![]() In about 1640, the Flemish chemist Jan Baptist van Helmont observed that when he burned charcoal in a closed vessel, the mass of the resulting ash was much less than that of the original charcoal. Ĭarbon dioxide was the first gas to be described as a discrete substance. It has a sharp and acidic odor and generates the taste of soda water in the mouth, but at normally encountered concentrations it is odorless. It is a byproduct of fermentation of sugars in bread, beer and wine making, and is added to carbonated beverages like seltzer and beer for effervescence. The frozen solid form of CO 2, known as dry ice, is used as a refrigerant and as an abrasive in dry-ice blasting. It is an unwanted byproduct in many large scale oxidation processes, for example, in the production of acrylic acid (over 5 million tons/year). It is also a feedstock for the synthesis of fuels and chemicals. Sequestered CO 2 is released into the atmosphere through burning fossil fuels or naturally by volcanoes, hot springs, geysers, and when carbonate rocks dissolve in water or react with acids.ĬO 2 is a versatile industrial material, used, for example, as an inert gas in welding and fire extinguishers, as a pressurizing gas in air guns and oil recovery, and as a supercritical fluid solvent in decaffeination of coffee and supercritical drying. CO 2 is eventually sequestered (stored for the long term) in rocks and organic deposits like coal, petroleum and natural gas. These sinks can become saturated and are volatile, as decay and wildfires result in the CO 2 being released back into the atmosphere. About half of excess CO 2 emissions to the atmosphere are absorbed by land and ocean carbon sinks. Since plants require CO 2 for photosynthesis, and humans and animals depend on plants for food, CO 2 is necessary for the survival of life on earth.Ĭarbon dioxide is 53% more dense than dry air, but is long lived and thoroughly mixes in the atmosphere. CO 2 is released from organic materials when they decay or combust, such as in forest fires. In turn, oxygen is consumed and CO 2 is released as waste by all aerobic organisms when they metabolize organic compounds to produce energy by respiration. ![]() Plants, algae and cyanobacteria use energy from sunlight to synthesize carbohydrates from carbon dioxide and water in a process called photosynthesis, which produces oxygen as a waste product. Its concentration in Earth's pre-industrial atmosphere since late in the Precambrian has been regulated by organisms and geological phenomena. ![]() Īs the source of available carbon in the carbon cycle, atmospheric carbon dioxide is the primary carbon source for life on Earth. When carbon dioxide dissolves in water it forms carbonic acid (H 2CO 3), which causes ocean acidification as atmospheric CO 2 levels increase. Carbon dioxide is soluble in water and is found in groundwater, lakes, ice caps, and seawater. Burning fossil fuels is the primary cause of these increased CO 2 concentrations and also the primary cause of global warming and climate change. It is a trace gas in Earth's atmosphere at 417 ppm (about 0.04%) by volume, having risen from pre-industrial levels of 280 ppm. In the air, carbon dioxide is transparent to visible light but absorbs infrared radiation, acting as a greenhouse gas. ![]() It is found in the gas state at room temperature. Carbon dioxide ( chemical formula CO 2) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms.
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