1.
Melting point
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The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances, melting and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs. Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can also be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
2.
Glycerol
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Glycerol /ˈɡlɪsərɒl/ is a simple polyol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting, the glycerol backbone is found in all lipids known as triglycerides. It is widely used in the industry as a sweetener and humectant. Glycerol has three groups that are responsible for its solubility in water and its hygroscopic nature. Although achiral, glycerol is prochiral with respect to reactions of one of the two primary alcohols, thus, in substituted derivatives, the stereospecific numbering labels each carbon as either sn-1, sn-2, or sn-3. Glycerol is generally obtained from plant and animal sources where it occurs as triglycerides, triglycerides are esters of glycerol with long-chain carboxylic acids. Approximately 950,000 tons per year are produced in the United States and it was projected in 2006 that by the year 2020, production would be six times more than demand. Glycerol from triglycerides is produced on a scale, but the crude product is of variable quality. It can be purified, but the process is expensive, some glycerol is burned for energy, but its heat value is low. High purity glycerol is obtained by distillation, vacuum is helpful due to the high boiling point of glycerol. Although usually not cost-effective, glycerol can be produced by various routes from propylene and this epichlorohydrin is then hydrolyzed to give glycerol. Chlorine-free processes from propylene include the synthesis of glycerol from acrolein, because of the large-scale production of biodiesel from fats, where glycerol is a waste product, the market for glycerol is depressed. Thus, synthetic processes are not economical, owing to oversupply, efforts are being made to convert glycerol to synthetic precursors, such as acrolein and epichlorohydrin. In food and beverages, glycerol serves as a humectant, solvent, and sweetener and it is also used as filler in commercially prepared low-fat foods, and as a thickening agent in liqueurs. Glycerol and water are used to preserve certain types of plant leaves, as a sugar substitute, it has approximately 27 kilocalories per teaspoon and is 60% as sweet as sucrose. It does not feed the bacteria that form plaques and cause dental cavities, as a food additive, glycerol is labeled as E number E422. It is added to icing to prevent it from setting too hard, as used in foods, glycerol is categorized by the Academy of Nutrition and Dietetics as a carbohydrate. The U. S. Food and Drug Administration carbohydrate designation includes all caloric macronutrients excluding protein, glycerol is used in medical, pharmaceutical and personal care preparations, mainly as a means of improving smoothness, providing lubrication, and as a humectant
3.
Epoxy
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Epoxy is either any of the basic components or the cured end products of epoxy resins, as well as a colloquial name for the epoxide functional group. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups, Epoxy resins may be reacted either with themselves through catalytic homopolymerisation, or with a wide range of co-reactants including polyfunctional amines, acids, phenols, alcohols and thiols. These co-reactants are often referred to as hardeners or curatives, reaction of polyepoxides with themselves or with polyfunctional hardeners forms a thermosetting polymer, often with high mechanical properties, temperature and chemical resistance. Epoxy resins are low molecular weight pre-polymers or higher molecular weight polymers which contain at least two epoxide groups. The epoxide group is sometimes referred to as a glycidyl or oxirane group. A wide range of epoxy resins are produced industrially, the raw materials for epoxy resin production are today largely petroleum derived, although some plant derived sources are now becoming commercially available. Epoxy resins are polymeric or semi-polymeric materials, and as such rarely exist as pure substances, high purity grades can be produced for certain applications, e. g. using a distillation purification process. One downside of high purity liquid grades is their tendency to form crystalline solids due to their highly regular structure, an important criterion for epoxy resins is the epoxide content. Epoxies are typically cured with stoichiometric or near-stoichiometric quantities of curative to achieve maximum physical properties, use of blending, additives and fillers is often referred to as formulating. Important epoxy resins are produced from combining epichlorohydrin and bisphenol A to give bisphenol A diglycidyl ethers, as the molecular weight of the resin increases, the epoxide content reduces and the material behaves more and more like a thermoplastic. Very high molecular weight polycondensates form a class known as phenoxy resins and these resins do however contain hydroxyl groups throughout the backbone, which may also undergo other cross-linking reactions, e. g. with aminoplasts, phenoplasts and isocyanates. Bisphenol F may also undergo epoxidation in a fashion to bisphenol A. Compared to DGEBA, bisphenol F epoxy resins have lower viscosity and a higher mean epoxy content per gramme, reaction of phenols with formaldehyde and subsequent glycidylation with epichlorohydrin produces epoxidised novolacs, such as epoxy phenol novolacs and epoxy cresol novolacs. These are highly viscous to solid resins with typical mean epoxide functionality of around 2 to 6, the high epoxide functionality of these resins forms a highly crosslinked polymer network displaying high temperature and chemical resistance, but low flexibility. Aliphatic epoxy resins are typically formed by glycidylation of aliphatic alcohols or polyols, the resulting resins may be monofunctional, difunctional, or higher functionality. These resins typically display low viscosity at room temperature and are referred to as reactive diluents. They are rarely used alone, but are employed to modify the viscosity of other epoxy resins. This has led to the term ‘modified epoxy resin’ to denote those containing viscosity-lowering reactive diluents, a related class is cycloaliphatic epoxy resin, which contains one or more cycloaliphatic rings in the molecule
4.
