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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 st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hygroscopic
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance's molecules, adsorbing substances can become physically changed, e.g., changing in volume, boiling point, viscosity or some other physical characteristic or property of the substance. For example, a finely dispersed hygroscopic powder, such as a salt, may become clumpy over time due to collection of moisture from the surrounding environment. ''Deliquescent'' materials are sufficiently hygroscopic that they absorb so much water that they become liquid and form an aqueous solution. Etymology and pronunciation The word ''hygroscopy'' () uses combining forms of '' hygro-'' and '' -scopy''. Unlike any other ''-scopy'' word, it no longer refers to a viewing or imaging mode. It did begin that way, with the word ''hygroscope'' referring in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonal Pyramidal Molecular Geometry
In chemistry, a trigonal pyramid is a molecular geometry with one atom at the apex and three atoms at the corners of a trigonal base, resembling a tetrahedron (not to be confused with the tetrahedral geometry). When all three atoms at the corners are identical, the molecule belongs to point group ''C3v''. Some molecules and ions with trigonal pyramidal geometry are the pnictogen hydrides (XH3), xenon trioxide (XeO3), the chlorate ion, , and the sulfite ion, . In organic chemistry, molecules which have a trigonal pyramidal geometry are sometimes described as sp3 hybridized. The AXE method for VSEPR theory states that the classification is AX3E1. Trigonal pyramidal geometry in ammonia The nitrogen in ammonia has 5 valence electrons and bonds with three hydrogen atoms to complete the octet. This would result in the geometry of a regular tetrahedron with each bond angle equal to cos−1(−) ≈ 109.5°. However, the three hydrogen atoms are repelled by the electron l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetaldehyde
Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale in industry. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants. It is also produced by the partial oxidation of ethanol by the liver enzyme alcohol dehydrogenase and is a contributing cause of hangover after alcohol consumption. Pathways of exposure include air, water, land, or groundwater, as well as drink and smoke. Consumption of disulfiram inhibits acetaldehyde dehydrogenase, the enzyme responsible for the metabolism of acetaldehyde, thereby causing it to build up in the body. The International Agency for Research on Cancer (IARC) has listed acetaldehyde as a Group 1 carcinogen. Acetaldehyde is "one of the mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glyoxal
Glyoxal is an organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ... with the chemical formula OCHCHO. It is the smallest dialdehyde (a compound with two aldehyde groups). It is a crystalline solid, white at low temperatures and yellow near the melting point (15 °C). The liquid is yellow, and the vapor is green.O'Neil, M.J. (2001): ''The Merck Index'', 13th Edition, page 803. Pure glyoxal is not commonly encountered because glyoxal is usually handled as a 40% aqueous solution (density near 1.24 g/mL). It forms a series of hydrates, including oligomers. For many purposes, these hydrated oligomers behave equivalently to glyoxal. Glyoxal is produced industrially as a precursor to many products. Production Glyoxal was first prepared and named by the German-British ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicarbonyl
In organic chemistry, a dicarbonyl is a molecule containing two carbonyl () groups. Although this term could refer to any organic compound containing two carbonyl groups, it is used more specifically to describe molecules in which both carbonyls are in close enough proximity that their reactivity is changed, such as 1,2-, 1,3-, and 1,4-dicarbonyls. Their properties often differ from those of monocarbonyls, and so they are usually considered functional groups of their own. These compounds can have symmetrical or unsymmetrical substituents on each carbonyl, and may also be functionally symmetrical (dialdehydes, di ketones, diesters, ''etc.'') or unsymmetrical (keto-esters, keto-acids, ''etc.''). 1,2-Dicarbonyls 1,2-Dialdehyde The only 1,2-dialdehyde is glyoxal, . Like many alkyldialdehydes, glyoxal is encountered almost exclusively as its hydrate and oligomers thereof. These derivatives often behave equivalently to the aldehydes since hydration is reversible. Glyoxal condenses r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one of the most important branches of organic chemistry. There are several main areas of research within the general area of organic synthesis: ''total synthesis'', ''semisynthesis'', and ''methodology''. Total synthesis A total synthesis is the complete chemical synthesis of complex organic molecules from simple, commercially available petrochemical or natural precursors. Total synthesis may be accomplished either via a linear or convergent approach. In a ''linear'' synthesis—often adequate for simple structures—several steps are performed one after another until the molecule is complete; the chemical compounds made in each step are called synthetic intermediates. Most often, each step in a synthesis refers to a separate rea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patination
