Researchers

Lizzie Clark with Andrew Lang

Objective

To measure the solubility of palmitic acid in 2-butanol using the density method.

Materials

25 mL volumetric flask
2-Butanol
Electronic Balance
Hot Water Bath
Parafilm
Weigh Paper
Chemical Spatula (for measuring out solute)
Thermometer
Palmitic Acid
Lab Coat
Gloves
Goggles

Procedure

1. Put on safety gear including goggles, lab coat, and gloves.
2. Gather the materials listed above.
3. Measure and record the temperature of the balance room (preferably in Celcius to make later calculations easier).
4. Using the electron balance, weigh and record the empty 25 mL volumetric flask (g).
5. Carefully pour 25 mL of 2-butanol into the volumetric flask.
6. Using the electronic balance, measure and record the weight of the filled volumetric flask and 2-butanol.
7. Calculate the predicted amount of palmitic acid needed for saturation of 30mL of 2-butanol, plus 33% more than that. Measure out this amount of palmitic acid using the electron balance. Record weight.
8. Pour approximately 30mL of 2-butanol into a 100mL beaker.
9. Add measured amount of palmitic acid to the 2-butanol in the beaker, swirl, and parafilm.
10. Measure and record the temperature of the laboratory area (in Celsius).
11. Place beaker in warm water bath of around 45C and observe until crystals form (indicating that the solution is saturated).
12. Weigh empty 25mL volumetric flask (to assure that it is the original one used or to obtain the new weight).
13. Pipette 25mL of the saturated 2-butanol + palmitic acid solution into ā€¨flask and weigh.
Planning Sheet

Results

The solubility of palmitic acid in 2-butanol at 25 C was measured to be 1.19M. See Calculation Spreadsheet

Log

9:15 Measured ~2.18 (2.1901g) of palmitic acid.
9:16 Weight of the empty flask measured to be 20.0402g.
9:17 Pipetted 25 mL of 2-butanol into a 25 mL volumetric flask.
Note: Room temperature at 19.5 C.
9:18 Weight of flask and solvent measured to be 40.1728g.
9:19 Added solvent to beaker and added more 2-butanol to fill to ~30mL.
9:20 Added the 2/1901g of palmitic acid to the ~30mL of 2-butanol and parafilmed.
9:25 Placed beaker in 54 C hot water bath and swirled till solute dissolved
9:28 Solute completely dissolved.
9:30 Beaker placed in 25 C cool water bath.
10:40 No precipitate had formed. Added ~1g more solute, parafilmed, and placed in 50C water bath.
10:45 All solute dissolved after swirling. Placed parafilmed beaker in 25C water bath.
12:30 Crystals had formed.
12:40 Weight of empty flask 20.0440g
12:45 Wieght of flask plus saturated solution 40.6040g