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Sodium Polysulfide
Sodium polysulfide is a general term for salts with the formula sodium, Na2Sulfur, Sx, where ''x'' = 2 to 5. The species Sx2−, called polysulfide anions, include disulfide (S22−), trisulfide (S32−), tetrasulfide (S42−), and pentasulfide (S52−). In principle, but not in practice, the chain lengths could be longer. The salts are dark red solids that dissolve in water to give highly alkaline and corrosion, corrosive solutions. In air, these salts oxidize, and they evolve hydrogen sulfide by hydrolysis. Structure The polysulfide anions form chains with S---S bond distances around 2 Å in length. The chains adopt skewed conformations. In the solid state, these salts are dense solids with strong association of the sodium cations with the anionic termini of the chains. Production and occurrence Sodium polysulfide can be produced by dissolving sulfur in a solution of sodium sulfide. Alternatively they are produced by the redox reaction of aqueous sodium hydroxide with sulfu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium
Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the periodic table. Its only stable isotope is 23Na. The free metal does not occur in nature and must be prepared from compounds. Sodium is the Abundance of elements in Earth's crust, sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars, sodalite, and halite (NaCl). Many salts of sodium are highly water-soluble: sodium ions have been Leaching (chemistry), leached by the action of water from the Earth, Earth's minerals over eons, and thus sodium and chlorine are the most common dissolved elements by weight in the oceans. Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful sodium compounds, sodium hydroxide (lye) is used in Soap, soap manufac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Sulfide
Sodium sulfide is a chemical compound with the formula Na2 S, or more commonly its hydrate Na2S·9 H2O. Both the anhydrous and the hydrated salts are colorless solids, although technical grades of sodium sulfide are generally yellow to brick red owing to the presence of polysulfides. It is commonly supplied as a crystalline mass, in flake form, or as a fused solid. They are water-soluble, giving strongly alkaline solutions. When exposed to moisture, Na2S immediately hydrates to give sodium hydrosulfide. Sodium sulfide has an unpleasant rotten egg smell due to the hydrolysis to hydrogen sulfide in moist air. Some commercial samples are described as Na2S·''x''H2O, where a weight percentage of Na2S is specified. Commonly available grades have around 60% Na2S by weight, which means that ''x'' is around 3. These grades of sodium sulfide are often marketed as 'sodium sulfide flakes'. These samples consist of NaSH, NaOH, and water. Structure The structures of sodium sulfides have bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiokol (polymer)
''Thiokol'' is a trade mark for various organic polysulfide polymers. Thiokol polymers are used as an elastomer in seals and sealants. The distinction between the polymers first commercialized by the Thiokol Chemical Company and subsequent polysulfide materials is often unclear. The name Thiokol is a portmanteau of the Greek words for sulfur () and glue () Preparation and structure A variety of thiokols are recognized. Typically they are prepared by the combination of 2-chloroethanol, formaldehyde, and sodium polysulfide (Na2S''x''). The chloroethanol is produced in situ from ethylene oxide and hydrogen chloride. The rank ''x'' of the polysulfide is an important variable. Crosslinking agents are used, such as 1,2,3-trichloropropane. An idealized polymer is represented by this formula HS(CH2CH2OCH2OCH2CH2SS)''n''CH2CH2OCH2OCH2CH2SH. Thiol-terminated resins can be cured oxidatively. History In 1838, Swiss chemists reported the preparation of hydrophobic rubbery materials by the a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tanning (leather)
Tanning, or hide tanning, is the process of treating Skinning, skins and Hide (skin), hides of animals to produce leather. A tannery is the place where the skins are processed. Historically, vegetable based tanning used tannin, an acidic chemical compound derived from the bark of certain trees, in the production of leather. An alternative method, developed in the 1800s, is chrome tanning, where chromium salts are used instead of natural tannins. History Tanning hide into leather involves a process which permanently alters the protein structure of skin, making it more durable and less susceptible to decomposition and coloring. The place where hides are processed is known as a ''tannery''. The English word for tanning is from the medieval Latin verb , from the noun (oak bark). This term may be derived from a Celtic word related to the Proto-Indo-European *' meaning 'fir tree'. (The same root is the source for Old High German meaning 'fir', related to modern German ''Tannenb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polysulfide Bromide Battery
