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Stibane
Stibine (IUPAC name: stibane) is a chemical compound with the formula SbH3. A pnictogen hydride, this colourless, highly toxic gas is the principal covalent hydride of antimony, and a heavy analogue of ammonia. The molecule is pyramidal with H–Sb–H angles of 91.7° and Sb–H distances of 170.7 pm (1.707 Å). This gas has an offensive smell like hydrogen sulfide (rotten eggs). Preparation SbH3 is generally prepared by the reaction of Sb3+ sources with H− equivalents: :2 Sb2O3 + 3 LiAlH4 → 4 SbH3 + 1.5 Li2O + 1.5 Al2O3 :4 SbCl3 + 3 NaBH4 → 4 SbH3 + 3 NaCl + 3 BCl3 Alternatively, sources of Sb3− react with protonic reagents (even water) to also produce this unstable gas: :Na3Sb + 3 H2O → SbH3 + 3 NaOH Properties The chemical properties of SbH3 resemble those for AsH3. Typical for a heavy hydride (e.g. AsH3, H2Te, SnH4), SbH3 is unstable with respect to its elements. The gas decomposes slowly at room temperature but rapidly at 200 °C: ::2 SbH3 → 3 H2 + 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Sulfide
Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The underground mine gas term for foul-smelling hydrogen sulfide-rich gas mixtures is ''stinkdamp''. Swedish chemist Carl Wilhelm Scheele is credited with having discovered the chemical composition of purified hydrogen sulfide in 1777. The British English spelling of this compound is hydrogen sulphide, a spelling no longer recommended by the Royal Society of Chemistry or the International Union of Pure and Applied Chemistry. Hydrogen sulfide is toxic to humans and most other animals by inhibiting cellular respiration in a manner similar to hydrogen cyanide. When it is inhaled or it or its salts are ingested in high amounts, damage to organs occurs rapidly with symptoms ranging from breathing difficulties to convulsions and death. Despite this, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. There are two classes of redox reactions: * ''Electron-transfer'' – Only one (usually) electron flows from the reducing agent to the oxidant. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * ''Atom transfer'' – An atom transfers from one substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously the oxidation state of oxygen decreases as it accepts electrons released by the iron. Although oxidation reactions are commonly associated with the formation of oxides, other chemical species can serve the same function. In hydrogenation, C=C (and other) bon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pfaff
PFAFF (german: PFAFF Industriesysteme und Maschinen AG, PFAFF Industrial) is a German manufacturer of sewing machines and is now owned by the SGSB Co. Ltd. History PFAFF was founded in Kaiserslautern, Germany, in 1862 by instrument maker Georg Michael Pfaff (1823–1893). Pfaff's first machine was handmade, and designed to sew leather in the manufacture of shoes. In 1885, Georg Michael Pfaff opened a sewing machine shop in London. The PFAFF factory was expanded and modernized. Georg Pfaff, the second son of the founder, took over the management of the company after his father's death in 1893 and expanded it further with great success. The founder's firstborn son, Jacob Pfaff, died in 1889. His daughter, Lina Pfaff, took over the company in 1917 when her brother Georg died and ran it successfully on a global scale until 1926. Her nephew, Karl Pfaff, took over the company when she retired at the age of seventy-two. It made its one-millionth machine in 1910. Pfaff was bough ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewis Thomson
Lewis may refer to: Names * Lewis (given name), including a list of people with the given name * Lewis (surname), including a list of people with the surname Music * Lewis (musician), Canadian singer * "Lewis (Mistreated)", a song by Radiohead from ''My Iron Lung'' Places * Lewis (crater), a crater on the far side of the Moon * Isle of Lewis, the northern part of Lewis and Harris, Western Isles, Scotland United States * Lewis, Colorado * Lewis, Indiana * Lewis, Iowa * Lewis, Kansas * Lewis Wharf, Boston, Massachusetts * Lewis, Missouri * Lewis, Essex County, New York * Lewis, Lewis County, New York * Lewis, North Carolina * Lewis, Vermont * Lewis, Wisconsin Ships * USS ''Lewis'' (1861), a sailing ship * USS ''Lewis'' (DE-535), a destroyer escort in commission from 1944 to 1946 Science * Lewis structure, a diagram of a molecule that shows the bonding between the atoms * Lewis acids and bases * Lewis antigen system, a human blood group system * Lewis number, a dimensionless ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfuric Acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formula . It is a colorless, odorless and viscous liquid that is miscible with water. Pure sulfuric acid does not exist naturally on Earth due to its strong affinity to water vapor; it is hygroscopic and readily absorbs water vapor from the air. Concentrated sulfuric acid is highly corrosive towards other materials, from rocks to metals, since it is an oxidant with powerful dehydrating properties. Phosphorus pentoxide is a notable exception in that it is not dehydrated by sulfuric acid, but to the contrary dehydrates sulfuric acid to sulfur trioxide. Upon addition of sulfuric acid to water, a considerable amount of heat is released; thus the reverse procedure of adding water to the acid should not be performed since the heat released ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic table. In some respects, zinc is chemically similar to magnesium: both elements exhibit only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size.The elements are from different metal groups. See periodic table. Zinc is the 24th most abundant element in Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende), a zinc sulfide mineral. The largest workable lodes are in Australia, Asia, and the United States. Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity ( electrowinning). Zinc is an essential trace element for humans, animals, plants and for microorganisms and is necessary for prenatal and postnatal development. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Marsh (chemist)
