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Anonymous users2024-02-05Using a bowl, a straight glass, a candle, a small piece of wood, water and matches, a test was designed to determine the oxygen content in the air.
1. Briefly write down the test plan, phenomenon and results.
2. What is the difference between the test result and the standard result of oxygen content in the air? What is the reason?
3. What substances can be used instead of candles to burn in the air to make the test results more accurate?
4. If the candle is not changed, what liquid can be used instead of water to make the test results more accurate?
1.Solution: Fill the bowl with water;
Fix the candle on a small wooden board, put it in a bowl (the wooden board will not sink due to the buoyancy of the water) and light it with a match, and then turn the glass upside down on the small wooden board (note: the mouth of the cup must be submerged in the water);
Observe the phenomenon. Phenomenon: The water level in the cup will rise slowly, and the candle will be extinguished when it is lit.
Result: The water level in the cup rises slightly by 20 and the candle goes out.
2.Unclear, cause: combustion produces carbon dioxide, soluble in water; The air contains a small number of gases that can be burned, such as nitrogen dioxide, etc., and the combustion products are also contained in water; Slightly larger. Candles occupy a portion of the volume; Slightly smaller.
3.Combustibles that are relatively small in size.
4.Mercury.
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Anonymous users2024-02-04It is proved that the essence of buoyancy is the pressure difference between the upper and lower surfaces:
Equipment: 1 drink bottle, 1 table tennis ball, water.
1. Cut the bottle from the middle, not the bottom, as long as there is a bottle mouth on it.
2. Turn the drink bottle upside down and put the ping pong ball in it.
3. Add water to the bottle until the water submerges the table tennis ball, and we will find that the table tennis ball does not float.
4. Plug the bottle mouth with your hands, and the table tennis ball will quickly float up.
Analysis: Step 3: Since there is no water on the lower surface of the table tennis ball, only the upper surface is subject to the downward pressure of the water, so the table tennis ball will not float, that is, it will not be buoyant.
Step 4: Plug the bottle mouth with your hands, and if there is water under the ping pong ball, it will be subject to upward pressure. Since the pressure on the lower surface is greater than the pressure on the upper surface, the ping pong ball will float up.
You'll have to analyze the rest.
The buoyancy part is the knowledge of the 8th grade, I don't know if you have learned it.
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Anonymous users2024-02-03The little science experiments I've done are as follows:
1. Candles absorb water
Prepare a candle, a bottle of pigment, a bowl of water, a tray and a cup, then pour some pigment into the water, stir to dye it, prevent the candle from floating on the water, and then use a lighter to light the candle, and when the fire gradually increases, cover the candle with a cup, wait for the fire to gradually extinguish, and finally you will find that the liquid level in the cup has risen. In fact, it is because the outside atmospheric pressure is greater than the air pressure inside the cup that causes the liquid level to riseI hadn't learned anything about it at the time, so I thought it was interesting and did it again.
2. "Pharaoh's Serpent".
I saw this experiment on the Internet, and I thought it was a bit magical, so I followed it in the laboratory with the teacher's permission. Start by preparing a basin of sand, a bottle of alcohol, sugar, baking soda and matches; Then pour alcohol into the sand, add sugar and baking soda to the sand, and then light the mixture with a lit match, and you can see a black mass coming out of the sand, which is the "Pharaoh's Serpent". This experiment is similar to the one in high school, and the addition of concentrated sulfuric acid to white sugar will also show a similar situation, but the reasons for the two experimental phenomena are different.
3. Table tennis does not fall
All you need is a hairdryer and a table tennis ball. Turn on the hair dryer and put the ping pong ball on the hair dryer, you will find that the ping pong ball will not fall, even if the hair dryer is tilted 45 degrees, the ping pong ball will not fall. This is actually Bernoulli's principleAlthough I learned Bernoulli's principle in my freshman year, I still haven't figured out the reason, and I haven't found out why even though I've done many experiments, maybe I didn't learn it!
Fourth, the bottle rotates
Prepare a bowl of water, two glass beads, and a mineral water bottle. Pour the water into the mineral water bottle, almost a third of the bottle, then put two glass beads into the bottle, tighten the cap, turn the bottle upside down, manually rotate it for a while and then let go, only to find that the bottle actually turns on its own, and sometimes even flies off the table. This is actually using the principle of inertia to make the bottle turn on its own.
