Dominican University Student Project
1/23/09 Raquel Robles

Solute
Benzoic Acid
SMILES
OC(=O)C1=CC=CC=C1
Type/Classification
Carboxylic Acid
Chemspider Link
http://www.chemspider.com/Search.aspx?q=benzoic+acid
Solvent
Methanol
SMILES
OC
Average Solubility (g/100g)
37.8/100
Average Concentration (mol/L)
2.37
Chemspider link of solvent
http://www.chemspider.com/Search.aspx?q=methanol

Solubility Procedure
This lab started by gathering the solute (Benzoic acid) and the solvent (Methanol). The solute was placed inside a beaker and 5 mL of the solvent was pipetted into a 25 mL glass Pyrex Erlenmeyer flask for each trial. The solute was transferred to the mixing flask in small increments using a spatula. It was immediately noticeable that the solute was extremely soluble in the solvent. To quicker the mixing process, a sonic wave bath was used to dissolve large amounts of solute. Saturation was reached when a couple of small white flakes of solute were not dissolving. Four samples were created.
The solution was transferred to a small test tube using a glass pipette; then were placed inside a centrifuge to remove any extra solute in solution. The tubes were in the centrifuge for 5 minutes each. The evaporation vessels (20 mL scintillation vials) were weighed at this time.
When the test tubes were taken out the centrifuge, a 5 mL glass pipette was used to measure the volume of each solution, and then the solution was transferred to the evaporation vessels. The evaporation vessels with the solution inside them were weighed. A hot water bath was set up using a 125 mL glass Pyrex beaker 1/5 filled with water on top of a “Lab Companion” hot plate. The vessels were placed inside a hot water bath and while trying to transfer them carefully, one fell over inside the bath. The liquid and vessel were removed and another solution was created in the same way as the others as a replacement. Then, this vessel was also placed inside the hot water bath. A thermometer was placed in the beaker with water to make sure the water did not get unnecessarily hot.
The methanol evaporated quickly at around 80 degrees Celsius and left behind solute. The evaporation vessels with the solute in them were weighed and left out to dry more thoroughly. After prolonged drying, the samples were weighed again for a more accurate reading.

TABLE 1: Raw Data and Calculated Solubility

EXPERIMENT
1
2
3
4
Solute
Benzoic Acid
Solvent
Methanol
Solvent Density (g/mL)
0.792
Mass of Empty Evaporation Vessel (g)
12.812
12.854
12.790
12.872
Volume of Solution (mL)
6.0
6.4
6.0
6.0
Mass of evaporation vessel + solution (g)
17.572
17.669
17.448
17.322
Mass of evaporation vessel + solute (g)
14.675
14.716
14.591
14.579
Mass of evaporation vessel + solute after prolonged drying (g) (used for calculations)
14.674
14.722
14.416
14.573
Solubility (g/mL)
0.310
0.292
0.271
0.284
Concentration (mol/L)
2.54
2.39
2.22
2.32
Molality (mol/kg solution)
5.24
5.19
4.39
5.07
Solubility (g/100g solution)
39.1/100
38.8/100
38.7/100
38.4/100