Ordinary
limestone can be used to
neutralize acidity in lakes caused by
acid rain. It can also be used to
neutralize acid soil in fields. It works much better and faster if turned into
slaked lime first.
First, the limestone, which is mostly calcium carbonate, is heated, turning it into calcium oxide.
CaCO3 -> CaO + CO2
CaO is also known as quicklime. This quicklime then reacts violently with water to form slaked lime -
CaO + H2O -> Ca(OH)2
Slaked lime is a white powder that can be applied to fields/lakes just like powdered limestone.