Problem 39
Starting with magnesium and concentrated nitric acid, describe how you would prepare magnesium oxide. [Hint: First convert Mg to \(\mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}\). Next, \(\mathrm{MgO}\) can be obtained by heating \(\mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}\).
Problem 40
Describe two ways of preparing magnesium chloride.
Problem 41
The second ionization energy of magnesium is only about twice as great as the first, but the third ionization energy is 10 times as great. Why does it take so much more energy to remove the third electron?
Problem 42
List the sulfates of the Group \(2 \mathrm{~A}\) metals in order of increasing solubility in water. Explain the trend. (Hint: You need to consult a chemistry handbook.)
Problem 43
Helium contains the same number of electrons in its outer shell as do the alkaline earth metals. Explain why helium is inert whereas the Group 2 A metals are not.
Problem 44
When exposed to air, calcium first forms calcium oxide, which is then converted to calcium hydroxide, and finally to calcium carbonate. Write a balanced equation for each step.
Problem 45
Write chemical formulas for (a) quicklime and (b) slaked lime.
Problem 46
Describe the Hall process for preparing aluminum.
Problem 48
With the Hall process, how many hours will it take to deposit \(664 \mathrm{~g}\) of \(\mathrm{Al}\) at a current of \(32.6 \mathrm{~A}\) ?
Problem 49
The overall reaction for the electrolytic production of aluminum by means of the Hall process may be represented as $$ \mathrm{Al}_{2} \mathrm{O}_{3}(s)+3 \mathrm{C}(s) \longrightarrow 2 \mathrm{Al}(l)+3 \mathrm{CO}(g) $$ At \(1000^{\circ} \mathrm{C}\), the standard free-energy change for this process is \(594 \mathrm{~kJ} / \mathrm{mol}\). (a) Calculate the minimum voltage required to produce 1 mole of aluminum at this temperature. (b) If the actual voltage applied is exactly three times the ideal value, calculate the energy required to produce \(1.00 \mathrm{~kg}\) of the metal.
