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CELamCheng
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shocked.gif posted on 27-6-2020 at 02:13
What phenomenon this is?


I dissolved KNO3 in room temperature water and filtered. The solution almost saturated. I filtered more solution. This solution is more saturated. When the more saturated solution drop in the not so saturated solution it sink to bottom. I also saw when solution drops into the another solution some rare bubbles formed. The bubbles sink to bottom then break. Some air float back up. What bubbles these are?



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mackolol
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[*] posted on 27-6-2020 at 02:34


How did you filter it?
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Ubya
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[*] posted on 27-6-2020 at 02:47


the more saturated solution going at the bottom of the less saturated solution is not something strange, a denser solution will stay below a less dense one.
the bubbles? you said "some air floats back up" do you mean that some bubbles are still at the bottom?





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CELamCheng
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[*] posted on 29-6-2020 at 02:09


I use paper towel to filter.
Solution density I understand. I only dont understand why have bubble sink to bottom. I saw largest bubble diametre about 5mm. When it break has a smaller bubble float back up surface. I guess small bubble is air. The small bubble smaller than 1mm.




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B(a)P
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[*] posted on 29-6-2020 at 02:49


Quote: Originally posted by CELamCheng  
I dissolved KNO3 in room temperature water and filtered. The solution almost saturated. I filtered more solution. This solution is more saturated. When the more saturated solution drop in the not so saturated solution it sink to bottom. I also saw when solution drops into the another solution some rare bubbles formed. The bubbles sink to bottom then break. Some air float back up. What bubbles these are?


Are you certain that the 'bubbles' are not in part small crystals of KNO3 forming? Dissolved gasses may come out of solution and adhere to the crystals. When the crystals hit the bottom the gas bubble is bumped off and rises to the surface.
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CELamCheng
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[*] posted on 29-6-2020 at 19:47


Not crystals. Bubbles are spheres. I dont think 5mm crystal can through filter lor.



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[*] posted on 30-6-2020 at 14:26


I think you may have observed so-called antibubbles.

Sounds like a joke, but it is not: https://en.wikipedia.org/wiki/Antibubble

Rather than a bubble of air, they consist of a droplet of liquid surrounded by a film of air.
They are easy to make with a soapy solution by allowing drops to fall in a glass of soapy water from a few cm's above the surface. They look very similar to bubbles, but you can recognise them because they float to the surface much more slowly.

The antibubbles you made contain a droplet of concentrated solution, which makes them more dense than the solution they are in. The thin film of air does not provide enough buoyancy, hence they sink rather than float. When they break, the little film of air forms a small regular air bubble that floats to the surface.

Edit: I found a video on youtube with a nice demonstration, showing many aspects of the phenomenon that you also observed: https://www.youtube.com/watch?v=cosjx9fGuPY

[Edited on 30-6-2020 by phlogiston]




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mysteriusbhoice
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[*] posted on 20-7-2020 at 04:37


Quote: Originally posted by CELamCheng  
I dissolved KNO3 in room temperature water and filtered. The solution almost saturated. I filtered more solution. This solution is more saturated. When the more saturated solution drop in the not so saturated solution it sink to bottom. I also saw when solution drops into the another solution some rare bubbles formed. The bubbles sink to bottom then break. Some air float back up. What bubbles these are?


A more saturated solution is denser than less saturated one and hence 1st phenomenon is related to difference in density.
The 2nd one is called an anti bubble where you have a fluid surrounded by air in another fluid and sometimes occurs when dropping one fluid on another in a small stream and can be replicated much more easily and sustained using transducers which sonicate the water.
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