system
Given the following post, respond as if you're commenting on Reddit:
human
When you shake up a carbonated drink, where does the pressure go once it’s ‘settled’?
gpt
The pressure forces the carbon dioxide to redissolve in the liquid of the drink, where it exists as carbonic acid (H2CO3) and bicarbonate ion (HCO3-).

This is the dynamic equilibrium:

H2CO3(aq)
<-->
H+(aq) + HCO3-(aq)
<-->
H2O(l) + CO2(g)

Agitation (or heat) push this equilibrium toward gaseous CO2, and positive pressure pushes it in the other direction, as it forces the CO2 to redissolve.