Have you ever noticed rust on a car? This is an example of an oxidation-reduction reaction. You see, when metals were originally mined from the earth, they were impure ores. The metals then went through many processes to purify them so they can be used to make things (like cars.) So, corrosion can be thought of as a process to return metals back to their impure states.
Many times, you want to protect metals from corroding. A common process that is used to protect metals is called electroplating. Electroplating, is a process of dipping a piece of metal into a substance that you wish to use as a protective coating, and then applying electricity to allow the reaction to take place. Once the coating is placed on the metal, the coating oxidizes and the metal stays unharmed. A common type of electroplating that is used often is called galvanizing. Galvaniziing, is a process that coats iron with zinc. (Look through the nails section the next time that you are in the hardware store and you will probably find that outside nails are galvanized.)
Electrolyis is exactly opposite what happens in a galvanic cell. (Remember, that in a galvanic cell, a chemical reaction is used to produce electricity.) In a electrolytic cell (a cell that undergoes electrolysis) electricity is used to produce a chemical reaction.
Now, I know that you have seen your chemistry teacher do a lab called "Electrolysis of Water". Basically, all the teacher did was to apply electricity to water and the water decomposes into H2 and O2. Making a reaction take place due to the presence of elctricity is what electrolysis is all about.
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