* If you can use an existing case or make one, this will save some money. Metal case*, assorted screws & nuts, brackets, electrical terminals & wire, assorted screws $ 20.00 Aluminium Tubing, 10 mm ø x 150 mm $ 1.00 White LED 6000 mcd 5 mm ø Dimmer control $ 2.00 Digital Thermometer 0- 1300 oC x 0.1 oC Type K Thermocouple § $ 20.00 Rocker switch, SPST 220 V + SPST Toggle Switch $ 4.00 2 x Computer Cooling Fans, 40 mm ø ,12 V DC $ 4.00 Soldering iron 220 V 60 W Temperature Controlled ~400 C $ 18.00 Aluminium Heating Block, 30 mm x 20 mm x 20 mm $ 5.00 The following items are required ( approximate prices as found on eBay )
MELTING POINT MEASURE APPARATUS HOW TO
Here I describe how to build an apparatus which will do the job at very reasonable cost, while providing many of the features of the more expensive commercial versions. Prices for these items range from a few hundred up to several thousand dollars. Electrically heated melting point devices were introduced to reduce these risks, and there are now several designs on the market, ranging from a simple electrically heated metal block up to computer controlled automatic instruments which record the entire operation on a video camera. This method involves some hazards from the use of an open flame and the chance of spilling the hot liquid while the operator has their face next to the bath observing the sample. Originally the sample, contained in a 1.5 mm diameter glass capillary tube, was heated in a bath filled with mineral oil ( or sometimes concentrated sulphuric acid ) with a Bunsen burner until melting occurred, and the bath temperature read from a thermometer. The temperature at which a sample melts is indicative of the purity and identity of the substance. Note that unlike boiling point, the melting point is relatively insensitive to pressure and no pressure correction needs to be made.A very frequently performed operation in organic chemistry laboratories is the determination of the melting point of a solid specimen.
temperature changing only about 2 ☌/min) until you obtain two consistent values.
The most commonly a heated metal block such as a Mel-Temp apparatus Thiele Tube The sample is loaded in a sealed capillary tube and the temperature gradually raised by means of an internal metal block. This is the most common piece of apparatus for determining melting point (as shown in the picture at the top of the page). There are a few ways of doing this Melting point apparatus The general method is to heat a sample indirectly by placing the prepared sample (either packed in a glass capillary or on a glass cover slip) in or on a heated medium and observing it, and the temperature, closely until melting is complete. Pure samples usually have sharp melting points, for example 149.5-150☌ or 189-190☌ impure samples of the same compounds melt at lower temperatures and over a wider range, for example 145-148☌ or 186-189☌. You can find out more about melting points below. Determining the melting point of a compound is one way to test if the substance is pure and is often used to test samples made from organic synthesis (eg of aspirin or paracetomol).
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