Researcher

Matthew McBride

Objective

To recrystallize trans-cinnamic acid from cyclohexane using the sintered glass funnel method

Procedure

A 0.23M solution of trans-cinnamic acid in cyclohexane was created in a 10 mL test tube and dissolved at the boiling point of cyclohexane using a water bath. The crystals were cooled to room temperature, vacuum filtered using a sintered glass funnel and dried over air.

Results

Recrystallization Sheet
Concentration: 0.23 M
Amount of Product: 0.2166 g
Yield: 88%

Discussion

The predicted solubility at the boiling point of cyclohexane is about 0.77 M and this experiment measured the solubility at 0.23 M. However, as stated in EXP351, some of the solvent that was measured as being in the solution could have evaporated off and the solubility could actually be higher.

Using the predicted solubility of 0.77 M at the boiling point and the room temperature solubility of 0.029 M, the predicted recrystallization yield was 96%. Using the measured boiling point solubility of 0.23 M, the predicted recrystallization yield is 88%. The measured recrystallization yield of 88% demonstrated that this is a good solvent for recrystallizing trans-cinnamic acid.

Conclusion

The solubility of trans-cinnamic acid in cyclohexane was measured to be 0.23 M at the boiling point and the recrystallization yield was measured to be 88%.

Log

2013-04-12

12:04 The weight of the empty 10 mL screw cap test tube (tube #1) was 21.6052 g. 0.2472 g of trans-cinnamic acid was added to tube #1.
12:11 1.9993 g of cyclohexane was added to tube #1. The solution was placed in the hot water bath with the cap of the test tube loose.
12:17 The content of tube #1 reached a boil and not all of the crystals had dissolved into the solution. An additional 1.8195 g of cyclohexane was added and the test tube was placed back in the hot water bath.
12:21 The content of tube #1 reached a boil and not all of the crystals had dissolved into the solution. An additional 0.3242 g of cyclohexane was added and the test tube was placed back in the hot water bath.
12:28 The content of tube #1 reached a boil and not all of the crystals had dissolved into the solution. An additional 1.3875 g of cyclohexane was added and the test tube was placed back in the hot water bath.
12:32 All of the crystals had dissolved into the boiling solution. Tube #1 was removed from the hot plate to cool at room temperature.
12:35 Crystals were visible in tube #1.
13:23 The weight of the 5.5 cm diameter sintered glass funnel empty was 56.9334 g. The content of tube #1 was transfered to this sintered glass funnel using a spatula. 1 mL of cyclohexane was used to complete the transfer. The vacuum was turned on to complete the suction filtration. The crystals were spread across the surface of the funnel to dry the crystals.
13:54 The weight of the empty 5-dram vial was 11.8411 g.
14:01 The suction was removed from the filtration flask and the weight of the sintered glass funnel with the crystals was 57.1500 g.
14:12 The crystals were transfered to the 5-dram vial and the vial with crystals (Product A) weighed 12.0339 g.