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Hair Dryer , Carbon monoxide IUPAC name   Carbon monooxide Carbon monoxide Carbon(II) oxide Other names Carbonic oxide Identifiers CAS number [630-08-0] PubChem 281 EC number 211-128-3 UN number 1016 ChEBI 17245 RTECS number FG3500000 ChemSpider ID 275 Properties Molecular formula CO Molar mass 28.010 g/mol Appearance colourless, odorless gas Density 0.789 g/mL, liquid 1.250 g/L at 0 C, 1 atm 1.145 g/L at 25 C, 1 atm Melting point 205 C (68 K) Boiling point 191.5 C (81 K) Solubility in water 0.0026 g/100 mL (20 C) Solubility soluble in chloroform, acetic acid, ethyl acetate, ethanol, ammonium hydroxide Dipole moment 0.112 D Hazards MSDS External MSDS EU Index 006-001-00-2 EU classification Highly flammable (F+) Repr. Cat. 1 Toxic (T) R-phrases R61, R12, R23, R48/23 S-phrases S53, S45 NFPA 704 2 4 0   Flash point -191 C Autoignition temperature 609 C Related compounds Related carbon oxides Carbon dioxide Carbon suboxide Oxocarbons Supplementary data page Structure and properties n, r, etc. Thermodynamic data Phase behaviour Solid, liquid, gas Spectral data UV, IR, NMR, MS Except where noted otherwise, data are given for materials in their standard state (at 25 C, 100 kPa) Infobox references Carbon monoxide, with the chemical formula CO, is a colorless, odorless and tasteless, yet highly toxic gas. Its molecules consist of one carbon atom and one oxygen atom, connected by a covalent double bond and a dative covalent bond. It is the simplest oxocarbon, and can be viewed as the anhydride of formic acid (CH2O2). Carbon monoxide is produced from the partial oxidation of carbon-containing compounds; it forms in preference to the more usual carbon dioxide (CO2) when there is a reduced availability of oxygen, such as when operating a stove or an internal combustion engine in an enclosed space. Carbon monoxide has significant fuel value, burning in air with a characteristic blue flame, producing carbon dioxide. Despite its serious toxicity, it was once widely used (as the main component of coal gas) for domestic lighting, cooking and heating, and in the production of nickel. Carbon monoxide still plays a major role in modern technology, in industrial processes such as iron smelting and as a precursor to myriad products. Contents 1 History 2 Molecular properties 3 Biological and physiological properties 3.1 Toxicity 3.2 Human physiology 3.3 Microbiology 4 Occurrence 4.1 Atmospheric presence 4.2 Urban pollution 4.3 Indoor pollution 5 Production 5.1 Laboratory preparation 5.2 Industrial production 6 Coordination chemistry 7 Organic and main group chemistry 8 Uses 8.1 Chemical industry 8.2 Meat coloring 8.3 Medicine 9 See also 10 References 11 External links // History Carbon monoxide has been unknowingly used by humans since prehistoric times, for the smelting of iron and other metallic ores.[citation needed] The gas was used for executions by the Greek and Romans in Classical Antiquity, and was described by the Spanish doctor Arnaldus de Villa Nova in the 11th century[citation needed]. In 1776 the French chemist de Lassone produced CO by heating zinc oxide with coke, but mistakenly concluded that the gaseous product was hydrogen as it burned with a blue flame.[citation needed] The gas was identified as a compound containing carbon and oxygen by the English chemist William Cumberland Cruikshank in the year 1800. Its toxic properties on dogs were thoroughly investigated by Claude Bernard around 1846. During World War II, carbon monoxide was used to keep motor vehicles running in parts of the world where gasoline was scarce. External charcoal or wood burners were fitted, and the carbon monoxide produced by gasification was piped to the carburetor.[citation needed] The CO in this case is known as "wood gas". Carbon monoxide was also reportedly used on a small scale during the Holocaust at some Nazi extermination camps (most notably by gas vans in Chelmno), and in the Action T4 "euthanasia" program.