carbon monoxide

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carbon monoxide,

chemical compound, CO, a colorless, odorless, tasteless, extremely poisonous gas that is less dense than air under ordinary conditions. It is very slightly soluble in water and burns in air with a characteristic blue flame, producing carbon dioxide; it is a component of producer gasproducer gas,
fuel gas consisting chiefly of carbon monoxide and nitrogen. It is prepared in a furnace or generator in which air is forced upward through a burning fuel of coal or coke. Although the fuel is introduced through the top, no air is admitted there.
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 and water gaswater gas,
colorless poisonous gas that burns with an intensely hot, bluish (nearly colorless) flame. The gas is a mixture of carbon monoxide and hydrogen with very small amounts of other gases, e.g., carbon dioxide, and is almost entirely combustible as a result.
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, which are widely used artificial fuels. At high pressures and elevated temperatures it reacts with hydrogen in the presence of a catalyst to form methanolmethanol,
 methyl alcohol,
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;.
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, and under similar conditions reacts with methanol to produce acetic acid. It is also used in the production of polycarbonate and polyurethane as well as detergents. As a reducing agent, removing oxygen from many compounds, it is used in the reduction of metals, e.g., ironiron,
metallic chemical element; symbol Fe [Lat. ferrum]; at. no. 26; at. wt. 55.845; m.p. about 1,535°C;; b.p. about 2,750°C;; sp. gr. 7.87 at 20°C;; valence +2, +3, +4, or +6. Iron is biologically significant.
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 (see blast furnaceblast furnace,
structure used chiefly in smelting. The principle involved in this means of extracting metals is that of the reduction of the ores by the action of carbon monoxide, i.e., the removal of oxygen from the metal oxide in order to obtain the metal.
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), from their ores.

Carbon monoxide is formed by combustion of carbon in oxygen at high temperatures when there is an excess of carbon. It is also formed (with oxygen) by decomposition of carbon dioxide at very high temperatures (above 2,000°C;). It is present in the exhaust of internal-combustion engines (e.g., in automobiles) and is generated in coal stoves, furnaces, and gas appliances that do not get enough air (because of a faulty draft or for other reasons).

Carbon monoxide is an extremely poisonous gas. Breathing air that contains as little as 0.1% carbon monoxide by volume can be fatal; a concentration of about 1% can cause death within a few minutes. The gas is especially dangerous because it is not easily detected by human senses. Early symptoms of carbon monoxide poisoning include drowsiness and headache, followed by unconsciousness, respiratory failure, and death. First aid for a victim of carbon monoxide poisoning requires access to fresh air; administration of artificial respirationartificial respiration,
any measure that causes air to flow in and out of a person's lungs when natural breathing is inadequate or ceases, as in respiratory paralysis, drowning, electric shock, choking, gas or smoke inhalation, or poisoning.
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 and, if available, oxygen; and, as soon as possible, expert medical attention. When carbon monoxide is inhaled, it reacts with hemoglobin, the red blood pigment that normally carries oxygen to all parts of the body. Because carbon monoxide is attracted to the hemoglobin about 210 times as strongly as is oxygen, it takes the place of oxygen in the blood, causing oxygen starvation throughout the body. Carbon monoxide detectors for homes are now readily available.

Carbon monoxide from automobile and industrial emissions is a dangerous pollutant that may contribute to the greenhouse effect and global warmingglobal warming,
the gradual increase of the temperature of the earth's lower atmosphere as a result of the increase in greenhouse gases since the Industrial Revolution. Global warming and its effects, such as more intense summer and winter storms, are also referred to as climate
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. In urban areas carbon monoxide, along with aldehydes, react photochemically to produce peroxy radicals. Peroxy radicals react with nitrogen oxide to increase the ratio of NO2 to NO, which reduces the quantity of NO that is available to react with ozone (see smogsmog
[smoke+fog], dense, visible air pollution. Smog is commonly of two types. The gray smog of older industrial cities like London and New York derives from the massive combustion of coal and fuel oil in or near the city, releasing tons of ashes, soot, and sulfur
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). Carbon monoxide is also a constituent of tobacco smoke.

carbon monoxide

A molecule, CO, consisting of an atom of oxygen bound to a carbon atom. It is commonly found in giant molecular clouds, where there is one CO molecule to about 10 000 hydrogen molecules. Collisions with hydrogen and other molecules easily excite the CO molecules and cause them to emit characteristic radio waves at wavelengths that are integer submultiples of 2.6 mm. Carbon monoxide is thus used in radio astronomy as the best tracer of molecular gas over wide areas: the molecular hydrogen in the cool clouds has no emission at radio wavelengths. The CO emission lines are analyzed to determine the density, velocity, and temperature of the molecules in the clouds.

Carbon monoxide

A colorless, odorless, poisonous gas produced by incomplete fossil-fuel combustion, usually associated with incomplete combustion of gas stoves, fireplaces, kerosene appliances, tobacco smoke, and automobile exhaust. Proper ventilation is important to prevent negative health effects such as fatigue, dizziness, nausea, and even death.