Biofuel
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Biofuels can be derived directly from plants, or indirectly from agricultural, commercial, domestic, and/or industrial wastes. Renewable biofuels generally involve contemporary carbon fixation, such as those that occur in plants or microalgae through the process of photosynthesis, other renewable biofuels are made through the use or conversion of biomass. This biomass can be converted to convenient energy-containing substances in three different ways, thermal conversion, chemical conversion, and biochemical conversion and this biomass conversion can result in fuel in solid, liquid, or gas form. This new biomass can also be used directly for biofuels, bioethanol is an alcohol made by fermentation, mostly from carbohydrates produced in sugar or starch crops such as corn, sugarcane, or sweet sorghum. Cellulosic biomass, derived from sources, such as trees and grasses, is also being developed as a feedstock for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, bioethanol is widely used in the USA and in Brazil. Current plant design does not provide for converting the portion of plant raw materials to fuel components by fermentation. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe, in 2010, worldwide biofuel production reached 105 billion liters, up 17% from 2009, and biofuels provided 2. 7% of the worlds fuels for road transport. Global ethanol fuel production reached 86 billion liters in 2010, with the United States and Brazil as the top producers. The worlds largest biodiesel producer is the European Union, accounting for 53% of all production in 2010. As of 2011, mandates for blending biofuels exist in 31 countries at the national level, the International Energy Agency has a goal for biofuels to meet more than a quarter of world demand for transportation fuels by 2050 to reduce dependence on petroleum and coal. The production of biofuels also led into an automotive industry. There are various social, economic, environmental and technical issues relating to production and use. Most transportation fuels are liquids, because vehicles usually require high energy density and this occurs naturally in liquids and solids. High energy density can also be provided by a combustion engine. The fuels that are easiest to burn cleanly are typically liquids, thus, liquids meet the requirements of being both energy-dense and clean-burning. In addition, liquids can be pumped, which means handling is easily mechanized, first-generation or conventional biofuels are made from sugar, starch, or vegetable oil. Biobutanol is often claimed to provide a replacement for gasoline
5.
Chirality
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Chirality /kaɪˈrælɪtiː/ is a property of asymmetry important in several branches of science. The word chirality is derived from the Greek, χειρ, hand, an object or a system is chiral if it is distinguishable from its mirror image, that is, it cannot be superposed onto it. Conversely, an image of an achiral object, such as a sphere. A chiral object and its image are called enantiomorphs or. A non-chiral object is called achiral and can be superposed on its mirror image, human hands are perhaps the most universally recognized example of chirality. The left hand is a mirror image of the right hand. This difference in symmetry becomes obvious if someone attempts to shake the hand of a person using their left hand. In mathematics, chirality is the property of a figure that is not identical to its mirror image, in mathematics, a figure is chiral if it cannot be mapped to its mirror image by rotations and translations alone. For example, a shoe is different from a left shoe. A chiral object and its image are said to be enantiomorphs. The word enantiomorph stems from the Greek ἐναντίος opposite + μορφή form, a non-chiral figure is called achiral or amphichiral. The helix and Möbius strip are chiral two dimensional objects in three dimensional ambient space, the J, L, S and Z-shaped tetrominoes of the popular video game Tetris also exhibit chirality, but only in a two dimensional space. Many other familiar objects exhibit the same symmetry of the human body, such as gloves, glasses. A similar notion of chirality is considered in theory, as explained below. Some chiral three dimensional objects, such as the helix, can be assigned a right or left handedness, in geometry a figure is achiral if and only if its symmetry group contains at least one orientation-reversing isometry. In two dimensions, every figure that possesses an axis of symmetry is achiral, and it can be shown that every bounded achiral figure must have an axis of symmetry, in three dimensions, every figure that possesses a plane of symmetry or a center of symmetry is achiral. There are, however, achiral figures lacking both plane and center of symmetry, in terms of point groups, all chiral figures lack an improper axis of rotation. This means that they contain a center of inversion or a mirror plane
6.
Marcellin Berthelot
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Pierre Eugène Marcellin Berthelot FRS FRSE was a French chemist and politician noted for the Thomsen-Berthelot principle of thermochemistry. He is considered as one of the greatest chemists of all time and he gave all his discoveries not only to the French government but to humanity. He was born in Rue du Mouton, Paris, France, after doing well at school in history and philosophy, he became a scientist. He decided with his friend, the great historian Ernest Renan and he was an atheist but was very influenced by his wife, who was a Calvinist. The fundamental conception that underlay all Berthelots chemical work was that all chemical phenomena depend on the action of forces which can be determined and measured. In 1863 he became a member of the Académie Nationale de Médecine and he was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1880. In 1881 he became a member of the Royal Netherlands Academy of Arts. His investigations on the synthesis of compounds were published in numerous papers and books, including Chimie organique fondée sur la synthèse. Untersuchungen über die Affinitäten, über Bildung und Zersetzung der Äther and his professorship was filled by Emil Jungfleisch. He was buried with his wife in the Panthéon and he had six children, Marcel André, Marie-Hélène, Camille, Daniel, Philippe, and René. Auguste Rodin has created a bust of Berthelot, abiogenic petroleum origin Berthelots reagent This article incorporates text from a publication now in the public domain, Chisholm, Hugh, ed. Berthelot, Marcellin Pierre Eugène. Crosland, M. P. Berthelot, Pierre Eugène Marcelin
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