IV
11. Set up the Hirsh funnel from the microkit as shown in the illustration to the right. Be sure to clamp the filter flask to a ring stand and to place a piece of filter paper in the funnel. Connect a rubber hose from the side-arm on the flask to the side-arm of the aspirator. Turn on the aspirator. Pour the crystals and mother liquor from the beaker into the Hirsh funnel. If some crystals stick to the beaker, you can scrape them out with a spatula or wash them out with the mother liquor in the filter flask if you used a clean flask. Allow air to be drawn through the crystals for 10 minutes. Place the crystals in an unstoppered vial in your drawer.
12. Next time weight the crystals of caffeine and determine their melting point. The melting point reported in the literature is 238o C, so you can heat the Thiele tube rapidly at least up to 200o C. Do not exceed the 260o C limit of the thermometer. Hand your sample of caffeine in along with your report sheet.