Melting point apparatus
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A melting point apparatus is a scientific instrument used to determine the melting point of a substance.
Design and operation
While the outward designs of apparatuses varies depending on the brand, their MO is similar. A glass capillary sealed at one end is loaded with the desired solid substance and placed in sample holder of the apparatus. The sample is observed through an eyepiece that magnifies the capillary, which is illuminated via a light source. The capillary is heated using a heating element. A digital thermometer measures and displays the temperature. The melting temperature range of the compound is determined by averaging the first value when the compound begins to melt with the value when the compound is completely melted. If the sample decomposes, the first temperature value when the decomposition begins, is recorded.
Some apparatuses have a control panel that allows the starting and final temperatures, as well as the temperature gradient, while others simply contain a on-off switch and temperature dial button. Some devices have several channels which permit more than one sample to be tested at a time.
Melting point apparatuses can be purchased from various chemical suppliers, or from eBay. The prices vary, depending on the brand, country of origin, performance and quality. Some apparatuses can be purchased for as little as 60$, while others can cost over 2000 $.
DIY melting point apparatus
Some Sciencemadness members have successfully made their own melting point apparatuses, much cheaper. See the SM threads below for more info.