question about carbonation

April 21, 2024 6:41 AM

My experience is that when I drop a (yet-unopened) can of carbonated beverage on a hard concrete or cement floor, the impact has a later result: namely, when I open the can, the beverage explodes out as if it has been shaken. Can time cure this? Is there going to be difference if I open the can 30 seconds later or 30 days later?
posted by PaulVario to Science & Nature (12 answers total)

You don't need to wait long, if you just tap on the bottom of the can for ten or twenty seconds it will crack open without foaming everywhere.
posted by mhoye at 6:47 AM on April 21 [4 favorites]

I tap on the top of the can and it’s effective. Assuming next answerer taps on the side.
posted by theora55 at 7:11 AM on April 21 [12 favorites]

Side tapper here! I believe that the only important thing is that the can be upright when tapped, wherever you do it--the goal is to get the bubbles back up so that they (and not the liquid) are the first to exit.
posted by LadyInWaiting at 8:05 AM on April 21 [10 favorites]

Carbonated beverages explode on opening when you introduce a pile of nucleation sites within the can. This is usually tiny bubbles sticking to the side of the can: in the mentos trick it is the mircoscopic rough surface of the mentos.

Tiny bubbles in a standard carbonated beverage are not stable: they will be absorbed by the fluid over time. More importantly, such bubbles cannot remember how they are made.

The tap trick dislodges the tiny bubbles from the side of the can. They float to the surface and fall apart faster there.

Shaking, on the other hand, introduces new tiny bubbles sticking to the side of the can. Apparently so will dropping it on a hard surface.

The stable state of a carbonated beverage when sealed has next to no bubbles within it. When the surface pressure drops, the co2 in the fluid attempts to dissolve, but this is a slow process without nucleation sites. With plentiful nucleation sites this is very fast: the expanding gas bubbles take up extra room, and the fluid explodes.
posted by NotAYakk at 8:12 AM on April 21 [7 favorites]

This may be off topic but: As far as I can tell, evidence seems to be that tapping does not actually help:

https://www.technologyreview.com/2019/12/11/131624/does-tapping-the-bottom-of-a-beer-can-really-stop-it-fizzing-over/

https://www.snopes.com/fact-check/on-tap/
posted by ManInSuit at 8:14 AM on April 21 [3 favorites]

You don't need to wait long, if you just tap on the bottom of the can for ten or twenty seconds it will crack open without foaming everywhere.


I think the skeptical interpretation here is that if you just waited 20 seconds without tapping, you'd see the same effect.
posted by ManInSuit at 8:20 AM on April 21 [2 favorites]

(Raises hand)
I'm one that hates the tapping thing - I just don't like doing it, and don't feel like it helps much - and I can truthfully inform you that I've been exploded on entirely too many times after 2-3 minutes, or even 10-15.

I've learned the hard way it's safer to either put it back in the fridge for another day, or give in and tap, if it's the only one I have. (And then it still usually at least fizzes/spits/slow erupts on me some, even if it doesn't outright explode.)
posted by stormyteal at 3:25 PM on April 21

Also to answer your actual question: Yes, if you let it sit for a while, it will return to its unshaken state.

As a sort of thought-experiment - think of all the cans that you've opened the did not explode.

What seems the more likely explanation:

a) All of those cans got to you without ever having been shaken - through the entire process of shipping, stocking, etc. No accidental jostling, no truck on a bumpy road. No mischeivious teenager shaking it for fun. They *all* made it to you unshook

or

b) If you shake a can, it eventually goes back to normal
posted by ManInSuit at 5:10 PM on April 21 [2 favorites]

Related but not exactly what you are asking:

https://physics.csuchico.edu/kagan/professional/papers/soda.pdf


They find that if they shake a botle of coke, it rolls slower down an incline. But the effect only lasts a couple of hours, and then goes back to normal.
posted by ManInSuit at 5:12 PM on April 21 [2 favorites]

Putting the can in a cold place will speed the recovery, but I cant say by how much or how quickly.
posted by SemiSalt at 6:39 PM on April 21

These two videos from Action Lab actually take transparent bottles, shake, observe, measure different things, and so on. Since you can see what's going they seem to shed more light on the issue than some others.

If you search around for more experiments where they actually observe the carbonated beverage by way of a transparent container you might be able to find out more.
posted by flug at 12:43 AM on April 22

I could have sworn that there was an Ig Nobel awarded for answering this but I can't find it.
posted by Snowishberlin at 12:11 PM on April 22