Air pollution is by far the most harmful form of pollution in our environment.
History[ edit ] Aristotle — BC first recorded that burning coals produced toxic fumes. An ancient method of execution was to shut the criminal in a bathing room with smoldering coals.
What was not known was the mechanism of death. Greek physician Galen — AD speculated that there was a change in the composition of the air that caused harm when inhaled. The gas was identified as a compound containing carbon and oxygen by the Scottish chemist William Cruikshank in External with a few exceptions charcoal or wood gas generators were fitted, and the mixture of atmospheric nitrogen, hydrogen, carbon monoxide, and small amounts of other gases produced by gasification was piped to a gas mixer.
The gas mixture produced by this process is known as wood gas.
In the presence of oxygen, including atmospheric concentrations, carbon monoxide burns with a blue flame, producing carbon dioxide. Some processes in modern technology, such as iron smeltingstill produce carbon monoxide as a byproduct.
For this reason, the process off-gases have to be purified.
On the other hand, considerable research efforts are made in order to optimize the process conditions,  develop catalyst with improved selectivity  and to understand the reaction pathways leading to the target product and side products.
In biology, carbon monoxide is naturally produced by the action of heme oxygenase 1 and 2 on the heme from hemoglobin breakdown. This process produces a certain amount of carboxyhemoglobin in normal persons, even if they do not breathe any carbon monoxide.
Following the first report that carbon monoxide is a normal neurotransmitter in  as well as one of three gases that naturally modulate inflammatory responses in the body the other two being nitric oxide and hydrogen sulfidecarbon monoxide has received a great deal of clinical attention as a biological regulator.
In many tissues, all three gases are known to act as anti-inflammatoriesvasodilatorsand promoters of neovascular growth. Molecular properties[ edit ] Carbon monoxide has a molar mass of The bond length between the carbon atom and the oxygen atom is Carbon—oxygen double bonds are significantly longer, Bonding and dipole moment[ edit ] The carbon monoxide has a very high bond-dissociation energythe strongest of any neutral molecule, Carbon and oxygen together have a total of 10 electrons in the valence shell.
Following the octet rule for both carbon and oxygen, the two atoms form a triple bondwith six shared electrons in three bonding molecular orbitals, rather than the usual double bond found in organic carbonyl compounds. Since four of the shared electrons come from the oxygen atom and only two from carbon, one bonding orbital is occupied by two electrons from oxygen, forming a dative or dipolar bond.
By contrast, the isoelectronic dinitrogen molecule has no dipole moment. If carbon monoxide acts as a ligandthe polarity of the dipole may reverse with a net negative charge on the oxygen end, depending on the structure of the coordination complex.
Bond polarity and oxidation state[ edit ] Theoretical and experimental studies show that, despite the greater electronegativity of oxygen, the dipole moment points from the more-negative carbon end to the more-positive oxygen end. It is calculated by counting all the bonding electrons as belonging to the more electronegative oxygen.
Only the two non-bonding electrons on carbon are assigned to carbon. In this count, carbon then has only two valence electrons in the molecule compared to four in the free atom. Biological and physiological properties[ edit ] Main article:Elemental carbon exists in several forms, each of which has its own physical characteristics.
Two of its well-defined forms, diamond and graphite, are crystalline in structure, but they differ in physical properties because the arrangements of the atoms in their structures are dissimilar.A third form, called fullerene, consists of a variety of molecules composed entirely of carbon.
Chemical properties Carbon does not dissolve in or react with water, acids, or most other materials. It does, however, react with oxygen.
It burns in air to produce carbon dioxide (CO 2) and carbon monoxide (CO).The combustion (burning) of coal gave rise to the Industrial Revolution (). Carbon monoxide poisoning is the most common type of fatal air poisoning in many countries.
Carbon monoxide is colorless, odorless, and tasteless, but highly toxic. It combines with hemoglobin to produce carboxyhemoglobin, which usurps the space in hemoglobin that normally carries oxygen, but is ineffective for delivering oxygen to bodily tissues.. Concentrations as low as ppm may cause up.
Comprehensive and meticulously documented facts about pollution. Learn about air and water pollution, natural pollution, indoor pollution, and more. Carbon monoxide (CO) is only a very weak direct greenhouse gas, but has important indirect effects on global warming.
Carbon monoxide (CO) is only a very weak direct greenhouse gas, but has important indirect effects on global warming.