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For example, the melting point of silicon at ambient pressure (0.1 MPa) is 1415 °C, but at pressures in excess of 10 GPa it decreases to 1000 °C. [13] Melting points are often used to characterize organic and inorganic compounds and to ascertain their purity. The melting point of a pure substance is always higher and has a smaller range than ...
This melting-point apparatus for use with a microscope was developed by the Austrian pharmacognosist Ludwig Kofler (30 November 1891 Dornbirn - 23 August 1951 Innsbruck) and his wife mineralogist Adelheid Kofler. In 1936, the Koflers and Mayrhofer published their "Mikroskopische Methoden in der Mikrochemie" [Kofler, L., A.
For pure elements or compounds, e.g. pure copper, pure water, etc. the liquidus and solidus are at the same temperature, and the term melting point may be used. There are also some mixtures which melt at a particular temperature, known as congruent melting. One example is eutectic mixture. In a eutectic system, there is particular mixing ratio ...
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 ...
The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C.
During heating, the point at which melting is observed and the temperature constant is the melting point of the sample. [1] A more modern method uses dedicated equipment, known as a melting point apparatus. A slow heating rate at the melting point is needed in order to get an accurate measurement.
The technique is closely related to using gas adsorption to measure pore sizes, but uses the Gibbs–Thomson equation rather than the Kelvin equation.They are both particular cases of the Gibbs Equations of Josiah Willard Gibbs: the Kelvin equation is the constant temperature case, and the Gibbs–Thomson equation is the constant pressure case. [1]
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