(i) The name ‘carbon’ is derived from Latin word ‘carbo’ meaning coal. In the earth’s crust, carbon is present to an extent of approximately 0.27% in the form of carbonate, coal and petroleum. One of the non-crystalline and amorphous form of carbon is coal. Coal is a fossil fuel.
(ii) Peat, lignite, bituminous and anthracite are the four types of coal in the increasing order of their carbon content and heat produced respectively. Charcoal and coke are the other amorphous forms of carbon used as fuel.
(iii) Compounds of carbon such as hydrocarbons consist of carbon and hydrogen and they are easily combustible. For example, methane (CH4) which occurs in natural gas is highly inflammable. It bums by reacting with oxygen to give a bluish flame. In this reaction, 213 Kcal/mol of heat is given out. Methane bums completely.
Chemical reaction:
(iv) Thus when hydrocarbons are burnt in air, large amount of heat is evolved with formation of carbon dioxide (CO2) and water (H2O). Due to evolution of heat on combustion, carbon and its compounds are used as fuels.
