What is an Electrolyte?
In chemistry, an
electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an
ionic solution, but molten electrolytes and solid electrolytes are also possible.
Electrolytes
commonly exist as solutions of acids, bases or salts. Furthermore, some
gases may act as electrolytes under conditions of high temperature or
low pressure. Electrolyte solutions can also result from the dissolution
of some biological (e.g., DNA,
polypeptides) and synthetic polymers (e.g., polystyrene sulfonate),
termed polyelectrolytes, which contain charged functional group.
Electrolyte
solutions are normally formed when a salt is placed into a solvent such
as water and the individual components dissociate due to the
thermodynamic interactions between solvent and solute molecules, in a
process called solvation. For example, when table salt, NaCl, is placed
in water, the salt (a solid) dissolves into its component elements,
according to the dissociation reaction
- NaCl(s) → Na+(aq) + Cl−(aq).
It
is also possible for substances to react with water when they are added
to it, producing ions, e.g., carbon dioxide gas dissolves in water to
produce a solution which contains hydronium, carbonate, and hydrogen
carbonate ions.
Note that molten salts can be electrolytes as
well. For instance, when sodium chloride is molten, the liquid conducts
electricity.
An electrolyte in a solution may be described as
''concentrated'' if it has a high concentration of ions, or ''dilute''
if it has a low concentration. If a high ''proportion'' of the solute
dissociates to form free ions, the electrolyte is ''strong''; if most of
the solute does not dissociate, the electrolyte is ''weak''. The
properties of electrolytes may be exploited using electrolysis to
extract constituent elements and compounds contained within the
solution.