Have you ever wondered how a battery works? Oxidation‐reduction reactions transfer electrons from one species to another. Batteries use oxidation‐reduction reactions, but they are carefully designed so the flow of electrons takes place through a conducting wire. The first battery was made in 1796 by Alessandro Volta, and batteries are commonly called voltaic cells in his honor. There are many different ways to construct a voltaic cell, but in all cases, two different chemical species must be used. The voltage of the cell depends on which species are used.
If a chemical reaction can make electricity, it should not be surprising to learn that electricity can make a chemical reaction. Using an electric current to cause a chemical reaction is called electrolysis, a technique widely used to separate elements from their compounds. For example, pure sodium metal (Na) and chlorine gas (Cl 2) are obtained by passing electricity through molten sodium chloride (NaCl). The study of the interplay of electricity and oxidation‐reduction reactions is called electrochemistry.