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Tellurites
Tellurite is a oxyanion of tellurium with the formula . It is the ion of tellurous acid, and is chemically related to tellurium dioxide (), whose mineral appearance also bears the name tellurite. Tellurites are typically colorless or white salts, which in some ways are comparable to sulfite. Structure and reactions Tellurite dianion is pyramidal, like selenite and sulfite. The anion has C3v symmetry. Tellurites can be reduced to elemental tellurium by electrolysis or a strong reducing agent. When fused with nitrate salts, tellurite salts oxidize to tellurates (). Upon acidification of aqueous solutions of tellurite salts, solid hydrated tellurium dioxide (TeO2) precipitates. This reaction allows the separation of tellurium from selenium since selenous acid remains soluble at low pH. The intermediate in the protonation occurs at oxygen to give eO2(OH)sup>−. Compounds * Sodium tellurite * Potassium tellurite (K2TeO3) is used together with agar as part of a selecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tellurous Acid
Tellurous acid is an inorganic compound with the chemical formula, formula H2TeO3. It is the oxoacid of tellurium(IV). This compound is not well characterized. An alternative way of writing its formula is (HO)2TeO. In principle, tellurous acid would form by treatment of tellurium dioxide with water, that is by hydrolysis. The related conjugate base is well known in the form of several salts such as potassium hydrogen tellurite, KHTeO3. Properties In contrast to the analogous compound selenous acid, tellurous acid is only metastable. Most tellurite salts contain the ion. Oxidation of its aqueous solution with hydrogen peroxide gives the tellurate ion. It is usually prepared as an aqueous solution where it acts as a weak acid. :H2TeO3 + H2O H3O+ + ''K''a1 = : + H2O H3O+ + ''K''a2 = References Tellurites Chalcogen oxoacids {{inorganic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Na2TeO3
Sodium tellurite is an inorganic tellurium compound with formula Na2TeO3. It is a water-soluble white solid and a weak reducing agent. Sodium tellurite is an intermediate in the extraction of the element, tellurium; it is a product obtained from anode slimes and is a precursor to tellurium. Preparation The main source of tellurium is from copper anode slimes, which contain precious metals as well as various tellurides. These slimes are roasted with sodium carbonate and oxygen to produce sodium tellurite. :Ag2Te + Na2CO3 + O2 → 2Ag + Na2TeO3 + CO2 (400–500 °C) This is a reaction with silver telluride. The telluride is oxidized to tellurite and the silver(I) is reduced to silver. Purification The electrolysis of a tellurite solution yields purified tellurium. :Anode: 4OH− → 2H2O + O2 + 4e− :Cathode: TeO32− + 3H2O + 4e− → Te + 6OH− Structure and properties Tellurium has properties similar to sulfur and selenium. In the anhydrous form Na2TeO3 the tellurium atom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Tellurite
Potassium tellurite, K2TeO3, is an inorganic potassium-tellurium Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ... compound. It has been used as a selective growth medium in microbiology. References Tellurites Potassium compounds {{inorganic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Tellurite
Sodium tellurite is an inorganic tellurium compound with formula Na2TeO3. It is a water-soluble white solid and a weak reducing agent. Sodium tellurite is an intermediate in the extraction of the element, tellurium; it is a product obtained from anode slimes and is a precursor to tellurium. Preparation The main source of tellurium is from copper anode slimes, which contain precious metals as well as various tellurides. These slimes are roasted with sodium carbonate and oxygen to produce sodium tellurite. :Ag2Te + Na2CO3 + O2 → 2Ag + Na2TeO3 + CO2 (400–500 °C) This is a reaction with silver telluride. The telluride is oxidized to tellurite and the silver(I) is reduced to silver. Purification The electrolysis of a tellurite solution yields purified tellurium. :Anode: 4OH− → 2H2O + O2 + 4e− :Cathode: TeO32− + 3H2O + 4e− → Te + 6OH− Structure and properties Tellurium has properties similar to sulfur and selenium. In the anhydrous form Na2TeO3 the tellurium atom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tellurium
Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally found in its native form as elemental crystals. Tellurium is far more common in the Universe as a whole than on Earth. Its extreme rarity in the Earth's crust, comparable to that of platinum, is due partly to its formation of a volatile hydride that caused tellurium to be lost to space as a gas during the hot nebular formation of Earth. Tellurium-bearing compounds were first discovered in 1782 in a gold mine in Kleinschlatten, Transylvania (now Zlatna, Romania) by Austrian mineralogist Franz-Joseph Müller von Reichenstein, although it was Martin Heinrich Klaproth who named the new element in 1798 after the Latin 'earth'. Gold telluride minerals are the most notable natural gold compounds. However, they are not a commercially signif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tellurates
