Chemical weathering can be due to solution, carbonation, hydration or oxidation/reduction.
When something is dissolved in water or acids, the water or acid with dissolved content is called a solution. This process involves the removal of solids in solution and depends upon the solubility of a mineral in water or weak acids. When coming into contact with water, many solids disintegrate and mix up as a suspension in water. Soluble rock-forming minerals like nitrates, sulphates, potassium etc are affected by this process.
Carbonation is the reaction of carbonate and bicarbonate with minerals and is a common process helping to break down feldspar and carbonate minerals. Carbon dioxide from the atmosphere and soil air is absorbed by water to form carbonic acid that acts as a weak acid.
Hydration is the chemical addition of water. Minerals take up water and expand; this expansion causes an increase in the volume of the material itself or rock. The process is reversible and long, continued repetition of this process causes fatigue in the rocks and may lead to their disintegration.
Oxidation and reduction
In weathering, oxidation means a combination of a mineral with oxygen to form oxides or hydroxides. Minerals most commonly involved in this are iron, manganese, sulphur etc. The red colour of the iron upon oxidation turns to brown and yellow. In this process of oxidation, rock breakdown occurs due to the disturbance caused by the addition of oxygen.TSPSC Notes brings Prelims and Mains programs for TSPSC Prelims and TSPSC Mains Exam preparation. Various Programs initiated by TSPSC Notes are as follows:-
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