Gravity Filtrations

Gravity Filtrations

In this example we will be filtering solid copper metal from a solution.

1. Place a conical funnel in a ringstand. The stem of the funnel should be placed in a receiving vessel to collect the filtrate.

2. Select a piece of filter paper whose radius is slightly smaller than the height of the conical portion of the funnel.

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.

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.

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.

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.

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.

When filtering is complete, the filtrate should be in the receiving vessel, while the solid remains in the funnel.