Title: Carbon Dioxide
CAS Registry Number: 124-38-9
Additional Names: Carbonic acid gas; carbonic anhydride
Molecular Formula: CO2
Molecular Weight: 44.01
Percent Composition: C 27.29%, O 72.71%
Literature References: Occurs in the atms of many planets. In our solar system, e.g., on Venus, the optical layer thickness due to CO2 is 100,000 cm/atm, but only 220 cm/atm on Earth. Analyses of air in the temperate zones of the Earth show 0.027 to 0.036% (v/v) of CO2: G. P. Kuiper, The Atmospheres of the Earth and the Planets (Univ. of Chicago Press, 1949); Landolt-Bornstein, Zahlenwerte vol. III (Springer-Verlag, 6th ed., 1952) pp 59 and 585. Constituent of carbonate type of minerals and products of animal metabolism. Necessary for the respiration cycle of plants and animals. Obtained industrially as a by-product in the manuf of lime during the "burning" of limestone (CaCO3). Also produced by burning coke or other carbonaceous material. In the U.S.A. large amounts are produced by fermentation (Backus process and Reich process). When glucose is fermented by yeast, the chief products are ethyl alcohol and CO2. Prepd in the laboratory by dropping acid on a carbonate: E. H. Archibald, The Preparation of Pure Inorganic Substances (Wiley, New York, 1932) p 196; Loomis, Walters, J. Am. Chem. Soc. 48, 3103 (1926). Purification: Glemser in Handbook of Preparative Inorganic Chemistry G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) p 647. Discovery of a second polymorph of dry ice: L.-G. Liu, Nature 303, 508 (1983). Reviews: E. L. Quinn, J. Chem. Educ. 7, 151-162 and 403-419 (1930); J. Kuprianoff, Die feste Kohlensäure (Trockeneis) (Enke, Stuttgart, 1939); E. L. Quinn, C. L. Jones, Carbon Dioxide (Reinhold, New York, 1947); W. R. Ballou, in Kirk-Othmer Encyclopedia of Chemical Technology vol. 4 (Interscience, New York, 3rd ed., 1978) pp 725-742. Reviews of supercritical CO2 (scCO2) solvent uses and environmental benefits in polymer chemistry: S. L. Wells, J. DeSimone, Angew. Chem. Int. Ed. 40, 518-527 (2001); in catalysis: W. Leitner, Acc. Chem. Res. 35, 746-756 (2002).
Properties: Colorless, odorless, noncombustible gas. Faint acid taste. Usually a nonsupporter of combustion, athough burning magnesium continues to burn when transferred into a CO2 atm. Usually marketed in steel cylinders (under sufficient pressure to keep it liquid) or in solid form as Dry Ice (compressed carbon dioxide snow, d 1.35). When shipped in steel cylinders, CO2 is in the form of gas over liquid and at 20° exerts a pressure of 830 psi. Use gloves when handling dry ice, as its temp is at least -78.5°; momentary skin contact with dry ice has caused serious frostbites and blisters. At atmospheric pressures the solid form changes into the gaseous phase without liquefaction. d (gas) 1.527 (air = 1); d (gas) 1.557 (N2 = 1); abs d 0.1146 lb/cu ft at 25°; vol at 25°: 8.76 cu ft/lb. d (gas, 0°) 1.976 g/l at 760 mm; d (liq, 0°) 0.914 at 34.3 atm; d (solid, -56.6°) 1.512. Sublimes at -78.48° (760 mm). mp5.2 atm -56.6°. The gas is not affected by heat until temp reaches about 2000°. Crit temp 31.3°; crit press 72.9 atm; crit density 0.464. Triple point -56.6° at 5.11 atm. Vapor press at -120°: 10.5 mm; at -100°: 104.2 mm; at -82°: 569.1 mm. Heat of formation 94.05 kcal/mol. Latent heat of vaporization 83.12 g cal/g. Specific heat 0.19 to 0.21 Btu/lb. Soly in water (ml CO2/100 ml H2O at 760 mm): 0° = 171; 20° = 88; 60° = 36. More sol at higher pressures. Less sol in alcohol, other neutral organic solvents. Absorbed by alkaline solns with the formation of carbonates.
Melting point: mp5.2 atm -56.6°
Density: d 1.35; d (gas) 1.527 (air = 1); d (gas) 1.557 (N2 = 1); abs d 0.1146 lb/cu ft at 25°; d (gas, 0°) 1.976 g/l at 760 mm; d (liq, 0°) 0.914 at 34.3 atm; d (solid, -56.6°) 1.512
CAUTION: Potential symptoms of overexposure are headache, dizziness, restlessness and paresthesia; dyspnea; sweating, malaise; increased heart rate and cardiac output; elevated blood pressure; coma; asphyxia; convulsions; direct contact with liquid or dry ice may cause frostbite. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 52.
Use: In the carbonation of beverages; manuf of carbonates; in fire prevention and extinction; for inerting flammable materials during manuf, handling and transfer; as propellant in aerosols; as dry ice for refrigeration; to produce harmless smoke or fumes on stage; as rice fumigant; as antiseptic in bacteriology and in the frozen food industry. Supercritical or liquid CO2 used in extraction of caffeine and hops aroma; dry cleaning; metal degreasing; cleaning semiconductor chips; paint spraying; polymer modification. Environmentally benign alternative to potentially hazardous solvents in organic and polymer chemistry.
Therap-Cat: Respiratory stimulant.
Therap-Cat-Vet: Respiratory stimulant (inhalant).
Keywords: Respiratory Stimulant. |