Problem 21
An award is being plated with pure gold before it is presented to a recipient. If the area of the award is \(55.0 \mathrm{~cm}^{2}\) and will be plated with \(3.00 \mu \mathrm{m}\) of Au, what mass of Au will be plated on the award? The density of Au is \(19.3 \mathrm{~g} / \mathrm{cm}^{3}\).
Problem 22
The unit of electrical charge is called the coulomb (C). It takes 96,500 coulombs of charge to reduce \(27.0 \mathrm{~g}\) of \(\mathrm{Al}\) from \(\mathrm{Al}^{3+}\) to Al metal. At \(1,040 \mathrm{~cm}^{3}\), how many coulombs of charge were needed to reduce the aluminum in the cap of the Washington monument, assuming the cap is pure Al? The density of \(\mathrm{Al}\) is \(2.70 \mathrm{~g} /\) \(\mathrm{cm}^{3}\).
