Chemical Weathering

Chemical weathering is a process where minerals in a rock may be converted into clays, oxidized or simply dissolved.

Chemical Weathering involves processes like

• Conversion of silicates into clays by a reaction of silicate with water. i.e.

Silicates + water = Clays + dissolved SiO₂ and dissolved cations ( K⁺, Na⁺, etc.)

• Dissolving of minerals e.g.
• Slightly acidic rainwater dissolve limestone to form soluble calcium hydrogen carbonates

CaCO₃ + H₂CO₃ = Ca²⁺ 2HCO₃^–

• Halite dissolves directly into water

NaCl = Na+ + Cl-

(c) Oxidation e.g. oxidation of certain metals (Fe in particular) with oxygen in the process of stealing electrons.

metal + oxygen = metal oxide

4Fe + 3O₂ = 2Fe₂O₃