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Arsenic Pentoxide
Arsenic pentoxide is the inorganic compound with the formula As2O5. This glassy, white, deliquescent solid is relatively unstable, consistent with the rarity of the As(V) oxidation state. More common, and far more important commercially, is arsenic(III) oxide (As2O3). All inorganic arsenic compounds are highly toxic and thus find only limited commercial applications. Structure The structure consists of tetrahedral and octahedral centers linked by sharing corners. The structure differs from that of the corresponding phosphorus(V) oxide; as a result, although there is still a solid solution with that oxide, it only progresses to the equimolar point, at which point phosphorus has substituted for arsenic in all of its tetrahedral sites. Likewise, arsenic pentoxide can also dissolve up to an equimolar amount of antimony pentoxide, as antimony substitutes for arsenic only in its octahedral sites. Synthesis Historical Paracelsus Macquer found a crystallizable salt which he ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hygroscopic
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance's molecules, adsorbing substances can become physically changed, e.g., changing in volume, boiling point, viscosity or some other physical characteristic or property of the substance. For example, a finely dispersed hygroscopic powder, such as a salt, may become clumpy over time due to collection of moisture from the surrounding environment. ''Deliquescent'' materials are sufficiently hygroscopic that they absorb so much water that they become liquid and form an aqueous solution. Etymology and pronunciation The word ''hygroscopy'' () uses combining forms of '' hygro-'' and '' -scopy''. Unlike any other ''-scopy'' word, it no longer refers to a viewing or imaging mode. It did begin that way, with the word ''hygroscope'' referring in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Nitrate
Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitrate ions NO3−, and is therefore an alkali metal nitrate. It occurs in nature as a mineral, niter (or ''nitre'' in the UK). It is a source of nitrogen, and nitrogen was named after niter. Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpeter (or ''saltpetre'' in the UK). Major uses of potassium nitrate are in fertilizers, tree stump removal, rocket propellants and fireworks. It is one of the major constituents of gunpowder (black powder). In processed meats, potassium nitrate reacts with hemoglobin and myoglobin generating a red color. Etymology Potassium nitrate, because of its early and global use and production, has many names. Hebrew and Egyptian words for it had the consonants n-t-r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic(V) Compounds
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray form, which has a metallic appearance, is important to industry. The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices. It is also a component of the III-V compound semiconductor gallium arsenide. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining with the increasing recognition of the toxicity of arsenic and its compounds. A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, hamsters, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Government Publishing Office
The United States Government Publishing Office (USGPO or GPO; formerly the United States Government Printing Office) is an agency of the legislative branch of the United States Federal government. The office produces and distributes information products and services for all three branches of the Federal Government, including U.S. passports for the Department of State as well as the official publications of the Supreme Court, the Congress, the Executive Office of the President, executive departments, and independent agencies. An act of Congress changed the office's name to its current form in 2014. History The Government Printing Office was created by congressional joint resolution () on June 23, 1860. It began operations March 4, 1861, with 350 employees and reached a peak employment of 8,500 in 1972. The agency began transformation to computer technology in the 1980s; along with the gradual replacement of paper with electronic document distribution, this has led to a stea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emergency Planning And Community Right-to-Know Act
The Emergency Planning and Community Right-to-Know Act of 1986 is a United States federal law passed by the 99th United States Congress located at Title 42, Chapter 116 of the U.S. Code, concerned with emergency response preparedness. On October 17, 1986, President Ronald Reagan signed into law the Superfund Amendments and Reauthorization Act of 1986 (SARA). This act amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), commonly known as Superfund. A free-standing law, the Emergency Planning and Community Right-to-Know Act of 1986 (EPCRA) was commonly known as SARA Title III. Its purpose is to encourage and support emergency planning efforts at the state and local levels and to provide the public and local governments with information concerning potential chemical hazards present in their communities. Background During the early morning hours of December 3, 1984, a Union Carbide plant in a village just South of Bhopal, India rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Extremely Hazardous Substances
