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- Molecular formula: CO2
- Molar mass: 44.010
- CAS Registry Number: 124-38-9
- Appearance: Colorless, odorless gas. [Note: Shipped as a liquefied compressed gas. Solid form is utilized as dry ice.]; colourless odourless gas
- Melting point: -56.5
- Boiling point: -78
- Solubility: Water, 1480 mg/L (25 deg C)
- Safety sheet: Not available
- Spectra: ChemSpider (IR), Massbank MS (1, 2), also check on SDBS. Add Spectra (Help).
Carbon dioxide (chemical formula CO2) is a colorless, odorless gas vital to life on Earth. This naturally occurring chemical compound is composed of a carbon atom covalently double bonded to two oxygen atoms. Carbon dioxide exists in the Earth's atmosphere as a trace gas at a concentration of about 0.04 percent (400 ppm) by volume. Since carbon dioxide is soluble in water, it is found naturally in the oceans, lakes and rivers.
Atmospheric carbon dioxide is the primary source of carbon in life on Earth and its concentration in Earth's pre-industrial atmosphere since late in the Precambrian eon was regulated by photosynthetic organisms. As part of the carbon cycle, plants, algae, and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water, with oxygen produced as a waste product. However, photosynthesis cannot occur in darkness and at night some carbon dioxide is produced by plants during respiration.
It is produced during the respiration of all aerobic organisms and is exhaled in the breath of air-breathing land animals, including humans. Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread, beer and winemaking. It is an added constituent of carbonated beverages. It is produced by combustion of wood, carbohydrates and major carbon- and hydrocarbon-rich fossil fuels such as coal, peat, petroleum and natural gas. The frozen solid form of CO2 is available as a commodity in many Western supermarkets, where it goes by the name of dry ice.
The environmental effects of carbon dioxide are currently of significant interest. It is an important greenhouse gas and burning of carbon-based fuels since the industrial revolution has rapidly increased its concentration in the atmosphere, leading to global warming. It is also a major cause of ocean acidification since it dissolves in water to form carbonic acid.
Dry ice, sometimes referred to as "cardice" (chiefly British chemists), is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue (other than incidental frost from moisture in the atmosphere). It is useful for preserving frozen foods, ice cream, etc., where mechanical cooling is unavailable.
Dry ice sublimes at −78.5 °C (−109.3 °F) at Earth atmospheric pressures. This extreme cold makes the solid dangerous to handle without protection due to burns caused by freezing (frostbite). While generally not very toxic, the outgassing from it can cause hypercapnia due to buildup in confined locations.
Methanedione (IUPAC Name); Di-carbon oxide; carbonyl oxide; dioxidocarbon; dioxomethane; Dry ice; Dioxo-methane
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