How Will You Use a Filter Paper for Filtration?
The choice of filter paper should be determined according to the requirements of the analysis work for filtration and precipitation and the nature and quantity of the precipitation. There are two types of filter papers available in HAWACH. The difference between quantitative filter paper and qualitative filter paper is mainly in the amount of ash produced after ashing: qualitative filter paper does not exceed 0.13%, and quantitative filter paper does not exceed 0.0009%. they can be used in different experiments. According to the size of pores, both quantitative and qualitative filter paper can be divided into three types: fast, medium, and slow. Fast filter paper has large pores, while slow filter paper has small pores.
1. Fast filter paper: because the paper is loose and the spots are easy to spread, it is suitable for samples with large Rf values and developing agents with large viscosity;
2. Slow filter paper: spots are not easy to spread, suitable for samples with small Rf value and developing agents with low viscosity, but the developing time is long;
3. The medium-speed filter paper is between the two.
Filter paper usage
In experiments, filter paper is often used together with equipment such as filter funnels and Buchner funnels. Before use, it needs to be folded and a flower-like shape is commonly used. The higher the folding degree of the filter paper, the higher the surface area it can provide and the better the filtering effect, but be careful not to over-fold the filter paper and cause the filter paper to break. Put the drained glass rod on the multi-layer filter paper and apply it evenly to avoid damage to the filter paper. Here are the operation processes.
1. Fold the filter paper in half, twice in a row, into a 90° central angle shape.
2. Form a funnel by pressing one side of folded filter paper into three layers and one layer on the other side.
3. Put it into the funnel, with the filter paper edge lower than the funnel edge. Pour some water into the mouth of the funnel to make the soaked filter paper against the inner wall of the funnel, and then pour out the remaining water. Set aside.
4. Place the funnel with the filter paper on the funnel holder for filtering (such as the ring of the iron frame), place the beaker or test tube that receives the filtrate under the neck of the funnel, and make the tip of the neck of the funnel rest against the surface of the receiving container. on the wall.
5. When pouring the liquid to be filtered into the funnel, hold the liquid beaker in the right hand and the glass rod in the left. Make the glass rod’s lower end is close to the three-layer funnel lower side, to ensure the cup mouth is close to the glass rod until the filtrate body flows out along the cup mouth, and then along the slope of the glass rod, it flows into the funnel, and the liquid flowing into the funnel cannot exceed the height of the filter paper in the funnel.6. When the liquid flows down the funnel neck through the filter paper, check whether the liquid flows down the wall of the cup and pours to the bottom of the cup. Otherwise, the beaker should be moved or the funnel should be rotated so that the tip of the funnel is firmly attached to the wall of the beaker so that the liquid can flow down slowly along the inner wall of the beaker.