This is the list of extremely hazardous substances defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002). The list can be found as an appendix to 40 C.F.R. 355. Updates as of 2006 can be seen on the Federal Register, 71 FR 47121 (August 16, 2006). The data were provided by the United States Environmental Protection Agency (EPA). __NOTOC__ A * Acetone cyanohydrin * Acetone thiosemicarbazide * Acrolein * Acrylamide * Acrylonitrile * Acryloyl chloride * Adiponitrile * Aldicarb * Aldrin * Allyl alcohol * Allylamine * Aluminum phosphide * Aminopterin * Amiton * Amiton oxalate * Ammonia * Amphetamine * Aniline * Aniline, 2,4,6-trimethyl- * Antimony pentafluoride * Antimycin A * ANTU (Alpha-Naphthylthiourea) * Arsenic pentoxide * Arsenous oxide * Arsenous trichloride * Arsine * Azinphos-ethyl * Azinphos-methyl B * Benzal chloride * Benzenamine, 3-(trifluoromethyl)- * Benzenearsonic acid * Benzimidazole, 4,5-dichloro-2-(tri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cysteine
Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, sometimes the symbol Cyz is used. The deprotonated form can generally be described by the symbol Cym as well. The thiol is susceptible to oxidation to give the disulfide derivative cystine, which serves an important structural role in many proteins. In this case, the symbol Cyx is sometimes used. When used as a food additive, it has the E number E920. Cysteine is encoded by the codons UGU and UGC. The sulfur-containing amino acids cysteine and methionine are more easily oxidized than the other amino acids. Structure Like other amino acids (not as a residue of a protein), cysteine exists as a zwitterion. Cysteine has chirality in the older / notation based on homology to - and -glyceraldehyde. In the newer ''R''/''S'' system of designating chi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orpiment
Orpiment is a deep-colored, orange-yellow arsenic sulfide mineral with formula . It is found in volcanic fumaroles, low-temperature hydrothermal veins, and hot springs and is formed both by sublimation and as a byproduct of the decay of another arsenic sulfide mineral, realgar. Orpiment takes its name from the Latin ''auripigmentum'' (''aurum'', "gold" + ''pigmentum'', "pigment") because of its deep-yellow color. Historical uses Orpiment was traded in the Roman Empire and was used as a medicine in China, even though it is very toxic. It has been used as fly poison and to tip arrows with poison. Because of its striking color, it was of interest to alchemists, both in China and the West, searching for a way to make gold. It also has been found in the wall decorations of Tutankhamun's tomb and ancient Egyptian scrolls, and on the walls of the Taj Mahal. For centuries, orpiment was ground down and used as a pigment in painting and for sealing wax, and was even used in ancient Chi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%–6% by weight) in water for consumer use, and in higher concentrations for industrial use. Concentrated hydrogen peroxide, or " high-test peroxide", decomposes explosively when heated and has been used as a propellant in rocketry. Hydrogen peroxide is a reactive oxygen species and the simplest peroxide, a compound having an oxygen–oxygen single bond. It decomposes slowly when exposed to light, and rapidly in the presence of organic or reactive compounds. It is typically stored with a stabilizer in a weakly acidic solution in a dark bottle to block light. Hydrogen peroxide is found in biological systems including the human body. Enzymes that use or decompose hydrogen peroxide are classified as peroxidases. Properties The boiling poi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lower atmosphere to (dioxygen). Ozone is formed from dioxygen by the action of ultraviolet (UV) light and electrical discharges within the Earth's atmosphere. It is present in very low concentrations throughout the latter, with its highest concentration high in the ozone layer of the stratosphere, which absorbs most of the Sun's ultraviolet (UV) radiation. Ozone's odour is reminiscent of chlorine, and detectable by many people at concentrations of as little as in air. Ozone's O3 structure was determined in 1865. The molecule was later proven to have a bent structure and to be weakly diamagnetic. In standard conditions, ozone is a pale blue gas that condenses at cryogenic temperatures to a dark blue liquid and finally a violet-black soli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidizing Agents
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxidizer is any substance that oxidizes another substance. The oxidation state, which describes the degree of loss of electrons, of the oxidizer decreases while that of the reductant increases; this is expressed by saying that oxidizers "undergo reduction" and "are reduced" while reducers "undergo oxidation" and "are oxidized". Common oxidizing agents are oxygen, hydrogen peroxide and the halogens. In one sense, an oxidizing agent is a chemical species that undergoes a chemical reaction in which it gains one or more electrons. In that sense, it is one component in an oxidation–reduction (redox) reaction. In the second sense, an oxidizing agent is a chemical species that transfers electronegative atoms, usually oxygen, to a substrate. Combust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scheele
Scheele is a surname of Germanic origin. Notable people with the surname include: *Carl Wilhelm Scheele (1742–1786), German-Swedish pharmaceutical chemist *George Heinrich Adolf Scheele (1808–1864), German botanist * Karin Scheele (b. 1968), Austrian politician; member of the European Parliament since 1999 * Leonard A. Scheele (1907–1993), American physician; Surgeon General of the United States, 1948-56 *Nick Scheele (1944–2014), British businessman; chief operating officer of Ford Motor Company *Thomas von Scheele Thomas von Scheele (born March 13, 1969 in Bollnäs) is a left-handed Swedish table tennis player. He competed in the men's doubles event at the 1996 Summer Olympics. He won a gold medal in the double event of the World Table Tennis Championsh ... (b. 1969), Swedish table tennis player See also * Scheele (crater), the lunar impact crater {{surname ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
