Home > categories > Minerals & Metallurgy > Copper Sheets > How is electrolysis used to make pure copper from a lump of impure copper?
Question:

How is electrolysis used to make pure copper from a lump of impure copper?

Describe and explain please. :)

Answer:

Two electrodes are placed in a bath of a copper electrolyte (E.g copper sulphate. This contains free ions vital to the process). The anode, one of the terminals, is coated in the impure copper, and the cathode, the other terminal, has a small amount of pure copper on. The electrodes are connected to a DC circuit, with the cathode on the negative side and the anode on the positive. The copper in the anode's lump of impure copper works as a carrier of the current through the electrolyte substance, as an ion, and is carried over to the cathode, where a very nearly pure (Around 99.97 %) copper substance is found. Hope this helps P
The final step in copper refining is done by a process called electrorefining. The 99% pure copper is refined to give 99.99% pure copper The 99% pure copper from the anode furnace is cast into 750-pound, 3-inch thick, rectangular slabs called anodes. These anodes from the smelter become positive electrodes and thin, three-foot square sheets of pure copper are used as negative electrodes. Forty-five anodes and 46 cathodes are interleaved and immersed in an electrolysis tank filled with a solution of sulfuric acid and copper(II) sulfate. Oxidation occurs at the anode, where copper metal is converted to copper(II) ions with the release of two electrons. At the cathode the opposite reaction occurs: copper(II) ions are joined with two electrons to form copper metal. During the migration of metal ions from anode to cathode through the aqueous solution, the impurities drop to the bottom of the electrolysis cell. Some of these impurities are gold, silver, nickel, selenium, tellurium, and platinum which are themselves recovered to be used. After two weeks, the cathodes are pulled from the tank- -- each one about 350 pounds of 99.99% pure copper. These are washed, bundled, and sold. A new set of cathode starter sheets is inserted and the process continues. After two more weeks, the second set of cathodes is pulled and the remainder of the anodes are melted and cast into new full-size anodes. Anode - oxidation: Cu metal (impure)--- Cu+2 + 2 electrons Cathode - reduction: Cu+2 + 2 electrons --- Cu metal (pure)

Share to: