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单词 carbon dioxide
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carbon dioxide


carbon dioxide

n. A colorless, odorless, incombustible gas, CO2, that is formed during respiration, combustion, and organic decomposition, is an essential component in photosynthesis, and is used in food refrigeration, carbonated beverages, inert atmospheres, fire extinguishers, and aerosols. Also called carbonic acid gas.

carbon dioxide

n (Elements & Compounds) a colourless odourless incombustible gas present in the atmosphere and formed during respiration, the decomposition and combustion of organic compounds, and in the reaction of acids with carbonates: used in carbonated drinks, fire extinguishers, and as dry ice for refrigeration. Formula: CO2. Also called: carbonic-acid gas

car′bon diox′ide


n. a colorless, odorless, incombustible gas, CO2, present in the atmosphere and formed during respiration: used as dry ice and in carbonated beverages and fire extinguishers. [1870–75]

carbon dioxide

A colorless, odorless gas, CO2, that is present in the atmosphere and is formed when any fuel containing carbon is burned. It is breathed out of an animal's lungs during respiration, produced by the decay of organic matter, and used by plants in photosynthesis. Carbon dioxide is also used in refrigeration, fire extinguishers, and carbonated drinks.

carbon dioxide

A gas in air. In the carbon cycle, plants make food with carbon dioxide, and breathing, burning, and decay return it to the air. See greenhouse gases.
Thesaurus
Noun1.carbon dioxide - a heavy odorless colorless gas formed during respiration and by the decomposition of organic substances; absorbed from the air by plants in photosynthesiscarbonic acid gas, CO2blackdamp, chokedamp - the atmosphere in a mine following an explosion; high in carbon dioxide and incapable of supporting lifedioxide - an oxide containing two atoms of oxygen in the moleculegreenhouse emission, greenhouse gas - a gas that contributes to the greenhouse effect by absorbing infrared radiation
Translations
二氧化碳

carbon

(ˈkaːbən) an element occurring as diamond and graphite and also in coal etc. 碳 碳carbon copy a copy of writing or typing made by means of carbon paper. 複寫本 复写本，副本 carbon dioxide (daiˈoksaid) a gas present in the air, breathed out by man and other animals. 二氧化碳 二氧化碳carbon monoxide (məˈnoksaid) a colourless, very poisonous gas which has no smell. Carbon monoxide is given off by car engines. 一氧化碳 一氧化碳carbon paper a type of paper coated with carbon etc which makes a copy when placed between the sheets being written or typed. 複寫紙 复写纸

carbon dioxide


carbon dioxide,

chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. It does not burn, and under normal conditions it is stable, inert and nontoxic. It will however support combustion of magnesium to give magnesium oxide and carbon. Although it is not a poison, it can cause death by suffocation if inhaled in large amounts. It is a fairly stable compound but decomposes at very high temperatures into carbon and oxygen. It is fairly soluble in water, one volume of it dissolving in an equal volume of water at room temperature and pressure; the resultant weakly acidic aqueous solution is called carbonic acidcarbonic acid,
H2CO3, a weak dibasic acid (see acids and bases) formed when carbon dioxide dissolves in water; it exists only in solution. Carbonic acid forms carbonate and bicarbonate (or acid carbonate) salts (see carbonate) by reaction with bases.
..... Click the link for more information. . The gas is easily liquefied by compression and cooling. If liquid carbon dioxide is quickly decompressed it rapidly expands and some of it evaporates, removing enough heat so that the rest of it cools into solid carbon dioxide "snow." A standard test for the presence of carbon dioxide is its reaction with limewater (a saturated water solution of calcium hydroxidecalcium hydroxide,
Ca(OH)2, colorless crystal or white powder. It is prepared by reacting calcium oxide (lime) with water, a process called slaking, and is also known as hydrated lime or slaked lime. When heated above 580&degC; it dehydrates, forming the oxide.
..... Click the link for more information. ) to form a milky-white precipitate of calcium hydroxide.

Carbon dioxide occurs in nature both free and in combination (e.g., in carbonatescarbonate
, chemical compound containing the carbonate radical or ion, CO3−2. Most familiar carbonates are salts that are formed by reacting an inorganic base (e.g., a metal hydroxide) with carbonic acid.
..... Click the link for more information. ). It is part of the atmosphereatmosphere
[Gr.,=sphere of air], the mixture of gases surrounding a celestial body with sufficient gravity to maintain it. Although some details about the atmospheres of other planets and satellites are known, only the earth's atmosphere has been well studied, the science of
..... Click the link for more information. , making up about 1% of the volume of dry air. Because it is a product of combustion of carbonaceous fuels (e.g., coal, coke, fuel oil, gasoline, and cooking gas), there is usually more of it in city air than in country air. For the last 800,000 years the carbon dioxide in the atmosphere has oscillated over tens of thousands of years between 180 to 280 parts per million (ppm), but since the Industrial RevolutionIndustrial Revolution,
term usually applied to the social and economic changes that mark the transition from a stable agricultural and commercial society to a modern industrial society relying on complex machinery rather than tools.
..... Click the link for more information.  it has steadily increased above 280 ppm in a relatively brief time, reaching 400 ppm in 2013. This extra carbon dioxide fuels the greenhouse effect, warming the atmosphere and further disrupting the natural carbon dioxide cycle (see 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
..... Click the link for more information. ).

In various parts of the world—notably in Italy, Java, and Yellowstone National Park in the United States—carbon dioxide is formed underground and issues from fissures in the earth. Natural mineral waters such as Vichy water sparkle (effervesce) because excess carbon dioxide that dissolved in them under pressure collects in bubbles and escapes when the pressure is released. The chokedamp (see dampdamp,
in mining, any mixture of gases in an underground mine, especially oxygen-deficient or noxious gases. The term damp probably is derived from the German dampf, meaning fog or vapor. Several distinct types of damp are recognized.
..... Click the link for more information. ) of mines, pits, and old, unused wells is largely carbon dioxide. Carbon dioxide is a raw material for photosynthesisphotosynthesis
, process in which green plants, algae, and cyanobacteria utilize the energy of sunlight to manufacture carbohydrates from carbon dioxide and water in the presence of chlorophyll. Some of the plants that lack chlorophyll, e.g.
..... Click the link for more information.  in green plants and is a product of animal respirationrespiration,
process by which an organism exchanges gases with its environment. The term now refers to the overall process by which oxygen is abstracted from air and is transported to the cells for the oxidation of organic molecules while carbon dioxide (CO2
..... Click the link for more information. . It is also a product of the decay of organic matter.

Carbon dioxide has varied commercial uses. Its greatest use as a chemical is in the production of carbonated beverages; it provides the sparkle in carbonated beverages such as soda water. Formed by the action of yeast or baking powder, carbon dioxide causes the rising of bread dough. The compound is also used in water softening, in the manufacture of aspirin and lead paint pigments, and in the Solvay processSolvay process
[for Ernest Solvay], commercial process for the manufacture of sodium carbonate (washing soda). Ammonia and carbon dioxide are passed into a saturated sodium chloride solution to form soluble ammonium hydrogen carbonate, which reacts with the sodium chloride to
..... Click the link for more information.  for the preparation of sodium carbonate. In some fire extinguishers carbon dioxide is expelled through a nozzle and settles on the flame, smothering it. It also has numerous nonchemical uses. It is used as a pressurizing medium and propellant, e.g., in aerosol cans of food, in fire extinguishers, in target pistols, and for inflating life rafts. Because it is relatively inert, it is used to provide a nonreactive atmosphere, e.g., for packaging foods, such as coffee, that can be spoiled by oxidation during storage. Solid carbon dioxide, known as dry ice, is used as a refrigerating agent.

There are three principal commercial sources for carbon dioxide. High-purity carbon dioxide is produced from some wells. The gas is obtained as a byproduct of chemical manufacture, as in the fermentation of grain to make alcohol and the burning of limestone to make lime. It is also manufactured directly by burning carbonaceous fuels. For commercial use it is available as a liquid under high pressure in steel cylinders, as a low-temperature liquid at lower pressures, and as the solid dry ice.

Carbon dioxide

(CO2)A colorless, odorless, nonpoisonous gas that exists in trace quantities (less than 400 parts per million) within ambient air. Carbon dioxide is a product of fossil-fuel combustion. Although carbon dioxide does not directly impair human health, it is a greenhouse gas that traps terrestrial (i.e., infrared) radiation and contributes to the potential for global warming.

Carbon Dioxide

 

(also carbonic anhydride, carbonic acid gas), CO2, carbon (IV) oxide, the highest oxide of carbon. In 1756, J. Black demonstrated that a gas, which he called “fixed” air, is liberated upon decomposition of magnesium carbonate. The gas’s composition was established in 1789 by A. Lavoisier.

Carbon dioxide is a colorless gas with a faintly pungent odor and acid taste; it has a density of 0.0019 g/cm3 (at 0°C and 0.1 meganewtons per sq m [MN/m2]), a melting point of -56.6°C, a boiling point of -78.5°C, a critical temperature of 31°C, and a critical pressure of 7.62 MN/m2, or 76.2 kilograms-force per sq cm (kgf/cm2). At atmospheric pressure and a temperature of -78.5°C, carbon dioxide hardens into a white, snowlike mass known as dry ice, thus bypassing the liquid state. Liquid carbon dioxide exists at room temperature only when the pressure exceeds 5.85 MN/m2 (58.5 kgf/cm2). The density of liquid CO2 is 0.771 g/cm3 at 20°C, while that of the solid form is 1.512 g/cm3. In the gaseous phase, the carbon dioxide molecule has the symmetrical form O=C=O, with a distance between the carbon and oxygen atoms of 1.162 angstroms (Å). Solid CO2 crystallizes in a face-centered cubic lattice, with a = 5.62 Å.

Carbon dioxide is thermostable, dissociating into carbon monoxide and oxygen only at a temperature above 2000°C. The compound is noticeably soluble in water, forming solutions of 0.335 percent (by weight) at 0°C and 0.169 percent at 20°C; it partially reacts with water to form carbonic acid (H2CO3). Carbon dioxide dissolves in the following organic solvents: acetone, benzene, chloroform, and alcohols. It reacts vigorously with bases to yield carbonates. CO2 does not burn and does not support combustion. It is reduced only by very highly reactive metals at high temperatures, for example, by magnesium at 600°C and by calcium at 700°C. Carbon dioxide reacts with red-hot coal: CO2 + C = 2CO, a reaction having great importance in metallurgy. It also reacts with ammonia at a temperature of 160°-200°C and a pressure of 10–40 MN/m2 (100–400 kgf/cm2): CO2 + 2NH3= CO(NH2)2 + H2O. Carbon dioxide reacts with hydrogen in the presence of cupric oxide, forming methane.

Carbon dioxide is a component of air, constituting 0.03 percent by volume; the total content is 2.3 × 1012 tons. In the hydrosphere, there are 1.4 × 1014 tons of carbon dioxide in equilibrium with the atmosphere. Carbon dioxide is formed and introduced into the atmosphere upon the combustion of fuels, the decay of organic matter, the process of fermentation, and the respiration of humans and animals. As a result of industrial pollution, the amount of carbon dioxide in the air of industrial cities greatly exceeds permissible levels. Measures have been taken to reduce this level in a number of industrially developed countries, including the USSR. Carbon dioxide is necessary for the growth of plants, which absorb the compound from the atmosphere in the process of photosynthesis. The atmospheres of the planets Mars and Venus contain carbon dioxide as their major component.

Carbon dioxide is produced industrially mainly by roasting limestone at 900°-1300°C, a process that also yields lime; the compound is purified through its absorption by solutions of soda, potash, or ethanolamine. It is stored and transported in the liquefied state under a pressure of 6 MN/m2 (60 kgf/cm2) in steel cylinders. In the laboratory, CO2 is usually obtained by the reaction of hydrochloric acid with marble.

Carbon dioxide is used in the production of soda water, beer, and sugar. Dry ice is used for the preservation and transport of perishable food products. In the chemical industry, CO2 is consumed in producing soda, urea, and hydroxycarboxylic acids; in graphite-moderated reactors, it functions as a heat carrier. Carbon dioxide is also used in extinguishing fires and transporting flammable substances.

B. A. POPOVKIN

In agriculture, carbon dioxide is used as a fertilizer. An insufficiency of carbon dioxide in the air, which frequently occurs when the ground is shielded, as is especially the case with hydroponic cultivation, lowers the rate of photosynthesis and the crop yield. Gaseous carbon dioxide (from cylinders) or purified products (containing up to 15 percent CO2) of the catalytic combustion of natural gas and solid fuel are introduced during the daytime into hothouses and greenhouses to improve the carbon supply to plants. Solid carbon dioxide (dry ice) can be used as a source of gaseous carbon dioxide; here, pieces of the solid are distributed about an area. Organic and mineral fertilizers that liberate carbon dioxide upon decomposition may also be used as sources. The efficiency of carbon dioxide fertilizers depends on the mineral supply available to plants, the illumination, and the temperature of the soil and air.

In humans and animals, carbon dioxide, together with bicar-bonates, forms an important buffer system of the blood. An increase in the partial pressure of carbon dioxide in the blood strengthens the bond of oxygen to hemoglobin. By acting, both directly and indirectly, on the centers of the medulla oblongata, carbon dioxide figures in the regulation of respiration and blood circulation. A mixture of 95 percent oxygen and 5 percent carbon dioxide (Carbogen) is used in medicine in the case of toxic dosages of narcotics and carbon monoxide poisoning. In high concentrations, carbon dioxide is toxic, inducing hypoxia. Breathing carbon dioxide for a period of several days, even in concentrations of 1.5–3 percent, causes headache, vertigo, and nausea. At concentrations greater than 6 percent (critical level), a person becomes drowsy and unable to work, and there is a weakening of respiratory and cardiac activity, posing a threat to life. An accumulation of carbon dioxide in the air with a concomitant decrease in the oxygen content is seen in enclosed, poorly ventilated spaces, for example, areas in mines and sewers, and in places, such as breweries, where fermentation is occurring. First aid calls for removing the victim into the fresh air and applying artificial respiration. Carbon dioxide does not reach critical levels in the air in residential and public buildings. The concentration of carbon dioxide serves as an environmental indicator of air purity.

