Researchers

Lacey Condron with Lizzie Clark and Samantha Gaines

Objective

To determine the solubility of trans-cinnamic acid in 2-propanol using the density method. The additivity of volumes is an assumption and the density of the solute is obtained from ChemSpider.

Procedure

2-propanol solution was obtained, volumetric flask was weighed (20.2636 g) and the weight of 25 ml of 2-propanol solution (19.6206 g) was obtained from electronic balance. Contents of flask was transferred to 100 ml beaker. An excess amount of solvent was added to the 100 mL beaker making approximately 30 mL of solvent. The amount of Cinnamic acid was previously calculated using the predicted value plus 33%-Planning Sheet. Cinnamic acid (5.7209 g) was added using a microspatula; this procedure was done in a room with a measured temperature at 19.9 degrees C. 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 25.0 degrees C water bath. This allowed the beaker to cool and begin to form crystals. After sitting for approximately 30 minutes crystals began forming. The flask was weighed (20.2754 g) at 19.0 degrees C. 25 mL of the supernatant liquid was pipetted into the 25 mL volumetric flask. The weight of the volumetric flask and supernatant was obtained (41.1984 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 24.3 degree C water bath, to the balance.

Results

The concentration of the saturated sample is 0.949 M at 24.3 degrees C.
Calculation Spreadsheet

Log

9:09 Weighed of 25mL volumetric flask- 20.2636 g
9:10 Pipetted 25mL of 2 propanol into the previously weighed volumetric flask. Weighed 25mL of 2-propanol- 19.6206 g
9:12 Poured the previously weighed 25mL of 2-propanol into 100mL beaker along with 10mL extra of solvent.
9:13 Weighed/ added cinnamic acid (5.7209 g) at 19.9 degrees C.
9:31 Placed beaker in 45 degree C water bath using tap water.
9:32 Beakers were continuously swirled to assist in the dissolving process while the temperature of the water bath was maintained to stay within 40-45 degrees C.
9:39 All cinnamic acid is dissolved, beaker was placed in a 24.3 degrees C water bath.
10:08 No precipitate visible. Swirled beaker and removed parafilm.
10:40 Crystals had formed. Temperature of bath 24.3C
10:45 Weighed empty 25mL volumetric flask - same one as used to weigh pure solvent - 20.2754g
10:53 Pipetted 25 mL of supernatant from beaker to volumetric flask 24.3C and parafilmed
11:05 Noted temperature of balance room 19C. Crystals had formed in the bottom of the volumetric flask.
11:06 Removed parafilm and weight flask plus supernatant - 41.1984g.