charcoal(redirected from Why is charcoal not an allotrope of coal)
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charcoal,substance obtained by partial burning or carbonization (destructive distillationdistillation,
process used to separate the substances composing a mixture. It involves a change of state, as of liquid to gas, and subsequent condensation. The process was probably first used in the production of intoxicating beverages.
..... Click the link for more information. ) of organic material. It is largely pure carboncarbon
[Lat.,=charcoal], nonmetallic chemical element; symbol C; at. no. 6; interval in which at. wt. ranges 12.0096–12.0116; m.p. about 3,550°C;; graphite sublimes about 3,375°C;; b.p. 4,827°C;; sp. gr. 1.8–2.1 (amorphous), 1.9–2.3 (graphite), 3.
..... Click the link for more information. . The entry of air during the carbonization process is controlled so that the organic material does not turn to ash, as in a conventional fire, but decomposes to form charcoal.
The most common variety of charcoal, wood charcoal, was formerly prepared by piling wood into stacks, covering it with earth or turf, and setting it on fire. In this process volatile compounds in the wood (e.g., water) pass off as vapors into the air, some of the carbon is consumed as fuel, and the rest of the carbon is converted into charcoal. In the modern method, wood is raised to a high temperature in an iron retort, and industrially important byproducts, e.g., methanolmethanol,
or wood alcohol,
CH3OH, a colorless, flammable liquid that is miscible with water in all proportions. Methanol is a monohydric alcohol. It melts at −97.8°C; and boils at 67°C;.
..... Click the link for more information. (wood alcohol or wood spirit), acetoneacetone
, dimethyl ketone
, or 2-propanone
, CH3COCH3, colorless, flammable liquid. Acetone melts at −94.8°C; and boils at 56.2°C;. It is the simplest aliphatic ketone.
..... Click the link for more information. , pyroligneous acidpyroligneous acid
, a dark liquid that is essentially a mixture of acetic acid and methanol (wood alcohol) and is obtained in the destructive distillation of wood. It once served as a commercial source of acetic acid.
..... Click the link for more information. , and acetic acidacetic acid
, CH3CO2H, colorless liquid that has a characteristic pungent odor, boils at 118°C;, and is miscible with water in all proportions; it is a weak organic carboxylic acid (see carboxyl group). Glacial acetic acid is concentrated, 99.
..... Click the link for more information. , are saved by condensing them to their liquid form. Air is not really needed in the carbonization process, and advanced methods of charcoal production do not allow air to enter the kiln. This results in a higher yield, since no wood is burned with the air, and quality is improved. Charcoal is also obtained from substances other than wood such as nut shells and bark; that obtained from bones is called bone black, animal black, or animal charcoal.
Charcoal yields a larger amount of heat in proportion to its volume than is obtained from a corresponding quantity of wood and has the further advantage of being smokeless. The greatest amount is used as a fuel. Charcoal is often used in blacksmithing, for cooking, and for other industrial applications. One of the most important applications of wood charcoal is as a component of gunpowdergunpowder,
explosive mixture; its most common formula, called "black powder," is a combination of saltpeter, sulfur, and carbon in the form of charcoal. Historically, the relative amounts of the components have varied.
..... Click the link for more information. . It is also used as a reducing agent in metallurgical operations, but this application was diminished by the introduction of cokecoke,
substance obtained by the destructive distillation of bituminous coal. Coke bears the same relation to coal as does charcoal to wood. A hard, gray, massive, porous fuel, coke is the solid residue remaining after bituminous coal is heated to a high temperature out of
..... Click the link for more information. . A limited quantity is made up into the form of drawing crayon. Bamboo charcoal is the principal ingredient in sumi-e, a form of Japanese ink painting that uses only black ink in various concentrations.
Because of its porous structure, finely divided charcoal is a highly efficient agent for filtering the adsorption of gases and of solids from solution. It is used in sugar refining, in water purification, in the purification of factory air, and in gas masks. Wood charcoal can remove coloring agents from solutions, but this is accomplished more efficiently by animal charcoal. By special heating or chemical processes the adsorptive property can be greatly increased; charcoal so treated is known as activated charcoal.
a drawing material made from charred wood, mainly twigs or sticks of linden, willow, and other trees. Hard pressed charcoal, made from charcoal powder with an added gum, became popular in the 19th century. Charcoal is widely used for finished drawings and preliminary sketches. It is valued because its stroke has a velvety texture and because it combines lines and tonal effects.