Carbon dioxide

Carbon dioxide is one chemical compound out Carbon and Oxygen and belongs thereby beside Carbon monoxide to the group of the carbon oxides. It becomes sometimes also as Carbon dioxide designated, which however not is correct, there the connection Oxide the element carbon and not (only carbon-containing ones) the coal are. Its chemical formula is CO₂.

Carbon dioxide is color and odorless gas. It is in small concentration a natural component that Air and develops with that Burn of carbon-containing substances, if oxygen is present in the surplus. Also in the organism of Organism carbon dioxide develops as Dome product that Zellatmung. The CO₂ becomes thereby over that Breath delivered. Turned around Plants, some Bacteria and Archaeen in the situation, CO₂ by those Carbon dioxide adjustment to convert into biomass. Thus plants produce for example with that Photosynthesis out inorganic CO₂ Glucose.

Physical characteristics

The carbon dioxide molecule is linear developed. Although the carbon oxygen connections polar are lift themselves of them electrical dipole moments by the molecule symmetry outward mutually up, so that the molecule does not exhibit an electrical dipole moment. Nevertheless carbon dioxide is good due to the internal dipole moments in water solubly and absorbs some narrow parts of the electromagnetic spectrum within the range that Infrared radiation.

Chemical characteristics

In Water solved carbon dioxide forms Carbonic acid H₂CO₃, whereby however more than 99% of the carbon dioxide are only physically solved. Carbonic acid as such lies forwards in one Equilibrium with their dissociation products (Species) Hydrogencarbonate ("Bicarbonat", HCO₃^-) and carbonate (CO₃²), in one of pH value stand for dependent quantitative proportion too each other. One catches with dissociation the formed OxoniumIons (H⁺, actually H₃O⁺) by addition of one Caustic solution with Hydroxyl ions (OH^-) off, thus the quantitative proportion shifts to favour of Carbonate.

Use

Carbon dioxide finds in the firm state of aggregation under the designation Dry ice Application in the technology. Dry ice does not melt, separate sublimated with?78 °C, however one can do it below that critical temperature consolidate from 31 °C with pressure pressure to a colorless liquid. With that Sublimation a white fog from that develops for cold CO₂air mixture and condensing air humidity, as effect in the stage technology the employment finds.

Many Beverages contain carbon dioxide, in order to obtain when drinking a better refreshment effect. With some beverages it develops through Fermentation (Beer, Sparkling wine), with others it is artificially added (Lemonade, Soda water) or it becomes kohlenstoffdioxidhaltiges, natural Mineral water used. As Food additive it carries the designation E 290. During the production carbon dioxide under high pressure is pumped to the beverage, whereby it with water to carbonic acid reacts. Since carbonic acid is an inconsistant acid, it disintegrates with the decrease of pressure by opening the container into its output products: Water and carbon dioxide, which ascends blaeschenfoermig. The decay of carbonic acid on the tongue when drinking stimulates the taste sensory cells, which entails a refreshment effect.

Carbon dioxide comes also into Fire extinguishers to the employment, there it oxygen of Fire source displaced (see also Fire fighting, Fire extinguishing agent).

Carbon dioxide becomes as Fertilizer used in greenhouses. Reason is that CO₂Lack by insufficient air interchange, particularly in the winter when closed ventilation and that plants with higher CO₂Faster grow contents. The carbon dioxide becomes either directly as pure gas (relatively expensive) or as verbrennungsprodukt out Propane or natural gas uses (coupling of fertilization and heating). Also by supply of organic substance that becomes CO₂Content increases. The possible yield increase depends on it, like strongly the CO₂ in the minimum stands, and the light intensity is as high (effectiveness rises with increasing light offer).

Supercritical Carbon dioxide can replace poisonous organic solvents within many ranges and becomes also in that Semiconductor industry to the cleaning of Wafern used. Also to the extraction of natural substances such as z. B. Koffein from plants supercritical carbon dioxide is used.

Carbon dioxide comes increasingly as natural Refrigerant in Air conditioning systems to the employment.

Carbon dioxide becomes also as Inert gas in that Welding engineering begun - either in pure form or more frequently than additive too Argon andor Helium. Since carbon dioxide is thermodynamically unstable at high temperatures, becomes it not as Inert gas separate as active gas designation.

CO₂ becomes also in Exhausting means (Zaepfchen) uses. By a chemical reaction during the dissolution of the zaepfchens CO becomes₂ set free and stretches that Intestine, which again that Chair reflex releases.

Greenhouse gas

Carbon dioxide absorbs a part of the radiant heat (Infrared radiation), during shorter-wave radiation, for example visible or ultraviolet light, to happen can. This characteristic makes carbon dioxide a in such a way specified Greenhouse gas.

From many scientists those becomes Hypothesis represented, that one of humans caused increase for that greenhouse gases in that Atmosphere to so the anthropogenen mentioned Greenhouse effect lead, a climatic change (Global heating up) has to the consequence. The CO makes a substantial contribution in addition₂, by the burn of the fossil Source of energy Oil, Natural gas and Coal one sets free.

During over the reduction of the CO₂Output agreement exists to a large extent (Kyoto minutes), become procedures for CO₂Attachment controversially discusses.

The contribution of CO₂ to the greenhouse effect and/or. whether such is provable, and thus the negative consequences that CO₂Release by humans, becomes however of Climatic critics denied, therefore it the also appropriate environmental protection measures as unnecessary reject.

