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Lead Iodide
Lead(II) iodide (or lead iodide) is a chemical compound with the formula . At room temperature, it is a bright yellow odorless crystalline solid, that becomes orange and red when heated. It was formerly called plumbous iodide. The compound currently has a few specialized applications, such as the manufacture of solar cells, X-rays and gamma-ray detectors. Its preparation is an entertaining and popular demonstration in chemistry education, to teach topics such as precipitation reactions and stoichiometry. It is decomposed by light at temperatures above , and this effect has been used in a patented photographic process. Lead iodide was formerly employed as a yellow pigment in some paints, with the name iodide yellow. However, that use has been largely discontinued due to its toxicity and poor stability. Preparation is commonly synthesized via a precipitation reaction between potassium iodide and lead(II) nitrate ()2 in water solution: : While the potassium nitrate is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethanol
Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the pseudoelement symbol for ethyl group, ethyl. Ethanol is a Volatility (chemistry), volatile, flammable, colorless liquid with a characteristic wine-like odor and pungent taste. As a psychoactive depressant, it is the active ingredient in alcoholic beverages, and the second most consumed drug globally behind caffeine. Ethanol is naturally produced by the fermentation process of sugars by yeasts or via petrochemical processes such as ethylene hydration. Historically it was used as a general anesthetic, and has modern medical applications as an antiseptic, disinfectant, solvent for some medications, and antidote for methanol poisoning and ethylene glycol poisoning. It is used as a chemical solvent and in the Chemical synthesis, synthesis of orga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Rays
A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz () and wavelengths less than 10 picometers (), gamma ray photons have the highest photon energy of any form of electromagnetic radiation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation ''gamma rays'' based on their relatively strong penetration of matter; in 1900, he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power. Gamma rays from radioactive decay are in the energy range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead(II) Sulfide
Lead(II) sulfide (also spelled '' sulphide'') is an inorganic compound with the formula Pb S. Galena is the principal ore and the most important compound of lead. It is a semiconducting material with niche uses. Formation, basic properties, related materials Addition of hydrogen sulfide or sulfide salts to a solution containing a lead salt, such as PbCl2, gives a black precipitate of lead sulfide. : Pb2+ + H2S → PbS↓ + 2 H+ This reaction is used in qualitative inorganic analysis. The presence of hydrogen sulfide or sulfide ions may be tested using "lead acetate paper." Like the related materials PbSe and PbTe, PbS is a semiconductor. In fact, lead sulfide was one of the earliest materials to be used as a semiconductor. Lead sulfide crystallizes in the sodium chloride motif, unlike many other IV-VI semiconductors. Since PbS is the main ore of lead, much effort has focused on its conversion. A major process involves smelting of PbS followed by reduction of the re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead
Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleable, and also has a relatively low melting point. When freshly cut, lead is a shiny gray with a hint of blue. It tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable nuclide, stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements. Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its Amphoterism, amphoteric nature; lead and lead oxides react with acids and base (chemistry), bases, and it tends to form covalent bonds. Lead compounds, Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodine
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a violet gas at . The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek , meaning 'violet'. Iodine occurs in many oxidation states, including iodide (I−), iodate (), and the various periodate anions. As the heaviest essential mineral nutrient, iodine is required for the synthesis of thyroid hormones. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities. The dominant producers of iodine today are Chile and Japan. Due to its high atomic number and ease of attachment to organic compounds, it has also found favour as a non-toxic radiocontrast material. Because of the spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Iodide
Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I−) in a crystal lattice. It is used mainly as a nutritional supplement and in organic chemistry. It is produced industrially as the salt formed when acidic iodides react with sodium hydroxide. It is a chaotropic salt. Uses Food supplement Sodium iodide, as well as potassium iodide, is commonly used to treat and prevent iodine deficiency. Iodized table salt contains 10 ppm iodide. Organic synthesis Sodium iodide is used for conversion of alkyl chlorides into alkyl iodides. This method, the Finkelstein reaction, relies on the insolubility of sodium chloride in acetone to drive the reaction: ::R–Cl + NaI → R–I + NaCl Nuclear medicine Some radioactive iodide salts of sodium, including Na 125I and Na 131I, have rad ... [...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] |
Precipitate
In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemical reagent causing the solid to form is called the precipitant. The clear liquid remaining above the precipitated or the centrifuged solid phase is also called the supernate or supernatant. The notion of precipitation can also be extended to other domains of chemistry (organic chemistry and biochemistry) and even be applied to the solid phases (e.g. metallurgy and alloys) when solid impurities segregate from a solid phase. Supersaturation The precipitation of a compound may occur when its concentration exceeds its solubility. This can be due to temperature changes, solvent evaporation, or by mixing solvents. Precipitation occurs more rapidly from a strongly supersaturated solution. The formation of a precipitate can be caused by a ch ... [...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 Iodide
Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are used. It is also used for treating skin sporotrichosis and phycomycosis. It is a supplement used by people with low dietary intake of iodine. It is administered orally. Common side effects include vomiting, diarrhea, abdominal pain, rash, and swelling of the salivary glands. Other side effects include allergic reactions, headache, goitre, and depression. While use during pregnancy may harm the baby, its use is still recommended in radiation emergencies. Potassium iodide has the chemical formula K I. Commercially it is made by mixing potassium hydroxide with iodine. Potassium iodide has been used medically since at least 1820. It is on the World Health Organization's List of Essential Medicines. Potassium iodide is available as a g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photography
Photography is the visual arts, art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science, manufacturing (e.g., photolithography), and business, as well as its more direct uses for art, film and video production, recreational purposes, hobby, and mass communication. A person who operates a camera to capture or take Photograph, photographs is called a photographer, while the captured image, also known as a photograph, is the result produced by the camera. Typically, a lens is used to focus (optics), focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed Exposure (photography), exposure. With an electronic image sensor, this produces an Charge-coupled device, electrical charge at each pixel, which is Image processing, electro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photolysis
Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by absorption of light or photons. It is defined as the interaction of one or more photons with one target molecule that dissociates into two fragments. Here, “light” is broadly defined as radiation spanning the vacuum ultraviolet (VUV), ultraviolet (UV), visible, and infrared (IR) regions of the electromagnetic spectrum. To break covalent bonds, photon energies corresponding to visible, UV, or VUV light are typically required, whereas IR photons may be sufficiently energetic to detach ligands from coordination complexes or to fragment supramolecular complexes. Photolysis in photosynthesis Photolysis is part of the light-dependent reaction, light phase, photochemical phase, or Hill reaction of photosynthesis. The general reaction of photosynthetic photolysis can be given in terms of photons as: :\ce + 2 \text \longri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
