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Cold Finger
A cold finger is a piece of laboratory equipment that is used to generate a localized cold surface. It is named for its resemblance to a finger and is a type of cold trap. The device usually consists of a chamber that a coolant fluid (cold tap water, or perhaps something colder) can enter and leave. Another version involves filling the device with a cold material (examples: ice, dry ice or a mixture such as dry ice/acetone or ice/water). Typically a cold finger is used in a sublimation apparatus, or can be used as a compact version of a condenser in either reflux reaction or distillation apparatus. Many commercially available rotary evaporators can be purchased with a cold finger in place of a Dimroth condenser, for example. When used as a condenser in a rotary evaporator, cold fingers can be cooled to a lower temperature of −78 °C (dry ice), compared with water condensers that can be cooled to −40 °C (ethylene glycol/water mixture). The lower temperat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sublimation Apparatus
image:sublimation apparatus.svg, 200px, Simple sublimation apparatus. Water usually cold, is circulated in cold finger to allow the desired compound to be deposited.1 Cooling water in 2 Cooling water out 3 Vacuum/gas line 4 Sublimation chamber 5 Sublimed compound 6 Crude material 7 External heating A sublimatory or sublimation apparatus is equipment, commonly laboratory glassware, for purification of Chemical compound, compounds by selective Sublimation (chemistry), sublimation. In principle, the operation resembles purification by distillation, except that the products do not pass through a liquid, liquid phase. Overview A typical sublimation apparatus separates a mix of appropriate solid materials in a vessel in which it applies heat under a controllable atmosphere (air, vacuum or inert gas). If the material is not at first solid, then it may freeze under reduced pressure. Conditions are so chosen that the solid volatility (chemistry), volatilizes and condenses as a purified comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laboratory Equipment
A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratories are found in a variety of settings such as schools, universities, privately owned research institutions, corporate research and testing facilities, government regulatory and forensic investigation centers, physicians' offices, clinics, hospitals, regional and national referral centers, and even occasionally personal residences. Overview The organisation and contents of laboratories are determined by the differing requirements of the specialists working within. A physics laboratory might contain a particle accelerator or vacuum chamber, while a metallurgy laboratory could have apparatus for casting or refining metals or for testing their strength. A chemist or biologist might use a wet laboratory, while a psychologist's laboratory might be a room with one-way mirrors and hidden cameras in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finger
A finger is a prominent digit (anatomy), digit on the forelimbs of most tetrapod vertebrate animals, especially those with prehensile extremities (i.e. hands) such as humans and other primates. Most tetrapods have five digits (dactyly, pentadactyly),#Cha1998, Chambers 1998 p. 603#OxfIll, Oxford Illustrated pp. 311, 380 and short digits (i.e. significantly shorter than the metacarpal/metatarsals) are typically referred to as toes, while those that are notably elongated are called fingers. In humans, the fingers are flexibly joint, articulated and opposable, serving as an important organ of somatosensory, tactile sensation and fine motor skill, fine movements, which are crucial to the dexterity of the hands and the ability to grasp and object manipulation, manipulate objects. Land vertebrate fingers As terrestrial vertebrates were evolution, evolved from lobe-finned fish, their forelimbs are phylogeny, phylogenetically equivalent to the pectoral fins of fish. Within the taxon, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold Trap
In vacuum applications, a cold trap is a device that condenses all vapors except the permanent gases (hydrogen, oxygen, and nitrogen) into a liquid or solid. The most common objective is to prevent vapors being evacuated from an experiment from entering a vacuum pump where they would condense and contaminate it. Particularly large cold traps are necessary when removing large amounts of liquid as in freeze drying. Cold traps also refer to the application of cooled surfaces or baffles to prevent oil vapours from flowing from a pump and into a chamber. In such a case, a baffle or a section of pipe containing a number of cooled vanes, will be attached to the inlet of an existing pumping system. By cooling the baffle, either with a cryogen such as a dry ice mixture, or by use of an electrically driven Peltier element, oil vapour molecules that strike the baffle vanes will condense and thus be removed from the pumped cavity. Applications Pumps that use oil either as their working fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dry Ice
Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and Sublimation (phase transition), sublimes directly from the solid state to the gas state. It is used primarily as a cooling agent, but is also used in fog machines at theatres for dramatic effects. Its advantages include lower temperature than that of Ice, water ice and not leaving any residue (other than incidental frost from moisture in the atmosphere). It is useful for preserving frozen foods (such as ice cream) where Refrigeration, mechanical cooling is unavailable. Dry ice sublimes at at Earth atmospheric pressure. This extreme cold makes the solid dangerous to handle without protection from frostbite injury. While generally not very toxic, the outgassing from it can cause hypercapnia (abnormally elevated carbon dioxide levels in the blood) due to a buildup in confined locations. Properties Dry ice is the soli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetone
Acetone (2-propanone or dimethyl ketone) is an organic compound with the chemical formula, formula . It is the simplest and smallest ketone (). It is a colorless, highly Volatile organic compound, volatile, and flammable liquid with a characteristic pungent odor. Acetone is miscibility, miscible with properties of water, water and serves as an important organic solvent in industry, home, and laboratory. About 6.7 million tonnes were produced worldwide in 2010, mainly for use as a solvent and for production of methyl methacrylate and bisphenol A, which are precursors to widely used plastics.Acetone World Petrochemicals report, January 2010Stylianos Sifniades, Alan B. Levy, "Acetone" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. It is a common building block in organic chemistry. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sublimation Apparatus
image:sublimation apparatus.svg, 200px, Simple sublimation apparatus. Water usually cold, is circulated in cold finger to allow the desired compound to be deposited.1 Cooling water in 2 Cooling water out 3 Vacuum/gas line 4 Sublimation chamber 5 Sublimed compound 6 Crude material 7 External heating A sublimatory or sublimation apparatus is equipment, commonly laboratory glassware, for purification of Chemical compound, compounds by selective Sublimation (chemistry), sublimation. In principle, the operation resembles purification by distillation, except that the products do not pass through a liquid, liquid phase. Overview A typical sublimation apparatus separates a mix of appropriate solid materials in a vessel in which it applies heat under a controllable atmosphere (air, vacuum or inert gas). If the material is not at first solid, then it may freeze under reduced pressure. Conditions are so chosen that the solid volatility (chemistry), volatilizes and condenses as a purified comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condenser (heat Transfer)
In systems involving heat transfer, a condenser is a heat exchanger used to Condensation, condense a gaseous substance into a liquid state through cooling. In doing so, the latent heat is released by the substance and transferred to the surrounding environment. Condensers are used for efficient heat rejection in many industrial systems. Condensers can be made according to numerous designs and come in many sizes ranging from rather small (hand-held) to very large (industrial-scale units used in plant processes). For example, a refrigerator uses a condenser to get rid of heat extracted from the interior of the unit to the outside air. Condensers are used in air conditioning, industrial chemical processes such as distillation, steam power plants, and other heat-exchange systems. The use of cooling water or surrounding air as the coolant is common in many condensers. History The earliest laboratory condenser, a "Heat exchanger, Gegenstromkühler" (counter-flow condenser), was inven ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflux
Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial and laboratory distillations. It is also used in chemistry to supply energy to Chemical reaction, reactions over a long period of time. Reflux in industrial distillation The term ''reflux'' is very widely used in industries that utilize large-scale Fractionating column, distillation columns and Fractional distillation, fractionators such as oil refinery, petroleum refineries, petrochemical and chemical plants, and natural gas processing plants. In that context, reflux refers to the portion of the overhead liquid product from a distillation column or fractionator that is returned to the upper part of the column as shown in the schematic diagram of a typical industrial distillation column. Inside the column, the downflowing reflux liquid provides cooling and condensation of the upflowing vapors thereby increasing the effi ... [...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] |
Rotary Evaporators
A rotary evaporator (rotovap) is a device used in chemical laboratories for the efficient and gentle removal of solvents from samples by evaporation. When referenced in the chemistry research literature, description of the use of this technique and equipment may include the phrase "rotary evaporator", though use is often rather signaled by other language (e.g., "the sample was evaporated under reduced pressure"). Rotary evaporators are also used in molecular cooking for the preparation of distillates and extracts. A simple rotary evaporator system was invented by Lyman C. Craig. It was first commercialized by the Swiss company Büchi in 1957. The device separates substances with different boiling points, and greatly simplifies work in chemistry laboratories. In research the most common size accommodates round-bottom flasks of a few liters, whereas large scale (e.g., 20L-50L) versions are used in pilot plants in commercial chemical operations. Design The main components of a ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
