Turn Pennies Silver and Gold

Note: The following video is a chemistry trick of turning pennies silver and gold; through the simple process of "Electroplating."

Electroplating is a process that uses an electric current to reduce dissolved metal cations so that they form a thin coherent metal coating on an electrode. The term is also used for electrical oxidation of anions on to a solid substrate, as in the formation of silver chloride on silver wire to make silver/silver-chloride electrodes. Electroplating is primarily used to change the surface properties of an object (such as abrasion and wear resistance, corrosion protection, lubricity, aesthetic qualities), but may also be used to build up thickness on undersized parts or to form objects by electroforming. The process used in electroplating is called electrodeposition. It is analogous to a concentration cell acting in reverse. The part to be plated is the cathode of the circuit. In one technique, the anode is made of the metal to be plated on the part. Both components are immersed in a solution called an electrolyte containing one or more dissolved metal salts as well as other ions that permit the flow of electricity. A power supply supplies a direct current to the anode, oxidizing the metal atoms that it comprises and allowing them to dissolve in the solution. At the cathode, the dissolved metal ions in the electrolyte solution are reduced at the interface between the solution and the cathode, such that they "plate out" onto the cathode. The rate at which the anode is dissolved is equal to the rate at which the cathode is plated, the current through the circuit. In this manner, the ions in the electrolyte bath are continuously replenished by the anode. The most common form of electroplating is used for creating coins, such as US pennies, which are made of zinc covered in a layer of copper.

Process
The cations associate with the anions in the solution. This cations are reduced at the cathode to deposit in the metallic, zero valence state. For example, for copper plating, in an acid solution, copper is oxidized at the anode to Cu2+ by losing two electrons. The Cu2+ associates with the anion SO2−4 in the solution to form copper(II) sulfate. At the cathode, the Cu2+ is reduced to metallic copper by gaining two electrons. The result is the effective transfer of copper from the anode source to a plate covering the cathode. The plating is most commonly a single metallic element, not an alloy. However, some alloys can be electrodeposited, notably brass and solder. Many plating baths include cyanides of other metals (such as potassium cyanide) in addition to cyanides of the metal to be deposited. These free cyanides facilitate anode corrosion, help to maintain a constant metal ion level and contribute to conductivity. Additionally, non-metal chemicals such as carbonates and phosphates may be added to increase conductivity. When plating is not desired on certain areas of the substrate, stop-offs are applied to prevent the bath from coming in contact with the substrate. Typical stop-offs include tape, foil, lacquers, and waxes. The ability of a plating to cover uniformly is called throwing power; the better the throwing power the more uniform the coating.

History
Modern electrochemistry was invented by Italian chemist Luigi Valentino Brugnatelli in 1805. Brugnatelli used his colleague Alessandro Volta's invention of five years earlier, the voltaic pile, to facilitate the first electrodeposition. Brugnatelli's inventions were suppressed by the French Academy of Sciences and did not become used in general industry for the following thirty years. By 1839, scientists in Britain and Russia had independently devised metal-deposition processes similar to Brugnatelli's for the copper electroplating of printing press plates. Boris Jacobi in Russia not only rediscovered galvanoplastics, but developed electrotyping and galvanoplastic sculpture.

Uses
Electroplating is widely used in various industries for coating metal objects with a thin layer of a different metal. The layer of metal deposited has some desired property, which the metal of the object lacks. For example, chromium plating is done on many objects such as car parts, bath taps, kitchen gas burners, wheel rims and many others for the fact that chromium is very corrosion-resistant, and thus prolongs the life of the parts. It is also used in making expensive jewelry.

". . . . And as always, thanks for watching. "

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why didn't you use alligator clips vs drilling holes into the zinc pennies, did you want the reaction with the zinc underneath the copper coating, also you created brass plated not solid brass, correct? great video