Problem 78a
A voltaic cell consists of a Pb/Pb2+ half-cell and a Cu/Cu2+ half-cell at 25°C. The initial concentrations of Pb2+ and Cu2+ are 0.0500 M and 1.50 M, respectively. a. What is the initial cell potential?
Problem 78b
A voltaic cell consists of a Pb/Pb2+ half-cell and a Cu/Cu2+ half-cell at 25°C. The initial concentrations of Pb2+ and Cu2+ are 0.0500 M and 1.50 M, respectively. b. What is the cell potential when the concentration of Cu2+ has fallen to 0.200 M?
Problem 78c
A voltaic cell consists of a Pb/Pb2+ half-cell and a Cu/Cu2+ half-cell at 25°C. The initial concentrations of Pb2+ and Cu2+ are 0.0500 M and 1.50 M, respectively. c. What are the concentrations of Pb2+ and Cu2+ when the cell potential falls to 0.35 V?
Problem 79
Make a sketch of a concentration cell employing two Zn/Zn2+ half-cells. The concentration of Zn2+ in one of the half-cells is 2.0 M and the concentration in the other half-cell is 1.0×10–3 M. Label the anode and the cathode and indicate the half-reaction occuring at each electrode. Also indicate the direction of electron flow.
Problem 80b
Consider the concentration cell: b. Indicate the direction of electron flow.
Problem 80c
Consider the concentration cell:
c. Indicate what happens to the concentration of Pb2+ in each half-cell.
Problem 81
A concentration cell consists of two Sn/Sn2+ half-cells. The cell has a potential of 0.10 V at 25°C. What is the ratio of the Sn2+ concentrations in the two half-cells?
Problem 82
A Cu/Cu2+ concentration cell has a voltage of 0.22 V at 25 °C. The concentration of Cu2+ in one of the half-cells is 1.5×10–3 M. What is the concentration of Cu2+ in the other half-cell? (Assume the concentration in the unknown cell is the lower of the two concentrations.)
Problem 83
Determine the optimum mass ratio of Zn to MnO2 in an alkaline battery.
Problem 84
What mass of lead sulfate is formed in a lead–acid storage battery when 1.00 g of Pb undergoes oxidation?
- Refer to the tabulated values of ∆Gf° in Appendix IIB to calculate E°cell for a fuel cell that employs the reaction between methane gas (CH4) and oxygen to form carbon dioxide and gaseous water.
Problem 85
Problem 86
Refer to the tabulated values of ∆G°f in Appendix IIB to calculate E°cell for the fuel-cell breathalyzer, which employs the following reaction. ((∆G° for HC2H3O2(g) = -374.2 kJ/mol.)
CH3CH2OH(g) + O2(g) → HC2H3O2(g) + H2O(g)
Problem 87a
Determine whether or not each metal, if coated onto iron, would prevent the corrosion of iron. a. Zn
Problem 87b
Determine whether or not each metal, if coated onto iron, would prevent the corrosion of iron. b. Sn
Problem 87c
Determine whether or not each metal, if coated onto iron, would prevent the corrosion of iron. c. Mn
Problem 88a
Determine whether or not each metal, if coated onto iron, would prevent the corrosion of iron. a. Mg
Problem 88b
Determine whether or not each metal, if coated onto iron, would prevent the corrosion of iron. b. Cr
Problem 88c
Determine whether or not each metal, if coated onto iron, would prevent the corrosion of iron. c. Cu
Problem 89b
Consider the electrolytic cell: b. Indicate the direction of electron flow.
Problem 90
Draw an electrolytic cell in which Mn2+ is reduced to Mn and Sn is oxidized to Sn2+. Label the anode and cathode, indicate the direction of electron flow, and write an equation for the half-reaction occurring at each electrode. What minimum voltage is necessary to drive the reaction?
Problem 91
Write equations for the half-reactions that occur in the electrolysis of molten potassium bromide.
Problem 92
What products are obtained in the electrolysis of molten NaI?
- Write equations for the half-reactions that occur in the electrolysis of a mixture of molten potassium bromide and molten lithium bromide.
Problem 93
Problem 94
What products are obtained in the electrolysis of a molten mixture of KI and KBr?
Problem 96a
Write equations for the half-reactions that occur at the anode and cathode for the electrolysis of each aqueous solution. a. Ni(NO3)2(aq)
Problem 97
Make a sketch of an electrolysis cell that electroplates copper onto other metal surfaces. Label the anode and the cathode and indicate the reactions that occur at each.
- How can one sketch an electrolysis cell that electroplates nickel onto other metal surfaces, labeling the anode and cathode and indicating the reactions that occur at each?
Problem 98
- Copper can be electroplated at the cathode of an electrolysis cell by the half-reaction: Cu2+(aq) + 2 e- → Cu(s). How much time would it take for 325 mg of copper to be plated at a current of 5.6 A?
Problem 99
Problem 100
Silver can be electroplated at the cathode of an electrolysis cell by the half-reaction: Ag+(aq) + e– → Ag(s) What mass of silver would plate onto the cathode if a current of 6.8 A flowed through the cell for 72 min?
Problem 101
A major source of sodium metal is the electrolysis of molten sodium chloride. What magnitude of current produces 1.0 kg of sodium metal in 1 hour?
Ch.20 - Electrochemistry