What is the reaction of #"CO"_2(g)# with #"Ca"("OH")_2(aq)#?
The reaction is NOT so obvious. You generally get a fine precipitate of
This is an acid - base reaction and is used as a qualitative test for
If you continue to pass
Carbonic acid is formed first:
This then reacts with the calcium carbonate in an acid / base reaction:
This process occurs in nature. Rain water is naturally acidic due to the presence of dissolved
Minerals such as limestone, which is a form of calcium carbonate, are subjected to chemical weathering. This results in cave formation in limestone areas.
You will notice that the reactions are reversible. As the solution naturally evaporates this can lead to a deposit of solid calcium carbonate resulting in the formation of stalagtites and stalagmites:
Water containing dissolved
A downside of this is that it forms an insoluble "scum" with soap - based detergents which is wasteful.
On the plus side hard water is good for making beer.