so, soda is under pressure and has gas dissolved in it. But, when you open it, the gas is still dissolved in it. But, if we wait a few hours, the gas has escaped into the atmosphere.

What factors determine the rate at which gas escapes the soda-gas solution?

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    $\begingroup$ Don't cross post physics.stackexchange.com/questions/379120/… $\endgroup$ – paparazzo Jan 11 '18 at 0:22
  • $\begingroup$ Posting the same question to different sites is not allowed, but asking related, essentially different questions to multiple sites is okay (it is even vote attractor). So break up your question into an engineering and to a physics part next time. Your question here will be closed. $\endgroup$ – peterh says reinstate Monica Jan 11 '18 at 5:51
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    $\begingroup$ I'm voting to close this question as off-topic because cross-post. $\endgroup$ – peterh says reinstate Monica Jan 11 '18 at 5:53
  • $\begingroup$ Isn't an engineering answer fundamentally different from a physics answer? $\endgroup$ – Mohammad Athar Jan 11 '18 at 12:38
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    $\begingroup$ I sure hope the engineering answer is the same as the physics answer. Physics kind of rules. $\endgroup$ – paparazzo Jan 11 '18 at 15:22

dissolved CO2 in water remains in solution even after removal of pressure because of the absence of nucleation sites at which the gas can come out of solution. without a population of those seed sites, significant amounts of gas will remain in solution for hours after the removal of pressure. Dropping a Mento mint into a bottle of soda provides tens of thousands of active nucleation sites and will "catalyze" the exsolvation process, causing a spectacular geyser to shoot out of the top of the bottle.

  • $\begingroup$ Significant amounts of gas will remain in solution for hours after the removal of pressure? It will be at or close to equilibrium in less than 1 hour. $\endgroup$ – paparazzo Jan 10 '18 at 20:11
  • $\begingroup$ have you bought a bottle of club soda and tried the experiment? $\endgroup$ – niels nielsen Jan 10 '18 at 22:23
  • $\begingroup$ Have you defined significant? Temperature is a big factor. $\endgroup$ – paparazzo Jan 10 '18 at 22:30

The solubility of carbon dioxide in soda is related to both the temperature and pressure. A cold, pressurized drink can hold more CO2 per ml of liquid. When you open a soda, the gas immediately starts to come out of solution. Bubbles form and rise to the surface - this is the familiar sight of a fizzy drink.

If you drink half of a large bottle of soda, and put the lid tightly back on, it will still go partially 'flat', since there is a large volume of compressible air above the liquid. Some CO2 comes out of solution until the pressure in the bottle rises, and an equilibrium is found.

To keep the remainder your drink fizzy if you only want to drink half of the large bottle, simply decant the part you wish to save for later into a smaller bottle, leaving less air inside.


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