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1- Use a centigram balance to weigh a 50 mL Erlenmeyer flask.Turn on the aspirator and transfer the aspirin slurry into the funnel.In the fume hood, the instructor will transfer 5.0 mL of acetic anhydride from a burette into the flask.3- While the flask is still in the water bath, slowly add 2 mL of distilled water to the flask to decompose any excess acetic anhydride.2- Clamp the flask in a beaker of tap water supported on a ring stand over a burner flame.Place the filter paper in the funnel and moisten with distilled water from a squirt bottle.6- Set up a Buchner funnel on a vacuum flask connected to a water aspirator.Place about 2 g of salicylic acid in the flask and weigh again.Add 5 drops of 85% phosphoric acid (catalyst) to the flask.

1- Use a centigram balance to weigh a 50 mL Erlenmeyer flask. Place about 2 g of
salicylic acid in the flask and weigh again. In the fume hood, the instructor will
transfer 5.0 mL of acetic anhydride from a burette into the flask. Add 5 drops of 85%
phosphoric acid (catalyst) to the flask.
2- Clamp the flask in a beaker of tap water supported on a ring stand over a burner
flame. Stir if needed to dissolve the salicylic acid. Heat the water to boiling, and shut
off the flame. Keep the flask in the hot water bath for 10 more minutes.
3- While the flask is still in the water bath, slowly add 2 mL of distilled water to the
flask to decompose any excess acetic anhydride.
4- After a minute, remove the flask from the water bath and add 20 mL of distilled
water. Let the flask cool to room temperature. As the solution cools, crystals of
aspirin will appear. Cool the solution further by placing the reaction flask in an ice
bath. Chill 5-10 mL of distilled water in a separate container.
5- Weigh a watch glass and filter paper on the centigram balance.
6- Set up a Büchner funnel on a vacuum flask connected to a water aspirator. Place
the filter paper in the funnel and moisten with distilled water from a squirt bottle.
Turn on the aspirator and transfer the aspirin slurry into the funnel. Wash the crystals
with 5 mL of the cold DI water.
7-Transfer the filter paper and aspirin to a pre-weighed watch glass and allow to
air dry in your locker until the next lab period.
8- It is safe to discard of the filtrate down the sink with water.