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Class 8, Science, Chapter-3, Lecture-1, Coal (Notes)

Natural Resources: 

Materials or agents occurring in nature that can be used to fulfil requirements of living organisms are called natural resources.
Examples: Sunlight, Air, Forests, Wildlife, Minerals, Cals, Petroleum, Natural gas.

Inexhaustible Natural Resources: 

Materials or agents occurring in unlimited quantity in nature that can be used to fulfil requirements of living organisms and will never get exhausted by human activity are called inexhaustible natural resources. 
Examples: Sunlight, Air

Exhaustible Natural Resources: 

Materials or agents occurring in limited quantity in nature that can be used to fulfil requirements of living organisms and will get exhausted by human activity are called exhaustible natural resources. 
Examples: Forests, Wildlife, Minerals, Cals, Petroleum, Natural gas

COAL: 

A combustible black or dark brown rock consisting of Carbon, Oxygen, Nitrogen, Sulphur and Hydrogen formed by carbonisation of plant matter found under the earth’s crust is termed as Coal. 

CARBONISATION: 

The process of conversion of plants and animals buried inside the earth under high temperature and pressure into coal is called carbonisation.

Formation of Coal:

  1. The large trees and animals got buried inside the earth.
  2. The high pressure of the above layers squeezed out the volatile materials.
  3. The layers of sand stopped supply of oxygen.
  4. Wood converted to coal in the absence of air due to high pressure and temperature.

Varieties of Coal:

  1. Peat 11 % Carbon
  2. Lignite (Soft Coal) 38 % Carbon
  3. Bituminous (Household Coal) 65 % Carbon
  4. Anthracite (Hard Coal) 96 % Carbon

Destructive Distillation of Coal:

The process of heating coal in the absence of air is called destructive distillation of coal.

Products of Destructive Distillation of Coal:

  1. Coke
  2. Coal Tar
  3. Coal Gas (Hydrogen + Methane + Carbon monoxide)
  4. Ammoniacal liquor (Ammonia + Water) 

Uses of Coke:

  1. Coke is used as a reducing agent in metallurgy.
  2. Coke is used for preparation of Water Gas (Carbon Monoxide + Hydrogen) 
    and Producer Gas (Carbon Monoxide + Nitrogen)

Coke is not used as fuel.

Reason: 
Coke is more valuable when used as reducing agent in extraction of metal from their ore.