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Dean–Stark Apparatus
upDean–Stark apparatus setup for an azeotrope with a solvent whose density is ''less than'' that of water: The Dean–Stark apparatus, Dean–Stark receiver, distilling trap, or Dean–Stark Head is a piece of laboratory glassware used in synthetic chemistry to collect water (or occasionally other liquid) from a reactor. It is used in combination with a reflux condenser and a distillation flask for the separation of water from liquids. This may be a continuous removal of the water that is produced during a chemical reaction performed at reflux temperature, such as in esterification reactions. It was invented by the American chemists Ernest Woodward Dean (1888–1959) and David Dewey Stark (1893–1979) in 1920 for determination of the water content in petroleum. Function left, A Dean–Stark apparatus in use; aluminium foil is used to reduce heat losses Two types of Dean–Stark traps exist – one for use with solvents with a density ''less'' than that of water and anoth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wild Arms 5
''Wild Arms 5'', released in Japan as , is the fifth video game in the '' Wild Arms'' series of Japanese role-playing games. The game celebrates the series' 10th anniversary by featuring cameo appearances of characters from the previous games. It was developed by Media.Vision for the Sony PlayStation 2 platform. Gameplay Combat system During combat, the field is split into seven hexagonal sections, some of which may have special properties. The player and enemies can move to different hexagons during their turn. This time around, the party count is three instead of four. Dean's party members and enemies can act instantly when they move onto the next hexagonal platform. The Force meter returns from '' Wild Arms 4''. This meter increases as Dean's party members make physical attacks or are attacked. This can be used for Original attacks, Team Combos or summoning Guardian beasts to attack enemies. The more powerful the attack is, the more the Force meter will be drained. The c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiling Chip
A boiling chip, boiling stone, porous bit anti-bumping granule is a tiny, unevenly shaped piece of substance added to liquids to make them boil more calmly. Boiling chips are frequently employed in distillation and heating. When a liquid becomes superheated, a speck of dust or a stirring rod can cause violent flash boiling. Boiling chips provide nucleation sites so the liquid boils smoothly without becoming superheated or bumping. Use Boiling chips should not be added to liquid that is already near its boiling point, as this could also induce flash boiling. The structure of a boiling chip traps liquid while in use, meaning that they cannot be re-used in laboratory setups. They also don't work well under vacuum; if a solution is boiling under vacuum, it is best to constantly stir it instead. Materials Boiling chips are typically made of a porous material, such as alumina, silicon carbide, calcium carbonate, calcium sulfate, porcelain or carbon, and often have a non ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Le Chatelier's Principle
Le Chatelier's principle (pronounced or ), also called Chatelier's principle (or the Equilibrium Law), is a principle of chemistry used to predict the effect of a change in conditions on chemical equilibria. The principle is named after French chemist Henry Louis Le Chatelier, and sometimes also credited to Karl Ferdinand Braun, who discovered it independently. It can be stated as: Phenomena in apparent contradiction to Le Chatelier's principle can also arise in systems of simultaneous equilibrium (see response reactions). Le Chatelier's principle is sometimes alluded to in discussions of topics other than thermodynamics. Thermodynamic statement The Le Chatelier–Braun principle analyzes the qualitative behaviour of a thermodynamic system when a designated one of its externally controlled state variables, say L, changes by an amount \Delta L, the 'driving change', causing a change \delta_ M, the 'response of prime interest', in its conjugate state variable M, all other ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Equilibrium
In a chemical reaction, chemical equilibrium is the state in which both the reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system. This state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but they are equal. Thus, there are no net changes in the concentrations of the reactants and products. Such a state is known as dynamic equilibrium. Historical introduction The concept of chemical equilibrium was developed in 1803, after Berthollet found that some chemical reactions are reversible. For any reaction mixture to exist at equilibrium, the rates of the forward and backward (reverse) reactions must be equal. In the following chemical equation, arrows point both ways to indicate equilibrium. A and B are reactant chemical species, S and T a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Esters typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones. They perform as high-grade solvents for a broad array of plastics, plasticizers, resins, and lacquers, and are one of the largest classes of synthetic lubricants on the commercial market. Polyesters are important plastics, with monomers linked by ester moieties. Phosphoesters form the backbone of DNA molecules. Nitrate esters, such as nitroglycerin, are known for their explosive properties. '' Nomenclature E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butanol
