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Magnesium–air Fuel Cell
Magnesium batteries are batteries that utilize magnesium cations as charge carriers and possibly in the anode in electrochemical cells. Both non-rechargeable primary cell and rechargeable secondary cell chemistries have been investigated. Magnesium primary cell batteries have been commercialised and have found use as reserve and general use batteries. Magnesium secondary cell batteries are an active research topic as a possible replacement or improvement over lithium-ion–based battery chemistries in certain applications. A significant advantage of magnesium cells is their use of a solid magnesium anode, offering energy density higher than lithium batteries. Insertion-type anodes ('magnesium ion') have been researched. Primary cells Primary magnesium cells have been developed since the early 20th century. In the anode, they take advantage of the low stability and high energy of magnesium metal, whose bonding is weaker by more than 250 kJ/mol compared to iron and most other tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnesium
Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic table), it occurs naturally only in combination with other elements and almost always has an oxidation state of +2. It reacts readily with air to form a thin Passivation (chemistry), passivation coating of magnesium oxide that inhibits further corrosion of the metal. The free metal burns with a brilliant-white light. The metal is obtained mainly by electrolysis of magnesium Salt (chemistry), salts obtained from brine. It is less dense than aluminium and is used primarily as a component in strong and lightweight magnesium alloy, alloys that contain aluminium. In the cosmos, magnesium is produced in large, aging stars by the sequential addition of three Helium nucleus, helium nuclei to a carbon nucleus. When such stars explo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mark 44 Torpedo
The Mark 44 torpedo is a now-obsolete air-launched and ship-launched lightweight torpedo manufactured in the United States, and under licence in Canada, France, Italy, Japan and the United Kingdom, with 10,500 being produced for U.S. service. It was superseded by the Mark 46 torpedo, beginning in the late 1960s. The Royal Australian Navy, however, continued to use it alongside its successor for a number of years, because the Mark 44 was thought to have superior performance in certain shallow-water conditions. It has been deployed by many navies and air forces including the USN, Royal Navy, Royal Australian Navy and the Royal Air Force from various launch vehicles. These include long-range maritime patrol aircraft, e.g. P-3 Orion, RAF Nimrod, Canadair Argus, LAMPS and other embarked naval helicopters, ASROC missiles, Ikara missiles. Development During the 1950s the US Navy ordered development of a new generation of lightweight anti-submarine torpedoes. Two programs were s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organoboron Chemistry
Organoboron chemistry or organoborane chemistry studies organoboron compounds, also called organoboranes. These chemical compounds combine boron and carbon; typically, they are organic derivatives of borane (BH3), as in the trialkyl boranes. Organoboranes and -borates enable many chemical transformations in organic chemistry — most importantly, hydroboration and carboboration. Most reactions transfer a nucleophilic boron substituent to an electrophilic center either inter- or intramolecularly. In particular, α,β-unsaturated borates and borates with an α leaving group are highly susceptible to intramolecular 1,2-migration of a group from boron to the electrophilic α position. Oxidation or protonolysis of the resulting organoboranes generates many organic products, including alcohols, carbonyl compounds, alkenes, and halides. Properties of the B-C bond The C-B bond has low polarity (electronegativity 2.55 for carbon and 2.04 for boron). Alkyl boron compounds are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ether
In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R′ represent the organyl groups. Ethers can again be classified into two varieties: if the organyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group is the solvent and anaesthetic diethyl ether, commonly referred to simply as "ether" (). Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin. Structure and bonding Ethers feature bent linkages. In dimethyl ether, the bond angle is 111° and C–O distances are 141 pm. The barrier to rotation about the C–O bonds is low. The bonding of ox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Victor Grignard
Francois Auguste Victor Grignard (6 May 1871 – 13 December 1935) was a French chemist who won the Nobel Prize for his discovery of the eponymously named Grignard reagent and Grignard reaction, both of which are important in the formation of carbon–carbon bonds. He also wrote some of his experiments in his laboratory notebooks. Biography Grignard was the son of a sailmaker. He was a hard-working student and was described as having a humble and friendly attitude. He also had a talent for mathematics. After attempting to major in mathematics, Grignard failed his entrance exams before being drafted into the army in 1892. After one year of service, he returned to pursue his studies of mathematics at the University of Lyon and finally obtained his degree Licencié ès Sciences Mathématiques in 1894. In December of the same year, he transferred to chemistry and began working with Professors Philippe Barbier (1848–1922) and Louis Bouveault (1864–1909). After working w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antimony
Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name Kohl (cosmetics), kohl. The earliest known description of this metalloid in the West was written in 1540 by Vannoccio Biringuccio. China is the largest producer of antimony and its compounds, with most production coming from the Xikuangshan Mine in Hunan. The industrial methods for refining antimony from stibnite are Roasting (metallurgy), roasting followed by carbothermic reaction, reduction with carbon, or direct reduction of stibnite with iron. The most common applications for metallic antimony are in alloys with lead and tin, which have improved properties for solders, Bullet, bullets, and plain bearings. It improves the rigidity of lead-alloy pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intermetallics
An intermetallic (also called intermetallic compound, intermetallic alloy, ordered intermetallic alloy, long-range-ordered alloy) is a type of metallic alloy that forms an ordered solid-state compound between two or more metallic elements. Intermetallics are generally hard and brittle, with good high-temperature mechanical properties. They can be classified as stoichiometric or nonstoichiometic. The term "intermetallic compounds" applied to solid phases has long been in use. However, Hume-Rothery argued that it misleads, suggesting a fixed stoichiometry and a clear decomposition into species. Definitions Research definition In 1967 defined intermetallic compounds as ''solid phases containing two or more metallic elements, with optionally one or more non-metallic elements, whose crystal structure differs from that of the other constituents''. This definition includes: * Electron (or Hume-Rothery) compounds * Size packing phases. e.g. Laves phases, Frank–Kasper phases and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrile
In organic chemistry, a nitrile is any organic compound that has a functional group. The name of the compound is composed of a base, which includes the carbon of the , suffixed with "nitrile", so for example is called " propionitrile" (or propanenitrile). The prefix '' cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons. Inorganic compounds containing the group are not called nitriles, but cyanides instead. Though both nitriles and cyanides can be derived from cyanide salts, most nitriles are not nearly as toxic. Structure and basic properties The N−C−C geom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonate Ester
In organic chemistry, a carbonate ester (organic carbonate or organocarbonate) is an ester of carbonic acid. This functional group consists of a carbonyl group flanked by two alkoxy groups. The general structure of these carbonates is and they are related to esters (), ethers () and also to the inorganic carbonates. Monomers of polycarbonate (e.g. Makrolon or Lexan) are linked by carbonate groups. These polycarbonates are used in eyeglass lenses, compact discs, and bulletproof glass. Small carbonate esters like dimethyl carbonate, ethylene carbonate, propylene carbonate are used as solvents, dimethyl carbonate is also a mild methylating agent. Structures Carbonate esters have planar OC(OC)2 cores, which confers rigidity. The unique O=C bond is short (1.173 Å in the depicted example), while the C–O bonds are more ether-like (the bond distances of 1.326 Å for the example depicted). Carbonate esters can be divided into three structural classes: acyclic, cyclic, and polym ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polar Aprotic Solvent
A polar aprotic solvent is a solvent that lacks an acidic proton and is polar. Such solvents lack hydroxyl and amine groups. In contrast to protic solvents, these solvents do not serve as proton donors in hydrogen bonding In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, Covalent bond, covalently b ..., although they can be proton acceptors. Many solvents, including chlorocarbons and hydrocarbons, are classifiable as aprotic, but polar aprotic solvents are of particular interest for their ability to dissolve salts. Methods for purification of common solvents are available. References * {{Chemical solutions Solvents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrafluoroborate
Tetrafluoroborate is the anion . This tetrahedral species is isoelectronic with tetrafluoroberyllate (), tetrafluoromethane (CF4), and tetrafluoroammonium () and is valence isoelectronic with many stable and important species including the perchlorate anion, , which is used in similar ways in the laboratory. It arises by the reaction of fluoride salts with the Lewis acid BF3, treatment of tetrafluoroboric acid with base, or by treatment of boric acid with hydrofluoric acid. As an anion in inorganic and organic chemistry The popularization of has led to decreased use of in the laboratory as a weakly coordinating anion. With organic compounds, especially amine derivatives, forms potentially explosive derivatives. Disadvantages to include its slight sensitivity to hydrolysis and decomposition via loss of a fluoride ligand, whereas does not suffer from these problems. Safety considerations, however, overshadow this inconvenience. With a formula weight of 86.8, BF is also conv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perchlorate
A perchlorate is a chemical compound containing the perchlorate ion, , the conjugate base of perchloric acid (ionic perchlorate). As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cation (). The term ''perchlorate'' can also describe perchlorate esters or covalent perchlorates. These are organic compounds that are alkyl or aryl esters of perchloric acid. They are characterized by a covalent bond between an oxygen atom of the ClO4 moiety and an organyl group. In most ionic perchlorates, the cation is non-coordinating. The majority of ionic perchlorates are commercially produced salts commonly used as oxidizers for pyrotechnic devices and for their ability to control static electricity in food packaging. Additionally, they have been used in rocket propellants, fertilizers, and as bleaching agents in the paper and textile industries. Perchlorate contamination of food and water endangers human health, primarily af ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
