White Yeti - 6-10-2011 at 08:11
Hello all.
I am planning on experimenting with carbonic acid, but I'm having trouble actually making it. I've tried chilling water down to 5C and bubbling some
CO2 through it, but nothing happened. I then tried to take two containers, one with a gas generator and the other with distilled water. The goal was
to pressurise the CO2 and force it into solution in the distilled water. That didn't work out too well either.
Then I read about carbonic anhydrase, an enzyme in cells that catalyses the formation of carbonic acid. The problem is that I have no idea how to
extract this enzyme from cells.
This enzyme is ubiquitous, but I still want a relatively pure sample of carbonic acid, so I can't just take crushed cells and mix them in with water.
Has anyone dealt with this enzyme before? Does anyone know how to extract it?
I know I can just buy seltzer, but it's not sufficient for my purposes. I need to be able to continually add carbonic acid to the reaction mixture to
keep the reaction going, without increasing the volume of the mixture.
Adas - 6-10-2011 at 09:05
Well, I think it is impossible to make "relatively pure" H2CO3, because most of CO2 only dissolves and does not react. That's why Coca-Cola-like
drinks haven't got acidic taste. 
blogfast25 - 6-10-2011 at 09:29
Carbonic acid just isn't stable enough for it to be isolated in any way, shape or form. You're chasing a mirage.
The equilibria that reign carbonated water are:
CO2(g) + H2O(l) < === > H2CO3(aq),
H2CO3(aq) + H2O(l) < === > H3O+(aq) + HCO3 (-)(aq) and
HCO3 (-)(aq) + H2O(l) < === > H3O+(aq) + CO3(2-)(aq)
All lean very much to the left.
Carbonated drinks are nonetheless slightly acidic, including Coke.