Answer in brief

What are the main types of chemical weathering?

Weathering is the disintegration, breaking down and decomposition of components in the earth’s crust through the action of natural or other agents. Weathering can occur due to exposure to the earth’s atmosphere. Weathering is controlled and determined by various factors like temperature, rainfall, vegetation and movements of other components in the earth’s crust. Weathering can be mechanical, chemical or biological.

Chemical weathering is the decomposition of components in the earth's crust through chemical reactions. It changes the chemical composition of rocks. Oxygen, carbon dioxide and hydrogen are the agents of decomposition. Chemical weathering is usually common in places with very hot and humid climates. It occurs in the climatic conditions of the hot and humid regions of the equators, tropics and sub-tropics. The action of the constant availability of water and the rising temperature is responsible for the faster weathering of rocks compared to other regions. The reaction between the atmospheric humidity and other elements are responsible for the higher rate of weathering. It can be further classified into different types. They are:

• Oxidation- This majorly occurs in ferrous rocks containing iron. The iron in these rocks reacts with the oxygen in the atmosphere resulting in the formation of iron oxide and rusting the rocks from within. This chemical reaction decomposes the rocks from within and results in its weathering.

• Carbonation- This mainly occurs in carbonate rocks. It is the reaction between the water molecules and the carbon dioxide in the atmosphere resulting in the formation of carbonic acids. The reaction of the carbonic acid with the carbonate rocks decomposes the rocks from within and results in its weathering. It basically occurs in the limestone region in the formation of caves.

• Solution- This is the reaction of water with the particles, minerals and substances found in the rocks. The action of water in rocks results in breaking down of its particles from within and results in its weathering. This is mostly found in limestone rocks.