Butanol (also called butyl alcohol) is a four-carbon alcohol with a formula of C4 H9 O H, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; all are a butyl or isobutyl group linked to a hydroxyl group (sometimes represented as BuOH, ''n''-BuOH, ''i''-BuOH, and ''t''-BuOH). These are ''n''-butanol, 2 stereoisomers of sec-butanol, isobutanol and ''tert''-butanol. Butanol is primarily used as a solvent and as an intermediate in chemical synthesis, and may be used as a fuel. Biologically produced butanol is called biobutanol, which may be ''n''-butanol or isobutanol. Isomers The unmodified term ''butanol'' usually refers to the straight chain isomer with the alcohol functional group at the terminal carbon, which is also known as ''n''-butanol or 1-butanol. The straight chain isomer with the alcohol at an internal carbon is ''sec''-butanol or 2-butanol. The branched isomer wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzoic Acid
Benzoic acid is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, which was for a long time its only source. Benzoic acid occurs naturally in many plants and serves as an intermediate in the biosynthesis of many secondary metabolites. Salts of benzoic acid are used as food preservatives. Benzoic acid is an important precursor for the industrial synthesis of many other organic substances. The salts and esters of benzoic acid are known as benzoates . History Benzoic acid was discovered in the sixteenth century. The dry distillation of gum benzoin was first described by Nostradamus (1556), and then by Alexius Pedemontanus (1560) and Blaise de Vigenère (1596). Justus von Liebig and Friedrich Wöhler determined the composition of benzoic acid. These latter also investigated how hippuric acid is r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Regensburg
The University of Regensburg (german: link=no, Universität Regensburg) is a public research university located in the medieval city of Regensburg, Bavaria, a city that is listed as a UNESCO World Heritage Site. The university was founded on 18 July 1962 by the Landtag of Bavaria as the fourth full-fledged university in Bavaria. Following groundbreaking in 1965, the university officially opened to students during the 1967–1968 winter semester, initially housing faculties in Law and Business Sciences and Philosophy. During the summer semester of 1968 the faculty of Theology was created. Currently, the University of Regensburg houses eleven faculties. The university actively participates in the European Union's SOCRATES programme as well as several TEMPUS programmes. Its most famous academic, the previous Pope Benedict XVI, served as a professor there until 1977 and formally retained his chair in theology. History Attempts to establish a university in Regensburg had been ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfuric Acid
Sulfuric acid ( American spelling and the preferred IUPAC name) or sulphuric acid ( 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 viscous liquid that is miscible with water. Pure sulfuric acid does not exist naturally on Earth due to its strong affinity to water vapor; it is hygroscopic and readily absorbs water vapor from the air. Concentrated sulfuric acid is highly corrosive towards other materials, from rocks to metals, since it is an oxidant with powerful dehydrating properties. 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 released; thus the reverse procedure of adding water to the acid should not be performed since the heat released ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetic Acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water and other trace elements. Acetic acid is the second simplest carboxylic acid (after formic acid). It is an important chemical reagent and industrial chemical, used primarily in the production of cellulose acetate for photographic film, polyvinyl acetate for wood glue, and synthetic fibres and fabrics. In households, diluted acetic acid is often used in descaling agents. In the food industry, acetic acid is controlled by the food additive code E260 as an acidity regulator and as a condiment. In biochemistry, the acetyl group, derived from acetic acid, is fundamental to all forms of life. When bound to coenzyme A, it is central to the metabolism of carbohydrates and fats. The global demand for aceti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butanol
Butanol (also called butyl alcohol) is a four-carbon alcohol with a formula of C4 H9 O H, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; all are a butyl or isobutyl group linked to a hydroxyl group (sometimes represented as BuOH, ''n''-BuOH, ''i''-BuOH, and ''t''-BuOH). These are ''n''-butanol, 2 stereoisomers of sec-butanol, isobutanol and ''tert''-butanol. Butanol is primarily used as a solvent and as an intermediate in chemical synthesis, and may be used as a fuel. Biologically produced butanol is called biobutanol, which may be ''n''-butanol or isobutanol. Isomers The unmodified term ''butanol'' usually refers to the straight chain isomer with the alcohol functional group at the terminal carbon, which is also known as ''n''-butanol or 1-butanol. The straight chain isomer with the alcohol at an internal carbon is ''sec''-butanol or 2-butanol. The branched isomer wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toluene
Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) attached to a phenyl group. As such, its systematic IUPAC name is methylbenzene. Toluene is predominantly used as an industrial feedstock and a solvent. As the solvent in some types of paint thinner, permanent markers, contact cement and certain types of glue, toluene is sometimes used as a recreational inhalant and has the potential of causing severe neurological harm. History The compound was first isolated in 1837 through a distillation of pine oil by the Polish chemist Filip Walter, who named it ''rétinnaphte''. In 1841, French chemist Henri Étienne Sainte-Claire Deville isolated a hydrocarbon from balsam of Tolu (an aromatic extract from the tropical Colombian tree '' Myroxylon balsamum''), which Deville recognized as simila ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
