Carbonate Dissolution
Carbonate rocks such as limestone, composed mostly of the mineral calcite (CaCO3) are very susceptible to dissolution by groundwater during the process of chemical weathering. Such dissolution can result in systems of caves and sinkholes.
Dissolution
Water in the atmosphere can dissolve small amounts of carbon dioxide (CO2 ). This results in rain water having a small amount of carbonic acid (H2CO3) when it falls on the Earth's surface. As the water infiltrates into the groundwater system and encounters carbonate rocks like limestone, it may start to dissolve the calcite in the limestone by the following chemical reaction:
CaCO3 + H2CO3 = Ca+2 + 2HCO3-2,
which states that calcite reacts with carbonic acid to produce dissolved Calcium ion plus dissolved Bicarbonate ion.
This reaction takes place as the water moves along fractures and other partings or openings in the rock. This results in dissolution of much of the limestone if the reaction continues to take place over a long period of time.