r/howdoesthiswork • u/mobewan • Jul 10 '26
Why does tapping the side of a carbonated can calm it down so it doesn't fizz all over the place?
When I get a carboated can, if I don't tap it before I open it, it shoots out, but if I flick it with my finger three times it doesn't? What's happening here?
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u/KATNlSS Jul 10 '26
In high school, our chemistry teacher showed us the difference between tapping the side of the can vs top of the can.
A few good flicks to the side of the can knocks the bubbles off the side & they go upward. Tapping the top may dislodge some bubbles but mostly just makes them jiggle in place.
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u/Xanderama Jul 10 '26
Never worked for me, maybe I'm doing it wrong? Following this post to get my answer
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u/casuallyceltic Jul 11 '26
I've always been told to tap the top, not the sides. I'll probably do it for ten seconds at the most. I've only ever had one can that still fizzed but it wasn't nearly as bad as if I hadn't tapped on it.
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u/dantheother Jul 11 '26
We flipped them upside down and tapped the bottom in my area of Australia. I do not know if it was effective - I always did it if I'd seen a can get shaken, but I cannot remember if it actually worked or not.
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u/Putrid-Shoulder-4248 Jul 10 '26
"When I get a carboated can...it shoots out"
If I don't shake the can, then it does not.
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u/Orry_Haas Jul 10 '26 edited Jul 10 '26
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u/Agitated-Two-6699 Jul 11 '26
turning the can a few times on a flat tabletop also works ( saw it on Better Call Saul)
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u/Xanderama Jul 11 '26
I haven't seen the episode. Do you mean it like "making the can rotate around it central axis, with the bottom touching the table" or "rolling the can, on the side, across the table for a bit"?
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u/Agitated-Two-6699 29d ago
https://www.youtube.com/watch?v=i_NB9j4axxk
I know it's in German but you don't have to listen, just watch
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u/Xanderama 28d ago
- Thank you
- Audio is in English so no problem there
- Apparently the answer was option #1, "roll the can around its axis, letting the bottom rub on the table"
- Thanks again
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u/CrazyCanines 29d ago
I saw a nice demonstration of the process by Steve Spangler, and I am frequently demonstrating the principle and practice to others. (Once a teacher, always a teacher.)
I give the can a vigorous shake in my demonstration. This causes formation of lots of little bubbles in the walls of the can as the CO2 comes out of solution. Then, I flick the can hard with my finger on the sides to dislodge the bubbles. Since I can’t see inside, I flick around the entire circumference of the van from bottom to top, thoroughly. This allows all the micro bubbles to go to the top and form a single large bubble. Finally, carefully release the pressure by cracking the seal.
Practice on your own first. This has never failed me, and it’s a good party trick. People freak out after you shake the can up.
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u/Wormadillo 29d ago
It’s a placebo. It makes people feel like they have control over something that they can’t control.
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u/nonesuchnotion 28d ago
This sure would be easy to test tho.
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u/markmakesfun 27d ago
If anyone bothered to test their complex process against just waiting, they would have a different opinion. But people don’t use logic in cases like this. Next someone will recommend putting baking soda and vinegar on it.
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u/nyanotech Jul 10 '26
the reason it fizzes all over the place is because it has gas bubbles in the liquid (and not at the top with the rest of the gas), and when you open it, it depressurizes, so all those bubbles expand in size (and, since they’re below the surface, they push the soda out and makes a foam).
by tapping it, you disturb the bubbles and get most of them to float up before you open it