Sublimation of Vanillin and O-Vanillin

Topics: Vapor pressure, Thermodynamics, Pressure Pages: 2 (708 words) Published: November 19, 2012
In this experiment a high vacuum sublimation was performed to determine the vapor pressure and finally the enthalpy of sublimation of Vanillin and o-Vanillin. AKnudsen cell with sample was weighed 10 times maybe just say weighed by difference, they don’t usually like it when you spell out the steps like that no way it was like 0.5 grams, check the lab again and at least 0.5 g of Vanillin or o-Vanillin was added to the cell and it was reweighed 10 times. This experiment depended heavily on the method of weigh by difference when determining the mass of sample (Vanillin or o-Vanillin) loss in sublimation. A water bath (70 °C for vanillin or 40 °C for o-Vanillin) is prepared for the sample. The Knudsen cell was inserted into the sample tube and the closed end of the sample tube was placed into the prepared water bath. The tube with the O-ring was connected to the sublimation apparatus. The diffusion pump was connected to the water supply and turned on to 90 V. The cold trap of the apparatus was filled with Liquid nitrogen every hour of the experiment. Maybe talk about the type of vacuum pump used since there was so much about it in the lab manual After the sample had reached and sustained the desired temperature for about 5 minutes the sublimation region was roughed.. Just say that you roughed, they don’t usually like this step by step stuff with the valves, but I do like that talk about the pressures that we reached The time between the opening of valve 1 and 3 was the uncertainty in total time. The sublimation apparatus was place under high vacuum to initiate the sublimation process. After making sure the exhaust region pressure did not rapidly increase the temperature of the water bath was recorded every couple of minutes until only 15 minutes were left in the laboratory. This experiment was repeated for a 2nd trial with the only change being the water bath ( 55 °C for Vanillin or 30 °C for o-Vanillin). Need degree signs

Data Analysis
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