Carbon dioxide

“ Carbon Dioxide. A Product of Burning. When any fuel, such as coal, gas, oil, or wood, burns, it sends forth gases into the surrounding atmosphere. These gases, like air, are invisible, and were unknown to us for a long time. The chief gas formed by a burning substance is called carbon dioxide (CO2) because it is composed of one part of carbon and two parts of oxygen. This gas has the distinction of being the most widely distributed gaseous compound of the entire world ”

“ Wood and coal, and in fact all animal and vegetable matter, contain carbon, and when these substances burn or decay, the carbon in them unites with oxygen and forms carbon dioxide.
The food which we eat is either animal or vegetable, and it is made ready for bodily use by a slow process of burning within the body; carbon dioxide accompanies this bodily burning of food just as it accompanies the fires with which we are more familiar. The carbon dioxide thus produced within the body escapes into the atmosphere with the breath. ”

“ The origin of the carbon dioxide, which is present as a normal constituent of the atmosphere, does not directly concern us at present, but it is important to bear in mind that this gas is one of the products of the respiration of animals, so that the animal kingdom is one of the sources of plant carbon. ”

“ It should not be confused with the opposite action of plants under the influence of sunlight in taking in and decomposing carbon dioxide and expelling pure oxygen.
Carbon Dioxide. It forms the chief food supply of all green-leaved plants. It is as necessary to the life of vegetation as is oxygen in the supporting of animal life. In the ratio of seventy-seven to one hundred there is less of this gas present in the atmosphere in the winter than in the summer; there also is a diurnal maximum and minimum. In the open country the amount averages about 0.035 per cent. ”

“ The carbon dioxide, which is present in rain water, is obtained from the air through which the rain passes. Carbon dioxide is also taken up by the water as it percolates through ground covered with vegetation. The presence of this gas increases the solvent powers of the water. Water may also contain metal in solution such as iron, arsenic and copper. ”

“ The air receives its carbon dioxide from such sources as respiration, fermentation, from chemical action in the soil, from mineral springs, and from oxidation of organic matter.
Carbon dioxide is a transparent, odorless and colorless gas. It is a very important constituent in the atmosphere and a very slight variation either in its increase or decrease will vitally interfere with both animal and vegetable life. Green plants in the sunlight absorb great quantities of carbon dioxide and give off oxygen. ”

“ The fire extinguisher is therefore the source of a liquid containing the fire-extinguishing substance and further the source of a stream of carbon dioxide gas.
FIG. 25.—Inside view of a fire extinguisher.
51. Carbon. Although carbon dioxide is very injurious to health, both of the substances of which it is composed are necessary to life. We ourselves, our bones and flesh in particular, are partly carbon, and every animal, no matter how small or insignificant, contains some carbon; while the plants around us, the trees, the grass, the flowers, contain a by no means meager quantity of carbon. ”

“ From the soil come the water and all the salts, ash constituents, and the like that may be dissolved therein, while the gases of the atmosphere bring, among its chief contributions, a constant and, in an always exceedingly diluted form, the carbon dioxide, or, sometimes called, the carbonic-acid gas. This compound, familiar to us as a product of combustion, fermentation, and decay, is composed of carbon and oxygen, and has the symbol CO2 associated with it by chemists. ”

“ But even purified carbon dioxide is itself a rather repugnant gas, a product of metabolism whether fast or slow, and forever associated with those life processes which are obnoxious to the fastidious. ”

“ Carbon dioxide is formed by the living body.—Breathe through a glass tube into clear lime-water, so that the air you expel from your lungs bubbles through the liquid. Does the lime-water remain clear, or turn milky? Does the air you breathe out contain a considerable quantity of carbon dioxide gas? ”

“ The effect of this arrangement is that the great body of coal reaches a higher temperature than in an ordinary fireplace, and this, together with the reduction of the carbon dioxide formed immediately above the grate by the red-hot coal in the upper part of the furnace, leads to the formation of carbon monoxide which later on, on the spot where the greatest heat is required, is burned into dioxide by admitting fresh air, preferably pre-heated. ”

