ABSTRACT
Electrochemistry is concerned with reactions proceeding with the production or consumption of electric energy. Reactions where there is electron transfer between two units are called redox reactions. The unit giving up electrons is called the reducing agent and the unit accepting electrons is the oxidizing agent. Accordingly, the electron-donor unit is said to have been oxidized, and the electron-acceptor unit is said to have been reduced. Redox reactions are more easily recognized by introducing the oxidation number concept. The oxidation number of an element in a chemical species is defined as the number of elementary charges that an element would have if all the chemical bonds within that species were ionic bonds. The maximum oxidation number that an element could have is then equal to the number of its valence electrons and the minimum oxidation number that an element could have is equal to the number of electrons needed to fill up its valence shell.
