Commercial copper mining operations convert CuS or CuO ore into
copper metal by smelting the ore in air. Solid Cu produced in this
fashion is ~99% pure. However, most Cu uses require Cu that is
99.99% or greater in purity. To remove that last ~1% of impurities,
Cu smelting operations electrolytically refine Cu by placing impure
Cu cathode ingots in a CuSO44 and sulfuric acid mixture with a
steel plate acting as the anode. The mixture is subjected to a
voltage of 0.35 V and current of 380.0 amps. Cu is oxidized to
Cu2+(aq) ions, which migrate to the steel anode where they are
reduced back to Cu(s). Any impurities in the copper (primarily Au,
Ag, and Pt) precipitate into the solution. How long, in hours, must
the company run this process to purify 200.0 pounds of Cu?