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| Fossil Fuels - Coal |
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| Coal is a fossil fuel mined from ancient deposits. |
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| It is a black mineral of plant origin which is chemically, a complex mixture of elemental carbon, compounds of carbon containing hydrogen, oxygen, nitrogen and sulphur. |
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| Coal is believed to have been formed about 300 million years ago under the Earth by a process called carbonization. |
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| Carbonization is the process of slow conversion of vegetable matter to coal under the Earth due to the action of high pressure, high temperature, anaerobic bacteria and absence of oxygen. |
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| Depending upon the extent of carbonization, coal can be classified into four types as follows: |
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| Classification of coal |
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| Peat is the first stage in the conversion of vegetable matter to coal while anthracite is the last. |
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| Destructive distillation of coal |
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| The process of heating coal in the absence of oxygen to obtain useful products is called destructive distillation of coal. |
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| Aim |
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| Destructive distillation of coal |
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| Materials required |
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| Two hard glass test tubes marked A and B, delivery tubes, clamp stand, burner, rubber stoppers, pieces of coal and water. |
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| Principle |
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| The volatile matter present in coal escapes on heating coal to a high temperature in the absence of oxygen. |
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| Procedure |
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 Small pieces of coal are taken in test tube A. |
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 Test tube A is fitted with a rubber stopper carrying a delivery tube and is clamped to the clamp stand. |
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 Test tube B containing water is clamped vertically to the clamp stand. |
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 The apparatus is assembled as shown in the figure. |
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 The burner is lighted and the test tube A is heated first gently and then intensely. |
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| The following products are formed. |
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| Products formed and their uses |
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| Flow chart of the process taking place in a coking plant (same as destructive distillation) |
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| Flow chart of the process taking place in a coking plant |
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 On destructive distillation, coal yields useful products like coal gas, coal tar, ammonia and coke. |
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 Generation of electricity |
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 Domestic fuel for cooking and heating |
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 Manufacture of synthetic petroleum and natural gas |
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 To heat water in steam engines and boilers |
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| Coal is thus regarded as the backbone of our national economy. |
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