Researcher

Matthew McBride

Objective

To determine the solubility of trans-cinnamic acid in acetonitrile and THF using the density method.

Procedure

Cinnamic acid was dissolved in solutions of acetonitrile and THF and placed in a 45C water bath for 15 minutes. The supernatant of each saturated solution was removed and placed in a new test tube. These supernatant solutions were placed in a 25C water bath for 30 minutes to allow precipitate to come out of the solution. The solutions were removed from the precipitate and weighed in a volumetric flask.

Results

ONS-EXP245-Sheet 1
Solubility of cinnamic acid in acetonitrile
5 mL volumetric flask: 0.291M
2 mL volumetric flask: 0.275M

The solubility of cinnamic acid in THF could not be measured because the solution did not precipitate, but it was determined that using a 5mL volumetric flask an approximately 2.4M solution of cinnamic acid in THF is soluble.

Discussion

One previous experiment had determined that the solubility of cinnamic acid in acetonitrile was 0.236M. That experiment was conducted at a temperature of 22.5C. This experiment found solubility values of 0.291M and 0.275M for cinnamic acid in acetonitrile at 24C. These findings strongly agree with the earlier experiment. The predicted solubility of cinnamic acid in acetonitrile was 0.374M. The findings of this experiment are slightly lower than the predicted value, but show some agreement with the predicted value of 0.374M.

The solution that had cinnamic acid dissolved in THF did not form a saturated solution. It was calculated, using an approximate density of 0.8767M for pure THF measured in EXP243, that the molarity of the unsaturated cinnamic acid in THF solution was 2.4M. This value is only an approximation because the density of pure THF was not measured as the experiment was being conducted. However this value of 2.4M supports the hypothesis that the solubility of cinnamic acid in THF is within the range of 2M-3M. EXP242 found that a 2M solution of cinnamic acid in THF was unsaturated and EXP243 found that the solubility of cinnamic acid in THF was 2.3M. Then EXP246 found that in a 3M solution, the cinnamic acid did not fully dissolve into the THF and consequently the solubility had to be less than 3M. The results of these experiments show excellent agreement with the predicated solubility value of 2.824M.

Conclusion

From this experiment, it was determined that at 24C the solubility of cinnamic acid in acetonitrile was measured to be 0.291M and 0.275M. These values support the predicted value of 0.374M.

It was concluded from this experiment that an approximately 2.4M solution of cinnamic acid in THF can be soluble and that based on previous experiments, the solubility of cinnamic acid in THF is in 2M-3M range. This range strongly supports the predicted solubility value of 2.824M.

Log

2012-01-10

14:24 Created a water bath by filling a 150mL beaker with water and placing it on a hot plate. The initial water temperature was 24C.
14:30 Approximately 1.57g of cinnamic acid was transferred to the test tube labeled #1.
14:34 Approximately 4g of of cinnamic acid was transferred to the test tube labeled #2.
14:50 14mL of acetonitrile was placed in test tube #1 and the tube was capped and sealed with parafilm. The tube was inverted several times to be certain that the solution was throughly mixed. This test tube was placed in the water bath that was at a temperature of 45C.
14:55 8mL of THF was placed in test tube #2 and the tube was capped and sealed with parafile. The tube was inverted several times to be certain that the solution was throughly mixed. This test tube was placed in the 45C water bath. The solid could be seen quickly dissolving into the solution.
14:58 All the cinnamic acid had dissolved into the THF (test tube #2). There was no solid visible.
15:00 Took picture #1 - the tubes in the 45C water bath. Took picture #2 - tube #1 (acetonitrile) with cinnamic acid at the bottom. Took picture #3 - tube #2 (THF) with all the cinnamic acid dissolved into the solution.
15:12 The supernatant was removed from test tube #1 and placed in a new tube that was also labeled #1. This solution was placed in a 25C water bath.
15:13 There was no solid visible in test tube #2, so the entire solution was supernatant and the test tube was placed in the 25C water bath.
15:14 Took picture #4 - the tubes in the 25C water bath.
15:15 Precipitate was visible in test tube #1 (acetonitrile), but there was no precipitate visible in test tube #2 (THF).
15:18 Test tube #2 was sonicated, but still no precipitate was visible.
15:21 The weight of the empty 5mL volumetric flask was 18.4978g.
15:22 The weight of the empty 2mL volumetric flask was 9.2263g.
15:27 The weight of the 5mL volumetric flask filled with acetonitrile was 22.4119g.
15:30 The weight of the 2mL volumetric flask filled with acetonitrile was 10.7913g.
15:31 The temperature of the water bath had decreased to 24.5C. The temperature of the lab was at 20C.
15:35 The weight of the empty 5mL volumetric flask was 18.5000g.
15:36 The weight of the empty 2mL volumetric flask was 9.2251g.
15:40 There was no precipitate in tube #2 (THF).
15:42 Tube #1 was removed from the 24C water bath.
15:46 The supernatant of tube #1 was transferred to the 5mL volumetric flask. The weight of the flask with the supernatant from tube #1 was 22.4871g. There appeared to be a very small amount of precipitate that had been transferred with the supernatant to the flask.
15:49 The supernatant of tube #1 was transferred to the 2mL volumetric flask and the weight of that flask was 10.8177g.

2012-01-11

10:41 There was no precipitate in the solution of tube #2 (THF). The water bath had a temperature of 18C.
10:46 The weight of the empty 5mL volumetric flask was 18.5028g.
10:56 The 5mL volumetric flask was filled with the unsaturated solution contained in tube #2 (THF). The weight of the 5mL flask with the solution was 23.3481g.