Strong heating of coal in the absence of air or oxygen is called destructive distillation.

Coal (Fossil Fuel):

Coal is an important solid fossil fuel.

Destructive distillation of coal provides useful by-products.

The fundamental by-products of coal are:

• coke

• coal tar

• ammoniacal alcohol

• coal gas

Let’s understand the concept of destructive distillation through experiment in the laboratory.

The materials needed for the experiment of destructive distillation are as follow:

Take little powdered coal in test tube A.
Test tube A is fitted with a rubber stopper carrying a delivery tube and is clamped to the stand.
Test tube B containing water is clamped vertically to the stand.
The burner is lighted and the test tube A is heated first gently and then intensely.
The gas liberated by heated coal pass through the water in test tube B.
You will notice dark coal tar settled down at the lower part of test tube B.
The ammoniacal compounds formed will dissolve in water in test tube B to form ammoniacal liquor.
Coal gas insoluble in water escapes through the side delivery tube. It can be lighted at the end of the open tube. It is a mixture of hydrogen, methane, carbon monoxide and other gases.
Solid hard black residue left behind in test tube A is coke. It is an almost pure form of carbon.