(3) If a current is allowed to flow through this cell, what substance is deposited?
Lanthanum loses electrons and escapes into the solution as lanthanum ions. Gold ions in solution are reduced by these electrons. The result of the reduction is gold in solid form, which plates out as metallic gold on the cathode.
(4) Describe the structure of a galvanic cell using these reactions and give the path of the electron flow.
Since gold is being reduced, it is gaining electrons. The electrons gained by the gold must have been released by the lanthanum. A galvanic cell would consist of solid gold in a solution containing gold ions. Such a solution could be aqueous gold phosphate. The anode would consist of solid lanthanum in lanthanum phosphate. The two electrodes must be connected by a wire and the two solutions by a salt bridge. The solid lanthanum loses electrons. The resulting lanthanum ions join the solution while the electrons travel through the wire to the cathode. At the cathode, the extra electrons cause solid gold to plate out of the solution. The charge distribution is balanced by the flow of ions through the salt bridge.
