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Sodium Metavanadate
Sodium metavanadate is the inorganic compound with the formula NaVO3. It is a yellow, water-soluble salt. Sodium metavanadate is a common precursor to other vanadates. At low pH it converts to sodium decavanadate. It is also precursor to exotic metalates such as ³-PV2W10O40sup>5-, ±-PVW11O40sup>4-, and ²-PV2W10O40sup>5-. Minerals Sodium metavanadate occurs as two minor minerals, metamunirite ( anhydrous) and a dihydrate, munirite. Both are very rare, metamunirite is now known only from vanadium- and uranium-bearing sandstone formations of central-western USA and munirite from Pakistan and South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the .... References Vanadates Sodium compounds {{inorganic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Orthovanadate
Sodium orthovanadate is the inorganic compound with the chemical formula . It forms a dihydrate . Sodium orthovanadate is a salt of the oxyanion. It is a colorless, water-soluble solid. Synthesis and structure Sodium orthovanadate is produced by dissolving vanadium(V) oxide in a solution of sodium hydroxide: : The salt features tetrahedral anion centers linked to octahedral cation sites. Condensation equilibria Like many oxometalates, orthovanadate is subject to a number of reactions, which have been analyzed by 51V NMR studies. At high pH, ions exist in equilibrium with . At lower pH's, condensation ensues to give various polyoxovanadates. Ultimately, decavanadate is formed. Biochemistry Vanadates exhibit a variety of biological activities, in part because they serve as structural mimics of phosphates. It acts as a competitive inhibitor of ATPases, alkaline and acid phosphatases, and protein-phosphotyrosine phosphatases, and its inhibitory effects can be reversed by diluti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonium Metavanadate
Ammonium metavanadate is the inorganic compound with the formula NH4VO3. It is a white salt, although samples are often yellow owing to impurities of V2O5. It is an important intermediate in the purification of vanadium.Günter Bauer, Volker Güther, Hans Hess, Andreas Otto, Oskar Roidl, Heinz Roller, Siegfried Sattelberger "Vanadium and Vanadium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. Synthesis and structure The compound is prepared by the addition of ammonium salts to solutions of vanadate ions, generated by dissolution of V2O5 in basic aqueous solutions, such as hot sodium carbonate. The compound precipitates as a colourless solid. This precipitation step can be slow. The compound adopts a polymeric structure consisting of chains of O3sup>−, formed as corner-sharing VO4 tetrahedra. These chains are interconnected via hydrogen bonds with ammonium ions. Uses Vanadium is often purified from aqueous extracts of slags and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inorganic Compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemistry''. Inorganic compounds comprise most of the Earth's crust, although the compositions of the deep mantle remain active areas of investigation. Some simple carbon compounds are often considered inorganic. Examples include the allotropes of carbon (graphite, diamond, buckminsterfullerene, etc.), carbon monoxide, carbon dioxide, carbides, and the following salts of inorganic anions: carbonates, cyanides, cyanates, and thiocyanates. Many of these are normal parts of mostly organic systems, including organisms; describing a chemical as inorganic does not necessarily mean that it does not occur within living things. History Friedrich Wöhler's conversion of ammonium cyanate into urea in 1828 is often cited as the starting point of modern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acta Crystallogr
''Acta Crystallographica'' is a series of peer-reviewed scientific journals, with articles centred on crystallography, published by the International Union of Crystallography (IUCr). Originally established in 1948 as a single journal called ''Acta Crystallographica'', there are now six independent ''Acta Crystallographica'' titles: *'' Acta Crystallographica Section A: Foundations and Advances'' *'' Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials'' *'' Acta Crystallographica Section C: Structural Chemistry'' *'' Acta Crystallographica Section D: Structural Biology'' *'' Acta Crystallographica Section E: Crystallographic Communications'' *'' Acta Crystallographica Section F: Structural Biology Communications'' ''Acta Crystallographica'' has been noted for the high quality of the papers that it produces, as well as the large impact that its papers have had on the field of crystallography. The current six journals form part of the journal port ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decavanadate
Sodium decavanadate describes any member of the family of inorganic compounds with the formula Na6 10O28H2O)n. These are sodium salts of the orange-colored decavanadate anion 10O28sup>6−. Numerous other decavanadate salts have been isolated and studied since 1956 when it was first characterized. Preparation The preparation of decavanadate is achieved by acidifying an aqueous solution of ortho-vanadate: :10 Na3 O4 + 24 HOAc → Na6 10O28 + 12 H2O + 24 NaOAc The formation of decavanadate is optimized by maintaining a pH range of 4–7. Typical side products include metavanadate, O3sup>−, and hexavanadate, 6O16sup>2−, ions. Structure The decavanadate ion consists of 10 fused VO6 octahedra and has D2h symmetry. The structure of Na6 10O28·18H2O has been confirmed with X-ray crystallography. The decavanadate anions contains three sets of equivalent V atoms (see fig. 1). These include two central VO6 octahedra (Vc) and four each peripheral tetragonal-pyramidal VO5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anhydrous
A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achieve perfect dryness; anhydrous compounds gradually absorb water from the atmosphere so they must be stored carefully. Solids Many salts and solids can be dried using heat, or under vacuum. Desiccators can also be used to store reagents in dry conditions. Common desiccants include phosphorus pentoxide and silica gel. Chemists may also require dry glassware for sensitive reactions. This can be achieved by drying glassware in an oven, by flame, or under vacuum. Dry solids can be produced by freeze-drying, which is also known as lyophilization. Liquids or solvents In many cases, the presence of water can prevent a reaction from happening, or cause undesirable products to form. To prevent this, anhydrous solvents must be used when performi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dihydrate
In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understood. Chemical nature Inorganic chemistry Hydrates are inorganic salts "containing water molecules combined in a definite ratio as an integral part of the crystal" that are either bound to a metal center or that have crystallized with the metal complex. Such hydrates are also said to contain ''water of crystallization'' or ''water of hydration''. If the water is heavy water in which the constituent hydrogen is the isotope deuterium, then the term ''deuterate'' may be used in place of ''hydrate''. A colorful example is cobalt(II) chloride, which turns from blue to red upon hydration, and can therefore be used as a water indicator. The notation "''hydrated compound''â‹…''n''", where ''n'' is the number of water molecules per formula un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer ( passivation) somewhat stabilizes the free metal against further oxidation. Spanish scientist Andrés Manuel del RÃo discovered compounds of vanadium in 1801 in Mexico by analyzing a new lead-bearing mineral he called "brown lead". Though he initially presumed its qualities were due to the presence of a new element, he was later erroneously convinced by French chemist Hippolyte Victor Collet-Descotils that the element was just chromium. Then in 1830, Nils Gabriel Sefström generated chlorides of vanadium, thus proving there was a new element, and named it "vanadium" after the Scandinavian goddess of beauty and fertility, VanadÃs (Freyja). The name was based on the wide range of colors found in vanadium compounds. Del Rio's lead mineral was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all isotopes of uranium are unstable; the half-lives of its naturally occurring isotopes range between 159,200 years and 4.5 billion years. The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99% of uranium on Earth) and uranium-235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238 (99. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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