Recrystallization:

1. Place 30 mL of 95% Ethanol into a 100 mL beaker, and place it atop your hot plate. Insert a boiling stick into the beaker. Set the hot plate to “3".

2. Seat a fluted filter paper in a stemless glass funnel over a 50 mL beaker on the countertop in your hood.

3. Weigh about 0.8 to 1.0 gm. of your unknown into a 100 mL beaker, using the top-loading balances provided in the laboratory.

4. Add small amounts of the now boiling 95% Ethanol (no more than 20 mL total) to the impure solid in the 100 mL beaker.

5. Insert a boiling stick and place the beaker on the hot plate to boil. Stir the mixture with a glass rod as it is being heated until all of the solid has dissolved. Note: there may be insoluble material such as rocks, boiling chips etc that will, of course, never dissolve…..

6. Pour a small amount of Ethanol (~5 mL) into the fluted filter paper to “wet” it.

7. Now pour your boiling solution as quickly as possible directly into the center of the fluted filter paper in the funnel.

8. At this point DO NOT MOVE THE 50 mL BEAKER UNDER THE FUNNEL UNTIL CRYSTALLIZATION HAS BEGUN.

9. Put the fluted filter paper, which may contain a lot of crystals, into the Recovered Organic Solids jar at the front of the lab (white plastic bottle).

10. Put the 50 mL beaker into an ice-water bath. During this cooling period, place ~10 mL 95% Ethanol in another clean beaker and place that beaker in the ice-water bath.

11. Clamp your 125 mL suction flask to a ringstand with a three-prong clamp, and place the smallest Buchner funnel (with rubber stopper attached) into the neck of the flask. Attach a length of black vacuum tubing to the side-arm of the flask and to the house vacuum line (the valve with the Yellow cap), or to the water aspirator. Place a disk of 4.25 cm filter paper into your Buchner funnel and wet it with a small portion of ice cold ethanol. Remove the beaker from the ice bath, turn on the vacuum, and filter the precipitated crystals with suction

            a) If there are no - or very few - crystals at this point, see the instructor.

            b) If there appears to be no liquid in the beaker and you have a solid mass, add

               another 5 - 10 mL ethanol and stir the mixture, while cooling it in an ice bath.

               Then, filter the solid.

12. After all the solution has drained from the funnel, wash the crystals with about 5 mL ice cold ethanol.

13. When all the liquid has again drained from the funnel, turn the vacuum off slowly, and remove the funnel from the flask. Pour the filtrate into the "Recovered Ethanol" bottle.

14. Leave the top part of the Buchner funnel flat in your drawer for the crystals to dry until the next lab period.

15. Return any excess unused ethanol to the plastic ethanol bottle.