Carbonic Acid Equilibrium and Fizz?

[tCan]

I was wondering why if you open a beer too soon after carbing, it explodes in a volcano of fizz. The only thing I can think of is that maybe the reaction rate for the equilibrium of Carbonic Acid with CO2 is a slow equilibrium. Meaning the CO2 would have then have to be regenerated from carbonic acid as the CO2 that was in solution left the liquid, again at a slower rate than just all the CO2 leaving solution. However, it seems that the overwhelming majority (Ka = 1.7*10^-3) of CO2 does not go to Carbonic acid, so this can't be right. Can it?

I dont think there would be a physical reaction like a mentos in a diet coke...

 

[ajdelange]

You are correct. Very little CO2 actually converts to carbonic acid. Most of it is in solution as hydrated CO2.

There are definitely, in my mind anyway, some mysteries associated with carbonated beer. Clearly it is super saturated with CO2 (hydrated plus carbonic) so that you would expect gas to escape when the bottle is opened but sometimes it escapes explosively and sometimes (the desired result) is escapes gradually over a period of a half hour or more. Clearly it has memory because if you take a keg of cold beer and drop it off the back of a truck it will be "wild" (pour nothing but foam) for many hours. Every home brewer knows that it takes time for the CO2 to "meld" with the beer which means that at first the bubbles are large and coarse, form immediately and leave the solution rapidly whereas after time (weeks) the bubbles become smaller and finer and the head creamier. I have no idea how this works but a clue may be that traditionally lagered beer has a finer head than beer lagered quickly after a diacetyl rest. I suspect it has to do with changes in surface tension caused by changes in the protein spectrum as lagering procedes.

 

[tCan]

Yeah. The only other thing I could come up with was "proteins". Though I didn't have anything articulable to go along with it.