physics question - tapping bottle to reduce fizzing

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Feil
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physics question - tapping bottle to reduce fizzing

Post by Feil »

A few days ago I was asked why tapping a bottle or can of a carbonated drink made it less fizzy when you open it. I didn't know the answer but I guessed that it had something to do with prompting the nucleation of the higher energy CO2 molecules, which would then bubble up and increase the pressure in the layer of gas between the liquid and the lid, at which point releasing the gas would cut the pressure as usual, at which point the remaining solution would be less saturated and have fewer high-energy CO2 per unit CO2 dissolved.

Am I on the right track here? Does energy of the CO2 molecules have anything to do with it, or does tapping just release bubbles that have already formed on the walls of the container and open up the easy-nucleation spots for other bubbles to form (or something else entirely)? For that matter, does tapping a bottle actually help at all? I want to be able to correct myself the next time I see the person if I was wrong.
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Borgholio
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Re: physics question - tapping bottle to reduce fizzing

Post by Borgholio »

Anecdotally, I've noticed no difference when I tap a carbonated bottle. In fact I've noticed that if I tap too hard, it can actually INCREASE the amount of bubbles I have.
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Napoleon the Clown
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Re: physics question - tapping bottle to reduce fizzing

Post by Napoleon the Clown »

Straight Dope says the tapping thing is bogus.

So the answer to your question is "It doesn't do shit."
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LaCroix
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Re: physics question - tapping bottle to reduce fizzing

Post by LaCroix »

The only thing it would do is to cause the bubbles on the inside to lose adhesion to the wall and rise up. That would make the gas bubble under the cap bigger, and get you a slightly more powerful hiss on opening. It wouldn't change the fizzyness, at all, since these bubbles are only a miniscule part of the total carbon, which is still in solution.
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Feil
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Re: physics question - tapping bottle to reduce fizzing

Post by Feil »

Alright, thanks. I'll make sure to correct myself later :)
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