carbon monoxide molecule which consists of one C atom and two O atoms (ie, the degree of oxidation of the carbon which equals 4) is called a carbon dioxide (other names: carbon dioxide, carbonic acid anhydride, carbon dioxide).This substance is made to record the molecular formula CO2.The molar mass of it is 44.01 g / mol.In appearance under normal conditions, carbon dioxide is a colorless gas.At low concentrations, it has no odor at higher concentrations becomes sharp, sour smell.
for this chemical there are three aggregate states, which are characterized by different values of the density:
- solid (dry ice);at 1 atm.and a temperature of -78,5 ° C - 1562 kg / m³;
- liquid (carbon dioxide);at a pressure of 56 atm.and a temperature of +20 ° C - 770 kg / m³;
- gaseous;at 1 atm.and 0 ° C - 1,977 kg / m³.
melting temperature of carbon dioxide is equal to -78 ° C, the temperature kipeniya- -57 ° C.The substance is dissolved in water: at 25 ° C and a pressure of 100 kPa, equal to its solubility 1.45 g / l.
Carbon dioxide is a natural chemical compound in which oxygen atoms of the molecule with the carbon atom linked by a covalent bond.A molecule of carbon dioxide is linear and centrosymmetric.Both the link between carbon and two oxygen atoms are equivalent (in fact are double).The molecule is symmetrical about its center, so it has no electric dipole moment.
Carbon dioxide is one of the first gaseous chemical compounds, which have ceased to be identified with the air.In the seventeenth century, the Flemish chemist Jan Baptist van Helmont observed that when he burned charcoal in a closed vessel, the mass of the resulting ash is much less than the ordinary charcoal.The properties of carbon dioxide were studied more thoroughly in 1750 by Scottish physician Joseph Black.
carbon dioxide at standard pressure and temperature in the atmosphere is in an amount of about 0.04% by volume.As part of the carbon cycle, known as photosynthesis, carbon dioxide is absorbed by plants, algae and cyanobacteria.As a result, water is formed and carbohydrates, but this process takes place only under the influence of light.Carbon dioxide is also produced during combustion of coal or hydrocarbons, in the fermentation liquid and air during exhalation humans and animals.In addition, ejected from volcanoes, hot springs, geysers.
The Earth's atmosphere, carbon dioxide plays a significant role (absorbs and emits radiation in the thermal infrared range).It is also a chemical compound is a major source of reducing the pH of the ocean: soluble in water, it forms a weak carbonic acid: CO2 + H2O ↔ H2CO3, inability to fully dissociate into ions.
Carbon dioxide does not support combustion and respiration.A lit torch in its atmosphere goes.Animals and people at high CO2 concentration pants.At 3% concentration in air breathing becomes more frequent, with 10% coming loss of consciousness and rapid death, and 20% content causes instant paralysis.
Carbon dioxide is the anhydride of carbonic acid, so it is characterized by the properties of the acidic oxide.In the laboratory it is prepared by reacting hydrochloric acid with chalk in the Kipp apparatus: CaCO3 + 2HCl → CaCl2 + CO2 + H2O.In the industry it is produced by thermal decomposition of limestone or chalk (less magnesite or dolomite): CaCO3 → CaO + CO2.Production of carbon dioxide is a byproduct of low-temperature air separation process into nitrogen and oxygen.Nowadays we produced special generators to produce carbon dioxide from the air.Such generators are used for the supply of CO2 in the greenhouse in order to create a favorable environment for plants.
Carbon dioxide is widely used in chemical industries.It is used to produce soda, for the synthesis of organic acids, for the manufacture of soft drinks.Dry ice is used as a refrigerant, for example, in the wine industry.Carbon dioxide atmosphere is created to prevent rotting food, the same grapes after collection and before the start of the production of wine.
production of carbon dioxide or liquefied carbon dioxide is carried out to fill in their carbon dioxide fire extinguishers are used to extinguish fires.However, it is impossible to extinguish the person, a significant portion of the jet of liquid CO2 evaporates, and the temperature drops sharply (which can cause frostbite) and CO2 is converted into dry ice.Carbon dioxide is usually extinguish flammable liquids and electrical wiring.The mechanism is to stop the flow of oxygen to the air fires.
