The process of decomposition of an electrolyte (a compound formed by electrovalent bonds) by the passage of an electric current through its molten state or its aqueous solution is called electrolysis and the experimental arrangement used for this purpose is called an electrolytic cell.
The process of electrolysis is applied in a number of fields for various purposes. Some of the important applications are discussed below:
It is a process of depositing one metal (generally a superior metal such as silver, gold , nickel or chromium) over another metal (which is generally a basal metal, such as iron or copper) through the process of electrolysis
Electroplating may be carried out for preservation of decoration. For example, articles made of iron are electroplated with tin, nickel or chromium to prevent rusting, Similarly, many household articles such as tea sets and decoration pieces made of metals like copper and brass and electroplated with gold or silver to enhance their beauty.
Metals can be refined (purified) by the electrolytic method. A thick slab of impure metal is made the anode and a thin sheet of pure metal is made the cathode in the solution of a suitable salt of the metal to be purified.
On passing electricity, the anode goes on dissolving and the pure metal gets deposited at the cathode. The impurities are thrown doen in the from of anode mud. Copper is industrially purified by this method.
In large-scale printing, impressing of the ordinary type page is made on wax of plaster of Paris. The wax plate is made a conductor by sprinkling graphite on it and then made cathode in copper plating bath. on passing electric current, copper deposits on the wax plate till a sufficient thickness of copper deposits is obtained. It is removed and strengthened by filling its back with type-metal. The mould obtained is an exact copy of the printer’s page and used in large scale printing.
The process of extraction of metal from its ore by electrolysis is called electrometallurgy. for example, sodium is obtained by electrolysis of fused sodium chloride, while aluminium is extracted by the electrolysis of bauxite is fused cryolite.
A large number of chemical used in industry and medicine are prepared electrolytically. for example, caustic soda, washing soda, chlorine and so on are obtained by electrolysis of sodium chloride, while hydrogen and oxygen are manufactured by electrolysis of acidulated water.