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I wish I could directly embed this video here

https://youtu.be/Syb3MHtjojQ

It can be seen that no external chemical has be put into the bottle, so the bottle content has clearly not been modified.

A friend of mine said it must be capillary action, but it doesn't look like it one to me.

It's doesn't look normal CO2 release either, since it flows steadily for 40+ seconds.

Assuming no battery/pump has been attached to the straw, how can this be explained scientifically?

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  • $\begingroup$ Please add a few relevant screenshots $\endgroup$
    – AJN
    Jan 4 at 14:16
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    $\begingroup$ "It's doesn't look normal CO2 release either, since it flows steadily for 40+ seconds" Your soda takes many minutes to go flat and is not normally sealed with only a tiny straw as the outlet. Release the pressure on a plastic soda bottle and reseal it. The bottle gets pressurized and firm again. $\endgroup$
    – DKNguyen
    Jan 4 at 14:40
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    $\begingroup$ @huenma, the title of your question should tell the reader what the question is about. Can you edit it so that if it showed up in search results the reader might know? $\endgroup$
    – Transistor
    Jan 4 at 15:58
  • $\begingroup$ you used the experimental-physics tag ... did you actually perform an experiment to determine the cause of the fountain effect? $\endgroup$
    – jsotola
    Jan 4 at 20:39

2 Answers 2

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I've seen similar action when a straw is in a glass of soda. Bubbles form on the straw, causing it to "float" upwards, then the bubbles break free and the straw sinks again. Rinse, lather, repeat.

In both scenarios what we're seeing is the slow release of CO2 from dissolved to gas-bubble phase. Similarly, opening a bottle of soda doesn't cause all the dissolved CO2 to release immediately. You can enjoy the drink for a couple hours (other then temperature change) before all the fizz is lost.

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It is CO2 that is released from the liquid. As the liquid warms up, it is unable to hold as much of the CO2 in a dissolved state. The CO2 raises the gas pressure above the liquid. I think that you can figure out the rest.

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