James Marsh (2 September 1794 – 21 June 1846) was a British chemist who invented the Marsh test for detecting arsenic. Born in Kent, he was working as a labourer in Woolwich in the late 1810s and early 1820s, before joining the Royal Artillery. He was married to Mary, and had four children, two of whom died in infancy. His surviving daughters were Lavinia Bithiah (1821-1896) and Lucretia Victoria (1829-1910). Scientific work While Marsh was most famous for inventing the test that bears his name, he was also a skilled and inventive scientist who held the post of Ordnance Chemist at the Royal Arsenal at Woolwich. He developed the screw time fuze for mortar shells and in 1830 the percussion tube. In 1832 ''HMS Castor'' was the first ship to have her guns modified with these innovations. They were not approved for the Army until 1845, when Woolwich began their manufacture—for coastal artillery only. They became obsolete in 1866. Marsh also worked as an assistant to Michael ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic
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, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marsh Test
The Marsh test is a highly sensitive method in the detection of arsenic, especially useful in the field of forensic toxicology when arsenic was used as a poison. It was developed by the chemist James Marsh and first published in 1836. The method continued to be used, with improvements, in forensic toxicology until the 1970s. Arsenic, in the form of white arsenic trioxide , was a highly favored poison, being odourless, easily incorporated into food and drink, and before the advent of the Marsh test, untraceable in the body. In France, it came to be known as ' ("inheritance powder"). For the untrained, arsenic poisoning will have symptoms similar to cholera. Precursor methods The first breakthrough in the detection of arsenic poisoning was in 1775 when Carl Wilhelm Scheele discovered a way to change arsenic trioxide to garlic-smelling arsine gas (AsH3), by treating it with nitric acid (HNO3) and combining it with zinc. :As2O3 + 6 Zn + 12 HNO3 → 2 AsH3 + 6 Zn(NO3)2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphine
Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting fish, due to the presence of substituted phosphine and diphosphane (). With traces of present, is spontaneously flammable in air (pyrophoric), burning with a luminous flame. Phosphine is a highly toxic respiratory poison, and is immediately dangerous to life or health at 50 ppm. Phosphine has a trigonal pyramidal structure. Phosphines are compounds that include and the organophosphines, which are derived from by substituting one or more hydrogen atoms with organic groups. They have the general formula . Phosphanes are saturated phosphorus hydrides of the form , such as triphosphane. Phosphine, PH3, is the smallest of the phosphines and the smallest of the phosphanes. History Philippe Gengembre (1764–1838), a student of Lavoisie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fumigation
Fumigation is a method of pest control or the removal of harmful micro-organisms by completely filling an area with gaseous pesticides—or fumigants—to suffocate or poison the pests within. It is used to control pests in buildings (structural fumigation), soil, grain, and produce. Fumigation is also used during the processing of goods for import or export to prevent the transfer of exotic organisms. Structural fumigation targets pests inside buildings (usually residences), including pests that inhabit the physical structure itself, such as woodborers and drywood termites. Commodity fumigation, on the other hand, is also to be conducted inside a physical structure, such as a storage unit, but it aims to eliminate pests from infesting physical goods, usually food products, by killing pests within the container which will house them. Each fumigation lasts for a certain duration. This is because after spraying the pesticides, or fumigants, only the pests around are e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Vapour Deposition
Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (substrate) is exposed to one or more volatile precursors, which react and/or decompose on the substrate surface to produce the desired deposit. Frequently, volatile by-products are also produced, which are removed by gas flow through the reaction chamber. Microfabrication processes widely use CVD to deposit materials in various forms, including: monocrystalline, polycrystalline, amorphous, and epitaxial. These materials include: silicon (dioxide, carbide, nitride, oxynitride), carbon (fiber, nanofibers, nanotubes, diamond and graphene), fluorocarbons, filaments, tungsten, titanium nitride and various high-κ dielectrics. The term ''chemical vapour deposition'' was coined 1960 by ''John M. Blocher, Jr.'' who intended to differentiate ''chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
