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Using the melting point apparatus
This page gives brief details on how to use the semi-automatic melting point apparatus featured in the video. It is not appropriate if you are using any other method of measuring melting point.
The machine needs to be plugged in and turned on about an hour before it is used. This will usually be done by the technical staff. The heating block has space for three sample tubes, and it is possible to watch three samples melt at the same time, although it is a little crowded. To save you time in doing a trial run, it is helpful if your teacher or lecturer gives you a melting point range before you start work.
You will need to prepare your melting point tube as shown in the video sealing one end. Your sample should be well ground in a clean, dry pestle and mortar. About 2-3 mm depth of sample should be transferred to the prepared melting point tube.
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Place your sample in the heating block in one of the holes. Set the apparatus to the starting temperature (that is the lower of the range). This is done using the up and down arrow keys at the bottom of the keypad. The up arrow raises the set temperature by 10 degrees centigrade, and the down arrow reduces the set temperature by one degree centigrade. |
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When you have set the correct temperature, press the arrow key in the centre of the keypad, and the machine will quickly raise the temperature to the set one. When this temperature is reached the machine bleeps three times. At this point, press the arrow key in the centre of the keypad again. The temperature will ramp upward slowly at around 1 degree centigrade per minute. |
The sample must be watched carefully and the starting and end melting temperatures noted. When your sample has fully melted don't forget to clear the apparatus, otherwise it will continue to rise in temperature. This can be done by pressing the clear key three times. Also, be careful to dispose of your used sample tube carefully. It is made of glass and may be sharp. It should be thrown away in a properly designated glass bin.
