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The connection between chemistry & electricity&is a very old one, going back to Alessandro&Volta‘s discovery, in 1793, that electricity&could be produced by placing two dissimilar&metals on opposite sides of a moistened paper. By using electrochemical principles, electrical energy is converted into the chemical energy of desirable materials. Nature can convert chemicals into electricity in ways that we regret: corrosion is an example of this unwelcome conversion. Electrodes are the places where chemistry converts to electricity, or vice versa. A typical electrode is the surface of a piece of metal in contact with a solution of salts and other chemicals dissolved in water.