Experiment No. 1: Melting Point and Boiling Points of Organic Compounds

2174 Words Jun 27th, 2013 9 Pages


The properties of organic compounds depend on their chemical structures.
Intermolecular forces of attraction affect physical properties such as melting and boiling point. Through the Thomas Hoover apparatus, the melting point of 8 test compounds was determined. Salicylic acid exhibited the highest melting point while naphthalene, the lowest. The stronger the intermolecular forces of attraction, the higher the melting point. Boiling point determination was done on 7 different test compounds using micro method. Results show that propanoic acid and n-hexane had the highest and lowest boiling point respectively. The former had the strongest intermolecular force
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Fill up the Thiele tube with glycerol up to the level slightly above its arm and assemble the set-up. 2. Get a capillary tube from the laboratory assistant and heat it at the middle until the tube becomes completely twisted.
3. Place the capillary tube inside the micro test tube containing two to three drops of the test compounds. 4. Place the micro test tube containing the sample and the capillary side by side with the thermometer. Use a 2-mm wide rubber tubing to hold the capillary tube. 5. Immerse the thermometer in the glycerol (bath liquid) ensuring that the rubber tubing is not immersed in the liquid.
6. Heat the oil bath rapidly until a flow of bubbles comes out of the capillary tube.
7. Remove the flame and allow the oil to cool down. As the temperature drops, the bubbling will slowly cease and the liquid will start to enter the capillary tube.
Record this temperature as the boiling point of the test compound.
8. To obtain the boiling point range of the test compound, reheat the oil slowly and note the temperature when the liquid comes out of the capillary tube. The temperature previously recorded and this current temperature is the boiling point range.
9. Repeat the above procedure until all the samples are tested.
Note: Allow the glycerol to cool down to room temperature before reusing it.
b. Branching
Test Compounds: n-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol Procedure: Follow the same procedure as of Part
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