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Carbon Dioxide is produced by people. It helps trees and other plants live. Carbon dioxide is also known as C02'.
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{{redirect|CO2|the postal district|CO postcode area}}
{{chembox
| Name = '''Carbon dioxide'''
| ImageFileL1 = Carbon-dioxide-2D-dimensions.svg
| ImageSizeL1 = 120px
| ImageFileR1 = Carbon-dioxide-3D-vdW.svg
| ImageSizeR1 = 120px
| ImageName = Carbon dioxide
| IUPACName = Carbon dioxide
| OtherNames = Carbonic acid gas; carbonic anhydride; [[dry ice]] (solid)
| Section1 = {{Chembox Identifiers
| CASNo = 124-38-9
| ChemSpiderID = 274
| UNNumber = [[List of UN Numbers 1001 to 1100|1013]]<br/>''Solid ([[dry ice]]): ''[[List of UN Numbers 1801 to 1900|1845]]<br/>''Mixtures with [[Ethylene oxide]]: ''[[List of UN Numbers 1901 to 2000|1952]],[[List of UN Numbers 3201 to 3300|3300]]
| PubChem = 280
| SMILES = C(=O)=O
| EINECS = 204-696-9
| RTECS = FF6400000
| InChI = 1/CO2/c2-1-3
}}
| Section2 = {{Chembox Properties
| Formula = {{co2}}
| MolarMass = 44.0095(14) g/mol
| Appearance = colorless gas
| Density = 1,600 g/L, solid; 1.98 g/L, gas
| Solubility = 1.45 g/L at 25°C, 100kPa
| MeltingPt = −56.6°C (216.6 K) −69.9°F (at 5.185 bar)
| BoilingPt = −78.5°C (194.7 K) −109.3°F ([[Sublimation (chemistry)|sublimes]])
| pKa = 6.35 and 10.33
| Viscosity = 0.07 c[[Poise|P]] at −78 °C
| Dipole = zero
}}
| Section3 = {{Chembox Structure
| MolShape = [[Linear (chemistry)|linear]]
}}
| Section8 = {{Chembox Related
| Function = [[oxide]]s
| OtherFunctn = [[carbon monoxide]]; [[carbon suboxide]]; [[dicarbon monoxide]]; [[carbon trioxide]]}}
}}
'''Carbon dioxide''' ([[chemical formula]]: '''{{co2}}''') is a [[chemical compound]] composed of two [[oxygen]] [[atom]]s [[covalent bond|covalently bonded]] to a single [[carbon]] atom. It is a [[gas]] at [[standard temperature and pressure]] and exists in [[Earth's atmosphere]] in this state. It is currently at a globally averaged concentration of approximately 387 [[parts per million|ppm]] by [[volume]] in the Earth's atmosphere,<ref>{{cite journal|title=Atmospheric CO<sub>2</sub> records from sites in the SIO air sampling network|first=Keeling, CD|last=Whorf, T.P.|year=2005|work=Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.|url=http://cdiac.ornl.gov/trends/co2/sio-mlo.htm|format={{dead link|date=October 2008}} &ndash; <sup>[http://scholar.google.co.uk/scholar?hl=en&lr=&q=author%3AWhorf%2C+T.P.+intitle%3AAtmospheric+CO%3Csub%3E2%3C%2Fsub%3E+records+from+sites+in+the+SIO+air+sampling+network&as_publication=&as_ylo=2005&as_yhi=2005&btnG=Search Scholar search]</sup>}} Period of record: 1958-2004</ref><ref name="nonanews">{{cite news |title=After two large annual gains, rate of atmospheric {{co2}} increase returns to average| url=http://www.noaanews.noaa.gov/stories2005/s2412.htm |date=2005-03-31 |publisher =NOAA News Online, Story 2412}}</ref>. Atmospheric concentrations of carbon dioxide fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth in the [[Northern Hemisphere]]. Concentrations of carbon dioxide fall during the northern spring and summer as plants consume the gas, and rise during the northern autumn and winter as plants go dormant, die and decay. Carbon dioxide is a [[greenhouse gas]] as it transmits [[visible spectrum|visible light]] but absorbs strongly in the [[infrared]] and [[near-infrared]] {{Fact|date=July 2008}}.

Carbon dioxide is used by plants during [[photosynthesis]] to make sugars which may either be consumed again in [[respiration]] or used as the raw material to produce [[polysaccharide]]s such as [[starch]] and [[cellulose]], [[protein]]s and the wide variety of other organic compounds required for plant growth and development. It is produced during [[respiration]] by plants, and by all animals, fungi and microorganisms that depend on living and decaying plants for food, either directly or indirectly. It is, therefore, a major component of the [[carbon cycle]]. Carbon dioxide is generated as a by-product of the combustion of [[fossil fuels]] or the burning of vegetable matter, among other chemical processes. Large amounts of carbon dioxide are emitted from [[volcano]]es and other [[geothermal]] processes such as [[hot springs]] and [[geysers]] and by the dissolution of carbonates in crustal rocks.

Carbon dioxide has no liquid state at pressures below 5.1 [[atmosphere (unit)|atm]]. At 1 atm it is a solid at temperatures below -78 °C. In its solid state, carbon dioxide is commonly called [[dry ice]].

{{co2}} is an [[acidic oxide]]: an aqueous solution turns [[litmus test (chemistry)|litmus]] from blue to pink.

{{co2}} in concentrations higher than 1% (10,000 ppm) will make some people feel drowsy{{Fact|date=June 2008}}. Concentrations of 7% to 10% cause dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few minutes to an hour<ref>
U.S. Environmental Protection Agency: [http://www.epa.gov/ozone/snap/fire/co2/co2report.html "Carbon Dioxide as a Fire Suppressant: Examining the Risks"]
</ref>.

==Chemical and physical properties==

[[Image:Carbon dioxide pressure-temperature phase diagram.svg|left|thumb|220px|Carbon dioxide pressure-temperature phase diagram showing the [[triple point]] and [[Critical point (thermodynamics)|critical point]] of carbon dioxide]]

{{details|Carbon dioxide (data page)}}Carbon dioxide is a colorless, odorless gas. When inhaled at concentrations much higher than usual atmospheric levels, it can produce a sour taste in the mouth and a stinging sensation in the nose and throat. These effects result from the gas dissolving in the [[mucous membranes]] and [[saliva]], forming a weak solution of [[carbonic acid]]. This sensation can also occur during an attempt to stifle a burp after drinking a [[Carbonation|carbonated beverage]]. Amounts above 5,000 ppm are considered very unhealthy, and those above about 50,000 ppm (equal to 5% by volume) are considered dangerous to animal life.<ref>{{cite web | author = Staff | date= 16 August 2006 | url = http://www.cdc.gov/niosh/idlh/124389.html | title = Carbon dioxide: IDLH Documentation | publisher = National Institute for Occupational Safety and Health | accessdate = 2007-07-05}}</ref>

At [[Standard conditions for temperature and pressure|standard temperature and pressure]], the density of carbon dioxide is around 1.98 kg/m³, about 1.5 times that of [[Earth's atmosphere|air]]. The carbon dioxide molecule (O=C=O) contains two [[covalent bond|double bonds]] and has a linear shape. It has no electrical [[dipole]], and as it is fully [[Redox|oxidized]], it is moderately [[Chemical reaction|reactive]] and is non-flammable, but will support the combustion of metals such as [[magnesium]].
{{clear}}
{| style = "float:left"
|-
|
[[Image:Dry Ice Pellets Subliming.jpg|thumb|left|220px|Small pellets of dry ice subliming in air.]]
|-
|
[[Image:Carbon-dioxide-crystal-3D-vdW.png|thumb|left|220px|Crystal structure of dry ice]]
|}
At −78.51° [[Celsius|C]] or -109.3° [[Fahrenheit|F]], carbon dioxide changes directly from a solid phase to a gaseous phase through [[sublimation (chemistry)|sublimation]], or from gaseous to solid through [[Deposition (chemistry)|deposition]]. Solid carbon dioxide is normally called "[[dry ice]]", a [[generic trademark]]. It was first observed in 1825 by the French chemist [[Charles Thilorier]]. Dry ice is commonly used as a cooling agent, and it is relatively inexpensive. A convenient property for this purpose is that solid carbon dioxide sublimes directly into the gas phase leaving no liquid. It can often be found in grocery stores and laboratories, and it is also used in the shipping industry. The largest non-cooling use for dry ice is [[Dry ice blasting|blast cleaning]].

Liquid carbon dioxide forms only at [[pressure]]s above 5.1 atm; the [[triple point]] of carbon dioxide is about 518 [[kPa]] at −56.6 °C (See phase diagram, above). The [[Critical point (thermodynamics)|critical point]] is 7.38 MPa at 31.1 °C.<ref>{{cite web|url=http://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Units=SI&Mask=4#Thermo-Phase|title=Phase change data for Carbon dioxide|publisher=National Institute of Standards and Technology|accessdate=2008-01-21}}</ref>

An alternative form of solid carbon dioxide, an [[amorphous]] glass-like form, is possible, although not at atmospheric pressure.<ref>{{cite journal | last=Santoro | first=M. | coauthors=et al | year=2006 | title=Amorphous silica-like carbon dioxide | url= | journal=Nature | issn=0028-0836 | volume=441 | issue=7095 | pages=857–860 | doi=10.1038/nature04879}}</ref> This form of glass, called [[amorphous carbonia|''carbonia'']], was produced by [[supercooling]] heated {{co2}} at extreme pressure (40–48 [[GPa]] or about 400,000 atmospheres) in a [[diamond anvil]]. This discovery confirmed the theory that carbon dioxide could exist in a glass state similar to other members of its elemental family, like [[silicon]] ([[silica|silica glass]]) and [[germanium]]. Unlike silica and germania glasses, however, carbonia glass is not stable at normal pressures and reverts back to gas when pressure is released.

{{seealso|Supercritical carbon dioxide|dry ice}}
{{clear}}

==History of human understanding==

Carbon dioxide was one of the first gases to be described as a substance distinct from air. In the seventeenth century, the [[Flemish people|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. His interpretation was that the rest of the charcoal had been transmuted into an invisible substance he termed a "gas" or "wild spirit" (''spiritus sylvestre'').

The properties of carbon dioxide were studied more thoroughly in the 1750s by the Scottish physician [[Joseph Black]]. He found that [[limestone]] ([[calcium carbonate]]) could be heated or treated with [[acid]]s to yield a gas he called "fixed air." He observed that the fixed air was denser than air and did not support either flame or animal life. Black also found that when bubbled through an aqueous solution of lime ([[calcium hydroxide]]), it would [[Precipitation (chemistry)|precipitate]] calcium carbonate. He used this phenomenon to illustrate that carbon dioxide is produced by animal respiration and microbial fermentation. In 1772, English chemist [[Joseph Priestley]] published a paper entitled ''Impregnating Water with Fixed Air'' in which he described a process of dripping [[sulfuric acid]] (or ''oil of vitriol'' as Priestley knew it) on chalk in order to produce carbon dioxide, and forcing the gas to dissolve by agitating a bowl of water in contact with the gas.<ref name="Priestley">{{cite journal | first = Joseph | last = Priestley | authorlink = Joseph Priestley | title = Observations on Different Kinds of Air | journal = Philosophical Transactions | issn = 0260-7085 | volume = 62 | year = 1772 | pages = 147–264 | url = http://web.lemoyne.edu/~GIUNTA/priestley.html | doi = 10.1098/rstl.1772.0021}}</ref>

Carbon dioxide was first liquefied (at elevated pressures) in 1823 by [[Humphry Davy]] and [[Michael Faraday]].<ref name="Davy">{{cite journal | first = Humphry | last = Davy | authorlink = Humphry Davy | title = On the Application of Liquids Formed by the Condensation of Gases as Mechanical Agents | journal = Philosophical Transactions | issn = 0261-0523 | volume = 113 | year = 1823 | pages = 199–205 | url = http://www.journals.royalsoc.ac.uk/content/r004631789435274/fulltext.pdf | doi = 10.1098/rstl.1823.0020 |format=PDF}}</ref> The earliest description of solid carbon dioxide was given by [[Charles Thilorier]], who in 1834 opened a pressurized container of liquid carbon dioxide, only to find that the cooling produced by the rapid evaporation of the liquid yielded a "snow" of solid {{co2}}.<ref>{{cite journal | title = Thilorier and the First Solidification of a "Permanent" Gas (1835) | last = Duane | first = H.D. Roller | coauthors = M. Thilorier | journal = Isis | issn = 0021-1753 | volume = 43 | issue = 2 | year = 1952 | pages = 109–113 | url = | doi = 10.1086/349402 }}</ref>

==Isolation and production==
Carbon dioxide may be obtained from air [[distillation]]. However, this yields only very small quantities of {{co2}}. A large variety of chemical reactions yield carbon dioxide, such as the reaction between most acids and most metal carbonates. For example, the reaction between [[hydrochloric acid]] and calcium carbonate (limestone or chalk) is depicted below:

: {{chem|HCl|| + CaCO|3| → CaCl|2| + H|2|CO|3}}

The {{chem|H|2|CO|3}} then decomposes to water and {{co2}}. Such reactions are accompanied by foaming or bubbling, or both. In industry such reactions are widespread because they can be used to neutralize waste acid streams.

The production of [[quicklime]] (CaO) a chemical that has widespread use, from limestone by heating at about 850 °C also produces {{co2}}:

: {{chem|CaCO|3| → CaO + CO|2}}

The [[combustion]] of all carbon containing fuels, such as [[methane]] ([[natural gas]]), petroleum distillates ([[gasoline]], [[diesel]], [[kerosene]], [[propane]]), but also of coal and wood, will yield carbon dioxide and, in most cases, water. As an example the chemical reaction between methane and oxygen is given below.

: {{chem|CH|4| + 2 O|2| → CO|2| + 2 H|2|O}}

[[Iron]] is reduced from its oxides with [[coke (fuel)|coke]] in a [[blast furnace]], producing [[pig iron]] and carbon dioxide:

: {{chem|2 Fe|2|O|3| + 3 C → 4 Fe + 3 CO|2}}

[[Yeast]] metabolizes [[sugar]] to produce carbon dioxide and [[ethanol]], also known as alcohol, in the production of wines, beers and other spirits, but also in the production of [[bioethanol]]:

: [[Glucose|{{chem|C|6|H|12|O|6}}]] → {{chem|2 CO|2| + 2 C|2|H|5|OH}}

All [[cellular respiration|aerobic]] organisms produce {{chem|CO|2}} when they oxidize [[carbohydrate]]s, [[fatty acid]]s, and proteins in the mitochondria of cells. The large number of reactions involved are exceedingly complex and not described easily. Refer to ([[cellular respiration]], [[anaerobic respiration]] and [[photosynthesis]]). [[Photoautotrophs]] (i.e. plants, [[cyanobacteria]]) use another ''modus operandi'': Plants absorb {{chem|CO|2}} from the air, and, together with water, react it to form carbohydrates:

: {{chem|''n''CO|2| + ''n''H|2|O → (CH|2|O)|n| + ''n''O|2}}

Carbon dioxide is [[soluble]] in water, in which it spontaneously interconverts between {{co2}} and {{chem|H|2|CO|3}} ([[carbonic acid]]). The relative concentrations of {{chem|CO|2|, H|2|CO|3}}, and the deprotonated forms {{chem|HCO|3|<sup>−</sup>}} ([[bicarbonate]]) and {{chem|CO|3|<sup>2−</sup>}}([[carbonate]]) depend on the [[pH]]. In neutral or slightly alkaline water (pH > 6.5), the bicarbonate form predominates (>50%) becoming the most prevalent (>95%) at the pH of seawater, while in very alkaline water (pH > 10.4) the predominant (>50%) form is carbonate. The bicarbonate and carbonate forms are very soluble, such that air-equilibrated ocean water (mildly alkaline with typical pH = 8.2 – 8.5) contains about 120 mg of bicarbonate per liter.

==Uses==
[[Image:Soda bubbles macro.jpg|thumb|250px|Carbon dioxide bubbles in a soft drink.]]

Carbon dioxide is used by the food industry, the oil industry, and the chemical industry.<ref name="kirk">{{cite encyclopedia | title = Carbon Dioxide | first = Ronald | last = Pierantozzi | encyclopedia = Kirk-Othmer Encyclopedia of Chemical Technology | publisher = Wiley | year = 2001 | doi = 10.1002/0471238961.0301180216090518.a01.pub2 }}</ref> It is used in many consumer products that require pressurized gas because it is inexpensive and nonflammable, and because it undergoes a phase transition from gas to liquid at room temperature at an attainable pressure of approximately 60 [[Bar (unit)|bar]] (870 psi, 59 atm), allowing far more carbon dioxide to fit in a given container than otherwise would. Life jackets often contain canisters of pressured carbon dioxide for quick inflation. Aluminum capsules are also sold as supplies of compressed gas for [[Air gun|airguns]], [[paintball]] markers, for inflating bicycle tires, and for making [[carbonated water|seltzer]]. Rapid vaporization of liquid carbon dioxide is used for blasting in coal mines. High concentrations of carbon dioxide can also be used to kill pests, such as the [[Common Clothes Moth]].

=== Drinks ===

Carbon dioxide is used to produce [[carbonation|carbonated]] [[soft drink]]s and [[soda water]]. Traditionally, the carbonation in beer and sparkling wine comes about through natural fermentation, but some manufacturers carbonate these drinks artificially.

=== Foods ===
A candy called [[Pop Rocks]] is pressurized with carbon dioxide gas at about 40 bar (600 psi). When placed in the mouth, it dissolves (just like other hard candy) and releases the gas bubbles with an audible pop.

[[Leavening agent]]s produce carbon dioxide to cause dough to rise. [[Baker's yeast]] produces carbon dioxide by fermentation of sugars within the dough, while chemical leaveners such as [[baking powder]] and [[baking soda]] release carbon dioxide when heated or if exposed to [[acid]]s.

[[Image:Carbon Dioxide Laser At The Laser Effects Test Facility.jpg|thumb|right|300px|A [[carbon dioxide laser]].]]

=== Pneumatic systems ===

Carbon dioxide is the most commonly used compressed gas for pneumatic systems in portable pressure tools and [[Robot combat|combat robots]].

=== Fire extinguisher ===

Carbon dioxide extinguishes flames, and some [[Fire extinguisher#Carbon dioxide|fire extinguishers]], especially those designed for electrical fires, contain liquid carbon dioxide under pressure. Carbon dioxide has also been widely used as an extinguishing agent in fixed fire protection systems for total flooding of a protected space, (National Fire Protection Association Code 12). International Maritime Organisation standards also recognise carbon dioxide systems for fire protection of ship holds and engine rooms. Carbon dioxide based fire protection systems have been linked to several deaths. A review of CO2 systems (Carbon Dioxide as a Fire Suppressant: Examining the Risks, US EPA) identified 51 incidents between 1975 and the date of the report, causing 72 deaths and 145 injuries.

