Problem 53
What is the hourly production rate of chlorine gas (in \(\mathrm{kg})\) from an electrolytic cell using aqueous \(\mathrm{NaCl}\) electrolyte and carrying a current of \(1.500 \times 10^{3} \mathrm{~A} ?\) The anode efficiency for the oxidation of \(\mathrm{Cl}^{-}\) is 93.0 percent.
Problem 56
A quantity of \(0.300 \mathrm{~g}\) of copper was deposited from a \(\mathrm{CuSO}_{4}\) solution by passing a current of \(3.00 \mathrm{~A}\) through the solution for 304 s. Calculate the value of the Faraday constant.
Problem 57
In a certain electrolysis experiment, \(1.44 \mathrm{~g}\) of Ag were deposited in one cell (containing an aqueous \(\mathrm{AgNO}_{3}\) solution), while \(0.120 \mathrm{~g}\) of an unknown metal \(\mathrm{X}\) was deposited in another cell (containing an aqueous \(\mathrm{XCl}_{3}\) solution) in series with the \(\mathrm{AgNO}_{3}\) cell. Calculate the molar mass of \(\mathrm{X}\).
Problem 58
One of the half-reactions for the electrolysis of water is: $$2 \mathrm{H}^{+}(a q)+2 e^{-} \longrightarrow \mathrm{H}_{2}(g)$$ If \(0.845 \mathrm{~L}\) of \(\mathrm{H}_{2}\) is collected at \(25^{\circ} \mathrm{C}\) and \(782 \mathrm{mmHg}\), how many faradays of electricity had to pass through the solution?
Problem 59
Steel hardware, including nuts and bolts, is often coated with a thin plating of cadmium. Explain the function of the cadmium layer.
Problem 60
"Galvanized iron" is steel sheet that has been coated with zinc; "tin" cans are made of steel sheet coated with tin. Discuss the functions of these coatings and the electrochemistry of the corrosion reactions that occur if an electrolyte contacts the scratched surface of a galvanized iron sheet or a tin can.
Problem 61
Tarnished silver contains \(\mathrm{Ag}_{2} \mathrm{~S} .\) The tarnish can be removed by placing silverware in an aluminum pan containing an inert electrolyte solution, such as \(\mathrm{NaCl}\). Explain the electrochemical principle for this procedure. [The standard reduction potential for the half- cell reaction \(\mathrm{Ag}_{2} \mathrm{~S}(s)+2 e^{-} \longrightarrow 2 \mathrm{Ag}(s)+\mathrm{S}^{2-}(a q)\) is \(\left.-0.71 \mathrm{~V} .\right]\)
Problem 62
How does the tendency of iron to rust depend on the pH of the solution?
Problem 64
The oxidation of \(25.0 \mathrm{~mL}\) of a solution containing \(\mathrm{Fe}^{2+}\) requires \(26.0 \mathrm{~mL}\) of \(0.0250 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) in acidic solution. Balance the following equation, and calculate the molar concentration of \(\mathrm{Fe}^{2+}\) : $$ \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+\mathrm{Fe}^{2+}+\mathrm{H}^{+} \longrightarrow \mathrm{Cr}^{3+}+\mathrm{Fe}^{3+} $$
Problem 65
As discussed in Section \(19.5,\) the potential of \(\mathrm{a}\) concentration cell diminishes as the cell operates and the concentrations in the two compartments approach each other. When the concentrations in both compartments are the same, the cell ceases to operate. At this stage, is it possible to generate a cell potential by adjusting a parameter other than concentration? Explain.
