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Differential Scanning Calorimeter
Differential scanning calorimetry (DSC) is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. Both the sample and reference are maintained at nearly the same temperature throughout the experiment. Generally, the temperature program for a DSC analysis is designed such that the sample holder temperature increases linearly as a function of time. The reference sample should have a well-defined heat capacity over the range of temperatures to be scanned. Additionally, the reference sample must be stable, of high purity, and must not experience much change across the temperature scan. Typically, reference standards have been metals such as indium, tin, bismuth, and lead, but other standards such as polyethylene and fatty acids have been proposed to study polymers and organic compounds, respectively. The technique was developed by E. S. Watson and M. J. O'Nei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Analysis
Thermal analysis is a branch of materials science where the properties of materials are studied as they change with temperature. Several methods are commonly used – these are distinguished from one another by the property which is measured: * Dielectric thermal analysis: dielectric permittivity and loss factor * Differential thermal analysis: temperature difference versus temperature or time * Differential scanning calorimetry: heat flow changes versus temperature or time * Dilatometer, Dilatometry: volume changes with temperature change * Dynamic mechanical analysis: measures storage modulus (stiffness) and loss modulus (damping) versus temperature, time and frequency * Evolved gas analysis: analysis of gases evolved during heating of a material, usually decomposition products * Isothermal titration calorimetry * Isothermal microcalorimetry * Laser flash analysis: thermal diffusivity and thermal conductivity * Thermogravimetric analysis: mass change versus temperature or time ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indium
Indium is a chemical element; it has Symbol (chemistry), symbol In and atomic number 49. It is a silvery-white post-transition metal and one of the softest elements. Chemically, indium is similar to gallium and thallium, and its properties are largely intermediate between the two. It was discovered in 1863 by Ferdinand Reich and Hieronymous Theodor Richter by spectroscope, spectroscopic methods and named for the indigo blue line in its spectrum. Indium is used primarily in the production of flat-panel displays as indium tin oxide (ITO), a transparent and conductive coating applied to glass. It is also used in the semiconductor industry, in low-melting-point metal alloys such as Solder#Alloying element roles, solders and soft-metal high-vacuum seals. It is produced exclusively as a by-product during the processing of the ores of other metals, chiefly from sphalerite and other zinc Sulfide mineral, sulfide ores. Indium has no biological role and its compounds are toxic when inhaled ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vapor Pressure
Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's thermodynamic tendency to evaporate. It relates to the balance of particles escaping from the liquid (or solid) in equilibrium with those in a coexisting vapor phase. A substance with a high vapor pressure at normal temperatures is often referred to as '' volatile''. The pressure exhibited by vapor present above a liquid surface is known as vapor pressure. As the temperature of a liquid increases, the attractive interactions between liquid molecules become less significant in comparison to the entropy of those molecules in the gas phase, increasing the vapor pressure. Thus, liquids with strong intermolecular interactions are likely to have smaller vapor pressures, with the reverse true for weaker interactions. The vapor p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sublimation (phase Transition)
Sublimation is the Phase transition, transition of a substance directly from the solid to the gas state, without passing through the liquid state. The verb form of sublimation is ''sublime'', or less preferably, ''sublimate''. ''Sublimate'' also refers to the product obtained by sublimation. The point at which sublimation occurs rapidly (for further details, see #False correspondence with vaporization, below) is called critical sublimation point, or simply sublimation point. Notable examples include sublimation of dry ice at room temperature and atmospheric pressure, and that of solid iodine with heating. The reverse process of sublimation is deposition (phase transition), ''deposition'' (also called ''desublimation''), in which a substance passes directly from a gas to a solid phase, without passing through the liquid state. Technically, all solids may sublime, though most sublime at extremely low rates that are hardly detectable under usual conditions. At standard condi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enthalpy Of Fusion
In thermodynamics, the enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid, at constant pressure. The enthalpy of fusion is the amount of energy required to convert one mole of solid into liquid. For example, when melting 1 kg of ice (at 0 °C under a wide range of pressures), 333.55 kJ of energy is absorbed with no temperature change. The heat of solidification (when a substance changes from liquid to solid) is equal and opposite. This energy includes the contribution required to make room for any associated change in volume by displacing its environment against ambient pressure. The temperature at which the phase transition occurs is the melting point or the freezing point, according to context. By convention, the pressure is assumed to be unless otherwise specified. Overview T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melting Point