=== Welding ===
Carbon dioxide also finds use as an atmosphere for [[welding]], although in the welding arc, it reacts to [[oxidation|oxidize]] most metals. Use in the automotive industry is common despite significant evidence that welds made in carbon dioxide are [[brittle]]r than those made in more inert atmospheres, and that such weld joints deteriorate over time because of the formation of carbonic acid. It is used as a welding gas primarily because it is much less expensive than more inert gases such as [[argon]] or [[helium]].

=== Caffeine removal ===

Liquid carbon dioxide is a good [[solvent]] for many [[lipophilic]] [[organic chemistry|organic compounds]], and is used to remove [[caffeine]] from [[coffee]]. First, the green coffee beans are soaked in water. The beans are placed in the top of a column seventy feet (21 m) high. Then super-pressurized carbon dioxide in fluid form at about 93 degrees Celsius enters at the bottom of the column. The caffeine diffuses out of the beans and into the carbon dioxide.

=== Pharmaceutical and other chemical processing ===

Carbon dioxide has begun to attract attention in the [[pharmaceutical]] and other chemical processing industries as a less toxic alternative to more traditional solvents such as [[organochloride]]s. It's used by some [[dry cleaning|dry cleaners]] for this reason. (See [[green chemistry]].)

In the chemical industry, carbon dioxide is used for the production of [[urea]], [[carbonate]]s and [[bicarbonate]]s, and [[sodium salicylate]].

=== Biological applications ===

Plants require carbon dioxide to conduct [[photosynthesis]], and greenhouses may enrich their atmospheres with additional {{co2}} to boost plant growth, since its low present-day atmosphere concentration is just above the "suffocation" level for green plants. A [[photosynthesis]]-related drop in carbon dioxide concentration in a greenhouse compartment can kill green plants. At high concentrations, carbon dioxide is toxic to animal life, so raising the concentration to 10,000 ppm (1%) for several hours can eliminate pests such as [[whitefly|whiteflies]] and [[spider mite]]s in a greenhouse.

It has been proposed that carbon dioxide from power generation be bubbled into ponds to grow algae that could then be converted into [[biodiesel]] fuel.<ref name='csmon'>{{cite news | first=Mark | last=Clayton | coauthors= | title=Algae - like a breath mint for smokestacks | date=2006-01-11 | publisher= | url =http://www.csmonitor.com/2006/0111/p01s03-sten.html | work =[[Christian Science Monitor]] | pages = | accessdate = 2007-10-11 | language = }}</ref> Carbon dioxide is already increasingly used in greenhouses as the main carbon source for [[Spirulina]] algae.
In medicine, up to 5% carbon dioxide is added to pure [[oxygen]] for stimulation of breathing after [[apnea]] and to stabilize the {{chem|O|2|/CO|2}} balance in blood.

=== Lasers ===

A common type of industrial gas [[laser]] is the [[carbon dioxide laser]].

=== Polymers and plastics ===

Carbon dioxide can also be combined with [[limonene]] oxide from orange peels or other [[epoxides]] to create polymers and plastics.<ref>{{cite web |url=http://www.news.cornell.edu/releases/Jan05/Orangeplastic.deb.html |title=Sweet and environmentally beneficial discovery: Plastics made from orange peel and a greenhouse gas |accessdate=2007-09-09 |last=Davidson |first=Sarah |coauthors= |date=2005-01-17 |work= |publisher=Cornell News}}</ref>

=== Oil recovery ===

Carbon dioxide is used in [[enhanced oil recovery]] where it is injected into or adjacent to producing oil wells, usually under [[Supercritical fluid|supercritical]] conditions. It acts as both a pressurizing agent and, when dissolved into the underground [[crude oil]], significantly reduces its viscosity, enabling the oil to flow more rapidly through the earth to the removal well.<ref>{{cite journal |last=Austell |first=J Michael |authorlink= |coauthors= |year=2005 |month= |title=CO2 for Enhanced Oil Recovery Needs - Enhanced Fiscal Incentives |journal=Exploration & Production: the Oil & Gas Review - |volume= |issue= |pages= |id= |url=http://www.touchoilandgas.com/enhanced-recovery-needs-enhanced-a423-1.html |accessdate= 2007-09-28 |quote= }}</ref> In mature oil fields, extensive pipe networks are used to carry the carbon dioxide to the injection points.

=== As refrigerants ===

Liquid and solid carbon dioxide are important [[refrigerant]]s, especially in the food industry, where they are employed during the transportation and storage of ice cream and other frozen foods. Solid carbon dioxide is called "dry ice" and is used for small shipments where refrigeration equipment is not practical.

<span id="R744" />Liquid carbon dioxide (industry nomenclature R744 / R-744) was used as a refrigerant prior to the discovery of [[Dichlorodifluoromethane|R-12]]. Its physical properties are highly favorable for cooling, refrigeration, and heating purposes, having a high volumetric cooling capacity. Due to their operation at pressures of up to 130 bars, {{co2}} systems require highly resistant components that have been already developed to serial production in many sectors. {{weasel}} Its environmental advantages ([[Global warming potential|GWP]] of 1, non-ozone depleting, non-toxic, non-flammable) could make it the future working fluid to replace current HFCs in cars, supermarkets, hot water heat pumps, among others. Some applications: Coca-Cola has fielded {{co2}}-based beverage coolers and the [[US Army]] is interested in {{co2}} refrigeration and heating technology.<ref name='ccref1'> {{cite web|url=http://www.thecoca-colacompany.com/presscenter/nr_20060605_corporate_hfc-free.html |title=THE COCA-COLA COMPANY ANNOUNCES ADOPTION OF HFC-FREE INSULATION IN REFRIGERATION UNITS TO COMBAT GLOBAL WARMING |accessdate=2007-10-11 |date=2006-06-05 |publisher=The Coca-Cola Company }}</ref><ref name='usforces'>{{cite news | title = Modine reinforces its {{co2}} research efforts | url = http://www.r744.com/news/news_ida145.php | date = 2007-06-28 | publisher = R744.com}}</ref>

By the end of 2007, the global car industry is expected to decide on the next-generation refrigerant in car air conditioning. {{co2}} is one discussed option.(see [[The Cool War]])

=== Coal bed methane recovery ===

In [[enhanced coal bed methane recovery]], carbon dioxide is pumped into the coal seam to displace methane.<ref>{{cite web|url=http://www.ipe.ethz.ch/laboratories/spl/research/adsorption/project03|title=Enhanced coal bed methane recovery|publisher=ETH Zurich|date=2006-08-31}}</ref>

=== Wine making ===

Carbon dioxide in the form of [[dry ice]] is often used in the [[wine making]] process to cool down bunches of [[grape]]s quickly after picking to help prevent spontaneous [[Fermentation (wine)|fermentation]] by wild [[yeast]]s. The advantage of using dry ice over regular water ice is that it cools the grapes without adding any additional water that may decrease the [[sugar]] concentration in the [[grape must]], and therefore also decrease the [[alcohol]] concentration in the finished wine.

