| 1.
| Place the stem of a Buchner funnel thorough a one hole stopper that fits an available filter flask. Attach the filtering flask to a vacuum trap and the vacuum trap to a vacuum pump or aspirator. To prevent the tubing from collapsing under vacuum the tubing must be heavy walled. The trap will prevent water from being drawn back into the system should the aspirator be accidentally or incorrectly turned off.
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| 2.
| Buchner funnels have small holes in the bottom. Obtain a piece of filter paper that fits flatly inside in the Buchner funnel and completely covers all of the holes.
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| 3.
| Wet the filter paper with a small amount of the solvent present in your solution. For example, if you have an aqueous solution, wet the filter paper with some water from your wash bottle.
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| 4.
| Turn on the suction. The partial vacuum created will speed up the filtration.
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| 5.
| Let the solid settle to the bottom of your container and then gently pour the liquid from the beaker into the funnel using a stirring rod as a guide (do not fill the funnel up more than two thirds full). This process is called decanting.
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| 6.
| Now transfer the solid to the beaker using a glass stirring rod or rubber policeman. When most of the solid is transferred, rinse the stirring rod and beaker with some solvent. Pour this into the funnel as well.
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| 7.
| Allow all the liquid to drain through the funnel. Wash the precipitate in the funnel with some more solvent, allowing the solvent to be drawn through the funnel between each wash.
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| 8.
| Allowing air to be drawn through the solid will help it dry, but should be avoided if the material will react with the oxygen or carbon dioxide present in the air.
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| 9.
| Release the vacuum on the system by removing the tubing connecting the vacuum trap to the vacuum or by opening the vent valve on the pump. Now turn off the vacuum or aspirator.
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