{"id":39006,"key":"Carbon_dioxide","title":"Carbon dioxide","latest":{"id":1243608,"timestamp":"2026-04-16T17:02:12Z"},"content_model":"wikitext","license":{"url":"https://www.appropedia.org/Appropedia:Copyrights","title":"CC-BY-SA-4.0"},"source":"[[File:CO2 World 1960-2018.png|thumb|Total worldwide CO2 emissions. Data source: World Bank]]\n\n'''Carbon dioxide''' is formed by the complete combustion of carbon or compounds of carbon (principally the hydrocarbons). It is a [[greenhouse gas]] and one of the main drivers behind [[climate change]].\n\n== Chemistry ==\n\nCarbon dioxide is first a tri-atomic molecule {one atom of carbon and two of oxygen, yet it is not usually known as such}. Carbon dioxide is a compound (that is to say, a substance that is made up from more than one type of atom).\n\nCarbon dioxide <math>CO2</math> is chemically represented as <math>O=C=O</math>. The molecule is linear and non-polar.\n\nCO2 is made from two different types of atoms - this is noted by the -ide suffix. In this case, diox- means two oxygens.\n\nOxygen needs to make and share two covalent chemical bonds to be stable; carbon needs to make four. This is to help explain the molecular formula <math>O=C=O</math>.\n\nIt is also produced by the reaction of carbonates or hydrogen carbonates with acids, and by heating carbonates (without water).\n\nPlants convert atmospheric CO2 and water vapor into carbohydrates through photosynthesis, which requires both chlorophyll and Sunlight.\n\nChemical double bonds occur in many instances, starting with <math>H2C=CH2<math> (ethylene) and <math>O=C=O</math>.\n\n== Behavior ==\n\nCO2 is moderately soluble in water; it is the acid-anhydride of carbonic acid. In other words, solutions of carbon dioxide are acidic. Carbon dioxide reacts with water to form carbonic acid, H2CO3; however the reaction is not complete - most of the carbon dioxide exists in solution as CO2 molecules.\n\nThe phase [solid/liquid/gas/plasma phases] diagram for CO2 shows that at one Atmosphere [1 atm] of pressure CO2 has a freezing point temperature of -78.5 degrees C. CO2 like most substances contracts upon freezing.\n\nHowever, upon thawing, CO2 sublimates - it trans-phases directly from Solid to Vapor.\n\nThe phase diagram also shows that The Triple Point of CO2 [where solid, liquid and gaseous States (phases) may co-exist] 'occurs' at 5.11 atm and at -56.6 degrees C. In this case, this means that CO2 cannot be a Liquid below 5.11 atm.\n\n== Climate change and CO<sub>2</sub> ==\n\nIncreasing levels of carbon dioxide in the atmosphere trap more of the sun's heat, raising average temperatures and changing climate patterns - i.e. causing [[climate change]].\n\nThis is due to human activity, releasing carbon underground trapped in [[fossil fuels]].\n\nThere are other chemical atmospheric discharges that are more actively greenhouse gases than carbon, yet the effects of these are 'side-lined' when put up against our incessantly increasing deposition of CO<sub>2</sub> - into Our One and Only Paper Thin Atmosphere.\n\n{{Page data\n| license = CC-BY-SA-3.0\n| description = CO₂ drives climate change. Appropedia explains its role in global warming, biology, and what we can do.\n}}\n\n[[Category:Chemical substances]]\n[[Category:Climate change]]\n[[Category:Technical briefs]]"}