Combustion Carbon Dioxide

.. carbon dioxide plus carbonic acid. The carbonic acid can neutralize hydroxide ions which if added, would increase the pH of the blood and cause alkalosis. The bicarbonate ion can neutralize hydrogen ions that, if added, would cause a decrease in the pH of the blood and lead to acidosis. Both changes in pH are life threatening.

The carbon dioxide in the earth’s atmosphere helps regulate the planet’s temperature. When sunlight reaches the earth, some of it is converted into heat. The carbon dioxide absorbs some of the heat and so helps keep it near the earth’s surface. If all the heat from the sunlight escaped into outer space, the earth would become very cold. The amount of carbon dioxide in the atmosphere has been increasing since about 1890, chiefly as a result of the burning of fuels that contain carbon.

This increase has caused a slight rise in the earth’s average temperature. Carbon dioxide has important uses in the home and in industry. For example, carbon dioxide released by baking powder or yeast makes cake batter rise. Carbon dioxide in soft drinks, beer, and sparkling wines gives the beverages their fizz. Some fire extinguishers use carbon dioxide because it does not bum and because pure carbon dioxide is denser than air. Carbon dioxide’s heaviness enables it to blanket a fire and prevent oxygen from getting to the fire thus starving the burning material of the oxygen it needs to continue burning. Dry ice is solid carbon dioxide.

Carbon dioxide becomes a solid at -78.5 0C. The name dry ice refers to the fact that the substance changes from a solid to a gas without first becoming a liquid. Because of this property, dry ice is widely used in industry to refrigerate food, medicine, and other materials that would be damaged by the melting of ordinary ice. Carbon dioxide is one of the most important compounds on earth. Its importance to industry and the survival of all life are well documented. Without it, all human life would cease to exist. We all owe a debt of gratitude to our friend CO2 of burning, releases heat.

If the heat so released cannot escape the substance, the temperature of the substance rises until ignition takes place. Spontaneous combustion often occurs in piles of oily rags, green hay, leaves, or coal; it can constitute a serious fire hazard. Carbon dioxide CO2, chemical compound, occurs as a colorless, odorless, tasteless gas that is about 1 1/2 times as dense as air under ordinary conditions. It does not burn and will not support combustion of ordinary materials. Its weakly acidic aqueous solution is called carbonic acid. The gas, easily liquefied by compression and cooling, provides the sparkle in carbonated beverages.

Solid carbon dioxide, or dry ice, is a refrigerant. Dough rises because of carbon dioxide formed by the action of yeast or baking powder. Carbon dioxide is a raw material for photosynthesis in green plants, and is a product of animal respiration and of the decay of organic matter. Carbon dioxide occurs both free and combined in nature, and makes up about 1% of the volume of dry air. It can cause death by suffocation if inhaled in large amounts. Carbon dioxide is a gas that occurs in the atmosphere and is produced in body tissues as a waste product of energy-generating processes. Dissolved in the blood, carbon dioxide is carried to the lungs, and from there it is exhaled as a gas.

Some carbon dioxide also leaves the body in urine and in perspiration. If the level of carbon dioxide in the blood rises above normal, the brain automatically stimulates the lungs into working faster. The increase in breathing rate is necessary to rid the body of the extra carbon dioxide, but it may be harmful in other ways. CO2, a colorless gas having a faint, sharp odor and a sour taste; it is a minor component of the Earth’s atmosphere (about 3 volumes in 10,000), formed in combustion of carbon-containing materials, in fermentation, and in respiration of animals and employed by plants in the photosynthesis of carbohydrates. The presence of the gas in the atmosphere keeps some of the radiant energy received by the Earth from being returned to space, thus producing the so-called greenhouse effect.

Industrially, it is recovered for numerous diverse applications from flue gases, as a by-product of the preparation of hydrogen for synthesis of ammonia, from limekilns, and from other sources. Carbon dioxide was recognized as a gas different from others early in the 17th century by a Belgian chemist, Jan Baptist van Helmont, who observed it as a product of both fermentation and combustion. By the mid-20th century, most carbon dioxide was sold as the liquid. If the liquid is allowed to expand to atmospheric pressure, it cools and partially freezes to a snow like solid called Dry Ice that sublimes (passes directly into vapor without melting) at -78.5 C (-109.3 F) at the pressure of the normal atmosphere. At ordinary temperatures, carbon dioxide is quite unreactive; above 1,700 C (3,100 F) it partially decomposes into carbon monoxide and oxygen.

Hydrogen or carbon also converts it to carbon monoxide at high temperatures. Ammonia reacts with carbon dioxide under pressure to form ammonium carbonate, then urea, an important component of fertilizers and plastics. Carbon dioxide is slightly soluble in water (1.79 volumes per volume at 0 C and atmospheric pressure, larger amounts at higher pressures), forming a weakly acidic solution. This solution contains the dibasic acid called carbonic acid (H2CO3). Carbon dioxide is used as a refrigerant, in fire extinguishers, for inflating life rafts and life jackets, blasting coal, foaming rubber and plastics, promoting the growth of plants in greenhouses, immobilizing animals before slaughter, and in carbonated beverages. Ignited magnesium continues to burn in carbon dioxide, but the gas does not support the combustion of most materials.

Prolonged exposure of humans to concentrations of 5 percent carbon dioxide may cause unconsciousness and death. Bibliography Combustion & Carbon dioxide Bibliography F. P. Tully, Combustion Reactions of OH, Sandia T Albuquerque, NM (1989) .Technology, Sandia National Laboratories J. O. Keller and P. K.

Barr, Premixed Combustion in a Periodic Flow Field. Part I: Experimental Investigation, Combust. Flame 99, 29 (1994). R. J.

Kee, J. A. Miller, G. H. Evans, and G. Dixon-Lewis, A Computational Model of the Structure and Extinction of Strained, Opposed Flow, Premixed Methane-Air Flames, Twenty-Second Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, PA, 1479-1494 (1989).

W. Kollmann and J. H. Chen, Dynamics of the Flame Surface Area in Turbulent Non-premixed Combustion, Twenty-Fifth Symposium (International) on Combustion, (The Combustion Institute, Pittsburgh, PA, 1994) pp. 1091-1098. Brady, James and Holum, John, Fundamentals of Chemistry, New York, John Wiley & Sons, 1988.

World Book Encyclopedia, 1992 edition, see Carbon dioxide. Science and Invention, 1983 edition, see Carbon dioxide. McGraw-Hill Encyclopedia of Science and Technology, 1987 edition, see Carbon dioxide.