V. F. KIRILLOV

REFERENCES

Remy, H. Kurs neorganicheskoi khimii, vol. 1. Moscow, 1972. (Translated from German.)
Nekrasov, B. V. Osnovy obshchei khimii, 3rd ed., vols. 1–2. Moscow, 1973.
Akhmetov, N. S. Neorganicheskaia khimiia, 2nd ed. Moscow, 1975.

carbon dioxide

[¦kär·bən dī′äk‚sīd] (inorganic chemistry) CO2 A colorless, odorless, tasteless gas about 1.5 times as dense as air.

carbon dioxide

a colourless odourless incombustible gas present in the atmosphere and formed during respiration, the decomposition and combustion of organic compounds, and in the reaction of acids with carbonates: used in carbonated drinks, fire extinguishers, and as dry ice for refrigeration. Formula: CO2

carbon dioxide


carbon dioxide

 an odorless, colorless gas, CO2, resulting from oxidation of carbon, formed in the tissues and eliminated by the lungs; used in some pump oxygenators to maintain the carbon dioxide tension in the blood. It is also used in solid form; see carbon dioxide snow and carbon dioxide slush.carbon dioxide combining power the ability of blood plasma to combine with carbon dioxide; indicative of the alkali reserve and a measure of the acid-base balance of the blood.carbon dioxide content the amount of carbonic acid and bicarbonate in the blood; reported in millimoles per liter.carbon dioxide–oxygen therapy administration of a mixture of carbon dioxide and oxygen (commonly 5 per cent CO2 and 95 per cent O2 or 10 per cent CO2 and 90 per cent O2); used for improvement of cerebral blood flow, stimulation of deep breathing, or treatment of singultation (hiccupping). Carbon dioxide acts by stimulating the respiratory center; it also increases heart rate and blood pressure. Therapy is given for 6 minutes or less with a 5 per cent mixture and 2 minutes or less with a 10 per cent mixture. Potential adverse effects include headache, dizziness, dyspnea, nausea, tachycardia and high blood pressure, blurred vision, mental depression, coma, and convulsions.carbon dioxide slush solid carbon dioxide combined with a solvent such as acetone, and sometimes also alcohol; used as an escharotic to treat skin lesions such as warts and moles and as a peeling agent in chemabrasion.carbon dioxide snow the solid formed by rapid evaporation of liquid carbon dioxide, giving a temperature of about −79°C (−110°F). It has been used in cryotherapy to freeze the skin, thus producing local anesthesia and arrest of blood flow. See also carbon dioxide slush.

car·bon di·ox·ide (CO2),

the product of the combustion of carbon with an excess of oxygen; in concentrations not less than 99.0% by volume of CO2. Synonym(s): carbonic acid gas, carbonic anhydride

carbon dioxide

n. A colorless, odorless, incombustible gas, CO2, that is formed during respiration, combustion, and organic decomposition, is an essential component in photosynthesis, and is used in food refrigeration, carbonated beverages, inert atmospheres, fire extinguishers, and aerosols. Also called carbonic acid gas.

carbon dioxide

CO2 Physiology A metabolic byproduct of carbohydrate metabolism; it accumulates in tissues, is released to the blood in veins, and is eliminated via the lungs

car·bon di·ox·ide

(CO2) (kahr'bŏn dī-oks'īd) The product of the combustion of carbon with an excess of air; in concentrations not less than 99.0% by volume of CO2, used as a respiratory stimulant.

carbon dioxide

A compound in which an atom of carbon is linked to two atoms of oxygen (CO2 ). Carbon dioxide is a colourless, odourless gas and is one of the chief waste products of tissue metabolism.

carbon dioxide

a colourless, odourless gas, heavier than air, produced in respiration of organisms, and utilized to form sugars in PHOTOSYNTHESIS. Formula: CO2 .

Carbon dioxide

A heavy, colorless gas that dissolves in water.Mentioned in: Laser Surgery

hypercapnia

The presence of a raised carbon dioxide content or tension in a milieu (e.g. blood, tears). Contact lens wear tends to give rise to this condition, especially lenses of low gas transmissibility. See acidosis.

car·bon di·ox·ide

(CO2) (kahr'bŏn dī-oks'īd) Product of the combustion of carbon with an excess of oxygen.
See CO2
See CO2

carbon dioxide


Related to carbon dioxide: Carbon dioxide poisoning
  • noun

Synonyms for carbon dioxide

noun a heavy odorless colorless gas formed during respiration and by the decomposition of organic substances

Synonyms

  • carbonic acid gas
  • CO2

Related Words

  • blackdamp
  • chokedamp
  • dioxide
  • greenhouse emission
  • greenhouse gas
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