In electroplating electrical energy provides electrons to convert metal ions into atoms. A thin metal coating is deposited on a surface to protect it or to make it more beautiful. Electroplating is used to apply a thin layer of gold to a cheap jewelry base or to apply silver to stainless steel to create formal tableware. An electroplating cell consists of an anode and a cathode (two electrodes), a solution of metal ions, and a source of electricity. Electroplating is a form of electrolysis. Electrolysis means separation by electricity. Electroplating is an oxidation reduction reaction where one group of atoms is oxidized or loses electrons and the other group of atoms is reduced or gains electrons.
A beginners guide to copper electroplating involves creating a piece of copper jewelry. A small piece of copper jewelry can be electroplated using the following procedure. 250 ml of a 0.5 molar solution of copper sulfate is poured into a 400 ml beaker. A leaf about three inches long will be used as the base of the jewelry piece. Gently wash the leaf with soap and water ensuring that no oil from the hands is present. Oil will prevent copper from plating onto the leaf surface.
Attach a wire lead from the anode (negative terminal) to a strip of copper foil. Attach the other wire lead of the cathode (positive terminal) to the leaf. Immerse the leaf and the copper strip in the copper sulfate electroplating solution. Attach the anode (strip of copper foil) wire lead to the negative side of a 6 volt battery. Attach the cathode (leaf) wire lead to the positive side of a 6 volt battery. Allow the electric current to flow until copper is plated onto the leaf. The cooper strip should partially dissolve. The copper goes into solution at the anode and is “plated out” at the cathode. Every copper atom that dissolves releases two electrons. Every copper atom that is electroplated onto the leaf absorbs two electrons.
Disconnect the leads from the battery. Remove the copper plated leaf gently from the copper sulfate plating solution with a pair of tweezers. Rinse the copper plated leaf gently with water and pat dry with a paper towel. A pin back may be glued to the back side of the copper leaf. A very delicate, life-like unique piece of jewelry has been created in an afternoon.
Industrial copper electroplating operations are not conducted in beakers. Industrial electroplating takes place in large open vats with electrical connections.