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Hydrogen Iodide
Hydrogen iodide (HI) is a diatomic molecule and hydrogen halide. Aqueous solutions of HI are known as hydroiodic acid or hydriodic acid, a strong acid. Hydrogen iodide and hydroiodic acid are, however, different in that the former is a gas under standard conditions, whereas the other is an aqueous solution of the gas. They are interconvertible. HI is used in organic and inorganic synthesis as one of the primary sources of iodine and as a reducing agent. Properties of hydrogen iodide HI is a colorless gas that reacts with oxygen to give water and iodine. With moist air, HI gives a mist (or fumes) of hydroiodic acid. It is exceptionally soluble in water, giving hydroiodic acid. One liter of water will dissolve 425 liters of HI gas, the most concentrated solution having only four water molecules per molecule of HI. Hydroiodic acid Hydroiodic acid is an aqueous solution of hydrogen iodide. Commercial "concentrated" hydroiodic acid usually contains 48–57% HI by mass. The solut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodonium
A halonium ion is any onium ion containing a halogen atom carrying a positive charge. This cation has the general structure where X is any halogen and no restrictions on R, this structure can be cyclic or an open chain molecular structure. Halonium ions formed from fluorine, chlorine, bromine, and iodine are called fluoronium, chloronium, bromonium, and iodonium, respectively. The 3-membered cyclic variety commonly proposed as intermediates in electrophilic halogenation may be called haliranium ions, using the Hantzsch-Widman nomenclature system. Structure The simplest halonium ions are of the structure (X = F, Cl, Br, I). Many halonium ions have a three-atom cyclic structure, similar to that of an epoxide, resulting from the formal addition of a halogenium ion to a C=C double bond, as when a halogen is added to an alkene. The formation of 5-membered halonium ions (e.g., chlorolanium, bromolanium ions) via neighboring group participation is also well studied. Diaryliodonium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azeotrope
An azeotrope () or a constant heating point mixture is a mixture of two or more liquids whose proportions cannot be changed by simple distillation.Moore, Walter J. ''Physical Chemistry'', 3rd e Prentice-Hall 1962, pp. 140–142 This happens because when an azeotrope is boiled, the vapour has the same proportions of constituents as the unboiled mixture. Knowing an azeotrope's behavior is important for distillation. Each azeotrope has a characteristic boiling point. The boiling point of an azeotrope is either less than the boiling point temperatures of any of its constituents (a positive azeotrope), or greater than the boiling point of any of its constituents (a negative azeotrope). For both positive and negative azeotropes, it is not possible to separate the components by fractional distillation and azeotropic distillation is usually used instead. For technical applications, the pressure-temperature-composition behavior of a mixture is the most important, but other important ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Sulfide
Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist Carl Wilhelm Scheele is credited with having discovered the chemical composition of purified hydrogen sulfide in 1777. Hydrogen sulfide is toxic to humans and most other animals by inhibiting cellular respiration in a manner similar to hydrogen cyanide. When it is inhaled or its salts are ingested in high amounts, damage to organs occurs rapidly with symptoms ranging from breathing difficulties to convulsions and death. Despite this, the human body produces small amounts of this sulfide and its mineral salts, and uses it as a signalling molecule. Hydrogen sulfide is often produced from the microbial breakdown of organic matter in the absence of oxygen, such as in swamps and sewers; this process is commonly known as anaerobic digestio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfuric Acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, and hydrogen, with the molecular formula . It is a colorless, odorless, and Viscosity, viscous liquid that is Miscibility, miscible with water. Pure sulfuric acid does not occur naturally due to its Dehydration reaction, strong affinity to water vapor; it is Hygroscopy, hygroscopic and readily absorbs water vapor from the Atmosphere of Earth, air. Concentrated sulfuric acid is a strong oxidant with powerful dehydrating properties, making it highly corrosive towards other materials, from rocks to metals. Phosphorus pentoxide is a notable exception in that it is not dehydrated by sulfuric acid but, to the contrary, dehydrates sulfuric acid to sulfur trioxide. Upon addition of sulfuric acid to water, a considerable amount of heat is releas ... [...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. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorus Pentoxide
