[Graeme McRae]

Graeme McRae  asked the Naked Scientists:
   
Your scientific consensus was not to squeeze the gas out of a pop bottle to keep it fizzy, but rather to keep it full of air, which is mostly nitrogen. However, the equilibrium concentration of dissolved CO2 depends on the PARTIAL pressure of CO2 in the gas at the top of the bottle.  If the gas is mostly N then the gas will reach maximum pressure and then begin leaking before significant CO2 partial pressure builds up  So a better strategy would be to squeeze out the gas, close the bottle, and let the top of the bottle fill up with CO2 gas that comes out of solution.  Then the partial pressure of CO2 in the gas will be much higher.

--Graeme McRae,
Palmdale, CA

What do you think?

[Bill.D.Katt.]

That's what I was thinking. But I wasn't sure about the proportions, I thought the most important thing was to keep it cold.

[tommya300]

That's what I was thinking. But I wasn't sure about the proportions, I thought the most important thing was to keep it cold.

Keeping the soda bottle sealed and coldest above freezing temperature works best for me.
Although as an example of a 2 liter of soda, as the level gets to be less then half it seems to starts becoming less frizzy even when it is kept cold, but gets flat faster when warm.

Even when kept cold, if I pour it out opening the bottle once, and not open it several times, it seems to lose its friz either way, over 3 days.
If it were kept under compression, leaving no room for expansion, keeping the CO₂ in the liquid mix cold seems to reduce the escape of the gas from the liquid.
We all notice the colder the soda is, the smaller the CO₂ bubbles are, more concentrated per area of fluid, seems more sharp tingles as you drink it.

.