|Formula weight||44.0 amu|
|Melting point||Liquifies under high pressure at 216 K (-57 °C)|
|Boiling point||sublimes at 195 K (-78 °C)|
|Density||1.6 ×103 kg/m3 (solid)|
|Solubility||0.145 g in 100g water|
|S0gas, 1 bar||213.79 J/mol·K|
|Ingestion||May cause nausea, vomiting, GI hemorrhage.|
|Inhalation||Asphyxiant (suffocating), causes hyperventilation[?]. Repeated exposure dangerous.|
|Skin||Dry ice may cause frostbite.|
|Eyes||Can be dangerous.|
|More info||Hazardous Chemical Database (http://ull.chemistry.uakron.edu/erd/chemicals/7/6259)|
|SI units were used where possible. Unless otherwise stated, standard conditions were used.|
Carbon dioxide is a colorless gas with a weak odor. It is about 1.5 times as dense as air. The carbon dioxide molecule
O=C=Ocontains two double bonds and has a linear shape. It has no electrical dipole. As it is fully oxidized, it is not very reactive and in particular not flammable.
Carbon dioxide can be reduced to a liquid and solid form by intense pressure. At standard pressure, it is never liquid: it directly passes between the gaseous and solid phase at -78°C in a process called sublimation.
Water will absorb its own volume of carbon dioxide, and more than this under pressure. About 1% of the dissolved carbon dioxide turns into carbonic acid, resulting in a slightly acidic taste. The carbonic acid in turn dissociates partly to form bicarbonate and carbonate ions.
Carbon dioxide in its solid frozen form it is also known as dry ice. It is used
Carbon dioxide extinguishes flames, and some fire extinguishers[?] contain pressured liquid carbon dioxide. Life jackets[?] often contain capsules of pressured liquid carbon dioxide used for quick inflation.
Water containing dissolved carbon dioxide is also known as carbonated water or soda water. Carbonated water is contained in many soft drinks and some natural springs. Some beverages, such as beer and sparkling wine contain carbon dioxide as a result of fermentation.
Carbon dioxide is a waste product in organisms that obtain energy from breaking down sugars or fats with oxygen as part of their metabolism, in a process known as cellular respiration. This includes all animals, many fungi and some bacteria. In higher animals, the carbon dioxide travels in the blood (where most of it is held in solution) from the body's tissues to the lungs where it is exhaled.
Carbon dioxide, when breathed in high concentrations (about 5% by volume), is toxic to humans and other animals. Hemoglobin, the main molecule in red blood cells, can bind both to oxygen and to carbon dioxide. If the CO2 concentration is too high, then all hemoglobin is saturated with carbon dioxide and no oxygen transport takes place (even if plenty of oxygen is in the air). Carbon dioxide and dry ice should therefore only be handled in well ventilated areas.
Plants remove carbon dioxide from the atmosphere by photosynthesis, which uses light energy to produce organic plant materials by combining carbon dioxide and water. This releases free oxygen gas. Sometimes carbon dioxide gas is pumped into greenhouses to promote plant growth.
Despite its low concentration of about 0.037% or 370 ppm by volume, CO2 is a very important component of Earth's atmosphere, because it traps infrared radiation and thus participates in the greenhouse effect. Atmospheric CO2 has increased about 30 percent since the early 1800s, with an estimated increase of 17 percent since 1958 (burning fossil fuels such as coal and petroleum is the leading cause of increased CO2, deforestation the second major cause).
The increased amounts of CO2 in the atmosphere are widely believed to enhance the greenhouse effect and thus contribute to global warming; this has led to international agreements such as the Kyoto Protocol which aim to limit the release of CO2 into the atmosphere. Some have proposed carbon sequestration as a method to reduce the concentration (or at least slow the rate of increase) of human-made CO2 from entering the atmosphere.