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Rhenium(VII) Sulfide
Rhenium(VII) sulfide is a chemical compound with the formula Re2S7. It has a complex structure, but can be synthesized from direct combination of the elements: 2Re + 7S -> atop\DeltaRe2S7Alternatively, rhenium(VII) oxide reacts with hydrogen sulfide in 4N HCl to the same end: Re2O7 + 7H2S -> atop\DeltaRe2S7 + 7H2O The compound catalyses the reduction of nitric oxide to nitrous oxide and hydrogenation of double bonds. In this regard, it unusually tolerates sulfur compounds, which poison noble metal catalysts. Rhenium(VII) sulfide decomposes when heated. In vacuum, it generates rhenium(IV) sulfide: :\mathrm In air, the sulfur oxidizes to sulfur dioxide: :\mathrm References * Kunyants, I. L. ''et al'', eds. (1995). ''Химическая энциклопедия'' 'Chemical encyclopedia''. Moscow: Soviet Encyclopedias. * Nikolsky, B. P. ''et al'', eds. (1971). ''Справочник химика'' 'Handbook of Chemistry''. 3rd (revised) ed. Leningrad: Khimi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and ''plus'' (+) and ''minus'' (−) signs. These are limited to a single typographic line of symbols, which may include Subscript and superscript, subscripts and superscripts. A chemical formula is not a chemical nomenclature, chemical name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulae can fully specify the structure of only the simplest of molecules and chemical substances, and are generally more limited in power than chemical names and structural formulae. The simplest types of chemical formulae are called ''empirical formulae'', which use letters and numbers ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhenium(VII) Oxide
Rhenium(VII) oxide is the inorganic compound with the formula Re2 O7. This yellowish solid is the anhydride of HOReO3. Perrhenic acid, Re2O7·2H2O, is closely related to Re2O7. Re2O7 is the raw material for all rhenium compounds, being the volatile fraction obtained upon roasting the host ore. Structure Solid Re2O7 consists of alternating octahedral and tetrahedral Re centres. Upon heating, the polymer cracks to give molecular (nonpolymeric) Re2O7. This molecular species closely resembles manganese heptoxide, consisting of a pair of ReO4 tetrahedra that share a vertex, i.e., O3Re–O–ReO3. Synthesis and reactions Rhenium(VII) oxide is formed when metallic rhenium or its oxides or sulfides are oxidized at in air. Re2O7 dissolves in water to give perrhenic acid. Heating Re2O7 gives rhenium dioxide, a reaction signalled by the appearance of the dark blue coloration:O. Glemser "Rhenium" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic ... [...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] |
Hydrochloric Acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbolised by the chemical formula HA, to dissociate into a proton, H+, and an anion, A-. The dissociation of a strong acid in solution is effectively complete, except in its most concentrated solutions .... It is a component of the gastric acid in the digestive systems of most animal species, including humans. Hydrochloric acid is an important laboratory reagent and industrial chemical. History In the early tenth century, the Persian physician and alchemist Abu Bakr al-Razi ( 865–925, Latin: Rhazes) conducted experiments with sal ammoniac (ammonium chloride) and vitriol (hydrated sulfates of various metals), which he distilled together, thus producing the gas hydrogen chloride. In doing so, al-Razi may have stumbled upon a primitive method ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitric Oxide
Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ... (•N=O or •NO). Nitric oxide is also a heteronuclear diatomic molecule, a class of molecules whose study spawned early modern molecular orbital theory, theories of chemical bonding. An important Reaction intermediate, intermediate in chemical industry, industrial chemistry, nitric oxide forms in combustion systems and can be generated by lightning in thunderstorms. In mammals, including humans, nitric oxide is a signaling molecule in many physiological and pathological pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrous Oxide
Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has a slightly sweet scent and taste. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen. Nitrous oxide has significant medical uses, especially in surgery and dentistry, for its anaesthetic and pain-reducing effects. Its colloquial name, "laughing gas", coined by Humphry Davy, is due to the euphoric effects upon inhaling it, a property that has led to its recreational use as a dissociative anaesthetic. It is on the World Health Organization's List of Essential Medicines. It is also used as an oxidiser in rocket propellants, and in motor racing to increase the power output of engines. Nitrous oxide's atmospheric concentration reached 333 parts per billion (ppb) in 2020, increasing at a rate of abo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noble Metal
