A convenient property for this purpose is that solid carbon dioxide sublimes directly into the gas phase leaving no liquid. Dry ice is commonly used as a cooling agent, and it is relatively inexpensive. It was first observed in 1825 by the French chemist Charles Thilorier. Solid carbon dioxide is normally called " dry ice", a generic trademark. It has no electrical dipole, and as it is fully oxidized, it is moderately reactive and is non-flammable, but will support the combustion of metals such as magnesium.Īt −78.51 ° C or −109.3 ° F, carbon dioxide changes directly from a solid phase to a gaseous phase through sublimation, or from gaseous to solid through deposition. The carbon dioxide molecule (O=C=O) contains two double bonds and has a linear shape. Īt standard temperature and pressure, the density of carbon dioxide is around 1.98 kg/m 3, about 1.5 times that of air. 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. This sensation can also occur during an attempt to stifle a burp after drinking a carbonated beverage. These effects result from the gas dissolving in the mucous membranes and saliva, forming a weak solution of carbonic acid. 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. Carbon dioxideįor more details on this topic, see Carbon dioxide (data page).Carbon dioxide is a colourless, odorless gas. Carbon dioxide is a greenhouse gas as it transmits visible light but absorbs strongly in the infrared and near-infrared. Carbon dioxide exists in Earth's atmosphere currently at a globally averaged concentration of approximately 385 parts per million by volume. It is a gas at standard temperature and pressure.
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