The passage of an electric current through a conducting
solution or molten salt either is a type of Electrolyte
that is decomposed in the process.
When a cathode,
or negative electrode, and an anode, or positive electrode,
are dipped into a solution, and a direct-current source
is connected to the electrodes, the positive ions
migrate to the negative electrode and the negative
ions migrate to the positive electrode. At the negative
electrode each positive ion gains an electron and
becomes neutral; at the positive electrode each negative
ion gives up an electron and becomes neutral.
migration of the ions through the electrolyte constitutes
the electric current flowing from one electrode to
Electrolysis is used in the commercial preparation
of various substances, e.g., chlorine by the electrolysis
of a solution of common salt, and hydrogen by the
electrolysis of water. The electrolysis of metal salts
is used for plating.