Patina ( or ) is a thin layer that variously forms on the surface of copper, brass, bronze and similar metals and metal alloys (tarnish produced by oxidation or other chemical processes) or certain stones and wooden furniture (sheen produced by age, wear, and polishing), or any similar acquired change of a surface through age and exposure. Additionally, the term is used to describe the aging of high-quality leather. The patinas on leather goods are unique to the type of leather, frequency of use, and exposure. Patinas can provide a protective covering to materials that would otherwise be damaged by corrosion or weathering. They may also be aesthetically appealing. Usage On metal, patina is a coating of various chemical compounds such as oxides, carbonates, sulfides, or sulfates formed on the surface during exposure to atmospheric elements (oxygen, rain, acid rain, carbon dioxide, sulfur-bearing compounds). In common parlance, weathering rust on steel is often mistakenl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron(II,III) Oxide
Iron(II,III) oxide is the chemical compound with formula Fe3O4. It occurs in nature as the mineral magnetite. It is one of a number of iron oxides, the others being iron(II) oxide (FeO), which is rare, and iron(III) oxide (Fe2O3) which also occurs naturally as the mineral hematite. It contains both Fe2+ and Fe3+ ions and is sometimes formulated as FeO ∙ Fe2O3. This iron oxide is encountered in the laboratory as a black powder. It exhibits permanent magnetism and is ferrimagnetic, but is sometimes incorrectly described as ferromagnetic. Its most extensive use is as a black pigment. For this purpose, it is synthesized rather than being extracted from the naturally occurring mineral as the particle size and shape can be varied by the method of production. Preparation Heated iron metal interacts with steam to form iron oxide and hydrogen gas. 3Fe + 4H2O->Fe3O4 + 4H2 Under anaerobic conditions, ferrous hydroxide (Fe(OH)2) can be oxidized by water to form magnetite and m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper Selenide
Copper selenide is an inorganic binary compound consisting of copper and selenium. Its formula is sometimes described as CuSe or Cu2Se. The crystalline structure and electronic behavior is determined by its elemental composition. Stoichiometric copper selenide is a zero bandgap material with metal-like behavior. Copper-deficient Cu2-xSe (non-stoichiometric) is an intrinsic p-type semiconductor with direct and indirect bandgap energies in the range of 2.1–2.3 eV and 1.2–1.4 eV, respectively. It is frequently grown as nanoparticles or other nanostructures. Uses Copper selenide is produced in-situ to form a protective black coating on iron or steel parts in some cold-bluing processes. Bluing solutions that operate in this manner will typically be labeled as containing selenous acid or selenium dioxide. It has also been investigated for use in the treatment of colon cancer. Natural occurrences Copper selenides are the most common selenium minerals. CuSe is known in minera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphoric Acid
Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, which is a colourless, odourless, and non- volatile syrupy liquid. It is a major industrial chemical, being a component of many fertilizers. The compound is an acid. Removal of all three ions gives the phosphate ion . Removal of one or two protons gives dihydrogen phosphate ion , and the hydrogen phosphate ion , respectively. Phosphoric acid forms esters, called organophosphates. The name "orthophosphoric acid" can be used to distinguish this specific acid from other "phosphoric acids", such as pyrophosphoric acid. Nevertheless, the term "phosphoric acid" often means this specific compound; and that is the current IUPAC nomenclature. Production Phosphoric acid is produced industrially by one of two routes, wet processes and dry. We ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper(II) Sulfate
Copper(II) sulfate, also known as copper sulphate, is an inorganic compound with the chemical formula . It forms hydrates , where ''n'' can range from 1 to 7. The pentahydrate (''n'' = 5), a bright blue crystal, is the most commonly encountered hydrate of copper(II) sulfate. Older names for the pentahydrate include blue vitriol, bluestone, vitriol of copper,Antoine-François de Fourcroy, tr. by Robert Heron (1796) "Elements of Chemistry, and Natural History: To which is Prefixed the Philosophy of Chemistry". J. Murray and others, Edinburgh. Page 348. and Roman vitriol.Oxford University Press,Roman vitriol, Oxford Living Dictionaries. Accessed on 2016-11-13 It exothermically dissolves in water to give the aquo complex , which has octahedral molecular geometry. The structure of the solid pentahydrate reveals a polymeric structure wherein copper is again octahedral but bound to four water ligands. The centers are interconnected by sulfate anions to form chains. Anhydrous copper sulfa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitric Acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into 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 pigments in inks and dyes. Nitric acid is also commonly used as a strong oxidizing agen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
