Difference between revisions of "Carbon dioxide"
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It is used by plants in the process of [[photosynthesis]] to generate [[oxygen]]. | It is used by plants in the process of [[photosynthesis]] to generate [[oxygen]]. | ||
| − | At room temperature and atmospheric [[pressure]], it is a gas. It becomes solid at -78 ºC, forming dry ice. When it thaws, it turns directly into a gas again (see [[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> | + | [[Image:CO2phase.jpg|thumb|right|300px|[[Phase diagram]] for CO<sub>2</sub>]] |
| + | At room temperature and atmospheric [[pressure]], it 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 (see [[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> | ||
Each molecule of carbon dioxide has one carbon atom and two oxygen atoms, so its chemical formula is CO<sub>2</sub>. | Each molecule of carbon dioxide has one carbon atom and two oxygen atoms, so its chemical formula is CO<sub>2</sub>. | ||
CO<sub>2</sub> is one of the so-called "greenhouse" gases. 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, though not scientific, debate. | CO<sub>2</sub> is one of the so-called "greenhouse" gases. 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, though not scientific, debate. | ||
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[[Category: Chemistry]] | [[Category: Chemistry]] | ||
Revision as of 02:54, April 20, 2007
Carbon dioxide in an odorless, colorless gas formed by the combustion of hydrocarbons, both naturally, in the human body, and artificially, as fuel. It is one of the human body's major waste products, being excreted through exhalation. It is used by plants in the process of photosynthesis to generate oxygen.
At room temperature and atmospheric pressure, it 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 (see sublimation). [1]
Each molecule of carbon dioxide has one carbon atom and two oxygen atoms, so its chemical formula is CO2.
CO2 is one of the so-called "greenhouse" gases. Heat-trapping by CO2 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, though not scientific, debate.
References
- ↑ "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." How Stuff Works