Researcher

Rida Atif

Objective

To determine the recrystallization yield of cinnamic acid in carbon tetrachloride

Procedure

An empty erlenmeyer flask and cap were massed empty. About 0.5 of cinnamic acid was added into the flask and massed again. Approximately 2mL of carbon tetrachloride was added to the same flask and set on hot plate. CCl4 was added into the flask until all of the cinnamic acid dissolved; after all of the cinnamic acid dissolved into the solvent, the flask was removed from the hot plate, massed, then set to cool down. The mass of the flask was taken again before filtering, and the contents of the flask were filtered through a suction filter. The crystals were massed.

Results

Calculation Sheet
The melting point of exp316a was around 129C
The solubility at boiling point was 1.31M
The predicted recrystallization yield with this solubility (with a room temperature solubility of 0.126M) is 90.4%.
The actual yield was 86.4%

Discussion

The melting point of cinnamic acid is 131C, and the melting point of exp316a is about 2C below this meaning that there might be a very small amount of CCl4 in the crystals but not enough to affect the yield significantly.
According to Model003, carbon tetrachloride was predicted as an excellent solvent to recrystallize cinnamic acid from with a boiling point solubility of 0.7M and room temperature solubility of 0.036M. With these solubilities, the predicted recrystallization yield is 95%.
According to the temperature curve, the solubility at boiling point is 1.24M (while room temperature solubility is 0.126M). The predicted recrystallization yield for these values is about 90%.
The solubility at boiling point for this experiment ended up being 1.3M which is very close to the predicted value from the temperature curve. The predicted recrystallization yield for this solubility was 90% while the actual ended up being slightly lower at 86.4%.
About 22% of the CCl4 evaporated overnight which means that the actual yield is higher than what it should have been.

Conclusion

The solvent selector predicted very well for the solubility of cinnamic acid in carbon tetrachloride
Carbon tetrachloride is a good solvent to recrystallize cinnamic acid from.
From this point onward, in addition to a loose cap being left on the flask overnight, the flask will also be covered in parafilm.

Log

2012-07-11

11:11 - Turned on hot plate to 170C
11:58 - Added carbon tetrachloride into a small flask and set on hot plate to boil.
12:03 - Added 0.4272g of cinnamic acid into a 10mL erlenmeyer flask.
12:05 - Added about 2mL of CCl4 into same flask and set on hot plate.
12:09 - All of the cinnamic acid dissolved into the CCl4. The flask was removed from the hot plate and set to cool down.

2012-07-12

11:32 - Filtered contents of the flask through a suction filter
11:35 - Mass of empty vial and cap: 13.7343g
12:02 - Stopped vacuum for the filter
12:06 - Mass of vial, cap, and crystals (exp316a): 14.1034g