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So when you open a new bottle of sparkling water (or soda) it's very fizzy and aerated. However, when it is stored for quite a bit (no matter how tightly you close the bottle cap) it loses some gases and when you drink it later it's not as fizzy as it was before.

From my chemistry class I remember that sparkling water is basically a carbonic acid (H2CO3) that is constantly decomposing, producing water (H2O) and carbon dioxide (CO2). Then carbon dioxide escapes through the bottle cap little by little (but since it is heavier than air and hence is not rising upwards, I assume it escapes when having bottle opened due to pressure built up inside).

The question is: what if the bottle was stored upside down (so there is no way for gas to escape through the bottle cap), and shaken thoroughly before opened, so that carbon dioxide dissolved in water, like so image

I also thought that it could be even better if the volume of the bottle was decreased (leaving enough volume for sparkling water only) like so image2 Therefore carbon dioxide doesn't have enough volume to spread inside the bottle and most of it will stay dissolved in water.

Could anyone explain whether this will work or not?

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Solubility of a gas in liquid depends upon several factors. Temperature and pressure are two of our interest since they can be easily controlled. The method you suggest the method of shrinking volume can also be the good way but there are practical limitations to it.

As temperature increases gas will tend more to escape from solution, hence storing the bottle of sparkling water in refrigerator can be a good idea. When you open the bottle of sparkling water container for first time, a pressure drop will be created which reduces the solubility of gas. With time it reduces further. Having the water pressurized again is also not possible for everyone.

While reducing the volume of container may also be the good idea since it will decrease the volume of air in it thus increasing the pressure over the liquid. One may incorrectly think that they can use brute force by leaving no space for gas to escape. The reason why this may not work is that gas molecules have their own volume! The best this can do is to prevent escape of gas from solution by increasing pressure. The best way should be to store the bottle in refrigerator after crushing the empty part. The idea of keeping it upside down to prevent leakage is good as long as you don't spill it all.

We have obviously ignored the chemistry part of it. Decomposition of carbonic acid is endothermic reaction and at low temperatures you may not get fizz you want. It will be better to say it's trade off between several factors and optimal condition is somewhere in between which has to be determined more rigorously. But this effort won't be worth doing for a petty little bottle of sparkling water, at industrial level when you are storing the product in large silos then it makes more sense to invest time in it, but then it enters into domain of engineering rather than mainstream physics.

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