Date: 31st Jan ‘13
EXPERIMENT # 2RECRYSTALLIZATION; FILTRATION
1. To perform recrystallization and filtration of given impure organic compound. 2. To purify impure acetanilide using reflux condenser apparatus and Hirsch funnel filtration. 3. To determine percentage recovery of pure material (which is), purified by recrystallization and filtration.
1. Operate the aspirator with the maximum water-flow using a stop cock to control the amount of vacuum. 2. Do not leave the apparatus unattended for long if several students are using aspirators on same water line, because of the possible pressure fluctuations.
CHEMICALS: Impure acetanilide, charcoal, water.
EQUIPMENTS: Reflux condenser apparatus, 250 mL round bottomed flask, Hirsch funnel and filter flask.
1. Take a 50-mL round-bottomed flask and a small condenser and set up a reflux apparatus. Arrange a ceramic fibre-centered wire gauze on an iron ring such that it remains two inches above the burner. Position the clamps on flask and condenser accordingly. 2. Weigh a 2.0-g of impure acetanilide and keep just pinch of it aside for melting point determination. Add rest of it to the 50-mL flask by temporarily removing reflux condenser. 3. Add one or two boileezers to the flask, reset the apparatus properly and add 30 mL of water through the top of the condenser. 4. Keep the water circulating through the condenser by attaching the lower end of its water jacket to a water outlet and the upper end to the sink with help of rubber tubing. 5. Adjust the burner to heat the water and let it boil gently such that the water refluxes in a steady drip from the bottom of the condenser. 6. Keep on heating the mixture till the solid stops to dissolve. Then remove the burner and cool the flask for a moment. 7. Remove the condenser carefully and add a very small amount of decolourizing charcoal to the...