# Preserving Soda Fizz

You can buy closures which include a hand pump for compressing air into a partially filled soda bottle which is supposed to preserve the fizz? Can that actually work? I thought the space would have to be filled with carbon dioxide to have any effect.

We have bought these in the past, and they do work. My (limited) understanding of the principle is that by keeping a high level of air pressure within the bottle the carbon dioxide dissolved in the soda stays there, rather than evaporating into thin air (excuse the pun).

I’m agraid that’s a rather lame reply - I’m surprised you bothered.

The concentration of solute [in this case carbon dioxide] is supposed to be proportional to the partial pressure of that gas in the atmosphere over the solution [Henry’s Law or something like that]. There is only a few hundred part per million of CO2 in the air so I don’t see how that can be reponsible for maintaining the fizz.

Can anybody provide more insight here?

It’s not the CO2 in the air in the bottle; it’s the partial pressure of all the air.

If the air is of lower pressure than pressure on the CO2 in the liquid, the CO2 will will bubble up until it reaches equilibrium. If the pressure in the air above is the same as the pressure of the CO2 in the liquid, then it will remain in equilibrium and won’t escape from the liquid. If the air above is at a higher pressure, some of the air will dissolve back into the liquid.

The air in an unopened soda bottle is just plain air, and the liquid can go a very long time before losing its fizz. Similarly, if you shake a bottle of soda, and then let it sit for a day or so, the CO2 will redissolve and you won’t have the bubling up you usually get when you shake the bottle.

I haven’t tried the pump closures, and they may have other problems (e.g., they may leak, negating any advantage). But the theory is sound.

That’s gotta be wrong too. I’m new to this board but so far I think you’re a bunch of poseurs. I just looked up Henry’s Law:

Henry’s law is states that, at a given temperature, the amount of gas dissolved in a solute is directly proportional to the pressure of the gas above the substance. This can be represented by the equation where the pressure is measured in atmospheres and the Henry’s Law constant is also measured in atmospheres and where is the mole fraction of gas.

So that says that it’s NOT the total pressure of gas above the solution that is relevant. Only the proportion of the headspace gas that is CO2 is relevant. I know that bottles are factory-filled with CO2 in the headspace so it makes no sense that replacing it with air will do anything according to Henry’s Law.

If you want to maintain the fizz in an opened 2 litre bottle of soda, all you have to do is squeeze in the sides a little. Pour yourself a glass, and then squeeze in the sides so the liquid is near where it would be when the bottle is new. The next day, the bottle will have expanded out to its original size and the pop will still fizz. AFAIK, you want to limit the area that the CO[sub]2[/sub] can expand into.

Wrong AGAIN! Squeezing the bottle reduces the area above the liquid temporarily until more dissolved CO2 escapes to equilibrate the pressure to atmospheric. Hence, a decrease in dissolved CO2 concentration and LESS fizz.

No. It isn’t wrong. I do this all the time and soda that would normally be flat after 2 days is still fizzy after 4 days.

How’s this for an answer. Why don’t you: a) buy one and try it out yourself; or b) Just drink all the damn soda at one sitting and back off on the belligerent attitude a bit.

Attitude shmattitude. Only a controlled experiment can determine if that product works. And the point here is to explain on why or how it can work.

Are you all unemployed and on Prozac?

I just thought of why you morons think that pump works: when you repressurize the bottle, it will then hiss when you release it. That gives the PERCEPTION of fizz but it’s actually just a sound effect. I bet if you did a double blind test, you would find the soda is equally flat in the pumped bottle as the control.

Plenty of people think that copper or magnetic bracelets cure arthritis but it doesn’t. There’s a sucker born every minute.

Sounds to me like someone’s been burned, before.

I bought one of those “devices” and it does work, I was surprised.
And Ein Stein, you know it all anyway so why do you ask?

Ein Stein, insulting other posters outside the BBQ Pit is not permitted here. If you repeat the behavior you are subject to being banned.

bibliophage
moderator GQ

I believe that you are overlooking the simple fact that the partial pressure of the CO2 is proportional to the total pressure of the gas mixture (i.e. the air). So, when you compress air into the soda bottle, you are increasing the partial pressure of CO2. Given that higher partial pressure of CO2, the amount of C02 that can remain dissolved in the soda increases (Henry’s Law).

In essence, if you want to maintain the fizz in your soda, you have to choices: increasing the proportion of CO2 in the gas mixture above the soda, or increasing the total pressure and therefore also the partial CO2 pressure.

Wrong yet again! Increasing the pressure of an air mixture that doesn’t include CO2 does NOT increase the partial pressure of CO2.

You guys are a fountain of misinformation. I am banning myself. This board is pathetic. I’d like to know it all but I’m not going to learn it here.

Who says that air doesn’t include C02?

By the way, Good Riddance!

Air contains about 1.5% CO[sub]2[/sub]. So, nyah!

I can’t help myself…

The concentration of CO2 in the atmosphere is about 350 ppm. That about 0.035% not 1.5%. You can look that up, you don’t have to make it up. So that’s approximately nothing as I said at the beginning.

And compared to Bill Gate’s yearly income, mine is approximately nothing.