A noble metal is ordinarily regarded as a metallic chemical element that is generally resistant to corrosion and is usually found in nature in its raw form. Gold, platinum, and the other platinum group metals (ruthenium, rhodium, palladium, osmium, iridium) are most often so classified. Silver, copper and mercury are sometimes included as noble metals, however less often as each of these usually occurs in nature combined with sulfur. In more specialized fields of study and applications the number of elements counted as noble metals can be smaller or larger. In physics, there are only three noble metals: copper, silver and gold. In dentistry, silver is not always counted as a noble metal since it is subject to corrosion when present in the mouth. In chemistry, the term noble metal is sometimes applied more broadly to any metallic or semimetallic element that does not react with a weak acid and give off hydrogen gas in the process. This broader set includes copper, mercury, tech ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a ''perfect'' vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is considerably lower than atmospheric pressure. The Latin term ''in vacuo'' is used to describe an object that is surrounded by a vacuum. The ''quality'' of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%. But hig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhenium(IV) Sulfide
Rhenium disulfide is an inorganic compound of rhenium and sulfur with the formula ReS2. It has a layered structure where atoms are strongly bonded within each layer. The layers are held together by weak Van der Waals bonds, and can be easily peeled off from the bulk material. Production ReS2 is found in nature as the mineral rheniite. It can be synthesized from the reaction between rhenium and sulfur at 1000 °C, or the decomposition of rhenium(VII) sulfide at 1100 °C: :Re + 2 S → ReS2 :Re2S7 → 2 ReS2 + 3 S Nanostructured ReS2 can usually be achieved through mechanical exfoliation, chemical vapor deposition (CVD), and chemical and liquid exfoliations. Larger crystals can be grown with the assistance of liquid carbonate flux at high pressure. It is widely used in electronic and optoelectronic device, energy storage, photocatalytic and electrocatalytic reactions. Properties It is a two-dimensional (2D) group VII transition metal dichalcogenide : 220px, Cad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of copper extraction and the burning of sulfur- bearing fossil fuels. Structure and bonding SO2 is a bent molecule with ''C''2v symmetry point group. A valence bond theory approach considering just ''s'' and ''p'' orbitals would describe the bonding in terms of resonance between two resonance structures. The sulfur–oxygen bond has a bond order of 1.5. There is support for this simple approach that does not invoke ''d'' orbital participation. In terms of electron-counting formalism, the sulfur atom has an oxidation state of +4 and a formal charge of +1. Occurrence Sulfur dioxide is found on Earth and exists in very small concentrations and in the atmosphere at about 1 ppm. On other planets, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ivan Knunyants
Ivan Lyudvigovich Knunyants ( hy, Իվան Կնունյանց, russian: Иван Людвигович Кнунянц; – 21 December 1990), was a Soviet chemist of Armenian origin, academician of the Academy of Sciences of the Soviet Union, a major general and engineer, who significantly contributed to the advancement of Soviet chemistry. He made more than 200 inventions, many of which used in the Soviet industry. Graduated from Moscow Bauman Highest Technical School (MVTU) 1928, student of Aleksei Chichibabin. Leader of laboratory for elementooranic chemistry. He was one of the pioneers of the synthesis of poly-caprolactam (capron, nylon-6, polyamide-6), founder of Soviet school of fluorocarbon's chemistry, one of major developers of Soviet chemical weapons program, also an author of a few drugs for chemotherapy of cancer. He proposed the method of getting the 5-hydroxypentan-2-one from ethyl ethanoate and oxirane, also used in the industrial synthesis of vitamin B. His s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boris Nikolsky
Boris Petrovich Nikolsky (russian: Бори́с Петро́вич Нико́льский; – 4 January 1990) was a Soviet chemist and radiochemist Radiochemistry is the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads to ..., academician of the Soviet Academy of Sciences, and professor of Saint Petersburg (then Leningrad) Leningrad State University, State University. Boris Nikolsky was a 1925 graduate of Saint Petersburg State University, Leningrad State University. In the 1930s he studied the ion exchange processes between aqueous solutions and solids. During that time Nikolsky developed the theory of ion exchange in glass electrodes. He derived equations that describe properties of glass electrodes as well as other types of ion-selective electrodes depending on chemical structure and multi-component comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
