Researcher

Rida Atif

Objective

To determine the recrystallization yield of cinnamic acid in benzene

Procedure

0.9137g of cinnamic acid and 2.14mL of benzene were added into a 10mL Erlenmeyer flask and set on hot plate to boil. Once all of the acid was dissolved, the flask was removed from the heat and set over night to cool down. The crystals that formed inside the flask were then filtered through a suction filter, collected in a vial, and massed.

Results

Calculation Sheet
EXP312-HNMR
The solubility of the solution at the boiling point was 2.118M
The predicted recrystallization yield at this solubility was 85.5% while the actual recrystallization yield was 89.45%

Discussion

The NMR spectrum shows that there is no benzene left in the sample. This means that the cinnamic acid crystals are completely dry.
According to the temperature curve, the solubility at boiling point should have been 2.07, which means that about 85% of the crystals would have been recovered.
The actual yield may have been higher than the theoretical yield due to benzene evaporating overnight.

Conclusion

The solvent selector did a good job in predicting that benzene would be a good solvent to recrystallize cinnamic acid from.
Benzene is a very good solvent to recrystallize cinnamic acid from.

Log

2012-07-06

9:07 - Turned on hot plate to 200C
9:25 - Added 0.9137g of cinnamic acid into 10mL erlenmeyer flask
9:29 - Added about 2.5mL of benzene into flask and set on hot plate
9:30 - Added benzene into another small flask and set on hot plate to boil too
9:33 - All of the cinnamic acid has dissolved into the benzene
9:34 - The flask was removed from the hot plate and set to cool down

2012-07-09

10:46 - The contents of the flask were filtered through a suction filter.
10:58 - Mass of empty vial and cap: 13.5958g
11:07 - Stopped the vacuum for the filter
11:11 - Mass of vial, cap, and crystals (EXP312a): 14.4131g