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Barium Oxide
Barium oxide, also known as baria, is a white hygroscopic non-flammable compound with the formula BaO. It has a cubic structure and is used in cathode ray tubes, crown glass, and catalysts. It is harmful to human skin and if swallowed in large quantity causes irritation. Excessive quantities of barium oxide may lead to death. It is prepared by heating barium carbonate with coke, carbon black or tar or by thermal decomposition of barium nitrate. Uses Barium oxide is used as a coating for hot cathodes, for example, those in cathode ray tubes. It replaced lead(II) oxide in the production of certain kinds of glass such as optical crown glass. While lead oxide raised the refractive index, it also raised the dispersive power, which barium oxide does not alter. Barium oxide also has use as an ethoxylation catalyst in the reaction of ethylene oxide and alcohols, which takes place between 150 and 200 °C. It is also a source of pure oxygen through heat fluctuation. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barium Hydroxide
Barium hydroxide is a chemical compound with the chemical formula Ba(OH)2. The monohydrate (''x'' = 1), known as baryta or baryta-water, is one of the principal compounds of barium. This white granular monohydrate is the usual commercial form. Preparation and structure Barium hydroxide can be prepared by dissolving barium oxide (BaO) in water: :BaO + H2O → Ba(OH)2 It crystallises as the octahydrate, which converts to the monohydrate upon heating in air. At 100 °C in a vacuum, the monohydrate will yield BaO and water. The monohydrate adopts a layered structure (see picture above). The Ba2+ centers adopt a square anti-prismatic geometry. Each Ba2+ center is bound by two water ligands and six hydroxide ligands, which are respectively doubly and triply bridging to neighboring Ba2+ centre sites. In the octahydrate, the individual Ba2+ centers are again eight coordinate but do not share ligands. Uses Industrially, barium hydroxide is used as the precursor to other ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Black
Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of coal and coal tar, vegetable matter, or petroleum products, including fuel oil, fluid catalytic cracking tar, and ethylene cracking. Carbon black is a form of paracrystalline carbon that has a high surface-area-to-volume ratio, albeit lower than that of activated carbon. It is dissimilar to soot in its much higher surface-area-to-volume ratio and significantly lower (negligible and non-bioavailable) polycyclic aromatic hydrocarbon (PAH) content. However, carbon black can be used as a model compound for diesel soot to better understand how diesel soot behaves under various reaction conditions as carbon black and diesel soot have some similar properties such as particle sizes, densities, and copolymer adsorption abilities that contribute to them having similar behaviours under various reactions such as oxidation experiment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Separation
An air separation plant separates atmospheric air into its primary components, typically nitrogen and oxygen, and sometimes also argon and other rare inert gases. The most common method for air separation is fractional distillation. Cryogenic air separation units (ASUs) are built to provide nitrogen or oxygen and often co-produce argon. Other methods such as membrane, pressure swing adsorption (PSA) and vacuum pressure swing adsorption (VPSA) are commercially used to separate a single component from ordinary air. High purity oxygen, nitrogen, and argon, used for semiconductor device fabrication, require cryogenic distillation. Similarly, the only viable source of the rare gases neon, krypton, xenon is the distillation of air using at least two distillation columns. Helium is also recovered in advanced air separation processes Cryogenic distillation process Pure gases can be separated from air by first cooling it until it liquefies, then selectively distilling the com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peroxide
In chemistry, peroxides are a group of compounds with the structure , where R = any element. The group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable. The most common peroxide is hydrogen peroxide (), colloquially known simply as "peroxide". It is marketed as solutions in water at various concentrations. Many organic peroxides are known as well. In addition to hydrogen peroxide, some other major classes of peroxides are: * Peroxy acids, the peroxy derivatives of many familiar acids, examples being peroxymonosulfuric acid and peracetic acid, and their salts, one example of which is potassium peroxydisulfate. * Main group peroxides, compounds with the linkage (E = main group element). * Metal peroxides, examples being barium peroxide (), sodium peroxide Sodium peroxide is an inorganic compound with the formula Na2O2. This yellowish solid is the product of sodium ignited in excess oxygen. It is a strong base. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alcohol (chemistry)
In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is used as a drug and is the main alcohol present in alcoholic drinks. An important class of alcohols, of which methanol and ethanol are the simplest examples, includes all compounds which conform to the general formula . Simple monoalcohols that are the subject of this article include primary (), secondary () and tertiary () alcohols. The suffix ''-ol'' appears in the IUPAC chemical name of all substances where the hydroxyl group is the functional group with the highest priority. When a higher priority group is present in the compound, the prefix ''hydroxy-'' is used in its IUPAC name. The suffix ''-ol'' in non-IUPAC names (such as paracetamol or cholesterol) also typically indicates that the substance is an alcohol. However, some comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylene Oxide
