Page 210 - ICSE Chemistry 8
P. 210

Anthracite: Anthracite is the fi nal stage of coal forma  on. This is formed when bituminous coal remains in
                 the earth for a long   me and is subjected to extreme pressure. This is also called hard coal and contains
                 over 90–95% of carbon. Anthracite burns with very li  le smoke and for a longer   me than bituminous
                 coal.
                 The higher the carbon content of coal, the higher is its calorifi c value. Hence, the calorifi c value of
                 anthracite is maximum and that of peat is the least.

                 Uses of Coal

                     •  Coal is used as a domes  c and industrial fuel.
                     • Destruc  ve dis  lla  on of coal produces coke, coal gas, coal tar and ammonia solu  on.

                     •  It is used to manufacture synthe  c petroleum.

                     •  It is a source of various organic compounds like benzene, naphthalene, aniline and phenol.
                     •  Coal is used to manufacture some fer  lisers, drugs, synthe  c tex  le and perfumes.

                 Destructive Distillation of Coal

                 When coal is heated strongly in the absence of air it produces coke (destruc  ve dis  lla  on), coal gas, coal
                 tar and ammonia solu  on.

                                 destruc  ve dis  lla  on
                        Coal                             Coke  +  Coal gas  +  Coal tar  +       Ammonia solu  on
                 Coke is a tough, porous and black solid. It contains about 98% carbon and is used to manufacture steel
                 and to extract many metals from their ores.

                 Coal gas is a mixture of hydrogen, carbon monoxide and methane. It burns with a bluish fl ame when
                 ignited. It is used as a household and industrial fuel.

                 Coal tar is a foul-smelling, thick black liquid. It is used for making dyes, drugs, explosives, etc.
                 Ammonia solu  on which is ammonium hydroxide is used for making fer  lisers such as ammonium
                 sulphate, ammonium superphosphate, etc.


                      Take a Break!

                     Answer orally.

                      1.  How is coal formed?
                      2.  What are the four varie  es of coal?
                      3.  How is peat diff erent from anthracite?

                      4.  What are the uses of coal?
                      5.  What is the diff erence between coal gas and coal tar?



                 CARBON DIOXIDE

                 Carbon dioxide (CO ) is a colourless gas that cons  tutes about 0.04% of air by volume. It is present in the
                                     2
                 earth’s atmosphere at a low concentra  on and acts as a greenhouse gas. It acts as a major component of the


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