Seems if I drink a beer (stella in my case) from a bottle, and seal the opening with my mouth while drinking then put it down, the beer foams up, exploding beer all over the place, but if I leave a small opening between my lip and the rim of the opening as I drink, this doesnt occur. Does anyone know the scientific explanation as to why this happens? Seems to be more pronounced if the beer is closer to room temperature, but it also happens with cold beer.
Thanks!
Number 1. Stella Artois rocks.
Number 2. Don’t be so rough on the shaft. The same is true in other areas of life as well.
For there to be a scientific explanation, after you do the action quoted above, do you put the beer back on the table with the same intensity as you did while you drank it with a closed mouth?
I would say it doesn’t matter how you drink it, but how you set it back down. Take it easy putting it down.
Slight hijack: a popular jackass move back in the day was when you were drinking bottled beer with other guys, to tap the bottom of your bottle straight downward (and not even too hard) on the lip of the other guy’s bottle. His would usually begin foaming and overflow. Why, I never really understood.
Other foam facts (this one easier to figure): an overly foamy pint or pitcher could be quelled by rubbing your finger across the bridge of your nose (or over your ear) then dipping it in, as the grease would break down the foam. Yes, I know, a bit revolting, but it was usually by a late stage of the evening.
Re the OP: When you make a seal like that around the top of the bottle, you change the pressure in the bottle, because as you’re taking beer out, air can’t get in to replace it, so there’s a pressure difference between inside the beer and the environment.
When you break that seal quickly (by removing your mouth), the pressure increases rapidly, which upsets the CO[sub]2[/sub] equillibrium, and causes a bit of the CO[sub]2[/sub] to come out of the beer, which is what you see when it foams.
Re the hitting the other beer with the bottom of yours: It’s the same principle at work. You’re messing up the CO[sub]2[/sub] equillibrium. The same thing would happen if his beer were closed - some CO[sub]2[/sub] would come out of solution into the headspace of the bottle (like shaking a can of coke), but it eventually would go back into solution until the pressure of CO[sub]2[/sub] in the beer was at what it originally was, thus minimizing risk.
My WAG is that sealing the bottle with your lips doesn’t allow the gaseous carbon dioxide to escape, forcing it to build up inside the bottle. Tilting the bottle to drink causes a disturbance inside the bottle that allows more CO2 to attempt escape.
I don’t think that tilting the bottle like that would matter, though, since any CO[sub]2[/sub] produced in that process would be in the bottle while you were drinking, and depending on how much CO[sub]2[/sub] vs. how much beer, and how far you tip the bottle, etc, you might even end up consuming some of the carbon dioxide (like if the beer doesn’t fill the opening of the bottle? This is hard to explain what I mean, and I hope that you guys understand it.)
_____________
|cccccccccccc\_______
|cccccccccccccccccccccccccc
|bbbbbbbbbbbb _______
|____________/
where c=CO[sub]2[/sub] , and b=beer.
Sorry, I’m not the master of the code tags. 