I've done a lot of science experimentsBecause practice is the only criterion for testing the truth, only after practice can we remember it more deeply, and these little experiments are also very interesting and magical!
Hopefully, these science experiments will spark your interest in experimentation.
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Anonymous users2024-02-02——— because the high school I studied was a high school, I had many opportunities to practice science experiments during my time in school, and I did elephant toothpaste experiments, pharaoh's snake and hydrogen and oxygen mixture** experiments, etc., these three experiments were the most impressive experiments I did in high school.
The first is the elephant toothpaste experiment.
This was an expanded experiment when the chemistry teacher introduced us to hydrogen peroxide in class, but what we didn't expect was that the teacher arranged this experiment for us shortly after. The main process of the experiment is to mix the concentrated hydrogen peroxide with soap and stir it evenly, plus some potassium iodide as a catalyst to catalyze the rapid reaction, and soon you can see the test solution in this Erlenmeyer flask gushing out. It is important to note that the concentration of hydrogen peroxide must be greater than 30%.
Because the liquid sprayed resembles elephant toothpaste, it is called an elephant toothpaste experiment.
The principle of the experiment is mainly that hydrogen peroxide decomposes rapidly, decomposes a large amount of oxygen, and then combines with the foaming agent to produce a large number of bubbles. During the experiment, it is necessary to pay attention to the corrosive nature of high concentrations of hydrogen peroxide, and the heat phenomenon is accompanied by the experimental process, so personal protection is required.
This was followed by the brown bread experiment.
This experiment is an experiment arranged for us by our chemistry teacher as it is said in the chemistry textbook that concentrated sulfuric acid can carbonize sugar.
This experiment was based on the Pharaoh's Serpent Experiment. The original Pharaoh's Serpent experiment used mercury thiocyanide to decompose it by heat, but because mercuric thiocyanide is highly toxic, we used white sugar as the raw material for this brown bread experiment. The process of the experiment is very simple, only need to add a large amount of white sugar to the beaker, then pour concentrated sulfuric acid and stir quickly, use the dehydration of concentrated sulfuric acid to quickly oxidize and carbonize the sugar, and then a black sponge-like solid will be produced in the beaker and continue to extend out of the beaker, and produce a large amount of white gas.
After adding the material, it should be quickly kept away from the beaker, do not touch the black solid produced is easy to cause corrosion, and the gas produced is sulfur dioxide, do not inhale, pay attention to maintain ventilation.
Finally, there is a mixed light experiment with hydrogen and oxygen.
Because of the danger of this experiment, this experiment was done by the teacher on our behalf. Normally, hydrogen and oxygen will produce a pale blue flame when ignited, but if two gases are mixed 1:1 and then irradiated with strong light**.
**The power should not be underestimated, in the process of the experiment also need to do a good job of protective isolation, wear good goggles, when our teacher used two glass covers to conduct experiments, and finally the inner glass cover was completely broken.
Doing these interesting scientific experiments can increase our understanding of the principles of experiments, increase our interest in scientific experiments, improve learning efficiency, and improve our ability to practice.
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Anonymous users2024-02-01Children's imagination is the richest, and we who are growing up have long been contemporary"Stereotyped thinking"Influence, losing the ability to let your mind fly. I still remember when I was younger, I used to fantasize about itThe protagonist in "Flying House Travel" flies into the sky and soars freelyand bravely tried; When I grew up, I triedI used the ** and portrait in my mobile phone to complete the sports check-in, and I also used the sunlight to gather and ignite the wood.
I believe that everyone has had all kinds of strange ideas, but how many of them really find a way to achieve them?
I am one of the few who try to prove my ideas, and I am not like those scientists, who have left a legacy of knowledge for future generations by making their own efforts to discover the rules. I'm just standing on the shoulders of giants to further understand what my heart is eager to try"Why"。
When I was still young, I tied a lot of balloons with the help of my parents. The force of the balloons almost carried me up, but I just stumbled a little, and my parents were so frightened that they lifted the balloons off my waist, and they couldn't afford to have an accident. I thought that I shouldn't be able to bring it up with the power of the balloon alone, but as a result.
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