Carbon oxide. Odorless, colorless and tasteless gas , partially soluble in water , alcohol and benzene , resulting from incomplete oxidation of carbon during the combustion process. It consists of a carbon atom linked via a covalent bond (0.1128 nm long) to an oxygen (CO) atom .
Summary
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- 1 Other Names
- 2 Discovery
- 3 Physico-chemical characteristics
- 1 Chemical Formula
- 2 Physical Properties
- 4 Source of Obtaining
- 1 Other ways of obtaining
- 5 Effects
- 6 Source
- 7 Related Links
Other names
Carbon monoxide, Carbon (II) oxide, Carbon dioxide, Carbon gas
Discovery
Carbon monoxide was discovered by the French chemist de Lassone in 1776 while heating zinc oxide with coke. He mistakenly believed that it was hydrogen because it generated a blue flame. Later in 1800 , the English chemist William Cruikshank verified that said compound contained carbon and oxygen .
Its toxic properties of CO were thoroughly investigated by the French physicist Claude Bernard in 1846 . Poisoning dogs with the gas detected that their blood became redder and brighter in all tissues.
During the Second World WarCarbon monoxide was used in vehicle engines as gasoline was in short supply. Mineral or vegetal coal was introduced and the carbon monoxide generated by gasification fed the carburettor. CO was also used as a method of extermination during the Holocaust in concentration camps.
Physicochemical characteristics
Carbon oxide is an odorless, colorless, flammable, and highly toxic gas.
Chemical formula
The molecule is made up of a carbon atom attached to a CO oxygen atom.
Physical Properties
- Molecular weight: 28.0 amu
- Melting point: 68 K (-205 ° C)
- Boiling point: 81 K (-192 ° C)
- Density: 8.0 × 103 kg / m3 (liquid) 1,145 kg / m3 (gas at 298K) – lighter than air
- Solubility: 0.0026 g in 100g of water
Source of Obtaining
The generator gas is formed by the combustion of the coal with oxygen at high temperatures. The process is carried out in a furnace in which air passes through a bed of coke.
- O2 + 2 C ↔ 2 CO DH = – 221 kJ / mol
Synthesis gas, also called water gas, is produced through an endothermic reaction between water vapor and coal:
- H2O + C ↔ H2 + CO DH = 131 kJ / mol
Carbon monoxide is also a by-product of the reduction of minerals formed by metal oxides in the presence of carbon, as indicated in simplified form in the following reaction:
- MO + C ↔ M + CO ΔH = 131 kJ / mol
CO is the anhydride of formic acid. For this reason, it can also be obtained by dehydrating formic acid , for example with sulfuric acid .
Another possible way to obtain carbon monoxide in the laboratory involves heating a mixture of zinc and pulverized calcium carbonate.
- Zn + CaCO3 → ZnO + CaO + CO
Other ways of obtaining
CO is the most abundant and widely distributed air pollutant of those found in the lower layer of the atmosphere, called the troposphere.
Its main natural origin is the oxidation of CH4 and, since all the methane in the atmosphere is produced by anaerobic decomposition of organic matter, it can be said that these processes constitute a natural source of CO.
The oceans are the second largest source of atmospheric CO. Since surface water is in contact with the atmosphere, it should be expected to contain CO absorbed by it. However, the amount of actually dissolved CO found in the oceans is 10 to 40 times higher than expected based on this absorption. Algae and other biological sources are believed to contribute substantial amounts of CO to surface waters. This CO is then released into the atmosphere.
Volcanoes and fires also constitute a significant source of CO emission into the atmosphere, although their contribution is punctual.
Anthropogenic CO formation is generally the result of some of the following processes:
- Incomplete combustion of carbon, of compounds that contain them: This process takes place when the available oxygen is less than the amount necessary for complete combustion, from which CO2 is released
- High temperature reaction between CO2 and carbon-containing materials: This reaction takes place rapidly at the high temperatures common in many industrial mechanisms. CO released in this way is beneficial and necessary in certain applications, such as blast furnaces, where it acts as a reducing agent in the production of iron from iron oxide minerals. However, a certain amount of CO can escape into the atmosphere and act as a pollutant.
- Dissociation of CO2 at high temperatures: Under appropriate conditions, a reaction in which sufficient oxygen is available to complete combustion can still behave as a source of CO. This is due to the high temperature of dissociation of CO2 into CO and O. Higher temperatures favor the production of CO and O. For example, at a temperature of 1745 ºC there is a dissociation of CO2 of 1%, a percentage that rises to 5 % at 1940 ºC.
Effects
The danger of CO lies in that said gas has a high affinity for hemoglobin (240 times higher than that of oxygen), giving rise to carboxyhemoglobin, which when displacing oxygen from hemoglobin in the blood causes ischemia and hypoxia, situations those that the heart and brain are especially sensitive.
At low concentrations carbon monoxide causes fatigue in healthy people and chest pain in patients with heart disease.
At higher concentrations it causes problems with vision and coordination, headaches, dizziness, confusion and nausea, causing flu-like symptoms that disappear after exposure to the contaminant ceases.
When concentrations are very high, exposure to CO can be lethal, causing death within a few minutes.
Inhalation of fumes from all types of fires is the second leading cause of CO poisoning; firefighters are the group that suffers the greatest risk of poisoning from this pollutant.