Dry ice is also used during the cold soak phase of the wine making process to keep grapes cool. The carbon dioxide gas that results from the sublimation of the dry ice tends to settle to the bottom of tanks because it is heavier than regular air. The settled carbon dioxide gas creates an hyoxic environment which helps to prevent bacteria from growing on the grapes until it is time to start the fermentation with the desired strain of yeast.

Carbon dioxide is also used to create a hypoxic environment for [[carbonic maceration]], the process used to produce [[Beaujolais]] wine.

Carbon dioxide is sometimes used to top up wine bottles or other storage vessels such as barrels to prevent oxidation, though it has the problem that it can dissolve into the wine, making a previously still wine slightly fizzy. For this reason, other gasses such as [[nitrogen]] or [[argon]] are preferred for this process by professional wine makers.

==In the Earth's atmosphere==

[[Image:Mauna Loa Carbon Dioxide.png|thumbnail|right|280px|Atmospheric {{co2}} concentrations measured at [[Mauna Loa Observatory]].]]

{{main|Carbon dioxide in the Earth's atmosphere}}

Carbon dioxide in [[earth's atmosphere]] is considered a [[trace gas]] currently occurring at an average concentration of about 385 parts per million by volume or 582 parts per million by mass. The mass of the [[Earth atmosphere]] is 5.14×10<sup>18</sup> kg <ref>[http://www.agu.org/pubs/crossref/1988/87JD00743.shtml Global atmospheric mass, surface pressure, and water vapor variations<!-- Bot generated title -->]</ref>, so the total mass of atmospheric carbon dioxide is 3.0×10<sup>15</sup> kg (3,000 gigatonnes). Its concentration varies seasonally (see graph at right) and also considerably on a regional basis: in urban areas it is generally higher and indoors it can reach 10 times the background atmospheric concentration.

Carbon dioxide is a [[greenhouse gas]]. See [[greenhouse effect]] for more.

[[Image:CO2 increase rate.png|thumb|left|Yearly increase of atmospheric CO<sub>2</sub>: In the 1960s, the average annual increase was 37% of the 2000-2007 average.<ref>Dr. Pieter Tans (3 May 2008) [ftp://ftp.cmdl.noaa.gov/ccg/co2/trends/co2_gr_mlo.txt "Annual CO<sub>2</sub> mole fraction increase (ppm)" for 1959-2007] [[National Oceanic and Atmospheric Administration]] Earth System Research Laboratory, Global Monitoring Division ([http://www.esrl.noaa.gov/gmd/ccgg/trends/ additional details].)</ref>]]

Due to human activities such as the combustion of [[fossil fuels]] and [[deforestation]], and the increased release of CO<sub>2</sub> from the oceans due to the increase in the Earth's temperature, the concentration of atmospheric carbon dioxide has increased by about 35% since the beginning of the [[Industrial Revolution|age of industrialization]].<ref name="nonanews"/>
In 1999, 2,244,804,000 (=~2.2×10<sup>9</sup>) metric tons of {{co2}} were produced in the U.S. as a result of electric energy generation. This is an output rate of 0.6083 kg (1.341 pounds) per kWh.<ref>{{cite web | title=Carbon Dioxide Emissions from the Generation of Electric Power in the United States | url=http://www.eia.doe.gov/cneaf/electricity/page/co2_report/co2emiss.pdf }} </ref>

Five hundred million years ago carbon dioxide was 20 times more prevalent than today, decreasing to 4-5 times during the [[Jurassic]] period and then maintained a slow decline until the [[industrial revolution]], with [[Azolla Event|a particularly swift reduction]] occurring 49 million years ago.<ref>{{cite web | title = Climate and CO2 in the Atmosphere | url=http://earthguide.ucsd.edu/virtualmuseum/climatechange2/07_1.shtml| accessdate=2007-10-10 }}</ref><ref>{{cite web | title = GEOCARB III: A REVISED MODEL OF ATMOSPHERIC CO2 OVER
PHANEROZOIC TIME| url=http://www.geocraft.com/WVFossils/Reference_Docs/Geocarb_III-Berner.pdf | accessdate=2008-02-15 |format=PDF}}</ref>

Up to 40% of the gas emitted by some [[volcano]]es during subaerial [[volcanic eruptions]] is carbon dioxide.<ref>{{Cite book | last=Sigurdsson |first=Haraldur |coauthors=Houghton, B. F. |title=Encyclopedia of volcanoes |year=2000 |publisher=Academic Press |location=San Diego |isbn=0-12-643140-X}}</ref> According to the best estimates, volcanoes release about 130-230 million tonnes (145-255 million tons) of {{co2}} into the atmosphere each year. Carbon dioxide is also produced by hot springs such as those at the Bossoleto site near Rapolano Terme in Tuscany, Italy. Here, in a bowl-shaped depression of about 100 m diameter, local concentrations of {{co2}} rise to above 75% overnight, sufficient to kill insects and small animals, but warm rapidly when sunlit and disperse by convection during the day<ref>{{Cite book |last=van Gardingen |first=P.R. |coauthors=Grace, J.; Jeffree, C.E.; Byari, S.H.; Miglietta, F.; Raschi, A.; Bettarini, I. |chapter=Long-term effects of enhanced CO2 concentrations on leaf gas exchange: research opportunities using {{co2}} springs |title=Plant responses to elevated {{co2}}: Evidence from natural springs |editor=Raschi, A.; Miglietta, F.; Tognetti, R.; van Gardingen, P.R. (Eds.) |date=1997 |publisher=Cambridge University Press |location=Cambridge |isbn=0-521-58203-2 |pages=69–86}}</ref> Locally high concentrations of {{co2}}, produced by disturbance of deep lake water saturated with {{co2}} are thought to have caused 37 fatalities at [[Lake Monoun]], [[Cameroon]] in 1984 and 1700 casualties at [[Lake Nyos]], Cameroon in 1986.<ref>{{Cite book |last=Martini |first=M. |chapter={{co2}} emissions in volcanic areas: case histories and hazaards |title=Plant responses to elevated {{co2}}: Evidence from natural springs |editor=Raschi, A.; Miglietta, F.; Tognetti, R.; van Gardingen, P.R. (Eds.) |date=1997 |publisher=Cambridge University Press |location=Cambridge |isbn=0-521-58203-2 |pages=69–86}}</ref> However, emissions of {{co2}} by human activities are currently more than 130 times greater than the quantity emitted by volcanoes, amounting to about 27 billion tonnes per year.<ref>{{cite web | title = Volcanic Gases and Their Effects
| url=http://volcanoes.usgs.gov/Hazards/What/VolGas/volgas.html| accessdate=2007-09-07 }}</ref>

