Disintegration and Decomposition of rocks by chemical processes is called “Chemical weathering”. 

In this process secondary or new minerals are developed from the original minerals of the rocks. The rain water and atmospheric gases are the main agents of chemical weathering. It is vey common in humid regions. 

There are four types of chemical weathering process. They are;

• Oxidation: The rain water with oxygen reacts on rocks containing iron and produce oxides. This chemical reaction is known as “oxidation”. The common process of rusting of iron is an example of oxidation. 
• Carbonation: The rain water with carbon-di-oxide becomes a weak carbonic acid and it reacts with calcium carbonate or limestone to form calcium bicarbonate, which dissolves easily. This process is called “Carbonation”. It is very active in limestone regions. 
• Hydration: The rock minerals take up water the increased volume creates physical stress within the rock. As a result certain minerals like feldspar and gypsum are reduced into powder. This process is called “Hydration”. 
• Solution: The rain water is able to dissolve some of the soluble minerals, such as rock- salt, gypsum, potash. This process is called “Solution”.