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| | [[Image:CO2phase.jpg|thumb|right|300px|[[Phase diagram]] for CO<sub>2</sub>]] | | [[Image:CO2phase.jpg|thumb|right|300px|[[Phase diagram]] for CO<sub>2</sub>]] |
| | + | [[Image:CO2.gif|thumb|left|150px|The bonds of Carbon Dioxide]] |
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| − | '''Carbon dioxide''' (CO<sub>2</sub>) is an odorless, colorless [[gas]] formed by the [[oxidation]] of [[hydrocarbon]]s, both naturally, in animals, and artificially, as fuel<ref>If not enough oxygen is present, [[carbon monoxide]] will also be produced, in a process called [[incomplete combustion]].</ref>. It is one of the human body's major waste products, being excreted through exhalation. | + | '''Carbon dioxide''' (CO<sub>2</sub>) is an odorless, colorless [[gas]] formed by the [[oxidation]] of [[hydrocarbon]]s, both naturally, in animals, and artificially, as fuel.<ref>If not enough oxygen is present, [[carbon monoxide]] will also be produced, in a process called [[incomplete combustion]].</ref> |
| | + | It is used by [[plants]] in the process of [[photosynthesis]] to create complex carbohydrates ([[cellulose]] and [[sugar]]s), using water and the [[energy]] from sunlight. The waste product in this process is [[oxygen]]. ''Carbon dioxide is not a pollutant, but a pervasive byproduct of life''. CO<sub>2</sub> should be called an "emission", not a "pollutant", in debates about [[global warming]]. |
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| − | It is used by plants in the process of [[photosynthesis]] to create complex carbohydrates ([[cellulose]] and [[sugar]]s), using water and the energy from sunlight. The waste product in this process is [[oxygen]]. | + | It is one of the [[human]] body's major waste products, being excreted through exhalation (breathing). |
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| − | At room temperature and atmospheric [[pressure]], carbon dioxide is a gas. It becomes solid at -78 ºC at standard atmospheric pressure, forming dry ice. When it thaws, it turns directly into a gas again (called [[sublimation]]). <ref>"Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it breaks down, it turns directly into carbon dioxide gas rather than a liquid." [http://www.howstuffworks.com/question264.htm How Stuff Works] </ref> This can be seen from the phase diagram to the right, where at 1 atmosphere of pressure, there is no liquid state separating the solid and gas as temperature rises.
| + | It is the second simplest [[oxycarbon]], after [[Carbon Monoxide]]. The structure of Carbon Dioxide is that of a single carbon atom, double bonded to two oxygen atoms. |
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| − | CO<sub>2</sub> is one of the so-called [[greenhouse gas]]es. Heat-trapping by CO<sub>2</sub> has been observed on [[Earth]] and [[Venus]]. The extent of its role in the current increase in average global temperatures is a topic of active political and scientific debate.
| + | The [[Lewis structure]] indicates it has two double bonds, |
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| − | The Lewis structure indicates it has two double bonds:
| + | At room temperature and atmospheric [[pressure]], carbon dioxide is a gas. It becomes solid at -78 °C at standard atmospheric pressure, forming [[dry ice]]. When it thaws, it turns directly into a gas again (called [[sublimation]]).<ref>"Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it breaks down, it turns directly into carbon dioxide gas rather than a liquid." [http://www.howstuffworks.com/question264.htm How Stuff Works]</ref> This can be seen from the phase diagram to the right, where at 1 atmosphere of pressure, there is no liquid state separating the solid and gas as temperature rises. |
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| − | [[Image:CO2.gif]] | + | There is no catalytic converter for CO<sub>2</sub>, in contrast with the emissions control device used for automobiles. |
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| | + | ==Carbon Dioxide and Atmospheric Temperature== |
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| | + | CO<sub>2</sub> is one of the "[[greenhouse gas]]es". Heat-trapping by CO<sub>2</sub> has been observed on [[Earth]] and [[Venus]]. The extent of its role in the current increase in average global temperatures is a topic of active political and scientific debate. Rising CO<sub>2</sub> levels in the atmosphere have been observed to promote acidification of the oceans, through CO<sub>2</sub> + H<sub>2</sub>O → H<sub>2</sub>CO<sub>3</sub>. |
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| | + | [[Environmentalist]]s predict catastrophic [[global warming]] scenarios at the hands of excessive CO<sub>2</sub> released by industrial and commercial activities. A counterargument to this theory is that, the planet naturally gives off carbon dioxide, from natural sources such as volcanoes, and thus, it is not so bad for the Earth. |
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| | + | The effects of an increased level of CO<sub>2</sub> is increased [[plant]] growth since carbon dioxide is a reactant of the photosynthesis reaction, meaning that more CO<sub>2</sub> gives plants more energy, hence increased growth. This supposedly has beneficial effects for humans, such as greater crop yields and alleviating the effects of a growing human population. |
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| | + | ==See also== |
| | + | *[[Carbon dioxide in the atmosphere]] |
| | + | *"[[Greenhouse effect]]" |
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| | ==References== | | ==References== |
| | <references /> | | <references /> |
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| − | [[Category: Chemical Compounds]] | + | [[Category:Chemical Compounds]] |