Carbon dioxide dioxide carbon (CO2) is a gas colorless , dense and unreactive. It is part of the composition of the troposphere (layer of the atmosphere closest to Earth), currently at a rate of 350 ppm. (parts per million). Its cycle in nature is linked to that of oxygen. The carbon dioxide balance is extremely complex due to the interactions that exist between the atmospheric reserve of this gas, the plants that consume it in the photosynthesis process and the one transferred from the troposphere to the oceans.
Summary
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- 1 Cause of increased carbon dioxide in the atmosphere
- 2 Features
- 3 Uses
- 4 Medical use of carbon dioxide
- 5 Detection and quantification
- 6 Source
Cause of increased carbon dioxide in the atmosphere
The increase in carbon dioxide content that is currently verified is a component of global climate change, and possibly the best documented. From the mid-19th century until today, the increase has been 80 ppm. The analysis of gases retained in ice samples obtained at different depths in Antarctica and Greenland, has revealed the concentration of atmospheric carbon dioxide, and other gases from the so-called greenhouse effect, for at least the last 150,000 years. These concentrations have varied on the time scale of glaciations, with low concentrations during glacial periods (low temperatures) and relatively high during interglacial periods (high temperatures), with rapid transitions in both temperature variation and concentration of carbon dioxide. It has been debated whether this increase in atmospheric carbon dioxide content corresponds to these natural fluctuations or not, given that we are going through a post-glacial period. From the same source of information, the gas bubbles retained in ice of different ages, It has been verified that the current increase in the concentration of carbon dioxide is superimposed on the expected variation thereof and the levels reached exceed those recorded in the past, being the substantial and accelerated increase during the last 160 years and undoubtedly caused by the human activity. It is estimated that this increase is caused by a concurrence of factors among which the use offossil fuels (coal, oil and derivatives, gas) and burning for agricultural purposes can be identified as the most significant. This increase in the level of carbon dioxide is estimated to cause considerable climate change .
characteristics
- As its name implies, carbon dioxide is made up of two carbon atoms and one atom of oxygen, so its chemical formula is CO2. The carbon dioxide molecule has linear and symmetrical geometry, and the Lewis structure that represents it is: O = C = O. Formerly it was also called carbon dioxide or carbon dioxide.
- Physical properties: At room temperature and atmospheric pressure, carbon dioxide is a colorless and odorless gas, but it can solidify if subjected to temperatures below -79 ° C, as well as decompose if exposed to high temperatures (greater than 2000 ° C). C).
- Solubility and density: Carbon dioxide is well soluble in water (each volume of water dissolves 0.9 volume of C02) and its density is 1.5 g / cm3 (one and a half times that of air).
- Generation: Carbon dioxide is formed from various processes, including:
- Combustion: From fossil and non-fossil materials, such as oil, coal, gas.
- Fermentation: The fermentation of sugars carried out by bacteria and yeasts generally leads to the release of acids and / or alcohols and CO2.
- Breathing: Both higher animals and plants breathe; in this process there is oxygen uptake and carbon dioxide release.
- Reaction of carbonates in acidic medium.
Applications
It is used as an extinguishing agent, eliminating the oxygen found in that space, and preventing combustion. In the food industry, it is used in carbonated drinks to give them effervescence . It can also be used as a harmless or low polluting acid. Acidity can help to curdle dairy products in a faster and therefore cheaper way, without adding any flavor, and in the industry it can be used to neutralize alkaline residues without adding another more polluting acid such as sulfuric .
In agriculture, it can be used as compost . Although plants cannot absorb it by the roots, it can be added to lower the pH , avoid limescale, and make some soil nutrients more available .
Also in refrigeration it is used as a kind of coolant in refrigeration machines or frozen as dry ice . This same compound is used to create artificial fog and boil-over-water appearance in special effects in movies and shows.
Another use that is increasing is as an extracting agent when it is in supercritical conditions , given its little or no presence of residues in the extracts. This use is currently reduced to obtaining alkaloids such as caffeine and certain pigments , but a small review by scientific journals can give an insight into the enormous potential that this extraction agent presents, since it allows extractions in anoxic media, allowing obtain products with high antioxidant potential .
It is also used as an active material to generate coherent light ( CO 2 laser ).
Along with water, it is the most widely used solvent in processes with supercritical fluids .
Carbon dioxide is an unwanted by-product in many large-scale chemical processes, such as the selective oxidation of hydrocarbons to oxygenates. Carbon dioxide is the thermodynamically favored product in each oxidation reaction. Therefore, the challenge in developing these processes is to find an adequate catalyst and process conditions that allow the production of the thermodynamically less favored target product and minimize the production of carbon dioxide.
Medical use of carbon dioxide
- As an insufflation agent in laparoscopic surgeries .
- As a contrast agent in blood vessel radiology .
- In CO 2laser .
- As an agent for mechanical ventilation in surgeries.
- In treatment of cranial wounds and acute and chronic ulcers.
- In aesthetic treatments.
- In treatment of circulatory problems.
Detection and quantification
Carbon dioxide can be detected qualitatively in the gas form by the reaction with barite water (Ba (OH) 2 ) with which it reacts forming barium carbonate , a white precipitate insoluble in excess of reagent but soluble in acid solutions. The carbon dioxide quantification is done by acid-base methods indirectly and by instrumental methods by infrared.
