Exp188

=Researcher= Jianbo Zhao =Objective= This experiment is exploring the property of Piperonal Hexane solution in different temperature, specifically in the case of [|piperonal] (m.p. 35-37C) in //n//-hexane from 40C to16.5C, Based on EXP 185. Then measure two density and solubility in two different temperature(45C and 20C). The additivity of volumes is an [|assumption] and the densities of the solvent and solute are obtained from the ChemSpider prediction. =Procedure=

=Results= [|Measurement] [|Measurement(16.5C and 45C)]
 * 1) Make 0.16M, 0.076M, 0.032M, 0.016M, and 0.007M solutions of piperonal in //n//-hexane at room temperatue.
 * 2) Set water bath to 45C to equilibrate.
 * 3) Insert tubes in a way that facilitates periodic removal to examine samples. Make sure that all samples are completely submerged in the bath.
 * 4) Decreased the water bath temperature for every other minutes. Observed the change of 5 tubes. After each of them are crystalized, take it out.
 * 5) Measured the concentration of highest temperature (Tube 1) and lowest temperature (Tube 5)


 * Pic.1 and Pic.2 5 very tightly sealed tubes in 45C water bath**

=Discussion=
 * Pic.3 Different layers of 5 tubes at 42C**
 * 1) During the water bath, there are some water running into the tube. Which has to abord the observation of tube 2.
 * 2) While the experiment going on, the 5th tube did crystalize but not so obvious. Thus, I took other 4 tubes out and continued bath at until 16C to observe whether it was really saturated.
 * 3) The number calculated of concentration were a little bit different from exp186

=Conclusion= =Log=
 * 1) Through the whole trail, the concentration of Piperonal Hexane decreased when less solute were put in.
 * 2) The lowest concentration was less than the point it should in compare to exp186.

2010-11-08
10:30 Set water bath to 40C. 10:43 take out 5 tubes and marked them from 1 to 5. measured each empty one. Calibrated and out in Piperonal and measured the mass. After that, calibrated again with Piperonal and capped on. Pour in pure Hexanes and measured each mass again. 12:19 Seal the 5 tubes very tight and type them into 45C bath, take **Pic.1 and 2.** 12:20 Set temperature to 42C, but the actual temperature is 44C. See different layers for all 5 tubes. Shake them, still 2 layers. But the layers decreased from 1 to 5. **Take Pic.3** 12:37 Set it to 40C, it actually goes to 43.5C. See all the layers in tubes. However, they started to perticipate. 12:43 The actual temperature is 41.5C See all of them started to perticipate on the wall. 12:49 Actual temperature is 38.5C. Perticipate more. 12:51 Temperature is 35.5C. See the first 2 tubes started to have crystal inside the tube. But not the last 3 tubes. 12:55 Temperature is 33.5C Even though all of the tubes were crystalizing, there are still 2 layers existing. 12:59 Temperature is 31.5C First 2 tubes still have two layers but the last 3 are all crystalized. 13:02 Temperature is 29C. There were no layers at all. They started to crystalize on the wall. Expecially for tube 2. 13:04 Temperature is 28C, all crystal. But the 2 tube are some liquid inside, probably some water went in. Walls crystal became more. 13:06 26.5C The bottom crystal became more. 13:08 25.5C Turned more crystals, The crystal turned white. 13:13 Even tube 2 are crystalized. 13:18 23C, More solid on the wall. 13:23 21C, Transfer first 4 tubes out and left 5 in and continue cooling down. 13:30 16.5C See more crystals in tube 5 and take it out. 13:54 Measure pure Hexane desity using 5ml, 2ml, 1ml volume flasks 14:02 Measure tube 1 solution density using flasks. 14:05 Set the water bath to 45C again and reheat tube 5 to measure the density. 14:30 Seal and type, put tube 5 into the bath again.