==In the oceans==

There is about 50 times as much carbon dissolved in the oceans in the form of {{co2}} and {{co2}} hydration products as exists in the atmosphere. The oceans act as an enormous [[carbon sink]], having "absorbed about one-third of all human-generated {{co2}} emissions to date."<ref>{{cite web | last = Doney | first = Scott C. | authorlink = | coauthors = Naomi M. Levine | title = How Long Can the Ocean Slow Global Warming? | publisher = Oceanus | date = 2006-11-29 | url = http://www.whoi.edu/oceanus/viewArticle.do?id=17726 | accessdate = 2007-11-21 }}</ref> Generally, gas solubility decreases as water temperature increases. Accordingly carbon dioxide is released from ocean water into the atmosphere as ocean temperatures rise.

Most of the {{co2}} taken up by the ocean forms carbonic acid. Some is consumed in photosynthesis by organisms in the water, and a small proportion of that sinks and leaves the carbon cycle. There is considerable concern that as a result of increased {{co2}} in the atmosphere the acidity of seawater will increase and may adversely affect organisms living in the water. In particular, with increasing acidity, the availability of carbonates for forming shells decreases.<ref>{{cite book |title= Oceanography: An Invitation to Marine Science |last= Garrison |first= Tom |authorlink= |coauthors= |year= 2004 |publisher= [[The Thomson Corporation|Thomson Brooks]] |location= |isbn= 0534408877 |pages= 125 |url= }}</ref>

==Biological role==

Carbon dioxide is an end product in organisms that obtain energy from breaking down sugars, fats and [[amino acid]]s with [[oxygen]] as part of their [[metabolism]], in a process known as [[cellular respiration]]. This includes all plants, animals, many fungi and some bacteria. In higher animals, the carbon dioxide travels in the blood from the body's tissues to the lungs where it is exhaled. In plants using photosynthesis, carbon dioxide is absorbed from the atmosphere.

===Role in photosynthesis===

Plants remove carbon dioxide from the atmosphere by photosynthesis, also called [[carbon fixation|carbon assimilation]], which uses light energy to produce organic plant materials ([[cellulose]]) by combining carbon dioxide and water. Free oxygen is released as gas from the decomposition of water molecules, while the hydrogen is split into its protons and electrons and used to generate chemical energy via [[photophosphorylation]]. This energy is required for the fixation of carbon dioxide in the [[Calvin cycle]] to form sugars. These sugars can then be used for growth within the plant through respiration.

Even when vented, carbon dioxide must be introduced into greenhouses to maintain plant growth, as the concentration of carbon dioxide can fall during daylight hours to as low as 200 ppm (a limit of [[C3 carbon fixation]] photosynthesis{{Fact|date=December 2007}}). Plants can potentially grow up to 50 percent faster in concentrations of 1,000 ppm {{co2}} when compared with ambient conditions.<ref>{{cite web | title=Carbon Dioxide In Greenhouses | last=Blom | first=T.J. | coauthors=W.A. Straver; F.J. Ingratta; Shalin Khosla; Wayne Brown | url=http://www.omafra.gov.on.ca/english/crops/facts/00-077.htm | date=2002-12 | accessdate=2007-06-12 }}</ref>

Plants also emit {{co2}} during respiration, so it is only during growth stages that plants are net absorbers. For example a growing forest will absorb many tons of {{co2}} each year, however a mature forest will produce as much {{co2}} from respiration and decomposition of dead specimens (e.g. fallen branches) as used in [[biosynthesis]] in growing plants.<ref>{{cite web|url=http://www-wds.worldbank.org/external/default/WDSContentServer/WDSP/IB/2002/09/07/000094946_02081604154234/Rendered/INDEX/multi0page.txt|title=Global Environment Division Greenhouse Gas Assessment Handbook - A Practical Guidance Document for the Assessment of Project-level Greenhouse Gas Emissions|accessdate=2007-11-10|work=[[World Bank]]}}</ref> Regardless of this, mature forests are still valuable [[carbon sink]]s, helping maintain balance in the Earth's atmosphere. Additionally, and crucially to life on earth, phytoplankton photosynthesis absorbs dissolved {{co2}} in the upper ocean and thereby promotes the absorption of {{co2}} from the atmosphere.<ref>{{cite journal|last=Falkowski|first=P.|coauthors=Scholes, R.J.; Boyle, E.; Canadell, J.; Canfield, D.; Elser, J.; Gruber, N.; Hibbard, K.; Hogberg, P.; Linder, S.; Mackenzie, F.T.; Moore, B 3rd.; Pedersen, T.; Rosenthal, Y.; Seitzinger, S.; Smetacek V.; Steffen W.| year=2000 | title=The global carbon cycle: a test of our knowledge of earth as a system | journal=Science | issn=0036-8075 | volume=290 | issue=5490 | pages=291–296 | doi=10.1126/science.290.5490.291 | pmid=11030643 }}</ref>

===Toxicity===

Carbon dioxide content in fresh air (averaged between sea-level and 10 hPa level, i.e. about 30 km altitude) varies between 0.036% (360 ppm) and 0.039% (390 ppm), depending on the location (see [http://www.esrl.noaa.gov/gmd/ccgg/carbontracker/ graphical map of {{co2}}]).

