Researchers

Samantha Gaines with Lizzie Clark and Lacey Condron

Objective

To calculate the solubility of trans-cinnamic acid in methanol by density method. The additivity of volumes is an assumption and the density of the solid is obtained from Wikipedia .

Procedure

Weigh methanol solution in volumetric flask at room temperature. Record mass and volume. Decant solution from volumetric flask into Erlenmeyer flask. Add cinnamic acid until until it no longer dissolves into the solution at room temperature. Heat the solution in a hot water bath from 35 to 40 degrees Celcius until cinnamic acid is dissolved. Alternate between adding cinnamic acid and heating solution in water bath until cinnamic acid does not dissolve into the heated solution. This is a saturated solution. Decant solution into glass vial and let cool to room temperature. Precipitate should form as solution cools. When solution is completely cooled, decant supernatent into graduated cylinder. Weigh on electronic balance at room temperature. Record mass and volume. Calculate beginning and resulting densities and enter all data into "results" spreadsheet.

Results

Measured solubility of trans-cinnamic acid in methanol.

Discussion

The density of methanol solution was calculated to be .78741 g/mL. The density of the methanol solution saturated with cinnamic acid was calculated to be .87268 g/ mL. The known solubility of cinnamic acid in methanol is 1.431M. The solubility measured in this expiriment was slightly higher than the known value, with a deviation of .1300. Graduated cylinders are not as accurate as volumetric flasks. Future experiments will use volumetric flasks.

Conclusion

The solubility of trans-cinnamic acid in methanol was measured to be 1.561M.

References

Values for the known solubility of cinnamic acid in methanol were obtained from
http://old.oru.edu/cccda/sl/solubility/allsolvents.php?solute=cinnamic+acid.

Log

2011-09-26
10:02 - Weighed methanol solution in 10 mL graduated cylinder with electronic balance accurate to .0001 g at room temperature, or 20.4 degrees C. 10 mL of methanol weighed 7.8741 g. 10:15 - Added cinnamic acid to methanol. Originally used volumetric flask but transferred to Erlenmeyer flask.
10:38 - Held Erlenmeyer flask containing solution in 35 degrees C water bath for 5 minutes, swirled periodically.
10:43 - Added more cinnamic acid. Placed on stand in water bath at 30 degrees C for 10 minutes, swirled periodically.
10:55 - Took flask out, shook, put back in bath at 37 degrees C for approximately 3 more minutes.
11:03 - Decanted clear solution into glass vial.
exact time not recorded - Precipitate came out as solution cooled to room temperature.
11:18 - Decanted solution into graduated cylinder. Weighed 9.70 mL of solution at room temperature (20.6 degrees C). Solution weighed 8.4560 g.