[citation needed] Molecular properties The carbon monoxide molecule consists of one atom of carbon and one atom of oxygen, covalently bonded by a double bond and a dative covalent bond. Its bond length is 112.8 pm. The effects of atomic formal charge and electronegativity result in a small bond dipole moment with its negative end on the carbon atom The reason for this, despite oxygen's greater electronegativity, is that the highest occupied molecular orbital has an energy much closer to that of carbon's p orbitals, meaning that greater electron density is found near the carbon. In addition, carbon's lower electronegativity creates a much more diffuse electron cloud, enhancing the polarizability. This is also the reason that almost all chemistry involving carbon monoxide occurs through the carbon atom, and not the oxygen. The bond length of CO is consistent with a partial triple bond, and the molecule can be represented by three resonance structures: In this classical model, the leftmost structure contributes the most. As such, carbon monoxide resembles molecular nitrogen, and in addition, it has nearly the same molecular mass. Indeed, their physical properties (boiling point, melting point, etc.) are very similar. Biological and physiological properties Toxicity Carbon monoxide poisoning is the most common type of fatal poisoning in many countries. Carbon monoxide is colorless and odorless, but extremely toxic: it combines with hemoglobin in the blood to produce carboxyhemoglobin (HbCO), which is ineffective for delivering oxygen to the body tissues (a condition known as anoxemia). Concentrations as low as 667 ppm can cause up to 50% of the body's hemoglobin to convert to HbCO. In the United States, OSHA limits long-term workplace exposure levels to 50 ppm. The most common symptoms of CO poisoning can resemble the flu, including headache, nausea and vomiting, dizziness, lethargy and a feeling of weakness. Infants may be irritable and feed poorly. Neurological signs include confusion, disorientation, visual disturbance, syncope and seizures. In his pioneering 1846 study, Claude Bernard observed that that the blood of poisoned dogs was more rutilant ("gleaming" or "glowing") in all the vessels, a fact now known to be due to the formation of HbCO. Some classic descriptions of CO poisoning cite also retinal hemorrhages, bright reddish skin, and an abnormal "cherry-red" blood hue; but in most clinical diagnoses these signs are seldom seen. Carbon monoxide is believed to compromise other important molecules such as myoglobin, and mitochondrial cytochrome oxidase. Exposures can lead to significant damage to the heart and central nervous system, especially to the globus pallidus, often with long-term sequelae. Carbon monoxide can also have severe effects on the fetus of a pregnant woman. Human physiology Carbon monoxide is produced naturally in the human body as part of normal metabolism, such as the breakdown of heme (a part of the hemoglobin molecule) by the enzyme heme oxygenase to CO, biliverdin and a Fe3+ cation. The endogenously produced CO may have important physiological roles in the body, such as a neurotransmitter or a blood vessels relaxant. In the neuronal system it has been shown to be involved in learning and memory and odor response, among others.[citation needed] It provides cardiac protection in the circulatory system. It also has roles in the immune, respiratory, reproductive, and gastrointestinal systems, as well as in the kidneys and liver. Because of its expansive role, abnormalities in CO metabolism have been linked to a variety of disease processes, including neurodegenerations, hypertension, heart failure, and inflammation. In addition CO regulates inflammatory reactions in a manner that prevents the development of several diseases such as atherosclero sis or severe malaria.[citation needed] Microbiology CO is a nutrient for methanogenic bacteria, a building block for acetylcoenzyme A. This theme is the subject for the emerging field of bioorganometallic chemistry. In bacteria, CO is produced via the reduction of carbon dioxide via the enzyme carbon monoxide dehydrogenase, an Fe-Ni-S-containing protein. A heme-based CO-sensor protein, CooA, is known. The scope of its biological role is still unclear, it is apparently part of a signaling pathway in bacteria and archaea, but its occurrence in mammals is not established. Occurrence Carbon monoxide commonly occurs in various natural and artificial environments. Here are some typical concentrations: 0.1 ppm - natural background atmosphere level (MOPITT) 0.5 to 5 ppm - average background level in homes 5 to 15 ppm - levels near properly adjusted gas stoves in homes 100-200 ppm - Mexico City central area from autos etc. 5,000 ppm - chimney of a home wood fire 7,000 ppm - undiluted warm car exhaust - without catalytic converter Atmospheric presence MOPITT 2000 global carbon monoxide Carbon monoxide has always been present as a minor constituent of the atmosphere, chiefly as a product of volcanic activity but also from natural and man-made fires (such as forest and bushfires, burning of crop residues, and...