Carbon Dioxide (CO2)
arbon Dioxide (CO2) is a colorless gas, which was first discovered in 1577 by Van Helmont who detected it in the products of both fermentation and charcoal burning. CO2 is used in solid, liquid, and gas forms in a variety of industrial processes. These include: beverage carbonation, dry ice, welding and chemicals manufacturing. It is produced by the combustion of all carbonaceous fuels and can be recovered in an abundance of ways. It is widely used today as a by-product of synthetic ammonia production, fermentation, and from flue gases by absorption process. CO2 is also a product of animal metabolism and is important in the life cycles of plants and animals. It is present in the atmosphere only in small quantities (.03% by vol.)
CO2 is not very reactive at normal temperatures, but it does form carbonic acid, (H2CO3 ) in aqueous solution. This will undergo the typical reactions of a weak acid to form salts. I call it carbonic acid because in the presence of moisture, which we have all around us, it will make an acid. CO2 is also responsible for the acidic pH of rain water. So that nasty stuff called “acid rain” is caused by CO2. A solid hydrate CO28H20 separates from aqueous solutions of CO2 that are colder at elevated pressures. It is very stable at normal temperatures, but forms CO and O2 when heated above 1700oC.
CO2 can be reduced by several methods, the most common being its reaction with hydrogen (H). This is the reverse of the water gas shift reaction, commonly used in the production of hydrogen and ammonia. It can also be reduced with hydrocarbons and carbons at elevated temperatures. CO2 will react with ammonia to form ammonium carbonate. CO2 + NH3 ---? NH4 + CO3. We humans also produce CO2 with every breath we take, but the amount is too small to harm anyone. Carbon dioxide can be dangerous at higher levels though. A mere 5% by vol. of the gas in the air increases the breathing rate and long amounts of exposure can lead to unconsciousness or even death. The gas carbon dioxide is much heavier than the air around us and is also heavier than its friend carbon monoxide. Its density is much greater and it turn will cause the gas to be harder for plants to get rid of very quickly. Some scientist even say it will pour like a liquid into the air.

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