What is the cell voltage when the cell reaction reaches equilibrium?
Problem 122
Problem 123b
A mercury battery uses the following electrode half-reactions: (b) Calculate ∆G° (in kilojoules) and K at 25 °C for the cell reaction.
Problem 123c
A mercury battery uses the following electrode half-reactions: (c) What is the effect on the cell voltage of a tenfold change in the concentration of KOH in the electrolyte? Explain..
- How does the pH of the solution affect the formation of rust?
Problem 125
- Which of the following describes the process of galvanization that protects steel from rusting? (a) Steel is coated with a layer of paint. (b) Iron in steel is oxidized to form a protective oxide coating. (c) Steel is coated with zinc because zinc is more easily oxidized than iron. (d) A strip of magnesium is attached to steel because the magnesium is more easily oxidized than iron.
Problem 127
- What is meant by cathodic protection? (a) Steel is coated with a layer of paint. (b) Iron in steel is oxidized to form a protective oxide coating. (c) Steel is coated with zinc because zinc is more easily oxidized than iron. (d) A strip of magnesium is attached to steel because the magnesium is more easily oxidized than iron.
Problem 128
Problem 129
Zinc is attached to a ship's steel propeller to prevent the steel from rusting. Write balanced equations for the corro-sion reactions that occur (a) in the presence of Zn and (b) in the absence of Zn.
- Which of the following metals can offer cathodic protec-tion to iron? Select all the correct choices. Mn, Ni, Pb, Sn, Al
Problem 130
- Magnesium metal is produced by the electrolysis of molten magnesium chloride using inert electrodes. (a) Sketch the cell, label the anode and cathode, indicate the sign of the electrodes, and show the direction of electron and ion flow.
Problem 132
- (a) Sketch a cell with inert electrodes suitable for the elec-trolysis of an aqueous solution of sulfuric acid. Label the anode and cathode, and indicate the direction of electron and ion flow. Identify the positive and negative electrodes. (b) Write balanced equations for the anode, cathode, and overall cell reactions.
Problem 133