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Lead Difluoride
Lead(II) fluoride is the inorganic compound with the formula Pb F2. It is a white solid. The compound is polymorphic, at ambient temperatures it exists in orthorhombic (PbCl2 type) form, while at high temperatures it is cubic ( Fluorite type). Preparation Lead(II) fluoride can be prepared by treating lead(II) hydroxide or lead(II) carbonate with hydrofluoric acid: : Pb(OH)2 + 2 HF → PbF2 + 2 H2O Alternatively, it is precipitated by adding hydrofluoric acid to a lead(II) salt solution, or by adding a fluoride salt to a lead salt, such as potassium fluoride to a lead(II) nitrate solution, : 2 KF + Pb(NO3)2 → PbF2 + 2 KNO3 or sodium fluoride to a lead(II) acetate solution. : 2 NaF + Pb(CH3COO)2 → PbF2 + 2 NaCH3COO It appears as the very rare mineral fluorocronite. Uses Lead(II) fluoride is used in low melting glasses, in glass coatings to reflect infrared rays, in phosphors for television-tube screens, and as a catalyst for the manufacture of picoline. The Muon g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitric Acid
Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most commercially available nitric acid has a concentration of 68% in water. When the solution contains more than 86% , it is referred to as ''fuming nitric acid''. Depending on the amount of nitrogen dioxide present, fuming nitric acid is further characterized as red fuming nitric acid at concentrations above 86%, or white fuming nitric acid at concentrations above 95%. Nitric acid is the primary reagent used for nitration – the addition of a nitro group, typically to an organic molecule. While some resulting nitro compounds are shock- and thermally-sensitive explosives, a few are stable enough to be used in munitions and demolition, while others are still more stable and used as synthetic dyes and medicines (e.g. metronidazole). Nitric acid is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthorhombic Crystal System
In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a rectangular base (''a'' by ''b'') and height (''c''), such that ''a'', ''b'', and ''c'' are distinct. All three bases intersect at 90° angles, so the three lattice vectors remain mutually orthogonal In mathematics, orthogonality (mathematics), orthogonality is the generalization of the geometric notion of ''perpendicularity''. Although many authors use the two terms ''perpendicular'' and ''orthogonal'' interchangeably, the term ''perpendic .... Bravais lattices There are four orthorhombic Bravais lattices: primitive orthorhombic, base-centered orthorhombic, body-centered orthorhombic, and face-centered orthorhombic. For the base-centered orthorhombic lattice, the primitive cell has the shape of a right rhombic prism;See , ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infrared
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those of red light (the longest waves in the visible spectrum), so IR is invisible to the human eye. IR is generally (according to ISO, CIE) understood to include wavelengths from around to . IR is commonly divided between longer-wavelength thermal IR, emitted from terrestrial sources, and shorter-wavelength IR or near-IR, part of the solar spectrum. Longer IR wavelengths (30–100 μm) are sometimes included as part of the terahertz radiation band. Almost all black-body radiation from objects near room temperature is in the IR band. As a form of EMR, IR carries energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon. It was long known that fires e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glass
Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window panes, tableware, and optics. Some common objects made of glass are named after the material, e.g., a Tumbler (glass), "glass" for drinking, "glasses" for vision correction, and a "magnifying glass". Glass is most often formed by rapid cooling (quenching) of the Melting, molten form. Some glasses such as volcanic glass are naturally occurring, and obsidian has been used to make arrowheads and knives since the Stone Age. Archaeological evidence suggests glassmaking dates back to at least 3600 BC in Mesopotamia, Ancient Egypt, Egypt, or Syria. The earliest known glass objects were beads, perhaps created accidentally during metalworking or the production of faience, which is a form of pottery using lead glazes. Due to its ease of formability int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PbF2 Crystal SIPM
The Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Union. The initiative was to limit the amount of hazardous chemicals in electronics. The RoHS 1 directive took effect on 1 July 2006, and is required to be enforced and became a law in each member state. This directive restricts (with exceptions) the use of ten hazardous materials in the manufacture of various types of electronic and electrical equipment. In addition to the exceptions, there are exclusions for products such as solar panels. It is closely linked with the Waste Electrical and Electronic Equipment Directive (WEEE) 2002/96/EC (now superseded) which sets collection, recycling and recovery targets for electrical goods and is part of a legislative initiative to solve the problem of huge amounts of toxic electronic waste. In sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead(II) Acetate
