Objectives:
1. Purify a commercial sample of Phthalic acid by recrystallization.
2. Record the mass and melting point of the recrystallized product.
3. Calculate the percent recovery.
Procedure:
1. Place 100 mg of phthalic acid in a small test and add 1-1.5 mL of water (adding just enough to cover the solid)
2. Place a boiling stone in the test tube and heat the solution to boiling on a heating mantle with a Variac setting of 50. Use a test tube holder when heating your solution, making sure to point the tube away from yourself and others.
3. As soon as boiling begins, add water drop wise until most of the solid has dissolved. CAUTION! Do not add too much water! You must maintain a saturated solution. Insoluble impurities may remain in suspension. If insoluble impurities are not present, proceed to step 5.
4. Remove the insoluble impurities if present by hot gravity filtration (consult TA before performing this step; see page 308 for details).
5. Allow the hot solution in the test tube containing the phthalic acid and soluble impurities to stand for 5-10 minutes at room temperature.
6. Complete the recrystallization by cooling the solution in the test tube in an ice bath.
7. Collect the product by suction filtration.
8. Wash the product free of soluble impurities with a few drops of ice cold solvent (water). Why does it need to be cold?
9. Leave product draining the Büchner funnel for a few minutes to remove as much of the solvent as possible.
10. Carefully