In chemistry, tellurate is a compound containing an oxyanion of tellurium where tellurium has an oxidation number of +6. In the naming of inorganic compounds it is a suffix that indicates a polyatomic ion, polyatomic anion with a central tellurium atom.Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005 – Full text (PDF) Tellurium oxyanions Historically the name tellurate was only applied to oxyanions of tellurium with oxidation number +6, formally derived from telluric acid , and the name Tellurite (ion), tellurite referred to oxyanions of tellurium with oxidation number +4, formally derived from tellurous acid and these names are in common use. However tellurate and Tellurite (ion), tellurite are often referred to as tellurate(VI) ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chalcogen Oxyanions
The chalcogens (ore forming) ( ) are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family. Group 16 consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and the radioactive elements polonium (Po) and livermorium (Lv). Often, oxygen is treated separately from the other chalcogens, sometimes even excluded from the scope of the term "chalcogen" altogether, due to its very different chemical behavior from sulfur, selenium, tellurium, and polonium. The word "chalcogen" is derived from a combination of the Greek word () principally meaning copper (the term was also used for bronze, brass, any metal in the poetic sense, ore and coin), and the Latinized Greek word , meaning ''born'' or ''produced''. Sulfur has been known since antiquity, and oxygen was recognized as an element in the 18th century. Selenium, tellurium and polonium were discovered in the 19th century, and livermorium in 2000. All of the chalcog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corynebacteria
''Corynebacterium'' () is a genus of Gram-positive bacteria and most are aerobic. They are bacilli (rod-shaped), and in some phases of life they are, more specifically, club-shaped, which inspired the genus name (''coryneform'' means "club-shaped"). They are widely distributed in nature in the microbiota of animals (including the human microbiota) and are mostly innocuous, most commonly existing in commensal relationships with their hosts. Some, such as '' C. glutamicum'', are commercially and industrially useful. Others can cause human disease, including, most notably, diphtheria, which is caused by '' C. diphtheriae''. Like various species of microbiota (including their relatives in the genera '' Arcanobacterium'' and '' Trueperella''), they are usually not pathogenic, but can occasionally capitalize opportunistically on atypical access to tissues (via wounds) or weakened host defenses. Taxonomy The genus ''Corynebacterium'' was created by Lehmann and Neumann in 1896 as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenous Acid
Selenous acid (or selenious acid) is the chemical compound with the formula . Structurally, it is more accurately described by . It is the principal oxoacid of selenium; the other being selenic acid. Formation and properties Selenous acid is analogous to sulfurous acid, but it is more readily isolated. Selenous acid is easily formed upon the addition of selenium dioxide to water. As a crystalline solid, the compound can be seen as pyramidal molecules that are interconnected with hydrogen bonds. In solution it is a diprotic acid: : (p''K''a = 2.62) : (p''K''a = 8.32) It is moderately oxidizing in nature, but kinetically slow. In 1 M : : (''E''o = +0.74 V) In 1 M : : (''E''o = −0.37 V) Selenous acid is hygroscopic. Uses The major use is in protecting and changing the color of steel, especially steel parts on firearms. The so-called cold-bluing process uses selenous acid, copper(II) nitrate, and nitric acid to change the color of the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrolysis
In chemistry and manufacturing, electrolysis is a technique that uses Direct current, direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of chemical element, elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity." Etymology The word "electrolysis" was introduced by Michael Faraday in 1834, using the Greek language, Greek words "amber", which since the 17th century was associated with electrical phenomena, and ' meaning "dissolution". Nevertheless, electrolysis, as a tool to study chemical reactions and obtain pure chemical element, elements, precedes the coinage of the term and formal description by Faraday. History In the early nineteenth century, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
