Melting Point
Melting Point Determination Lab
Materials:
Graduated pipette
Capillary tube
Tin wipe
Sample
Melting temperature apparatus
Thermometer
Procedure:
Take open end of capillary tube and tap it gently into sample. Take tin wipe and place over the opening. Gently tab it so the sample will funnel to the bottom of the tube. You may also use a graduated pipette to accomplish this. Now, place the capillary tube in the designated spot in the melting apparatus, and once placed, turn the apparatus on. You will note observations through the eye piece. Make note of two observations: temperature when the sample starts to sweat and when the sample is completely melted. This will constitute the melt temperature range for your sample. Turn the dial to number 6 on the first run so as to run the temperature gauge to 150 degrees in five minutes. On the second run, the dial can be adjusted to 4 when you are 30-40 degrees away from previous temperature taken. You may also want to verify the temperature melting point chart to properly correlate the dial that needs to be used for a sample. Once you are done, turn off the apparatus, remove capillary tube and remove thermometer. Make sure to not place the thermometer horizontally to avoid breaking it; place it in the proper holder under the hood.
Discussion:
Melting point is an example of a physical property. This is lieu of the fact that we are observing a sample without changing the composition of the matter. As there are 3 states (solid, liquid and gas), the same matter remains intact in all three states. We use melting point measuring in organic chemistry as this is a method to identify a pure solid compound and compare it to the melting points listed in various sources of published data. Understanding of concepts in general chemistry leads us to be able to put it into practice in organic chemistry.
Materials:
Graduated pipette
Capillary tube
Tin wipe
Sample
Melting temperature apparatus
Thermometer
Procedure:
Take open end of capillary tube and tap it gently into sample. Take tin wipe and place over the opening. Gently tab it so the sample will funnel to the bottom of the tube. You may also use a graduated pipette to accomplish this. Now, place the capillary tube in the designated spot in the melting apparatus, and once placed, turn the apparatus on. You will note observations through the eye piece. Make note of two observations: temperature when the sample starts to sweat and when the sample is completely melted. This will constitute the melt temperature range for your sample. Turn the dial to number 6 on the first run so as to run the temperature gauge to 150 degrees in five minutes. On the second run, the dial can be adjusted to 4 when you are 30-40 degrees away from previous temperature taken. You may also want to verify the temperature melting point chart to properly correlate the dial that needs to be used for a sample. Once you are done, turn off the apparatus, remove capillary tube and remove thermometer. Make sure to not place the thermometer horizontally to avoid breaking it; place it in the proper holder under the hood.
Discussion:
Melting point is an example of a physical property. This is lieu of the fact that we are observing a sample without changing the composition of the matter. As there are 3 states (solid, liquid and gas), the same matter remains intact in all three states. We use melting point measuring in organic chemistry as this is a method to identify a pure solid compound and compare it to the melting points listed in various sources of published data. Understanding of concepts in general chemistry leads us to be able to put it into practice in organic chemistry.