Chemical Weathering Processes

Rocks and minerals are formed under a very high pressure and temperature. New rock is formed and the broken down through denudation. Denudation involves, first, weathering, then mass wasting, and finally erosion. (Strahler, 2013, page 448.) Weathering is the disintegration or decomposition of rock on site (in situ) at or near the Earth’s surface by physical break-up or chemical change. (Spencer, 2000, page 92.) There are 3 types of weathering, physical weathering, chemical weathering and biological weathering.Decomposition refers to chemical weathering and creates altered rock substances. On the other hand, disintegration refers to mechanical weathering, which produces smaller, angular fragments of the same rock, without chemical alteration of the minerals. (Nagle, 2000, page 30.) Biological factors; such as tree roots and burrowing animals; contributes to both chemical and physical weathering. All types of weathering processes are interrelated; they do not operate in isolation. Chemical weathering involve the direct effect of atmospheric chemicals or biologically produced chemicals.

Chemical weathering is a gradual and ongoing process as the mineralogy of the rocks adjusts to the surface environment. The following agents enhance it:

* Water – dissolves minerals in rocks.

* Oxygen – combines in other elements in the rock in an oxidation reaction.

* Carbon Dioxide – dissolves in water to form carbonic acid.

* Living Organisms – produces weak acids, which break down or dissolve rock.

* Acid Rain – contains acids that break down or dissolve rock.

There are 4 main types of chemical weathering:

* Hydration

* Hydrolysis

* Oxidation/ Reduction

* Carbonation - Solution

Hydration is the process by which certain minerals absorb water, expand and change. Ions have a tendency to absorb water (hydrate) and dissociate. It is the chemical combination of water molecules with minerals, leading to a change in structure. 1 It happens in...