Biochem - 19-6-2005 at 00:42
Was reading some textbook and it states that some lake gets neutralized from its original acidic state through calcium carbonate and CO2
and gives the following reaction:
CaCO3 + CO2 + H2O(l) -> Ca + 2HCO3
HCO3 + H (acid) -> CO2 + H2O
Why doesn't HCO3 + H go to H2CO3...HCO3 is negatively charged would seem it would take up a proton and if so wouldn't it just form carbonic
acid?
[Edited on 19-6-2005 by Biochem]
Tsjerk - 19-6-2005 at 01:25
It does form H2CO3, but that is very unstable and will form water en CO2
Carbolic acid
Lambda - 19-6-2005 at 02:20
If I am not mistaken, they wants had a hugh disaster in Africa some place (I think a volcanic region). There was this lake, in which massive ammounts
of carbolic acid had accumulated, deep down and under pressure. Due to a minor tremor, CO2 errupted from the bottom of this lake, and beeing heavier
than air, swept over this reigion at night. Thousands of people and animals perriched, due to sufocation. This same fenomenon allso occures with
methane hydrates (Bermuda triangle).
Under high pressure, and low temperatures there should deffinatly be a shift to the left of the equasion in favour of carbolic acid. In deep and cold
lakes, there should be a higher concentration possible, than in warm and shallow lakes.
sparkgap - 19-6-2005 at 03:49
That was Lake Nyos in Cameroon, friend Lambda. 
And it was a mini-earthquake that
triggered the release of carbon dioxide from the water (which was apparently in the same state as that of a soda pop bottle just shaken prior to
opening).
With the methane hydrates, it's actually more of the seabed being disturbed such that the crystals of methane hydrate are subjected to stress,
and that they accordingly release their greenhouse-warming cargo.
But wait a minute, where'd the phenol (a.k.a. carbolic acid) come from? 
As for the original question, Tsjerk's answer is correct. However, I must add that the outcome will depend on temperature, pressure and pH. Of
course, acidic, high-temp water tend to lessen gas solubility in general.
sparky (~_~)
neutrino - 19-6-2005 at 05:42
Think about it this way: any carbonic acid formed in these concentrations (lakes aren’t usually that acidic) would tend to release a proton rather
than decomposing altogether. The CO<sub>2</sub> formed from any decomposition would form more
H<sub>2</sub>CO<sub>3</sub> at about the same rate. It’s all an equilibrium.