“ Carbon completely burned to carbon dioxide produces 14,500 British thermal units per pound of carbon, while the incomplete combustion to carbon monoxide evolves only 4,452 British thermal units, or less than one-third of the heat produced by the complete combustion. ”

“ If the air in the well will not support combustion,—that is, if the torch is extinguished,—it usually means that carbon dioxide has drained into the place. The air of a closed schoolroom often contains far too much of this gas, along with little solid particles of waste matters. Carbon dioxide is often known as carbonic acid gas. ”

“ CO2 valorization, electrolysis, molten carbonates, carbon monoxide, carbon
The Problematic of CO2 and Its Valorization
Global warming due to rising levels of greenhouse effect gases, such as atmospheric carbon dioxide, and energy consumption are the major challenges in the energetic field. Decreasing carbon dioxide emissions is a key issue but not the only one ”

“ Carbon dioxide is in the heart of fundamental processes over millions of years on Earth. It allows stocking solar energy through synthesis, and it is a key molecule for producing fossil fuels and, thus, it is an indicator of the consumption of energy from fossil fuels. Of course, the negative effect of CO2 in the atmosphere is dramatic and contributes to a significant increase in the temperature of our planet, which is becoming alarming. ”

“ A well-documented rise in global temperatures has coincided with a significant increase in the concentration of carbon [p505] dioxide in the atmosphere. Respected scientists believe the two trends are related. For when carbon dioxide is released into the atmosphere, it acts like the ceiling of a greenhouse, trapping solar energy and retarding the escape of reflected heat. It is therefore a species--the most important species--of a "greenhouse gas." ”

“ Any such settling of the carbon dioxide is prevented by the rapid motion of its molecules. This motion not only prevents a separation of carbon dioxide and air after they are mixed, but causes them to mix rapidly when they are separated, if they still have surface contact. The carbon dioxide found in old wells is formed there by decaying vegetable or animal matter. In rooms it is no more abundant at the floor than in other parts. ”

“ Because of the absence of sunshine the chemical activities of the plant are altered at night and the absorption of carbon dioxide ceases; therefore over the land the maximum amount occurs during the nighttime. This gas is dissolved in sea water and given off with a rise in temperature, which causes the maximum amount over oceans to occur at midday.
Carbon dioxide is 1.50 times as dense as an equal volume of atmospheric air. Its greater density causes it to collect in mines, sewers, cellars, and other low places, unless there is forceful ventilation. ”

“ The liberation of heat, and the formation of carbon dioxide, which always accompany the burning of animal and plant tissues, are worthy of very careful attention.
Fig. 168.—Experiment to prove that
expired air contains carbon dioxide.
It is well known that the body of a living animal such as a rabbit or a man is always warm; and the experiment (Fig. 168) of passing through clear lime-water the air breathed out from the lungs shows, by the milkiness produced, that the animal is also constantly producing carbon dioxide during its life. ”

“ The rare gases of the air especially should originally have come from the exterior parts of the sun, as did the nitrogen.
An atmosphere of such a composition would be utterly unendurable to living beings. It must, if organisms are going to thrive therein, be purified from such poisons as carbon dioxide, gaseous sulphur, cyanogen, and sulphurous acid. We know that such a process has taken place and that the sunlight has been the great chemist who produced oxygen and carbon from the carbon dioxide. ”

“ When coal is burning in a stove or grate carbon dioxide is at first formed in the free supply of air, but as the hot gas rises through the glowing coal it is reduced to carbon monoxide. When the carbon monoxide reaches the free air above the coal it takes up oxygen to form carbon dioxide, burning with the blue flame so familiar above a bed of coals, especially in the case of hard coals. ”

