What is destructive distillation of coal?

(a) What is destructive distillation of coal?
(b) What are the various products of coal obtained by destructive distillation of coal? Explain them along with their uses.

(a) The strong heating of coal in the absence of air is called destructive distillation of coal.
(b) The various products obtained by destructive distillation of coal are: coal gas, coal tar and coke.

1. Coal Gas:
Coal gas is a gaseous fuel which is obtained by the strong heating of coal in the absence of air during the processing of coal to get coke. Coal gas is mainly a mixture of methane and hydrogen, with some carbon monoxide. All the gases present in coal gas can burn to produce heat, due to which coal gas is an excellent fuel (having high calorific value). Coal gas is used as a fuel in industries. These days, however, coal gas is used as a source of heat rather than light.

2. Coal Tar:
Coal tar is a thick, black liquid having an unpleasant smell which is obtained by heating coal in the absence of air. Coal tar is not a single compound. Coal tar is a mixture of about 200 carbon compounds (or organic compounds). The products of coal tar are used to make synthetic fibres, drugs (medicines), plastics, synthetic dyes, perfumes, paints, varnishes, pesticides, photographic materials, roofing materials and explosives, etc. Coal tar has been traditionally used for metalling the roads.

3. Coke:
Coke is a tough and porous black solid substance Coke is prepared by heating coal in the absence of air. Coke is an almost pure form of carbon. Coke is mainly used as a reducing agent in the extraction of metals (like iron, zinc etc.) Coke is used in the manufacture of steel. Coke is also used as a fuel.