Ethylene oxide is an organic compound with the formula . It is a cyclic ether and the simplest epoxide: a three-membered ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sweet odor. Because it is a strained ring, ethylene oxide easily participates in a number of addition reactions that result in ring-opening. Ethylene oxide is isomeric with acetaldehyde and with vinyl alcohol. Ethylene oxide is industrially produced by oxidation of ethylene in the presence of silver catalyst. The reactivity that is responsible for many of ethylene oxide's hazards also makes it useful. Although too dangerous for direct household use and generally unfamiliar to consumers, ethylene oxide is used for making many consumer products as well as non-consumer chemicals and intermediates. These products include detergents, thickeners, solvents, plastics, and various organic chemicals such as ethylene glycol, ethanolamines, simple an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usually gaseous or liquid) as the reactant, or heterogeneous, whose components are not in the same phase. Enzymes and other biocatalysts are often considered as a third category. Catalysis is ubiquitous in chemical industry of all kinds. Estimates are that 90% of all commercially produced chemical products involve catalysts at some stag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethoxylation
Ethoxylation is a chemical reaction in which ethylene oxide adds to a substrate. It is the most widely practiced alkoxylation, which involves the addition of epoxides to substrates. In the usual application, alcohols and phenols are converted into R(OC2H4)nOH where n ranges from 1 to 10. Such compounds are called alcohol ethoxylates. Alcohol ethoxylates are often converted to related species called ethoxysulfates. Alcohol ethoxylates and ethoxysulfates are surfactants, used widely in cosmetic and other commercial products. The process is of great industrial significance with more than 2,000,000 metric tons of various ethoxylates produced worldwide in 1994. Production The process was developed at the Ludwigshafen laboratories of IG Farben by Conrad Schöller and during the 1930s. Alcohol ethoxylates Industrial ethoxylation is primarily performed upon fatty alcohols in order to generate fatty alcohol ethoxylates (FAE's), which are a common form of nonionic surfactant (e.g. octa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Dispersion
In optics, and by analogy other branches of physics dealing with wave propagation, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency; sometimes the term chromatic dispersion is used for specificity to optics in particular. A medium having this common property may be termed a dispersive medium (plural ''dispersive media''). Although the term is used in the field of optics to describe light and other electromagnetic waves, dispersion in the same sense can apply to any sort of wave motion such as acoustic dispersion in the case of sound and seismic waves, and in gravity waves (ocean waves). Within optics, dispersion is a property of telecommunication signals along transmission lines (such as microwaves in coaxial cable) or the pulses of light in optical fiber. Physically, dispersion translates in a loss of kinetic energy through absorption. In optics, one important and familiar consequence of dispersion is the change in the angle of refra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refractive Index
In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or refracted, when entering a material. This is described by Snell's law of refraction, , where ''θ''1 and ''θ''2 are the angle of incidence and angle of refraction, respectively, of a ray crossing the interface between two media with refractive indices ''n''1 and ''n''2. The refractive indices also determine the amount of light that is reflected when reaching the interface, as well as the critical angle for total internal reflection, their intensity ( Fresnel's equations) and Brewster's angle. The refractive index can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is , and similarly the wavelength in that medium is , wher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Glass (optics)
Crown glass is a type of optical glass used in lenses and other optical components. It has relatively low refractive index (≈1.52) and low dispersion (with Abbe numbers around 60). Crown glass is produced from alkali-lime silicates containing approximately 10% potassium oxide and is one of the earliest low dispersion glasses. As well as the specific material named ''crown glass'', there are other optical glasses with similar properties that are also called crown glasses. Generally, this is any glass with Abbe numbers in the range 50 to 85. For example, the borosilicate glass Schott BK7 (Schott designates it as 517642. The first three digits tell you its refractive index (1.517) and the last three tell you its Abbé number (64.2))The crown/flint distinction is so important to optical glass technology that many glass names, notably Schott glasses, incorporate it. A ''K'' in a Schott name indicates a crown glass (''Krone'' in German — Schott is a German company). The ''B'' in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead(II) Oxide
Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula Pb O. PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern applications for PbO are mostly in lead-based industrial glass and industrial ceramics, including computer components. It is an amphoteric oxide. Types Lead oxide exists in two types: * Red tetragonal (α-PbO), obtained at lower temperatures than the β-PbO * Yellow orthorhombic (β-PbO), which is obtained temperatures higher than Synthesis PbO may be prepared by heating lead metal in air at approximately . At this temperature it is also the end product of decomposition of other oxides of lead in air: :PbO2->[] Pb12O19 ->[] Pb12O17 ->[] Pb3O4 ->[] PbO Thermal decomposition of lead(II) nitrate or lead carbonate, lead(II) carbonate also results in the formation of PbO: :2 → 2 PbO + 4 + : → PbO + PbO is produced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
