Researchers

Lizzie Clark

Objective

To measure the solubility of palmitic acid in 1-pentanol using the density method. [specify solvent and provide a link with a description of the density method (see other experiments for the link) JCB]

Materials

25 mL volumetric flask
1-Pentanol
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 1-pentanol into the volumetric flask.
6. Using the electronic balance, measure and record the weight of the filled volumetric flask and 1-pentanol.
7. Calculate the predicted amount of palmitic acid needed for saturation of 30mL of 1-pentanol, plus 33% more than that. Measure out this amount of palmitic acid using the electron balance. Record weight.
8. Pour approximately 30mL of 1-pentanoll into a 100mL beaker.
9. Add measured amount of palmitic acid to the 1-pentanol 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 1-pentanol + palmitic acid solution into ā€¨flask and weigh.
Planning Sheet

Results

The solubility of palmitic acid in 1-pentanol at 25 C was measured to be 1.23185814437747 M. See Calculation Spreadsheet [I cannot leave a comment or see formula used in sheet - you need to enable editing by anyone JCB]

Log

9:16- Empty 25mL volumetric flask weighed to be 20.258g
9:19- Volumetric flask filled with 25mL of 1-pentanol and weighed to be 40.548g
*Room temperature at 20.6 C
9:21- Poured approximately 30mL of 1-pentanol into a 100 mL beaker
9:26- Measured out approximately 10.33g of solute, according to the predicted needed value. (measured out exactly 10.372g)
9:31- Added the 10.372g of palmitic acid to the 30 mL of 1-pentanol in beaker and parafilmed.
9:32- Placed beaker in ~42 C hot water bath and swirled till all solute dissolved.
9:35- Added more hot water to bath to raise temperature to 46 C, continued swirling.
9:40- Added more hot water to bath to raise temperature to 50 C, continued swirling.
9:43- All solute dissolved. Parafilmed beaker placed in 26 C cool water bath.
10:02- Solution turned to slush. (In order to later beable to obtain 25 mL of solution) Added ~20 mL more 1-pentanol to the solution and dissolved in approximately 50 C water bath.
10:06- Replaced in cool water bath (26 C)
*Small crystals started forming after about 15 mins. We agitated the crystals and left them in cool bath again to cause more rapid crystal formation.
10:39- Empty flask weighed to be 20.238g.
10:46- Decanted solution and poured 25 mL into flask. Weighed 40.911g.