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state of matter, state from solid to liquid. At the melting point the solid and liquid phase (matter), phase exist in Thermodynamic equilibrium, equilibrium. The melting point of a substance depends on pressure and is usually specified at a Standard temperature and pressure, standard pressure such as 1 Atmosphere (unit), atmosphere or 100 Pascal (unit), kPa. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point. Because of the ability of substances to Supercooling, supercool, the freezing point can easily appear to be below its actual value. When the "characteristic freezing point" of a substance is determined, in fact, the actual methodology is almost always "the principle of observing the disappearance rather than the formation of ice, that is, the #Melting point measurements, melting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Chemistry
Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibria. Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a supra-molecular science, as the majority of the principles on which it was founded relate to the bulk rather than the molecular or atomic structure alone (for example, chemical equilibrium and colloids). Some of the relationships that physical chemistry strives to understand include the effects of: # Intermolecular forces that act upon the physical properties of materials ( plasticity, tensile strength, surface tension in liquids). # Reaction kinetics on the rate of a reaction. # The identity of ions and the electrical conductivity of materials. # Surface science and electrochemistry of cell m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Georgia (country)
Georgia is a country in the Caucasus region on the coast of the Black Sea. It is located at the intersection of Eastern Europe and West Asia, and is today generally regarded as part of Europe. It is bordered to the north and northeast by Russia, to the south by Turkey and Armenia, and to the southeast by Azerbaijan. Georgia covers an area of . It has a Demographics of Georgia (country), population of 3.7 million, of which over a third live in the capital and List of cities and towns in Georgia (country), largest city, Tbilisi. Ethnic Georgians, who are native to the region, constitute a majority of the country's population and are its titular nation. Georgia has been inhabited since prehistory, hosting the world's earliest known sites of winemaking, gold mining, and textiles. The Classical antiquity, classical era saw the emergence of several kingdoms, such as Colchis and Kingdom of Iberia, Iberia, that formed the nucleus of the modern Georgian state. In the early fourth centu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tbilisi
Tbilisi ( ; ka, თბილისი, ), in some languages still known by its pre-1936 name Tiflis ( ), ( ka, ტფილისი, tr ) is the Capital city, capital and List of cities and towns in Georgia (country), largest city of Georgia (country), Georgia, located on the banks of the Kura (Caspian Sea), Kura River. With around 1.2 million inhabitants, it contains almost one third of the country's population. Tbilisi was founded in the fifth century Anno Domini, AD by Vakhtang I of Iberia and has since served as the capital of various Georgian kingdoms and republics. Between 1801 and 1917, then part of the Russian Empire, it was the seat of the Caucasus Viceroyalty (1801–1917), Caucasus Viceroyalty, governing both the North Caucasus, northern and the South Caucasus, southern sides of the Caucasus. Because of its location at the crossroads between Europe and Asia, and its proximity to the lucrative Silk Road, throughout history, Tbilisi has been a point of contention ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pittsburgh Conference On Analytical Chemistry And Applied Spectroscopy
The Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, referred to internationally as Pittcon, is a non-profit educational organization based in Pennsylvania that organizes an annual Conference and Exposition on laboratory science. It is sponsored by the Spectroscopy Society of Pittsburgh and the Society for Analytical Chemists of Pittsburgh. The Conference has traditionally been the most attended annual conference on analytical chemistry and applied spectroscopy in the world, with attendance of approximately 20,000 people in the period of 2005-2011. Pittcon presents several awards each year to individuals who have made outstanding contributions to the various fields in analytical chemistry Analytical skill, Analytical chemistry studies and uses instruments and methods to Separation process, separate, identify, and Quantification (science), quantify matter. In practice, separation, identification or quantification may constitute t .... References {{R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fatty Acids
In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are a major component of the lipids (up to 70% by weight) in some species such as microalgae but in some other organisms are not found in their standalone form, but instead exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and important structural components for cells. History The concept of fatty acid (''acide gras'') was introduced in 1813 by Michel Eugène Chevreul, though he initially used some variant terms: ''graisse acide'' and ''acide huileux'' ("acid fat" and "oily acid"). Types of fatty acids Fatty acids are classified in many ways: by length, by saturation vs unsat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