According to the Australian Maritime Safety Authority, "Prolonged exposure to moderate concentrations can cause acidosis and adverse effects on calcium phosphorus metabolism resulting in increased calcium deposits in soft tissue. Carbon dioxide is toxic to the heart and causes diminished contractile force. At concentrations of three per cent by volume in air, it is mildly narcotic and causes increased blood pressure and pulse rate, and causes reduced hearing. At concentrations of about five per cent by volume it causes stimulation of the respiratory centre, dizziness, confusion and difficulty in breathing accompanied by headache and shortness of breath. At about eight per cent concentration it causes headache, sweating, dim vision, tremor and loss of consciousness after exposure for between five and ten minutes." <ref> Davidson, Clive. 7 February 2003. "Marine Notice: Carbon Dioxide: Health Hazard". Australian Maritime Safety Authority.</ref>

A natural disaster linked to {{co2}} intoxication occurred during the [[limnic eruption]]s in the {{co2}}-rich lakes of [[Lake Monoun|Monoun]] and [[Lake Nyos|Nyos]] in the Okun range of North-West [[Cameroon]]: the gas was brutally expelled from the mountain lakes and leaked into the surrounding valleys, killing most animal forms. During the Lake Nyos tragedy of 1986, 1700 villagers and 3500 livestock died.<ref>New York Times, "Trying to Tame the Roar of Deadly Lakes", 27 February 2001. [http://query.nytimes.com/gst/fullpage.html?res=9F04E2DC1F39F934A15751C0A9679C8B63&sec=&spon=&partner=permalink&exprod=permalink].</ref>

Due to the health risks associated with carbon dioxide exposure, the U.S. Occupational Safety and Health Administration says that average exposure for healthy adults during an eight-hour work day should not exceed 5,000 ppm (0.5%). The maximum safe level for infants, children, the elderly and individuals with cardio-pulmonary health issues is significantly less. For short-term (under ten minutes) exposure, the U.S. National Institute for Occupational Safety and Health (NIOSH) and American Conference of Government Industrial Hygienists (ACGIH) limit is 30,000 ppm (3%). NIOSH also states that carbon dioxide concentrations exceeding 4% are immediately dangerous to life and health. <ref>Occupational Safety and Health Administration. Chemical Sampling Information: Carbon Dioxide. Retrieved 5 June 2008 from: http://www.osha.gov/dts/chemicalsampling/data/CH_225400.html</ref>

Adaptation to increased levels of {{co2}} occurs in humans. Continuous inhalation of {{co2}} can be tolerated at three percent inspired concentrations for at least one month and four percent inspired concentrations for over a week. It was suggested that 2.0 percent inspired concentrations could be used for closed air spaces (ex. [[Submarine]]) since the adaptation is physiological and reversible. Decrement in performance or in normal physical activity does not happen at this level.<ref>{{cite journal |title=Carbon Dioxide Tolerance and Toxicity |author=Lambertsen, C. J. |year=1971 |journal=Environmental Biomedical Stress Data Center, Institute for Environmental Medicine, University of Pennsylvania Medical Center |volume=IFEM Report No. 2-71 |location=Philadelphia, PA |url=http://archive.rubicon-foundation.org/3861 |accessdate=2008-05-02 }}</ref><ref>{{cite journal |title=Carbon Dioxide Tolerance Studies |author=Glatte Jr H. A., Motsay G. J., Welch B. E. |year=1967 |volume=SAM-TR-67-77 |journal=Brooks AFB, TX School of Aerospace Medicine Technical Report|url=http://archive.rubicon-foundation.org/6045 |accessdate=2008-05-02 }}</ref>

These figures are valid for pure carbon dioxide. In indoor spaces occupied by people the carbon dioxide concentration will reach higher levels than in pure outdoor air. Concentrations higher than 1,000 ppm will cause discomfort in more than 20% of occupants, and the discomfort will increase with increasing {{co2}} concentration. The discomfort will be caused by various gases coming from human respiration and perspiration, and not by {{co2}} itself. At 2,000 ppm the majority of occupants will feel a significant degree of discomfort, and many will develop nausea and headaches. The {{co2}} concentration between 300 and 2,500 ppm is used as an indicator of indoor air quality.

Acute carbon dioxide toxicity is sometimes known by the names given to it by miners: [[blackdamp]] (also called ''choke damp'' or ''stythe''). [[Miners]] would try to alert themselves to dangerous levels of carbon dioxide in a mine shaft by bringing a caged canary with them as they worked. The canary would inevitably die before {{co2}} reached levels toxic to people. (The canary would also indicate dangerous levels of methane and other gases by the same principle.)

Carbon dioxide ppm levels (CDPL) are a surrogate for measuring indoor pollutants that may cause occupants to grow drowsy, get headaches, or function at lower activity levels. To eliminate most [[Indoor Air Quality]] complaints, total indoor CDPL must be reduced to below 600. [[NIOSH]] considers that indoor air concentrations that exceed 1,000 are a marker suggesting inadequate ventilation. [[ASHRAE]] recommends they not exceed 1,000 inside a space.

===Human physiology===
{{seealso|Arterial blood gas}}

{{co2}} is carried in blood in three different ways. (The exact percentages vary depending whether it is arterial or venous blood).

* Most of it (about 70% – 80%) is converted to [[bicarbonate]] ions HCO<sub>3</sub><sup>−</sup> by the enzyme [[carbonic anhydrase]] in the red blood cells,<ref name='solarnav'> {{cite web|url=http://www.solarnavigator.net/solar_cola/carbon_dioxide.htm |title=CARBON DIOXIDE |accessdate=2007-10-12 |work=solarnavigator.net }}</ref> by the reaction {{co2}} + H<sub>2</sub>O → H<sub>2</sub>CO<sub>3</sub> → H<sup>+</sup> + HCO<sub>3</sub><sup>−</sup>.

* 5% – 10% is dissolved in the [[Blood plasma|plasma]]<ref name='solarnav' />

* 5% – 10% is bound to [[hemoglobin]] as [[carbamino]] compounds<ref name='solarnav' />

[[Hemoglobin]], the main oxygen-carrying molecule in [[red blood cell]]s, carries both oxygen and carbon dioxide. However, the {{co2}} bound to hemoglobin does not bind to the same site as oxygen. Instead, it combines with the N-terminal groups on the four globin chains. However, because of [[allosteric regulation|allosteric]] effects on the hemoglobin molecule, the binding of {{co2}} decreases the amount of oxygen that is bound for a given partial pressure of oxygen. The decreased binding to carbon dioxide in the blood due to increased oxygen levels is known as the [[Haldane Effect]], and is important in the transport of carbon dioxide from the tissues to the lungs. Conversely, a rise in the partial pressure of {{co2}} or a lower pH will cause offloading of oxygen from hemoglobin, which is known as the [[Bohr Effect]].

Carbon dioxide is one of the mediators of local [[autoregulation]] of blood supply. If its levels are high, the [[capillaries]] expand to allow a greater blood flow to that tissue.

