Exp209

=Researcher= Mary Ziegler

=Objective= To calculate the solubility of (trans)-cinnamic acid in methanol by density method.

=Procedure= -weigh proper amount of solvent / solute -heat mixture -transfer supernatant -cool mixture -transfer supernatant -weigh supernatant

=Results= Mass and Molarity calculations The molarity of the solution of ethanol saturated with cinnamic acid was found to be: trial 1: 1.31 M trial 2: 1.18 M (both trials used 2 ml volumetric flasks)

=Discussion= The recorded molarity of ethanol saturated with cinnamic acid is 1.03 M. This experiment produced a recorded molarity of 1.31 M and 1.18 M, which are both significantly off (27% error and 15% error respectively). Aside from general human error in pure measurements, the solution was cooled below room temperature (19 C), which would effect the results. ===****Recommendations/For Future Reference** ** === -do not cool solution below 20 C -save and reuse solution for volumetric flasks (pour the 5ml into the 2 ml into the 1 ml) -be prepared! (come with goggles, lab coat, markers, etc) -rough estimate of critical values:  1 M = 1mmol/ml, so assume 1 ml, meaning 1mmol of solute (which is approximately the same as the molecular weight).  need the molecular weight in mg/ml, 1 ml too small for sample scale up to 10 ml (i.e. cinnamic acid 150 mg/ml * 10ml = 1500 mg = 1.5 g)  scale up, so approximately 2 g cinnamic acid needed **Conclusion** This experiment, while failed in the sense of the miscalculated molarity, served as a great learning experience for future ones.

=Log= April 12, 2011 10:40: start experiment/general set up (fill water bath, get drabs and flasks) 10:47: weigh out approximately 2 grams of cinnamic acid (2.034 grams) into 5 dram vial (vial A) 10:50: add 8 ml of ethanol (200 proof, anhydrous) 10:55: sonicate solution, check temperature of water bath (44 C) 10:57: place mixture in bath, keeping the levels approximately the same 11:02: remove mixture, sonicate ten seconds 11:03: take picture **[name the pic JCB]**, 11:05: transfer supernatant to vial B, sonicate ten seconds 11:06: started to cool mixture to approximately 20 C (blow air onto mixture) 11:10: check temperatue by putting thermometer into mixture (19C) **[was there any precipitate at this point? JCB]** 11:11: sonicate (take pictire) 11:14: transfer supernatant to vial C, take picture 11:16: weigh volumetric flasks before and after solution added 11:30: enter data into spreadsheet and start wiki page