Page 219 - ICSE Chemistry 8

Destruc ve dis lla on: The process in which break down of an organic substance takes place when it is
heated strongly in the absence of air
Wood charcoal: A type of charcoal which is black, porous and bri le and is obtained by destruc ve
dis lla on of wood
Wood gas: The combus ble mixture of carbon dioxide, carbon monoxide, methane and
hydrogen

Ac vated charcoal: A type of charcoal formed by hea ng wood charcoal at around 900°C
Bone charcoal: A type of granular black substance that contains only 10% carbon and a high
percentage of impuri es like calcium phosphate and calcium carbonate

Sugar charcoal: The purest available amorphous form of carbon prepared by destruc ve dis lla on
of cane sugar or glucose
Coal: A complex mixture of hydrocarbons and some free carbon
Dry ice: Solid carbon dioxide

Carbogen: A mixture of 5% carbon and 95% oxygen
Carboxyhaemoglobin: A compound formed when carbon monoxide on entering the human blood system
combines with haemoglobin present in the blood
Carbonisa on: The slow chemical process of conversion of dead and decaying ma er into coal

Quick Review

• A large number of things which we use in our daily life are made of carbon and its compounds.
• In nature, carbon occurs in both free and combined state.
• The number of carbon compounds already known at present is more than 5 million. All carbon
compounds are classifi ed into two classes—carbon compounds of biological origin and carbon
compounds of non-biological origin.
• The reason for the presence of such a large number of carbon compounds is its valency.
• The two allotropic forms of carbon are crystalline and amorphous.
• The crystalline forms of carbon include diamond, graphite and fullerene.
• The amorphous forms of carbon are charcoal, coke, gas carbon, lamp black (carbon black or soot) and
coal.
• Diamond is the purest form of carbon. It is the hardest known naturally occurring substance.
• Graphite is a greyish-black opaque substance.
• Buckminsterfullerene is a spherical, crystalline, allotropic form of carbon consis ng of 60 carbon atoms.
• Charcoal is obtained by destruc ve dis lla on of organic ma er such as wood, bones and sugar.
• Depending upon the source used, there are three types of charcoal—wood charcoal, bone or animal
charcoal and sugar charcoal.
• Coke is a greyish-black, solid substance that burns without smoke. It is obtained by destruc ve
dis lla on of coal.
• Gas carbon is a greyish substance obtained by destruc ve dis lla on of coal. It is also obtained by
hea ng petroleum products (or hydrocarbons) at a high temperature in a closed vessel.

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