Narration : 12. Gravity Filtration
- Coarse precipitates are easily separated by gravity filtration using basic apparatuses.
- Fold the filter paper into fourths and fit it into the funnel.
- When the filter paper does not fit well, offset the fold line slightly.
- In order to make the filter paper fit perfectly, cut obliquely the edge of the overlapping filter paper.
- Wet the paper with the solvent and press to fit the paper in.
- Place a beaker in a manner that the stem of the funnel touches its inside wall.
- Put a stirring stick on the mouth of the container and decant the sample slowly when the filtrate is required.
- Don't pour an excessive amount of the sample above edge of the filter paper.
- The filtration proceeds smoothly when the supernatant and then the mixture containing the precipitate are filtrated.
- When the precipitate is needed, quickly pour the swirling sample onto the filter paper.
- Next, add the filtrate to the remaining precipitate in the original container, and then pour the mixture onto the filter paper again.
- Wash the collected precipitate on the filter paper with a washing liquid 2 or 3 times.
- Occasionally, the precipitate can be dissolved by adding an appropriate reagent to yield the sample solution.