Pure crystalline carbon is found in the form of graphite and diamond. Free carbon is found in big reservoirs like hard coal, amorphous form of the element with other complex compounds of carbon-hydrogen-nitrogen. The estimation is that carbon forms 0,032% of The Earth’s crust. The most important of all may be the dichlorodifluoromethane, CCl 2F 2, called freon.Ĭarbon and its components are widely distributed in nature. At ambient temperature carbon tetrafluoride is gas, tetrachloride is liquid and the other two compounds are solids. Carbon forms compounds with the halogens with CX 4 as general formula, where X is fluorine, chlorine, bromine or iodine. The two first ones are the most important from the industrial point of view. It forms three gaseous components with the oxygen: carbon monoxide, CO, carbon dioxide, CO 2, and carbon suboxide, C 3O 2. A high number of metals combine with the element at high temperatures to form carbides. Among the halogens only fluorine reacts with elemental carbon. With hot oxidizing agents, like nitric acid and potassium nitrate, metilic acid C 6(CO 2H) 6 is obtained. At high temperatures it binds with oxygen to form carbon monoxide or dioxide. Elemental carbon is an inert substance, insoluble in water, diluted acids and bases, as well as organic solvents. The melting point of graphite is 3500✬ (6332✯) and the extrapolated boiling point is 4830✬ (8726✯). Its density fluctuates from 2.25 g/cm³ (1.30 ounces/in³) for graphite and 3.51 g/cm³ (2.03 ounces/in³) for diamond. The physical and chemical properties of carbon depend on the crystalline structure of the element. Chemically pure carbon can be prepared by termic decomposition of sugar (sucrose) in absence of air. Other forms with little crystallinity are vegetal carbon and black fume. 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.Įlemental carbon exists in two well-defined allotropic crystalline forms: diamond and graphite. We know a minimum of about 1 million organic components and this number increases rapidly every year. The biggest group of all these components is the one formed by carbon and hydrogen.
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