Gravity Filtrations |
| 1. | Place a conical funnel in a ringstand. The stem of the funnel should be placed in a receiving vessel to collect the filtrate.
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| 2. | Select a piece of filter paper whose radius is slightly smaller than the height of the conical portion of the funnel.
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| 3. | Fold the piece of filter paper in half, and then into quarters. When you make the second fold leave an angle of 5 or 10 degrees between the two edges of the filter paper. Tear the top corner off of the smaller section. Form a funnel such that there are three layers on one side and one layer on the other. Leaving the angle and removing the corner from the paper helps make a tighter seal in the funnel.
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| 4. | Place the filter paper in the funnel and wet it 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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| 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. | Let all the liquid drain through the funnel. Wash the precipitate in the funnel with some more solvent, allowing the solvent to drain through the funnel between each wash. |