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Poison Gas
Many gases have toxic properties, which are often assessed using the LC50 (median lethal dose) measure. In the United States, many of these gases have been assigned an NFPA 704 health rating of 4 (may be fatal) or 3 (may cause serious or permanent injury), and/or exposure limits ( TLV, TWA or STEL) determined by the ACGIH professional association. Some, but by no means all, toxic gases are detectable by odor, which can serve as a warning. Among the best known toxic gases are carbon monoxide, chlorine, nitrogen dioxide and phosgene. Definition *Toxic: it is a chemical that has a median lethal concentration (LC50) in air of more than 200 parts per million (ppm) but not more than 2,000 parts per million by volume of gas or vapor, or more than 2 milligrams per liter but not more than 20 milligrams per liter of mist, fume or dust, when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats weighing between 200 and 300 grams ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxicity
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell ( cytotoxicity) or an organ such as the liver ( hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large. Sometimes the word is more or less synonymous with poisoning in everyday usage. A central concept of toxicology is that the effects of a toxicant are dose-dependent; even water can lead to water intoxication when taken in too high a dose, whereas for even a very toxic substance such as snake venom there is a dose below which there is no detectable toxic effect. Toxicity is species-specific, making cross-species analysis problematic. Newer paradigms and metrics are evolving to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IDLH
The term immediately dangerous to life or health (IDLH) is defined by the US National Institute for Occupational Safety and Health (NIOSH) as exposure to airborne contaminants that is "likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment." Examples include smoke or other poisonous gases at sufficiently high concentrations. It is calculated using the LD50 or LC50. The Occupational Safety and Health Administration (OSHA) regulation (1910.134(b)) defines the term as "an atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual's ability to escape from a dangerous atmosphere." IDLH values are often used to guide the selection of breathing apparatus that are made available to workers or firefighters in specific situations. The NIOSH definition does not include oxygen deficiency (below 19.5 percent) although atmosphere-supplying breathing appara ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bromine Chloride
Bromine monochloride, also called bromine(I) chloride, bromochloride, and bromine chloride, is an interhalogen inorganic compound with chemical formula BrCl. It is a very reactive golden yellow gas with boiling point 5 °C and melting point −66 °C. Its CAS number is 13863-41-7, and its EINECS number is 237-601-4. It is a strong oxidizing agent. Uses Bromine monochloride is used in analytical chemistry in determining low levels of mercury, to quantitatively oxidize mercury in the sample to Hg(II) state. A common use of bromine monochloride is as an algaecide, fungicide, and disinfectant of industrial recirculating cooling water systems. Addition of bromine monochloride is used in some types of Li-SO2 batteries to increase voltage and energy density. See also * List of highly toxic gases * Interhalogen compounds In chemistry, an interhalogen compound is a molecule which contains two or more different halogen atoms (fluorine, chlorine, bromine, iodine, or astat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table ( halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig (in 1825) and Antoine Jérôme Balard (in 1826), its name was derived from the Ancient Greek (bromos) meaning "stench", referring to its sharp and pungent smell. Elemental bromine is very reactive and thus does not occur as a native element in nature but it occurs in colourless soluble crystalline mineral halide salts, analogous to table salt. In fact, bromine and all the halogens are so reactive that they form bonds in pairs—never in single atoms. While it is rather rare in the Earth's crust, the high solubility of the bromide ion (Br) has caused its accumulation in the oceans. Comme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occupational Safety And Health Administration
The Occupational Safety and Health Administration'' (OSHA ) is a large regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. Congress established the agency under the Occupational Safety and Health Act OSH Act, which President Richard M. Nixon signed into law on December 29, 1970. OSHA's mission is to "assure safe and healthy working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education, and assistance". The agency is also charged with enforcing a variety of whistleblower statutes and regulations. OSHA's workplace safety inspections have been shown to reduce injury rates and injury costs without adverse effects on employment, sales, credit ratings, or firm survival. History The Bureau of Labor Standards of the Department of Labor has worked on some work safety issues since its creation in 1922. Economic boom and associated l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boron Trifluoride
Boron trifluoride is the inorganic compound with the formula BF3. This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds. Structure and bonding The geometry of a molecule of BF3 is trigonal planar. Its D3h symmetry conforms with the prediction of VSEPR theory. The molecule has no dipole moment by virtue of its high symmetry. The molecule is isoelectronic with the carbonate anion, . BF3 is commonly referred to as " electron deficient," a description that is reinforced by its exothermic reactivity toward Lewis bases. In the boron trihalides, BX3, the length of the B–X bonds (1.30 Å) is shorter than would be expected for single bonds, and this shortness may indicate stronger B–X π-bonding in the fluoride. A facile explanation invokes the symmetry-allowed overlap of a p orbital on the boron atom with the in-phase combination of the three similarly oriented p orbi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boron Trichloride
