1, we can't see the dissolution process of salt in water. In order to let everyone clearly observe the dissolution process, the teacher asked a friend to realize this wish. This colored substance is called potassium permanganate. Because it is used for disinfection and antisepsis, you can't touch it directly with your hands, let alone put it in your mouth. The teacher made it with this medicine spoon. Now the teacher has prepared potassium permanganate for everyone.

Please open the small paper bag and observe the potassium permanganate carefully. After about 1 minute,

Let the students describe: potassium permanganate (a solid substance with purple-black metallic luster)

3. Experimental description: Now, observe the dissolution of potassium permanganate (show the third PPT).

4. Students in each group report: What happened before and after potassium permanganate entered the water? (The teacher shows the students' records on the projection, paying special attention to the students' description of the observation details) (Show the fourth PPT)

Potassium permanganate particles quickly sink to the bottom of the water after being put into it. Purple stripes appear in the water through which potassium permanganate passes, and the outside of potassium permanganate first becomes tiny particles, which are dispersed in the water. Purple cloud-like waters slowly appeared around the settled potassium permanganate, and more potassium permanganate particles were dispersed into the water. After stirring, the range of purple is constantly expanding, and all the water in the beaker becomes purple, and potassium permanganate particles are evenly distributed in the water.

Can we say that potassium permanganate has been dissolved in water now? (If you say it, just do it, if you can't guide it, just do it: What other methods did we use last class to get to know it? Can it be filtered and separated? ) demonstration. Please state the final result. Potassium permanganate is soluble in water.