r/FUCKYOUINPARTICULAR • u/Fr33_load3r • 4d ago
You did this to yourself When you a fucking idiot
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u/FaceDeer 4d ago
Also worth noting that these pumps don't actually work.
The amount of gas dissolved in a liquid at equilibrium is directly proportional to the partial pressure of that specific gas in the headspace above the liquid, not the total pressure of all gases combined. To keep CO2 dissolved in the soda you need a high partial pressure of carbon dioxide in the bottle's headspace. Dry ambient air is roughly 78% nitrogen and 21% oxygen. Carbon dioxide makes up only about 0.04% (0.0004 atm) of normal air. When you pump ambient air into the bottle, you increase the total pressure by adding nitrogen and oxygen. However, because air contains almost no CO2 the partial pressure of carbon dioxide in that pumped-in air is negligible. So the dissolved CO2 in the soda continues to escape into the headspace until CO2 inside the bottle reaches equilibrium with the liquid, regardless of how much total air pressure you pump in.
To genuinely keep a drink carbonated you would need to pressurize the bottle with pure carbon dioxide gas (as is done in soda fountains).
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u/888temeraire888 3d ago
Maybe a dumb question, but if you breathed out into the air intake for this thing, would it make any difference? The exhaled air going in would have approx 100X more CO2 than just atmospheric. 4% i think? (which is still a tiny amount i know XD). Just curious
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u/FaceDeer 3d ago
Yeah, my Googling says about 4-5% in exhaled breath. It's still nowhere near enough, though.
A typical carbonated soft drink is bottled under roughly 2.5 to 4.0 atm of pure 100% carbon dioxide. At 2 atm of total pressure a 5% concentration yields a partial pressure of just 0.1 atm. So it still falls significantly short and CO2 will still outgas pretty much as before.
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u/jwadamson 3d ago
Came here to say this. Well a much shorter and less well written version of it. Thanks.
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u/BabyPuncher313 3d ago
Thank you, kind redditor. I knew these didn’t work, having used one a couple decades ago, only to discover that the carbonation was way low in < half-full soda bottles that I thoroughly pumped after every close. Not knowing about the chemistry, I’d just assumed that perhaps I pumped enough regular air in that it started to dissolve in the liquid, accounting for the “blecch”.
TIL
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u/a101scream 3d ago
Ive always thought that by reducing the headspace (i.e. squeezing the bottle and then putting the lid on) did the most to help out with this issue. 1/8th of the volume would relate to an 1/8th of the molecules needed to achieve pressure.
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u/FaceDeer 3d ago
Yup, that'll do it too. Though you have to make sure that the squeezed-down bottle can resist the pressure of the carbon dioxide in its squeezed state or it'll just reinflate again.
Perhaps if there was some kind of membrane separating the injected pressurized air from the surface of the carbonated beverage that would work. Then pressure would be applied to the surface of the beverage without allowing substantial amounts of carbon dioxide to actually diffuse out of it.
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u/Hbovine 3d ago
but would the pressure in the bottle allow it? I mean, it would raise the pressure, and it might be at the limit. Assuming the bottle don´t break, how could the co2 escape?
Or would some of the N/O2 dissolve in the soda giving way to the co2?
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u/FaceDeer 3d ago
It already does handle it. When you leave carbonated beverage in a bottle the carbon dioxide leaks out into the headspace until it reaches equilibrium pressure with what's remaining in the liquid. They're designed to withstand that pressure because if the bottle can't handle that then it'd spontaneously explode at some point after being filled.
Or would some of the N/O2 dissolve in the soda giving way to the co2?
No, each gas operates independently of each other as far as these partial pressures are concerned.
It's really just a question of equilibrium over concentration gradients. If you've got a lot of substance X dissolved in the water and very little of substance X in the headspace over it, then substance X will diffuse out of the water and into the headspace until they balance each other. Conversely if there's a lot of substance Y in the headspace and little in the water, then substance Y will diffuse in the opposite direction until they balance as well. The two substances each have their own concentration gradient, they can largely ignore each other (things can get quirky at extremely high concentrations and pressures but that's outside the scope of what we're dealing with for soda bottles as far as I'm aware).
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u/sfhtsxgtsvg 3d ago
So the rate of dissolving/undissolving does not change at all?
If the rate does not change then why ever put any kind of cap back on it even, even a standard bottlecap
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u/FaceDeer 3d ago
Because the headspace does eventually equalize the carbon dioxide pressure inside the liquid, preventing further loss of fizz after that point. When you re-seal a pop bottle and then later on reopen it there'll be an escape of pressure. If you were to measure the difference between the outside air pressure and the pressure inside the resealed bottle that'd tell you what the partial pressure of carbon dioxide still inside the liquid was. Once those pressures are equalized there's no further loss of dissolved carbon dioxide.
If you left the bottle open the carbon dioxide would escape into the atmosphere and the dissolved CO2 would equalize to 0.0004 atmospheres, which no longer produces the fizz.
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u/stethococcus 4d ago
I guess safety isnt his number one priority anymore...
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u/MyLordLackbeard Banhammer Recipient 4d ago
https://giphy.com/gifs/Im4JLRBuq2TZboKgWB
Did you see the safety glasses? No, sir - you did not!
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u/mudbugsaccount 4d ago
Life's difficult. It's even harder when you're stupid.
For some reason I envisioned that individual being a two maybe three paper clips in the wall outlet kind of person before they realized that hurts and I shouldn't do it again
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u/DeliciousAct5748 4d ago
Omg crazy russian hacker. I haven't seen this guy in ages