Ch.19 - Electrochemistry

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Tro 4th Edition

Ch.19 - Electrochemistry

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?

Problem 93

Write equations for the half-reactions that occur in the electrolysis of a mixture of molten potassium bromide and molten lithium bromide.

Problem 94

What products are obtained in the electrolysis of a molten mixture of KI and KBr?

Problem 95

Write equations for the half-reactions that occur at the anode and cathode for the electrolysis of each aqueous solution. a. NaBr(aq) b. PbI₂(aq) c. Na₂SO₄(aq)

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 96b,c

Write equations for the half-reactions that occur at the anode and cathode for the electrolysis of each aqueous solution. b. KCl(aq) c. CuBr₂(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.

Problem 98

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 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?

Problem 103

Consider the reaction shown here occurring at 25 °C: A(s) + B2+(aq) → A2+(aq) + B(s). Given that ∆Gr°xn = -14.0 kJ, determine the value of Ec°ell and K for the reaction, and complete the following table for [B2+], [A2+], Q, Ecell, and ∆Grxn with initial values 1.00, 1, 1.0 * 10^-4, 3.54 * 10^-3, and 1.00 * 10^-4 respectively.

Problem 104

Consider the reaction shown here occurring at 25°C. Cr(s) + Cd²⁺(aq) → Cr²⁺(aq) + Cd(s) Determine E°_cell, K, and ∆G°_rxn for the reaction and complete the table.

[Cd²⁺] [Cr²⁺] Q E_cell 𝚫G_rxn

1.00 1.00

1.00 1.00 × 10^-5

1.00 × 10^-5 1.00

4.18 × 10^-4 1.00

Problem 105

Consider the unbalanced redox reaction: MnO4-(aq) + Zn(s) → Mn2+(aq) + Zn2+(aq). Balance the equation and determine the volume of a 0.500 M KMnO4 solution required to completely react with 2.85 g of Zn.

Problem 106

Consider the unbalanced redox reaction: Cr₂O₇^2-(aq) + Cu(s) → Cr³⁺(aq) + Cu²⁺(aq) Balance the equation and determine the volume of a 0.850 M K₂Cr₂O₇ solution required to completely react with 5.25 g of Cu.

Problem 109a

Determine whether HI can dissolve each metal sample. If it can, write a balanced chemical reaction showing how the metal dissolves in HI and determine the minimum volume of 3.5 M HI required to completely dissolve the sample. a. 2.15 g Al

Problem 109b

Problem 110

Determine if HNO₃ can dissolve each metal sample. If it can, write a balanced chemical reaction showing how the metal dissolves in HNO3 and determine the minimum volume of 6.0 M HNO3 required to completely dissolve the sample. a. 5.90 g Au b. 2.55 g Cu c. 4.83 g Sn

Problem 112

The cell potential of this electrochemical cell depends on the gold concentration in the cathode half-cell. Pt(s) | H₂(g, 1.0 atm) | H⁺(aq, 1.0 M) || Au³⁺(aq, ? M) | Au(s) What is the concentration of Au³⁺ in the solution if E_cell is 1.22 V?

Problem 113

A friend wants you to invest in a new battery she has designed that produces 24 V in a single voltaic cell. Why should you be wary of investing in such a battery?

Problem 114

What voltage can theoretically be achieved in a battery in which lithium metal is oxidized and fluorine gas is reduced, and why might such a battery be difficult to produce?

Problem 115a

A battery relies on the oxidation of magnesium and the reduction of Cu²⁺. The initial concentrations of Mg²⁺ and Cu²⁺ are 1.0 × 10^–4 M and 1.5 M, respectively, in 1.0-liter half-cells. a. What is the initial voltage of the battery?

Problem 115b

Problem 115c

Problem 116a

A rechargeable battery is constructed based on a concentration cell constructed of two Ag/Ag⁺ half-cells. The volume of each half-cell is 2.0 L, and the concentrations of Ag⁺ in the half-cells are 1.25 M and 1.0×10^–3 M. a. How long can this battery deliver 2.5 Aof current before it goes dead?

Problem 116b

A rechargeable battery is constructed based on a concentration cell constructed of two Ag/Ag⁺ half-cells. The volume of each half-cell is 2.0 L, and the concentrations of Ag⁺ in the half-cells are 1.25 M and 1.0 × 10^–3 M. b. What mass of silver is plated onto the cathode by running at 3.5 A for 5.5 h?

Problem 116c

A rechargeable battery is constructed based on a concentration cell constructed of two Ag/Ag⁺ half-cells. The volume of each half-cell is 2.0 L, and the concentrations of Ag⁺ in the half-cells are 1.25 M and 1.0 × 10^–3 M. c. Upon recharging, how long would it take to redissolve 1.00 × 10² g of silver at a charging current of 10.0 amps?

Problem 117

If a water electrolysis cell operates at a current of 7.8 A, how long will it take to generate 25.0 L of hydrogen gas at a pressure of 25.0 atm and a temperature of 25 °C?