Electrolysis

Subject : Science and technology

Section: Miscellaneous

Concept :

Electrolysis is defined as a process of decomposing ionic compounds into their elements by passing a direct electric current through the compound in a fluid form.
The cations are reduced at the cathode, and anions are oxidized at the anode. The main components that are required to conduct electrolysis are an electrolyte, electrodes, and some form of external power source is also needed.
Additionally, a partition, such as an ion-exchange membrane or a salt bridge, is also used, but this is optional. They are used mainly to keep the products from diffusing near the opposite electrode.
An acidified or salt-containing water can be decomposed by passing an electric current to its original elements, hydrogen and oxygen. Molten sodium chloride can be decomposed into sodium and chlorine atoms.

Electrolysis Process

Electrolysis is usually done in a vessel named ‘electrolytic cell’ containing two electrodes (cathode and anode), connected to a direct current source and an electrolyte which is an ionic compound undergoing decomposition, in either molten form or in a dissolves state in a suitable solvent.
Generally, electrodes that are made from metal, graphite and semiconductor materials are used.
However, the choice of a suitable electrode is done based on the chemical reactivity between the electrode and electrolyte as well as the manufacturing cost.

Electrolysis Applications

Electrolysis, as stated above, is a process of converting the ions of a compound in a liquid state into their reduced or oxidized state by passing an electric current through the compound.
Thus, electrolysis finds many applications, both in experimental and industrial products. Some of the important ones are given below:

1) Determination of equivalent weight of substances.

2) Metallurgy of alkali and alkaline earth metals.

3) Purification of metals.

4) Manufacture of pure gases.

5) Manufacture of compounds like sodium hydroxide, sodium carbonate, potassium chlorate etc.

6) Electroplating for corrosion resistance, ornaments etc.