EXP251

= Researcher = Alex Greene = Objective = To determine of the solubility of trans-cinnamic acid in 1,2 dichloroethane using the density method. = Procedure = 3.3330 grams of trans-cinnamic acid would be dissolved in approximately 15ml of 1,2 dichloroethane by placing the solution in a hot (40-45C) water bath for 15 minutes. Then the solution would cool at room temperature until a precipitate is observed. The supernatant of the solution would be taken and the molarity would be determined by weighing the solution in a volumetric flask. = Results = The experiment was inconclusive. The solubility of trans-cinnamic acid could not be determined in 1,2 dichloroethane because a suspension was formed. = Discussion = This experiment was inconclusive because of the similar densities of trans-cinnamic acid and 1,2 dichloroethane. This is a problem because the density method is most accurate with large differences in densities. Once a white suspension was observed after the heating cycle the density of 1,2 dichloroethane was research. The density of 1,2 dichloroethane is about 1.25g/cm3 and the density of trans-cinnamic acid is about 1.24g/cm3, these densities are too similar for the density method. = Conclusion = The density of trans-cinnamic acid will have to be determined via another experiment, most likely NMR where the similar densities are not a concern (EXP 255). **[This probably is not what you mean - reread carefully JCB]** = Log =
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2012-01-18
11:01 Hot Plate was set to 140C with water bath placed on hot plate. Desired temperature 40-45C 11:03 3.3330g of trans-cinnamic acid weighted out on balance 11:07 Temperature of water bath 25C 11:08 trans-cinnamic acid transferred to 20 ml tube (tube #1) 11:19 Tube #1 filled approximately 3/4 full with 1,2 dichloroethane. Estimate volume of 15 ml of a cloudy white suspension 11:20 Tube #1 was inverted several time and placed in water bath, temperature of 43C. White cloudy suspension still present 11:25 Water bath temperature 40C. Tube #1 was inverted several times and white cloudy suspension still present. 11:30 Water bath temperature 44C. Tube #1 was inverted several times and white cloudy suspension still present. 11:35 Tube #1 removed from water bath, temperature 43C. Inverted and white cloudy suspension persists. 11:38 Tube #1 contents filter using filter paper and gravity. Resulting solution still in suspension.