Researcher

Ha Pham

Objective

To calculate the solubility of 2-phenylbutyric acid in n-hexane by density method. The additivity of volumes is an assumption and the density of the solid is obtained from ChemSpider prediction.

Procedure

Made-up a mixture of 2-phenylbutyric acid in n-hexane (sample 1). Place the sample in a hot water bath (39 degree C - 43 degree C). When the sample was completely dissolved, removed it from the hot water bath. Observed the formation of precipitation. Let it cool down. Obtained the temperature of the sample before having decanted the supernatant and transferred that to a 1 mL volumetric flask. Weighed out the flask. Calculated the molarity of the concentrated solution from obtained information.

Results

Measured solubility of 2-phenylbutyric acid in n-hexane

Discussion

Previously measured solubility of 2-phenylbutyric acid in hexane had a range of 3.480 M - 6.638 M. The solubility obtained from this experiment was 3.163 M. The average solubility in the database is currently 5.683M, inconsistent with the 3.163M determined in this experiment. [That's not the average in the link you've shown below - EC]

Conclusion

The solubility of 2-phenylbutyric acid was determined to be 3.163 M

References

Solubility of 2-phenylbutyric acid in n-hexane

Log

2011-04-15
10:50 - Weighed out a dry clean 5 dram vial.(12.0722 g)
10:51 - Weighed out 2.1563g of 2-phenylbutyric acid then added to the vial.
10:54 - Weighed out the vial contained 2-phenylbutyric acid. (13.7653 g)
10:59 - Added 1 full pipette of n-hexane to the vial. Immediately covered the vial with screw cap. The mixture named sample 1. Just after having added n-hexane, we could clearly see a part of the acid dissolved in solvent.
11:00 - Used vortex to shake up the mixture.
11:02 - The acid was mostly disolved.
11:05 - Filled in a 400 mL beaker with hot water. Obtained the temperature of the water (39 degree C)
11:07 - Placed the vial into the hot water bath. Kept holding the vial so that it was not submerged completely in water.
11:10 - Removed the vial from hot water bath to add more hot water to the beaker. Obtained the temperature of water (43 degree C)
11:12 - Placed the vial back into the beaker (still kept holding). Also, used the sonicator (with heat on) to help the sample dissolved more quickly. (moved the sample back and forth between the water bath and the sonicator.
11:15 - There was only 1 small piece (flake) of the acid remained at the vial bottom.
11:19 - The acid was completely dissolved. Temperature of the beaker at the time was 42 degree C.
11:20 - Used house air (at low level) to evaporate the supernatant in the sample (placed the house air test tube right at top of the vial)
11:21 - Used the sonicator (heat on). Just after 10 seconds, the sample got cloudy, precipetation formed!
11:22 - Left the vial (with cap on) stand on the table to cool down.
11:30 - Could see clearly precipetation at the bottom of the vial
11:50 - Obtained the temperature of the sample: 21 degree C (the same as room temperature at the time). Immediately put the cap back on.
11:53 - Weighed out a clean dry 1 mL volumetric flask with cap on. (20.3759 g)
11:55 - Carefully transfered the supernatant from the vial to the flask. Covered the flask with its cap.
11:58 - Weighed out the flasked contained concentrated solution. (21.2356 g)
Forgot to obtained the weigh of 1mL volumetric flask contained pure n-hexane solution!
Used collected data from Exp 204 for pure n-hexane solution.