Researchers

Lacey Condron with Lizzie Clark

Objective

To determine the solubility of trans-cinnamic acid in ethyl acetate using the density method. The additivity of volumes is an assumption and the density of the solute is obtained from ChemSpider.

Procedure

Ethyl acetate solution was obtained, volumetric flask was weighed (20.2517 g) and the weight of 25 mL of ethyl acetate solution in the 25 mL volumetric flask (42.6683 g) was obtained from electronic balance. Contents of flask was transferred to 100 ml beaker. An excess amount of solvent (5 mL) was added to the 100 mL beaker. The amount of Cinnamic acid was previously calculated using the predicted value plus 33%- planning spreadsheet. Cinnamic acid (5.3100 g) was added using a microspatula. After the cinnamic acid was added, the beaker was covered with parafilm to avoid spilling, contamination and vaporization of the liquid.The beaker was placed in a hot water bath (tap water) at 45 degrees C to allow the solute to fully dissolve.The beaker was swirled periodically to assist in dissolving the solute. After the Cinnamic acid was all dissolved, the beaker was placed in a 25.2 degrees C water bath. This allowed the beaker to cool and begin to form crystals. After sitting for approximately 10 minutes crystals began forming. The flask was weighed with the stopper (23.7854 g) at 25.5 degrees C. 25 mL of the supernatant liquid was pipetted into the 25 mL volumetric flask and the stopper was put back in. The weight of the volumetric flask, supernatant, and the stopper was obtained (46.9090 g). More crystals formed on the bottom of the volumetric flask which was a result of the solution being slightly cooled when being transferred from the 25.5 degree C water bath, to the balance.

Results

The concentration of the saturated sample is 0.787 M at 25.5 degrees C.
https://docs.google.com/spreadsheet/ccc?key=0ArlmW2IqkSdwdHFvRDJyQi1xemhLOVZOMUhqMDRVbHc#gid=0


Log

9:23 - Weighed 25 mL volumetric flask (20.2517 g).
9:27 - Pipetted 25 mL of ethyl acetate into 25 mL volumetric flask. Weighed 25 mL of ethyl acetate (42.6683 g).
9:30 - Poured the previously weighed 25 mL of ethyl acetate into 100 mL along with 33% extra solvent. Added Cinnamic acid (5.3100 g) to beaker.
9:42 - Placed beaker in 45 degrees C water bath using tap water.
9:47 - Swirled the beaker periodically. Water bath maintained temperature between 40-45 degrees C.
10:00 - All Cinnamic acid is dissolved, placed beaker in 25.2 degrees C water bath to allow time for crystals to form.
10:10 - Noticed crystals forming
10:51 - Measured weight of flask plus stopper (same flask as used to measure the pure solvent). 23.7854g
10:52 - Noted temperature of water bath 25.5C
10:54 - Pipetted 25mL of supernatant into volumetric flask and put back stopper.
11:20 - weight volumetric flask plus supernatant and stopper, some crystals had formed on the bottom of the volumetric flask. 46.9090g