The filter paper used in the experiment was used together with instruments such as a filter funnel and a Buchner funnel. The filter paper must be folded into a suitable shape before use. A common method of folding is to fold the filter paper into a flower-like shape. The higher the degree of folding of the filter paper, the higher the surface area that can be provided and the better the filtering effect, but be careful not to overfold and cause the filter paper to break. Place the drained glass rod on a multi-layered filter paper and apply even pressure to avoid damaging the filter paper.

Operation process

1. Fold the filter paper in half, successively, and fold it into a 90° central angle.

2. Press the folded filter paper into three layers on one side and one layer on the other side to form a funnel.

3. Fill the funnel-shaped filter paper into the funnel. The edge of the filter paper should be lower than the edge of the funnel. Pour some clear water into the funnel mouth so that the soaked filter paper and the inner wall of the funnel will be in contact with each other. Then, pour out the remaining clear water and wait.

4. Place the filter paper-filled funnel on the filter hopper frame (such as the ring of the iron platform). Place a beaker or test tube under the funnel neck to receive the filtrate and place the funnel neck against the wall of the container. on.

5. When injecting the liquid to be filtered into the funnel, hold the liquid beaker in the right hand, and hold the glass rod in the left hand. The lower end of the glass rod should be tight against the lower surface of the funnel to make the cup close to the glass rod, and the liquid to be filtered flows out along the cup opening. Then, along the inclination of the glass rod, flow into the funnel, flow to the liquid in the funnel, the liquid level can not exceed the height of the filter paper in the funnel.

6. When the liquid passes through the filter paper and flows down the neck of the funnel, check to see if the liquid flows down the cup wall and into the bottom of the cup. Otherwise, the beaker or rotating funnel should be moved so that the tip of the funnel and the wall of the beaker are firmly attached, so that the liquid can slowly flow down along the inner wall of the beaker.