Experimental supplies: one bottle of toilet water (narrow neck, 195 mL), and about half a bottle of expired toilet water.
Experimental steps: pour about half a bottle of water into an empty toilet water bottle, then slowly pour about half a bottle of toilet water into the bottle mouth, block the bottle mouth with your thumb, turn the bottle upside down, and then reverse it, so as to make the liquid in the bottle mix evenly twice, and observe whether the liquid level is lower than the bottle mouth.
Experimental phenomenon: the liquid level is obviously lower than the bottle mouth.
2. Self-made simple water purifier
Take an empty plastic beverage bottle, cut off the bottom, plug the bottle with a single hole with a catheter, turn the bottle upside down, and put in washed fluffy cotton, gauze, activated carbon, quartz sand, pebbles, etc. Layers are stacked in the bottle from bottom to top to get a simple water purifier.
The experimental results show that: ① pebbles and quartz sand should be cleaned, and pebbles and quartz sand play a filtering role. ② If there is no single-hole plug with catheter at home, you can punch several small holes on the bottle cap instead of the single-hole plug with catheter. There are many experimental projects, and students can cooperate with each other. For example, students who have cotton at home can bring more cotton.
3. Graphite conductivity experiment
Connect the graphite electrode or the pencil lead of 6B with wires. Does the light bulb glow when the power is turned on? What does this experiment show?
The experimental results show that: ① For 6B pencil lead, it is not common to take out the graphite electrode from the waste dry battery in the market. ② You can use the dry battery and small light bulb in the flashlight. ③ Batteries, copper wires and small bulbs can be fixed with single-sided adhesive tape.
4. Reaction between eggshell and acid
Take a small glass, put it into the washed broken egg shell, add some vinegar (mainly acetic acid), and immediately cover it with a glass sheet soaked in clarified lime water. Observe carefully what happened. According to the experimental phenomenon, there may be something in the eggshell.
Experiments show that: ① families can make clear limewater. The main component of some food desiccants is quicklime, such as "strong desiccants" in laver. Take a glass, add about half a glass of water, add a pack of "strong desiccant", stir with chopsticks and let stand. Pay attention to the exothermic phenomenon of quicklime reacting with water. (2) When there is no glass at home, you can use a small mirror instead. ③ Experiments can also be done to clarify the blowing in limewater.
5, homemade soda
Add 2 spoonfuls of sugar and appropriate amount of fruit juice to a 500 mL beverage bottle, add about 1.5 g baking soda (sodium bicarbonate), inject cold water, then add about 1.5 g citric acid, immediately tighten the bottle cap, shake well and put it in the refrigerator. After half an hour, you can drink cool and sweet soda.
6. Write a secret letter with onion juice
Experimental supplies: onions (two), writing brush, white paper, candles.
experimental procedure
Take two onions, cut off their leaves, make them white, squeeze out onion juice, and then dip the onion juice with a brush and write on a piece of white paper. After a while, the onion juice dried up and the handwriting on the white paper disappeared. If this piece of white paper is baked by candlelight, the brown words will appear immediately. Onion juice can make paper undergo chemical changes, forming a substance similar to a transparent film with a lower ignition point than paper. It will burn when baked on the fire, so it will show brown handwriting. Lemon juice, garlic juice, onion juice and vinegar all have this property, so they can also be used to write secret letters.