“ There is a larger proportion of the gas in the more or less confined air of crowded assemblies, school rooms and industrial work rooms, but even here it very rarely reaches four tenths of one per cent., or ten times its usual amount, and this is still well below the harmful limit. It thus appears that carbon dioxide, like oxygen, may be eliminated from the problem of fresh air, except under the rarest and most extreme circumstances. ”

“ So if, as supposed, all the oxygen of our atmosphere were liberated from carbon dioxide by green plants then would the quantity of carbon dioxide of the earth's atmosphere have been seven hundred times more before the appearance of green plants than at present, while the proportion of oxygen, according to this hypothesis, would have increased from 0 to 21 per cent in volume, while the enormous proportion of carbon-dioxide would have fallen to its present mass, namely 0.03 per cent in volume. ”

“ When coal gas is burned, the hydrogen is supposed to be entirely converted into water vapor, and the carbon to finally escape into the air as carbon dioxide; and if this were so, every cubic foot of gas consumed would produce approximately 0.52 cubic foot of carbon dioxide and 1.34 cubic feet of water vapor, while the illuminating power yielded by the cubic foot of gas will, of course, vary with the kind of burner used. ”

“ The volume composition of carbon dioxide is determined by burning carbon in oxygen, when it is found that the volume of carbon dioxide formed is the same as that of the oxygen required for its production, hence carbon dioxide contains its own volume of oxygen. Carbon dioxide finds industrial application in the preparation of soda by the Solvay process, in the sugar industry, in the manufacture of mineral waters, and in the artificial production of ice. ”

“ The choice of absorbents and the order in which the gases are to be estimated is strictly limited. Confining ourselves to cases where titration methods are not employed, the general order is as follows: carbon dioxide, olefines, oxygen, carbon monoxide, hydrogen, methane and nitrogen (by difference) . This scheme is particularly applicable to coal-gas. Carbon dioxide is absorbed by a potash solution containing one part of potash to between two and three of water; the stronger solution absorbs about 40 volumes of the gas. ”

“ Traces of nitrous and nitric acid are also present in the air, produced by the direct combination of nitrogen and oxygen occurring as the result of the electric spark during lightning.
Carbonic Acid or carbon dioxide is always present in air, in the proportion of 3·36 to 4 parts in 10,000; but in impure air may be present in much larger amount. It is a heavy gas, incapable of supporting combustion, and therefore of supporting animal life. Being a heavy gas, it tends to accumulate where it is produced, as about lime-kilns by the heating of chalk. ”

“ If all the oxygen of the air were converted into CO2 and H2O, the amount of CO2 in the smoke gases should be in the case of pure carbon nearly 21 volumes %, as carbon dioxide occupies the same volume as oxygen; while ordinary coal, where the hydrogen takes up a certain quantity of oxygen as well, should show about 18.5% CO2. But the best smoke gases of steam boilers show only 12 or 13%, much more frequently only 10% CO2, and gases from reverberatory furnaces often show less than 5%. ”

“ This led to a remarkable series of experiments in which it was repeatedly demonstrated that a man could live and work for a week at a time without experiencing any ill effects whatever in an atmosphere of his own breath containing as high as 1.86 per cent. of carbon dioxide, or, in other words, the air had its impurity increased 62 times. This agrees with what every chemist and physiologist has long known, and that is that carbon dioxide is not poisonous, but is a harmless dilutant just as nitrogen. ”

“ In cases of complete combustion they are eventually oxidized into carbon dioxide before they are able to escape. If a piece of metal be held in the flame, it immediately becomes covered with soot or carbon, because it has reduced the temperature below the point at which the chemical reaction—the uniting of carbon with oxygen—will continue. ”

“ The original power came from the sun millions of years ago, and did work by enabling the leaves of plants to overcome the strong mutual affinity of carbon and oxygen in the carbonic dioxide in the air, and store up the carbon in the plant, where it remained since the coal era in the form of energy of position. By lighting the coal, or in other words separating its molecules more widely by heat, we enable them to exert once more their natural affinity for oxygen, and burn, that is recombine into carbonic dioxide. ”