Problem 106
Consider the unbalanced redox reaction: Cr2O72-(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
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. b. 4.85 g Cu
Problem 109c
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. c. 2.42 g Ag
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 111
The cell potential of this electrochemical cell depends on the pH of the solution in the anode half-cell. Pt(s) | H2(g, 1 atm) | H+(aq, ? M) || Cu2+(aq, 1.0 M) | Cu(s) What is the pH of the solution if Ecell is 355 mV?
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 Ecell 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?
- 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 114
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
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. b. What is the voltage of the battery after delivering 5.0 A for 8.0 h?
Problem 115c
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. c. How long can the battery deliver 5.0 A before going dead?
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?
- 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?
Problem 117
- When a suspected drunk driver blows 188 mL of their breath through the fuel-cell breathalyzer described in Section 19.7, the breathalyzer produces an average of 324 mA of current for 10 s. Assuming a pressure of 1.0 atm and a temperature of 25 °C, what percent (by volume) of the driver’s breath is ethanol?
Problem 118
- The Ksp of CuI is 1.1 * 10^-12. Find Ecell for the cell: Cu(s) | CuI(s) | I^-(aq)(1.0 M) || Cu^+(aq)(1.0 M) | Cu(s)
Problem 119
Problem 121
Calculate ∆G°rxn and K for each reaction.
a. The disproportionation of Mn2+(aq) to Mn(s) and MnO2(s) in acid solution at 25 °C.
b. The disproportionation of MnO2(s) to Mn2+(aq) and MnO4–(aq) in acid solution at 25 °C.
Problem 122a
Calculate ∆G°rxn and K for each reaction. a. The reaction of Cr2+(aq) with Cr2O72–(aq) in acid solution to form Cr3+(aq).
Problem 122b
Calculate ∆G°rxn and K for each reaction. b. The reaction of Cr3+(aq) and Cr(s) to form Cr2+(aq). [The electrode potential of Cr2+(aq) to Cr(s) is -0.91 V.]
- The molar mass of a metal (M) is 50.9 g/mol; it forms a chloride of unknown composition. Electrolysis of a sample of the molten chloride with a current of 6.42 A for 23.6 minutes produces 1.20 g of M at the cathode. Determine the empirical formula of the chloride.
Problem 123
Problem 124
A metal forms the fluoride MF3. Electrolysis of the molten fluo- ride by a current of 3.86 A for 16.2 minutes deposits 1.25 g of the metal. Calculate the molar mass of the metal.
Problem 125
A sample of impure tin of mass 0.535 g is dissolved in strong acid to give a solution of Sn2+. The solution is then titrated with a 0.0448 M solution of NO3–, which is reduced to NO(g). The equivalence point is reached upon the addition of 0.0344 L of the NO3– solution. Find the percent by mass of tin in the original sample, assuming that it contains no other reducing agents.
- A 0.0251-L sample of a solution of Cu+ requires 0.0322 L of 0.129 M KMnO4 solution to reach the equivalence point. The products of the reaction are Cu2+ and Mn2+. What is the concentration of the Cu+ solution?
Problem 126
Problem 127
A current of 11.3 A is applied to 1.25 L of a solution of 0.552 M HBr converting some of the H+ to H2(g), which bubles out of solution. What is the pH of the solution after 73 minutes?
Problem 129
An MnO2(s)/Mn2+(aq) electrode in which the pH si 10.24 is prepared. Find the [Mn2+] necessary to lower the potential of the half-cell to 0.00 V (at 25°C)
Problem 130
To what pH should you adjust a standard hydrogen electrode to get an electrode potential of -0.122 V? (Assume that the partial pressure of hydrogen gas remains at 1 atm.)
Ch.19 - Electrochemistry