Those have the world-wide highest carbon dioxide output per inhabitant The USA, Canada, Finland, Tschechien and Belgium (conditions 2002), whereby in the future also the strongly growing industry more asiatically States of a substantial role will play. In that European union becomes the output of CO₂ continue to increase, although by the improvement of the Efficiency for example with the generation of electricity of Coal in Power station the specific Emmissionsgrad of 0.41 million Tons CO₂ per Terawattstunde produced river in the year 2000 on 0.36 million tons CO₂ per TWh in the year 2020 will sink. Despite these measures one accepts, that the quantity of the carbon dioxide within the European Union in the same period of 1250 million tons, produced by the power stations, will increase on approximately 1600 million tons.

Since that 1. January 2005 exists a European-wide CO₂Handelssystem Emission right trade. Each state committed itself to certain reduction goals. The states again divide the enterprises, the CO₂ set free, only so much CO₂Emissionsberechtigungen too, as is necessary, around the CO₂To reach Reduktionsziele in the respective state. Enterprise, the authorizations fewer by saving measures need, when were assigned to them annually, can these sell. Enterprise, the more need, must buy to go with. At the end of a yearly each enterprise must indicate, how much CO₂ it discharged and the appropriate number of CO₂Authorizations again deliver. That CO₂Emissionsbericht of the enterprises becomes before delivery to the authority of independent experts, z.B. Environmental consultant examines.

The prices for authorizations for the output of 1 Ton CO₂ are from approx.. (6,-- euro at the beginning of 2005) on approx.. 25,-- euro (in the middle of July 2005) risen and give a clear incentive to the enterprises thereby for reduction that CO₂Emissions.

In Germany the responsible authority is the German emission commercial place (DEHSt) beside the Land authorities, for the permission and control of the monitoring and reports are zusstaendig. CO₂Authorizations become z.B. in Germany at the Leipziger stock exchange (EEX) acted.

Driven

It comes again and again to accidents with CO₂. In Wine cellars, Futtersilos and Liquid manure pits can itself by gaerprozesse considerable quantities of CO₂ form. During the fermentation of a litre Most (Apple wine) for instance litres fermenting gas develop up to 50. If not is provided for sufficient exhaust, form dangerous concentrations, due to the higher density of CO₂ compared with air particularly at ground level ("carbon dioxide lake").

(the density of gases leaves itself with the molecular mass and the rule of Avogadro measure: Air essentially consists of nitrogen (N₂) and oxygen (O₂), Carbon dioxide however from CO₂ Molecules, which a clearly larger molecular mass have. In a equivalent volume approximately equivalent many molecules are present, also with different gases thus the density of carbon dioxide must be larger than from air.)

The wide-spread opinion, CO₂ is actually innocuous and work only by displacing the vitally necessary Oxygen, is wrong. Therefore also the old "candle sample" is for recognizing more dangerously Oxygen scarceness too inaccurately. This is also because of it, that candles still burn also then, if the oxygen does not hand no more for breathing already.

CO comes₂ in atmospheric air still too approx.. 0.03 per cent forwards, there is in the human abgeatmeten Breathing air already approx.. 4,5 Percent by volume. In Blood solved CO₂ activated in physiological and easily increased concentration that Breath center the brain, in clearly higher concentration it leads however to the reduction or even abolition of the reflektorischen Incentive for breath (Breath depression; one knows this fact itself with straight hyper+ventilating Persons too use make, by letting it inhale into a hermetic container inside and also again from it, there so fast breath-depressive breathing air concentrations at CO₂ are reached and the exaggerated breath drive of the hyper+ventilating effectively one absorbs). Starting from approximately 5 per cent in inhaled air headache and swindles arise, with higher concentrations accelerated heart impact (Tachycardia), Blood pressure rise, Difficulty in breathing and unconsciousness (the in such a way specified CO₂Narkose). CO₂Concentrations over 8 per cent are deadly.

Whole families of a fermenting gas poisoning fall again and again to the victim, because several persons with the rescue of a family member carbon dioxide inhale and become unconscious. The Ersthelfer goes with a rescue attempt only in danger - nobody can carry an unconscious one from a cellar with stopped breath. Instead an exhaust (if available) is to be switched on and for that Emergency call to set off.

Those Rescue a had an accident one from CO₂suspicious situations (wine cellar etc..) is only for professional task forces (Fire-brigade) with heavy Respiratory protection possible.

In rare cases it comes also to natural catastrophes with Kohlenstoffdioxd; the most well-known occurred itself 1986 to Nyos lake in Cameroon.

See also

• Pasteur effect
• CO₂Partial pressure
• Emission right trade

Literature

• Eike Roth: "global environmental problems - causes and solutions", Friedmann publishing house Munich 2004, ISBN 3-933431-31-X (well readable representation of the Treibhausefektes including its causing and discussion of the arguments for and against a anthropogenen influence)

Web on the left of

• HTTP:www.university Bayreuth.de/departmentdidactics chemistryumat/csaeure/carbonic acid.htm
• HTTP:www.environmentalencyclopedia-on-line.de/fp/archivesRUBwerkstoffmaterialsubstanz/Carbon dioxide.php
• HTTP:www.dehst.de
• HTTP:www.eex.de