Chapter 21

A voltaic cell consists of two \(\mathrm{H}_{2} / \mathrm{H}^{+}\) half-cells. Half-cell \(\mathrm{A}\) has \(\mathrm{H}_{2}\) at 0.95 atm bubbling into \(0.10 \mathrm{M} \mathrm{HCl}\). Half-cell \(\mathrm{B}\) has \(\mathrm{H}_{2}\) at 0.60 atm bubbling into \(2.0 \mathrm{M} \mathrm{HCl}\). Which half-cell houses the anode? What is the voltage of the cell?

Both a D-sized and an AAA-sized alkaline battery have an output of \(1.5 \mathrm{~V}\). What property of the cell potential allows this to occur? What is different about these two batteries?

During reconstruction of the Statue of Liberty, Teflon spacers were placed between the iron skeleton and the copper plates that cover the statue. What purpose do these spacers serve?

A voltaic cell consists of \(\mathrm{Cr} / \mathrm{Cr}^{3+}\) and \(\mathrm{Cd} / \mathrm{Cd}^{2+}\) half-cells with all components in their standard states. After 10 minutes of operation, a thin coating of cadmium metal has plated out on the cathode. Describe what will happen if you attach the negative terminal of a dry cell ( \(1.5 \mathrm{~V}\) ) to the cathode and the positive terminal to the anode.

In the electrolysis of molten \(\mathrm{NaBr}\) (a) What product forms at the anode? (b) What product forms at the cathode?

In the electrolysis of molten \(\mathrm{BaI}_{2}\) (a) What product forms at the negative electrode? (b) What product forms at the positive electrode?

Write a balanced half-reaction for the product that forms at each electrode in the aqueous electrolysis of the following salts: (a) \(\mathrm{LiF} ;\) (b) \(\mathrm{SnSO}_{4}\).

Write a balanced half-reaction for the product that forms at each electrode in the aqueous electrolysis of the following salts: (a) \(\mathrm{Cr}\left(\mathrm{NO}_{3}\right)_{3} ;\) (b) \(\mathrm{MnCl}_{2}\).

Electrolysis of molten \(\mathrm{MgCl}_{2}\) is the final production step in the isolation of magnesium from seawater by the Dow process (Section 22.4). Assuming that \(45.6 \mathrm{~g}\) of Mg metal forms, (a) How many moles of electrons are required? (b) How many coulombs are required? (c) How many amps will produce this amount in \(3.50 \mathrm{~h} ?\)

How many grams of aluminum can form by passing 305 C through an electrolytic cell containing a molten aluminum salt?