Boron trichloride is the inorganic compound with the formula BCl3. This colorless gas is a reagent in organic synthesis. It is highly reactive toward water. Production and structure Boron reacts with halogens to give the corresponding trihalides. Boron trichloride is, however, produced industrially by direct chlorination of boron oxide and carbon at 501 °C. :B2O3 + 3 C + 3 Cl2 → 2 BCl3 + 3 CO The carbothermic reaction is analogous to the Kroll process for the conversion of titanium dioxide to titanium tetrachloride. In the laboratory BF3 reacted with AlCl3 gives BCl3 via halogen exchange. BCl3 is a trigonal planar molecule like the other boron trihalides, and has a bond length of 175pm. A degree of π-bonding has been proposed to explain the short B− Cl distance although there is some debate as to its extent. It does not dimerize, although NMR studies of mixtures of boron trihalides shows the presence of mixed halides. The absence of dimerisation contrasts with the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boron Tribromide
Boron tribromide, BBr3, is a colorless, fuming liquid compound containing boron and bromine. Commercial samples usually are amber to red/brown, due to weak bromine contamination. It is decomposed by water and alcohols. Chemical properties Boron tribromide is commercially available and is a strong Lewis acid. It is an excellent demethylating or dealkylating agent for the cleavage of ethers, also with subsequent cyclization, often in the production of pharmaceuticals. The mechanism of dealkylation of tertiary alkyl ethers proceeds via the formation of a complex between the boron center and the ether oxygen followed by the elimination of an alkyl bromide to yield a dibromo(organo)borane. :ROR + BBr3 → RO+(−BBr3)R → ROBBr2 + RBr Aryl methyl ethers (as well as activated primary alkyl ethers), on the other hand are dealkylated through a bimolecular mechanism involving two BBr3-ether adducts. :RO+(−BBr3)CH3 + RO+(−BBr3)CH3→ RO(−BBr3) + CH3Br + RO+(BBr2)CH3 The di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bis(trifluoromethyl)peroxide
Bis(trifluoromethyl)peroxide (BTP) is a fluorocarbon derivative first produced by Frédéric Swarts. It has recently been discovered that it is a good initiator for the polymerization of unsaturated ethylene-like molecules. It produces good quality polymers which are quite stable. This property is the reason an economical synthesis is sought for BTP. This chemical is unusual in the fact that unlike many peroxides, bis(trifluoromethyl)peroxide is a gas, is nonexplosive and has good thermal stability.Ellingboe, E.K.; McCleiland A.L. Polymerization initiator. US 3202718, June 20, 1960 History Bis(trifluoromethyl)peroxide was first created in trace elements by an electrolysis reaction using aqueous solutions containing trifluoroacetate ion. This was one of the byproducts Frédéric Swarts got when performing trifluoromethylation reactions. Later it was discovered that Bis(trifluoromethyl)peroxide had some unusual properties. This began a search for a more economical production of B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsine
Arsine (IUPAC name: arsane) is an inorganic compound with the formula As H3. This flammable, pyrophoric, and highly toxic pnictogen hydride gas is one of the simplest compounds of arsenic. Despite its lethality, it finds some applications in the semiconductor industry and for the synthesis of organoarsenic compounds. The term ''arsine'' is commonly used to describe a class of organoarsenic compounds of the formula AsH3−xRx, where R = aryl or alkyl. For example, As(C6H5)3, called triphenylarsine, is referred to as "an arsine". General properties At its standard state, arsine is a colorless, denser-than-air gas that is slightly soluble in water (20% at 20 °C) and in many organic solvents as well. Whereas arsine itself is odorless, owing to its oxidation by air, it is possible to smell a slight garlic or fish-like scent when the compound is present above 0.5 ppm. This compound is kinetically stable: at room temperature it decomposes only slowly. At temperatures of ca. 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic Pentafluoride
Arsenic pentafluoride is a chemical compound of arsenic and fluorine. It is a toxic, colorless gas. The oxidation state of arsenic is +5. Synthesis Arsenic pentafluoride can be prepared by direct combination of arsenic and fluorine: :2As + 5F2 → 2AsF5 It can also be prepared by the reaction of arsenic trifluoride and fluorine: :AsF3 + F2 → AsF5 or the addition of fluorine to arsenic pentoxide or arsenic trioxide. :2As2O5 + 10F2 → 4AsF5 + 5O2 :2As2O3 + 10F2 → 4AsF5 + 3O2 Properties Arsenic pentafluoride is a colourless gas and has a trigonal bipyramidal structure. In the solid state the axial As−F bond lengths are 171.9 pm and the equatorial 166.8 pm. Its point group is D3h. Reactions Arsenic pentafluoride forms halide complexes and is a powerful fluoride acceptor. An example is the reaction with sulfur tetrafluoride, forming an ionic hexafluoroarsenate complex.An investigation of the structures of the adducts of SF4 with BF3, PF5, AsF5, and SbF5 in the solid s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Conference Of Governmental Industrial Hygienists
The American Conference of Governmental Industrial Hygienists (ACGIH) is a professional association of industrial hygienists and practitioners of related professions, with headquarters in Cincinnati, Ohio. One of its goals is to advance worker protection by providing timely, objective, scientific information to occupational and environmental health professionals. History The National Conference of Governmental Industrial Hygienists (NCGIH) convened on June 27, 1938, in Washington, D.C. NCGIH's original constitution limited full membership to two representatives from each governmental industrial hygiene agency. Associate membership was made available to other professional personnel of the agencies holding full memberships, and also to personnel of educational institutions engaged in teaching industrial hygiene. Governmental industrial hygiene personnel of other countries were eligible for affiliated membership. The Conference came into being with 59 members, one affiliated me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