Lead(II) acetate is a white crystalline chemical compound with a slightly sweet taste. Its chemical formula is usually expressed as or , where Ac represents the acetyl group. Like many other lead compounds, it causes lead poisoning. Lead acetate is soluble in water and glycerin. With water it forms the trihydrate, , a colourless or white efflorescent monoclinic crystalline substance. The substance is used as a reagent to make other lead compounds and as a fixative for some dyes. In low concentrations, it formerly served as the principal active ingredient in progressive types of hair colouring dyes. Lead(II) acetate is also used as a mordant in textile printing and dyeing, and as a drier in paints and varnishes. It was historically used as a sweetener and preservative in wines and in other foods and for cosmetics. Production Lead(II) acetate can be made by boiling elemental lead in acetic acid and hydrogen peroxide. This method will also work with lead(II) carbonat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Fluoride
Sodium fluoride (NaF) is an inorganic compound with the formula . It is a colorless or white solid that is readily soluble in water. It is used in trace amounts in the fluoridation of drinking water to prevent tooth decay, and in toothpastes and topical pharmaceuticals for the same purpose. In 2022, it was the 221st most commonly prescribed medication in the United States, with more than 1million prescriptions. It is also used in metallurgy and in medical imaging. Uses Dental caries Fluoride salts are often added to municipal drinking water (as well as to certain food products in some countries) for the purpose of maintaining dental health. The fluoride enhances the strength of teeth by the formation of fluorapatite, a naturally occurring component of tooth enamel. Although sodium fluoride is used to fluoridate water and is the standard by which other water-fluoridation compounds are gauged, hexafluorosilicic acid (H2SiF6) and its salt sodium hexafluorosilicate (Na2Si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead(II) Nitrate
Lead(II) nitrate is an inorganic compound with the chemical formula Pb( NO3)2. It commonly occurs as a colourless crystal or white powder and, unlike most other lead(II) salts, is soluble in water. Known since the Middle Ages by the name plumbum dulce, the production of lead(II) nitrate from either metallic lead or lead oxide in nitric acid was small-scale, for direct use in making other lead compounds. In the nineteenth century lead(II) nitrate began to be produced commercially in Europe and the United States. Historically, the main use was as a raw material in the production of pigments for lead paints, but such paints have been superseded by less toxic paints based on titanium dioxide. Other industrial uses included heat stabilization in nylon and polyesters, and in coatings of photothermographic paper. Since around the year 2000, lead(II) nitrate has begun to be used in gold cyanidation. Lead(II) nitrate is toxic and must be handled with care to prevent inhalation, ingesti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Fluoride
Potassium fluoride is the chemical compound with the formula KF. After hydrogen fluoride, KF is the primary source of the fluoride ion for applications in manufacturing and in chemistry. It is an alkali halide salt and occurs naturally as the rare mineral carobbiite. Solutions of KF will etch glass due to the formation of soluble fluorosilicates, although HF is more effective. Preparation Potassium fluoride is prepared by reacting potassium carbonate with hydrofluoric acid. Evaporation of the solution forms crystals of potassium bifluoride. The bifluoride on heating yields potassium fluoride: : : Platinum or heat resistant plastic containers are often used for these operations. Potassium chloride converts to KF upon treatment with hydrogen fluoride. In this way, potassium fluoride is recyclable. Crystalline properties KF crystallizes in the cubic NaCl crystal structure. The lattice parameter at room temperature is 0.266 nm. Applications in organic chemistry In organic c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrofluoric Acid
Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. A common concentration is 49% (48–52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling point near room temperature. It is used to make most organofluorine compounds; examples include the commonly used pharmaceutical antidepressant medication fluoxetine (Prozac) and the material PTFE (Teflon). Elemental fluorine is produced from it. It is commonly used to etch glass and silicon wafers. Uses Production of organofluorine compounds The principal use of hydrofluoric acid is in organofluorine chemistry. Many organofluorine compounds are prepared using HF as the fluorine source, including Teflon, fluoropolymers, fluorocarbons, and refrigerants such as freon. Many pharmaceuticals contain fluorine. Production of inorganic fluorides Most high-volume inorganic fluoride compounds are prepared from hydrofluoric acid. Foremost ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead(II) Carbonate
Lead(II) carbonate is the chemical compound with the chemical formula . It is a white, toxic solid. It occurs naturally as the mineral cerussite. Structure Like all metal carbonates, lead(II) carbonate adopts a dense, highly crosslinked structure consisting of intact and metal cation sites. As verified by X-ray crystallography, the Pb(II) centers are seven-coordinate, being surrounded by multiple carbonate ligands. The carbonate centers are bonded bidentate to a single Pb and bridge to five other Pb sites. Production and use Lead carbonate is manufactured by passing carbon dioxide into a cold dilute solution of lead(II) acetate, or by shaking a suspension of a lead salt more soluble than the carbonate with ammonium carbonate at a low temperature to avoid formation of basic lead carbonate. : Lead carbonate is used as a catalyst to polymerize formaldehyde to poly(oxymethylene). It improves the bonding of chloroprene to wire. Regulations The supply and use of this compound is r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