Polysulfides are a class of chemical compounds derived from anionic chains of sulfur atoms. There are two main classes of polysulfides: inorganic and organic. The inorganic polysulfides have the general formula . These anions are the conjugate bases of polysulfanes . Organic polysulfides generally have the formulae , where R is an alkyl or aryl group. Polysulfide salts and complexes The alkali metal polysulfides arise by treatment of a solution of the sulfide with elemental sulfur, e.g. sodium sulfide to sodium polysulfide: In some cases, these anions have been obtained as organic salts, which are soluble in organic solvents. The energy released in the reaction of sodium and elemental sulfur is the basis of battery technology. The sodium–sulfur battery and the lithium–sulfur battery require high temperatures to maintain liquid polysulfide and -conductive membranes that are unreactive toward sodium, sulfur, and sodium sulfide. Polysulfides are ligands in coordination chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable, unalloyed metallic form. This means that copper is a native metal. This led to very early human use in several regions, from . Thousands of years later, it was the first metal to be smelted from sulfide ores, ; the first metal to be cast into a shape in a mold, ; and the first metal to be purposely alloyed with another metal, tin, to create bronze, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fungicide
Fungicides are pesticides used to kill parasitic fungi or their spores. Fungi can cause serious damage in agriculture, resulting in losses of yield and quality. Fungicides are used both in agriculture and to fight fungal infections in animals, including humans. Fungicides are also used to control oomycetes, which are not taxonomically/genetically fungi, although sharing similar methods of infecting plants. Fungicides can either be contact, translaminar or systemic. Contact fungicides are not taken up into the plant tissue and protect only the plant where the spray is deposited. Translaminar fungicides redistribute the fungicide from the upper, sprayed leaf surface to the lower, unsprayed surface. Systemic fungicides are taken up and redistributed through the xylem vessels. Few fungicides move to all parts of a plant. Some are locally systemic, and some move upward. Most fungicides that can be bought retail are sold in liquid form, the active ingredient being present at 0.08% i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polysulfide Polymer
''Thiokol'' is a trade mark for various organic polysulfide polymers. Thiokol polymers are used as an elastomer in seals and sealants. The distinction between the polymers first commercialized by the Thiokol Chemical Company and subsequent polysulfide materials is often unclear. The name Thiokol is a portmanteau of the Greek words for sulfur () and glue () Preparation and structure A variety of thiokols are recognized. Typically they are prepared by the combination of 2-chloroethanol, formaldehyde, and sodium polysulfide (Na2S''x''). The chloroethanol is produced in situ from ethylene oxide and hydrogen chloride. The rank ''x'' of the polysulfide is an important variable. Crosslinking agents are used, such as 1,2,3-trichloropropane. An idealized polymer is represented by this formula HS(CH2CH2OCH2OCH2CH2SS)''n''CH2CH2OCH2OCH2CH2SH. Thiol-terminated resins can be cured oxidatively. History In 1838, Swiss chemists reported the preparation of hydrophobic rubbery materials by the al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), base and alkali that decomposes lipids and proteins at ambient temperatures and at high concentrations may cause severe chemical burns. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. It forms a series of hydrates . The monohydrate crystallizes from water solutions between 12.3 and 61.8 °C. The commercially available "sodium hydroxide" is often this monohydrate, and published data may refer to it instead of the anhydrous compound. As one of the simplest hydroxides, sodium hydroxide is frequently used alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students. Sodium hydroxide is used in many industries: in the making of wood pulp and paper, tex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S52-
S5 or S-5 may refer to: Science * Pentasulfur (S5), an allotrope of sulfur * S5, the symmetric group on five elements * S5: Keep contents under ... (appropriate liquid to be specified by the manufacturer), a safety phrase in chemistry * Sacral spinal nerve 5, a spinal nerve of the sacral segment * S5, the fifth sacral vertebra of the vertebral column, in human anatomy Technology Electronics * Canon PowerShot S5 IS, a 2007 8.0 megapixel bridge digital camera * Coolpix S5, a 6 Megapixels Nikon Coolpix series digital camera * FinePix S5 Pro, a 2006 digital single lens reflex camera by Fujifilm * Samsung Galaxy S5, an Android smartphone by Samsung * Samsung Galaxy Tab S5e, an Android tablet * Simatic S5 PLC, a programmable logic controller family by Siemens Software * S5 (file format), for defining slideshows * ACPI S5 power state, of the Advanced Configuration and Power Interface in computing Transportation Airlines and airports * Star Air (India) (IATA airline code: S5) * Shutt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur
Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with the chemical formula S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature. Sulfur is the tenth most abundant element by mass in the universe and the fifth most common on Earth. Though sometimes found in pure, native form, sulfur on Earth usually occurs as sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, China, and ancient Egypt. Historically and in literature sulfur is also called brimstone, which means "burning stone". Almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum.. Downloahere Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