Bicarbonate ions are crucial for regulating blood pH. A person's breathing rate influences the level of {{co2}} in their blood. Breathing that is too slow or shallow causes [[respiratory acidosis]], while breathing that is too rapid leads to [[hyperventilation]], which may cause [[alkalosis|respiratory alkalosis]].

Although the body requires oxygen for metabolism, low oxygen levels do not stimulate breathing. Rather, breathing is stimulated by higher carbon dioxide levels. As a result, breathing low-pressure air or a gas mixture with no oxygen at all (such as pure nitrogen) can lead to loss of consciousness without ever experiencing [[air hunger]]. This is especially perilous for high-altitude fighter pilots. It is also why flight attendants instruct passengers, in case of loss of cabin pressure, to apply the oxygen mask to themselves first before helping others — otherwise one risks going unconscious.<ref name='solarnav' />

Typically the gas we [[breathing| exhale]] is about 4% to 5% carbon dioxide and 4% to 5% less oxygen than was inhaled.

According to a study by the [[United States Department of Agriculture]], an average person's respiration generates approximately 450 liters (roughly 900 grams) of carbon dioxide per day.<ref name="hannan">{{cite web | url=http://www.faithscience.org/oldsite/articles/90s/hannan.html | title=Your Role in the "Greenhouse Effect" | first=Jerry | last=Hannan | accessdate=2006-04-19}}</ref>

==See also==
<div style="-moz-column-count:3; column-count:3;">
* [[Bosch reaction]]
* [[Carbon cycle]]
* [[Carbon dioxide (data page)]]
* [[Carbon dioxide sink]]
* [[Carbon monoxide]]
* [[Center for the Study of Carbon Dioxide and Global Change]]
* [[Lake Nyos|{{co2}} degassing in Lake Nyos]]
* [[Carbon dioxide sensor]]
* [[EcoCute]] - As refrigerants
* [[Emission standard]]s
* [[Global warming]]
* [[Greenhouse gas]]
* [[Sabatier reaction|Sabatier process]]
* [[CO2 sequestration]]
</div>

==References==
<!-- ----------------------------------------------------------
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discussion of different citation methods and how to generate
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{{reflist|2}}

==External links==
* {{ICSC|0021}}<!-- in general: {{ICSC|AllDigits|TwoDigits}} -->
* {{PubChemLink|280}}
* [http://www.uigi.com/carbondioxide.html {{co2}} Carbon Dioxide Properties, Uses, Applications]
* [http://www.dryiceinfo.com/science.htm Dry Ice information]
* [http://www.cmdl.noaa.gov/ccgg/trends/ Trends in Atmospheric Carbon Dioxide] ''(NOAA)''
* [http://oco.jpl.nasa.gov NASA's Orbiting Carbon Observatory]

{{Oxides of carbon}}

[[Category:Carbon dioxide| ]]
[[Category:Inorganic carbon compounds]]
[[Category:Oxides]]
[[Category:Acidic oxides]]
[[Category:Greenhouse gases]]
[[Category:Propellants]]
[[Category:Household chemicals]]
[[Category:Inorganic solvents]]
[[Category:Refrigerants]]
[[Category:Fire suppression agents]]
[[Category:Coolants]]
[[Category:Laser gain media]]

[[ar:ثنائي أكسيد كربون]]
[[bn:কার্বন ডাই অক্সাইড]]
[[bs:Ugljik dioksid]]
[[bg:Въглероден диоксид]]
[[ca:Diòxid de carboni]]
[[cs:Oxid uhličitý]]
[[cy:Carbon deuocsid]]
[[da:Kuldioxid]]
[[de:Kohlenstoffdioxid]]
[[et:Süsihappegaas]]
[[el:Διοξείδιο του άνθρακα]]
[[es:Óxido de carbono (IV)]]
[[eo:Karbona dioksido]]
[[eu:Karbono dioxido]]
[[fa:کربن دی‌اکسید]]
[[fr:Dioxyde de carbone]]
[[ga:Dé-ocsaíde charbóin]]
[[gl:Dióxido de carbono]]
[[ko:이산화 탄소]]
[[hi:कार्बन डाईआक्साइड]]
[[hsb:Wuhlikowy dioksid]]
[[hr:Ugljikov dioksid]]
[[io:Karbo dioxido]]
[[id:Karbon dioksida]]
[[is:Koltvísýringur]]
[[it:Anidride carbonica]]
[[he:פחמן דו-חמצני]]
[[kn:ಇಂಗಾಲದ ಡೈಆಕ್ಸೈಡ್]]
[[la:Dioxydum carbonis]]
[[lv:Oglekļa dioksīds]]
[[lt:Anglies dioksidas]]
[[jbo:tabrelkijno]]
[[hu:Szén-dioxid]]
[[mk:Јаглерод диоксид]]
[[mr:कार्बन डायॉक्साइड]]
[[ms:Karbon dioksida]]
[[nl:Koolstofdioxide]]
[[ja:二酸化炭素]]
[[no:Karbondioksid]]
[[nn:Karbondioksid]]
[[oc:Dioxid de carbòni]]
[[om:Carbon dioxide]]
[[nds:Kohlenstoffdioxid]]
[[pl:Dwutlenek węgla]]
[[pt:Dióxido de carbono]]
[[ro:Dioxid de carbon]]
[[qu:Chimlasay]]
[[ru:Диоксид углерода]]
[[sc:Diòssidu de carboniu]]
[[sq:Dioksidi i karbonit]]
[[scn:Anidridi carbònica]]
[[simple:Carbon dioxide]]
[[sk:Oxid uhličitý]]
[[sl:Ogljikov dioksid]]
[[sr:Угљен-диоксид]]
[[su:Karbon dioksida]]
[[fi:Hiilidioksidi]]
[[szl:Dwutlynek wůngla]]
[[sv:Koldioxid]]
[[ta:காபனீரொட்சைட்டு]]
[[th:คาร์บอนไดออกไซด์]]
[[vi:Điôxít cacbon]]
[[tr:Karbondioksit]]
[[uk:Діоксид вуглецю]]
[[ur:کاربن دو اکسید]]
[[wa:Diyocside di carbone]]
[[yi:קוילן זייערס]]
[[zh-yue:二氧化碳]]
[[zh:二氧化碳]]

Revision as of 22:58, 19 November 2008

Carbon Dioxide is produced by people. It helps trees and other plants live. Carbon dioxide is also known as C02'.

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