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Science Innovation Centre · 006 · Carbon

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Carbon is unique in its chemical properties because it forms a number of components superior than the total addition of all the other elements in combination with each other.

The biggest group of all these components is the one formed by carbon and hydrogen. We know a minimum of about 1 million organic components and this number increases rapidly every year. Although the classification is not strict, carbon forms another series of compounds considered as inorganic, in a much lower number than that of the organic compounds.

Elemental carbon exists in two well-defined allotropic crystalline forms: diamond and graphite. Other forms with little crystallinity are vegetal carbon and black fume. Chemically pure carbon can be prepared by thermic decomposition of sugar (sucrose) in absence of air.

The free element has a lot of uses, including decoration purposes of diamonds in jewellery or black fume pigment in automobile’s rims and printer’s ink. Another carbon form, the graphite, is used for high temperature crucibles, dry cell and light arch electrodes, for pencil tips and as a lubricant. Vegetal carbon, an amorphous form of carbon, is used as gas absorbent and bleaching agent.

Carbon compounds have plenty of uses. Carbon dioxide is used in drinks carbonisation, in fire extinguishers and, in solid state, as a cooler (dry ice). Carbon monoxide is used as reduction agent in many metallurgic processes. Carbon tetrachloride and carbon disulphide are important industrial solvents. Freon is used in cooling systems. Calcium carbide is used to prepare acetylene; it’s used for welding and cutting metals, as well as for preparation of other organic compounds. Other metallic carbides have important uses as heat-resistants and metal cutters.