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Melting Point Apparatus
A melting-point apparatus is a scientific instrument used to determine the melting point of a substance. Some types of melting-point apparatuses include the Thiele tube, Fisher-Johns apparatus, Gallenkamp (Electronic) melting-point apparatus and automatic melting-point apparatus. Design While the outward designs of apparatuses can vary greatly, most apparatuses use a sample loaded into a sealed capillary tube (''melting-point tube''), which is then placed in the apparatus. The sample is then heated, either by a heating block or an oil bath, and as the temperature increases, the sample is observed to determine when the phase change from solid to liquid occurs. The operator of the apparatus records the temperature range starting with the initial phase-change temperature and ending with the completed phase-change temperature. The temperature range that is determined can then be averaged to gain the melting point of the sample being examined. Apparatuses usually have a control p ... [...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 from solid to liquid. 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 a standard pressure such as 1 atmosphere or 100 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 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." Examples For most substances, melting and freezing points are approximately equal. For example, the melting point ''and'' freezing point of mercury is . How ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiele Tube
The Thiele tube, named after the German chemist Johannes Thiele, is a laboratory glassware designed to contain and heat an oil bath. Such a setup is commonly used in the determination of the melting point of a substance. The apparatus resembles a glass test tube with an attached handle. Operation Oil is poured into the tube, and then the "handle" is heated, either by a small flame or some other heating element. The shape of the Thiele tube allows for formation of convection currents in the oil when it is heated. These currents maintain a fairly uniform temperature distribution throughout the oil in the tube. The side arm of the tube is designed to generate these convection currents and thus transfer the heat from the flame evenly and rapidly throughout the heating oil. The sample, packed in a capillary tube, is attached to the thermometer, and held by means of a rubber band or a small slice of rubber tubing. The Thiele tube is usually heated using a microburner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiele Tube V3
Thiele is a German-language surname. Geographical distribution As of 2014, 78.0% of all known bearers of the surname ''Thiele'' were residents of Germany, 10.9% of the United States, 2.3% of Australia, 2.0% of Brazil, 1.0% of Canada and 1.0% of South Africa. In Germany, the frequency of the surname was higher than national average (1:1,741) in the following states: * 1. Brandenburg (1:477) * 2. Saxony-Anhalt (1:522) * 3. Saxony (1:624) * 4. Bremen (state), Bremen (1:1,058) * 5. Thuringia (1:1,132) * 6. Lower Saxony (1:1,241) * 7. Hamburg (1:1,465) * 8. Mecklenburg-Vorpommern (1:1,689) * 9. Berlin (1:1,708) People * Alfonso Thiele (1922–1986), American Italian racing driver * Allen Thiele (1940–2017), Master Chief Petty Officer of the Coast Guard * Annekatrin Thiele (born 1984), German rower * Arthur Thiele (1860–1936), German illustrator * August Thiele (1894–1967), Vizeadmiral with the Kriegsmarine * Aurelie Thiele, French professor using optimization algorithms to contro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiling Point
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at low pressure has a lower boiling point than when that liquid is at atmospheric pressure. Because of this, water boils at under standard pressure at sea level, but at at altitude. For a given pressure, different liquids will boiling, boil at different temperatures. The normal boiling point (also called the atmospheric boiling point or the atmospheric pressure boiling point) of a liquid is the special case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level, one Atmosphere (unit), atmosphere. At that temperature, the vapor pressure of the liquid becomes suffici ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siwoloboff Method
The Siwoloboff method is used to determine the boiling point of small samples of liquid chemicals. A sample in an ignition tube (also called a fusion tube) is attached to a thermometer with a rubber band, and immersed in a Thiele tube The Thiele tube, named after the German chemist Johannes Thiele, is a laboratory glassware designed to contain and heat an oil bath. Such a setup is commonly used in the determination of the melting point of a substance. The apparatus resembl ..., water bath, or other suitable medium for heating. A sealed capillary, open end pointing down, is placed in the ignition tube. The apparatus is heated. Dissolved gases evolve from the sample first, and the air in the capillary tube expands. Once the sample starts to boil, heating is stopped, and the temperature starts to fall. The temperature at which the liquid sample is sucked into the sealed capillary is the boiling point of the sample. References Laboratory techniques {{Analytical chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
