Electrolysis：Electrolysis | Definition

electrolysis, process by which electric current[1] is passed through a substance to effect a chemical change. The chemical change is one in which the substance loses or gains an electron[2] (oxidation or reduction). The process is carried out in an electrolytic cell[3], an apparatus consisting of positive and negative electrodes[4] held apart and dipped into a solution containing positively and negatively charged ions. The substance to be transformed may form the electrode[5], may constitute[6] the solution, or may be dissolved in the solution. Electric current (i.e., electrons[7]) enters through the negatively charged electrode (cathode[8]); components of the solution travel to this electrode, combine with the electrons, and are transformed (reduced). The products can be neutral elements or new molecules. Components of the solution also travel to the other electrode (anode[9]), give up their electrons, and are transformed (oxidized) to neutral elements or n...