Carbon Monoxide


CO, carbon (II) oxide, a compound of carbon and oxygen; a colorless, odorless gas. Carbon monoxide was first isolated in 1776, when the French physician J.-M.-F. de Lassone obtained CO by heating charcoal with zinc oxide. The density of carbon monoxide is 0.00125 g/cm3 at a temperature of 0°C and a pressure of 0.1 meganewton per sq m (MN/m2), or 1 kilogram-force per sq cm (kgf/cm2). The compound has a melting point of -205°C, a boiling point of - 191.5°C, a critical temperature of -140°C, and a critical pressure of 3.46 MN/m2 (34.6 kgf/cm2). Although the carbon atom in carbon monoxide formally has a + 2 oxidation state, the high stability of the CO molecule (the dissociation energy being 1,036 kilojoules per mole, or 247 kilocalories per mole) and the short internuclear distance (1.128 angstroms) strongly suggest that the oxygen and carbon atoms have a supplementary donor-acceptor bond (Carbon Monoxide:).

Carbon monoxide is an oxide that does not form salts and does not react under ordinary conditions with water, acids, or alkalies. It is characterized by its reducing properties and tendency to undergo addition reactions. Thus, in the presence of light and catalysts, carbon monoxide combines with chlorine; upon heating, it combines with oxygen to form carbon dioxide (CO2). With sulfur, it forms carbonyl sulfide (COS), and with certain metals it forms metal carbonyls, for example, Ni(CO)4 and Fe(CO)5. At elevated temperatures, carbon monoxide reduces metal oxides to the free metals (Fe, Pb, Ni, Cu) and reacts with hydrogen to yield, depending on the reaction conditions, methane, a mixture of higher alcohols, aldehydes, or ketones.

Carbon monoxide is present in the atmosphere in very small amounts. It is encountered in the form of small inclusions in layers of hard coal. The compound is always formed from the combustion of carbon and carbon compounds when there is insufficient air, and it is present in significant amounts in flue gases, automotive-vehicle exhaust gases (2–10 percent by volume), and tobacco smoke (0.5–1 percent). Thus, it is a source of atmospheric pollution. Measures have been taken in many countries to reduce the concentration of carbon monoxide in the atmosphere of industrial cities.

Carbon monoxide is produced industrially by the reaction of red-hot coal with either carbon dioxide: C + CO2 = 2CO or steam: C + H2O = CO + H2. The producer gas and water gas obtained in the process are used as gaseous fuels. Carbon monoxide is obtained in the laboratory by heating formic acid with sulfuric acid at 100°C: HCOOH = H2O + CO.

Carbon monoxide is used in the chemical industry for the synthesis of alcohols, hydrocarbons, aldehydes, and organic acids, as well as for the production of synthetic liquid fuel.

Carbon monoxide poisoning is possible both in the workplace and at home. It can arise from working near blast furnaces or open-hearth furnaces or in foundries, from procedures of engine testing, and from using flue gases for drying and heating. Poisoning from this compound occurs in the chemical industry and in garages; the use of firewood for heating can also cause poisoning. Upon entering the organism through the respiratory organs, carbon monoxide reacts with hemoglobin to form carboxyhemoglo-bin, which does not possess the ability to transfer oxygen to the tissues. In addition, the coefficient of oxygen utilization by the tissues decreases. Hypocapnia, inhibition of the dissociation of oxyhemoglobin, and enzymatic disorders of tissue respiration result. The iron in blood plasma plays a protective role, forming a compound with carbon monoxide that hinders the formation of carboxyhemoglobin and facilitates the removal of carbon monoxide from the tissues.

With acute carbon monoxide poisoning, there is headache, vertigo, nausea, vomiting, asthenia, dyspnea, and rapid pulse. There can also be a rapid loss of consciousness, as well as convulsions, coma (with subsequent motor excitation), disorders relating to circulation and respiration, and damage to the optic nerve. Toxemic pneumonia may develop within two or three days. First aid calls for removing the victim into the open air, massaging the chest, administering ammonium hydroxide vapors, and providing a hot beverage. Chronic poisoning is accompanied by headache, vertigo, and insomnia; there is emotional instability, and the victim’s ability to remember and focus attention is adversely affected. Organic damage to the central nervous system, vasospasms, and an increase in the erythrocyte count in the blood are also possible. Preventive measures include monitoring the condition of gas lines and the amount of local ventilation, removing exhaust gases containing carbon monoxide from work areas, aerating buildings, conforming to safety rules in work involving explosives, and using gas masks. Regular medical examinations are recommended for workers exposed to the danger of carbon monoxide poisoning. In the home, poisoning can be prevented through the proper use of gas burners and furnaces.



Remy, H. Kurs neorganicheskoi khimii, vol. 1. Moscow, 1972. (Translated from German.)
Akhmetov, N. S. Neorganicheskaia khimiia, 2nd ed. Moscow, 1975.
Tiunov, L. A., and V. V. Kustov. Toksikologiia okisi ugleroda. Leningrad, 1969.

carbon monoxide

[¦kär·bən mə′näk‚sīd]
(inorganic chemistry)
CO A colorless, odorless gas resulting from the incomplete oxidation of carbon; found, for example, in mines and automobile exhaust; poisonous to animals.

carbon monoxide

a colourless odourless poisonous flammable gas formed when carbon compounds burn in insufficient air and produced by the action of steam on hot carbon: used as a reducing agent in metallurgy and as a fuel. Formula: CO
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