Phosphorus pentoxide is a chemical compound with molecular formula Phosphorus, P4Oxygen, O10 (with its common name derived from its empirical formula, P2O5). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydration reaction, dehydrating agent. Structure Phosphorus pentoxide crystallizes in at least four forms or polymorphism (materials science), polymorphs. The most familiar one, a metastable form (shown in the figure), comprises molecules of P4O10. Weak van der Waals forces hold these molecules together in a hexagonal lattice (However, in spite of the high symmetry of the molecules, the crystal packing is not a close packing). The structure of the P4O10 cage is reminiscent of adamantane with ''T''d symmetry point group. It is closely related to the corresponding anhydride of phosphorous acid, phosphorus trioxide, P4O6. The latter lacks terminal oxo groups. Its density is 2.30 g/cm3. It boils at 423 °C under atmospheric pre ... [...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] |
Tetrahydronaphthalene
Tetralin (1,2,3,4-tetrahydronaphthalene) is a hydrocarbon having the chemical formula C10H12. It is a partially hydrogenated derivative of naphthalene. It is a colorless liquid that is used as a hydrogen-donor solvent. Production Tetralin is produced by the catalytic hydrogenation of naphthalene. Although nickel catalysts are traditionally employed, many variations have been evaluated. Over-hydrogenation converts tetralin into decahydronaphthalene ( decalin). Rarely encountered is dihydronaphthalene ( dialin). Laboratory methods In a classic named reaction called the Darzens tetralin synthesis, named for Auguste Georges Darzens (1926), derivatives can be prepared by intramolecular electrophilic aromatic substitution reaction of a 1-aryl-pent-4-ene using concentrated sulfuric acid, Uses Tetralin is used as a hydrogen-donor solvent, for example in coal liquifaction. It functions as a source of H2, which is transferred to the coal. The partially hydrogenated coal is more s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distillation
Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixture and the condensation of the vapors in a still. Distillation can operate over a wide range of pressures from 0.14 bar (e.g., ethylbenzene/ styrene) to nearly 21 bar (e.g., propylene/propane) and is capable of separating feeds with high volumetric flowrates and various components that cover a range of relative volatilities from only 1.17 ( o-xylene/ m-xylene) to 81.2 (water/ ethylene glycol). Distillation provides a convenient and time-tested solution to separate a diversity of chemicals in a continuous manner with high purity. However, distillation has an enormous environmental footprint, resulting in the consumption of approximately 25% of all industrial energy use. The key issue is that distillation operates based on phase changes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. It is a common element in the universe, estimated at Abundance of the chemical elements, seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element chemical bond, bond to form N2, a colourless and odourless diatomic molecule, diatomic gas. N2 forms about 78% of Atmosphere of Earth, Earth's atmosphere, making it the most abundant chemical species in air. Because of the volatility of nitrogen compounds, nitrogen is relatively rare in the solid parts of the Earth. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772 and independently by Carl Wilhelm Scheele and Henry Cavendish at about the same time. The name was suggested by French chemist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydrazine hydrate (). Hydrazine is mainly used as a foaming agent in preparing Polymeric foam, polymer foams, but applications also include its uses as a precursor (chemistry), precursor to pharmaceuticals and agrochemicals, as well as a long-term storable propellant for in-outer space, space spacecraft propulsion. Additionally, hydrazine is used in various rocket propellant, rocket fuels and to prepare the gas precursors used in airbags. Hydrazine is used within both nuclear and conventional electrical power plant steam cycles as an oxygen scavenger to control concentrations of dissolved oxygen in an effort to reduce corrosion. , approximately 120,000 tons of hydrazine hydrate (corresponding to a 64% solution of hydrazine in water by weight) we ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acid Strength
Acid strength is the tendency of an acid, symbolised by the chemical formula , to dissociate into a hydron (chemistry), proton, , and an anion, . The Dissociation (chemistry), dissociation or ionization of a strong acid in solution is effectively complete, except in its most concentrated solutions. : Examples of strong acids are hydrochloric acid (), perchloric acid (), nitric acid () and sulfuric acid (). A weak acid is only partially dissociated, or is partly ionized in water with both the undissociated acid and its dissociation products being present, in solution, in Equilibrium chemistry, equilibrium with each other. : Acetic acid () is an example of a weak acid. The strength of a weak acid is quantified by its acid dissociation constant, K_a value. The strength of a weak organic chemistry, organic acid may depend on substituent effects. The strength of an inorganic chemistry, inorganic acid is dependent on the oxidation state for the atom to which the proton may be atta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
