Experiment: 8 Determining the Solubility of Aspirin at Different Temperatures and Calculating the Heat of Solution

Experiment: 8
Determining the Solubility of Aspirin at Different Temperatures and Calculating the Heat of Solution
Procedure
1) Grind up two aspirin tablet to a fine powder using the pestle and mortar.
2) Prepare saturated solution form aspirin in 100mL distilled water at room temperature (25 oC).
3) Filtrate the aspirin solution and transfer 10 ml from filtrated solution to conical flask.
4) Add 2-3 drops of phenolphthalein indicator solution (Swirl for at least 3 minutes).
5) Titrate carefully with 0.05M sodium hydroxide (Swirl the flask continuously, The NaOH solution should be added very slowly, The end point is reached at the first instance of the pink colour persisting).
6) Record the volume of the sodium hydroxide used. Repeat the titration procedure twice.
7) Repeat this procedure at 40 oC and 60 oC (using water bath for 10-15 min.).
8) To calculate the purity of aspirin in tablet:
I. Measure out accurately 10mL of ethanol and transfer to the conical flask. Note: Ethanol is used in this case as aspirin does not easily dissolve in water.
II. Add 25mL of distilled water to the conical flask. Finish the above procedure.