How Does Water Cause Chemical Weathering?

An example of chemical weathering of limestone

Chemical weathering caused by water is the breakdown of minerals into new minerals, which is needed in the formation of soil. Water either starts the reaction or carries the minerals that cause chemical weathering.

Hydrolysis

Hydrolysis is a chemical reaction that happens when water and mineral ions meet. This results in the decomposition of rocks by creating new compound minerals. During the reaction, hydroxide ions (OH-) are released and cause an increase in pH.

Hydration

Hydration happens when water and a mineral combine, causing the mineral to change its structure. When combined, minerals become soft and lose some of their basic properties such as sheen.

Carbonation

Carbonation is the process of carbon dioxide being dissolved in water to form carbonic acid. As the carbonic acid attacks rocks, it brings several types of minerals into a solution. This reaction is often seen in the etching of limestone, according to the My Agricultural Information Bank website.

Oxidation

Another form of chemical weathering is oxidation. This is chemical reaction between oxygen and different compounds where water loses oxygen and a mineral gains it. According to PhysicalGeography.net, oxidation can be seen in the red and yellowing staining (or rust) of soil when iron and aluminum minerals become corroded by the oxygen molecule in water.

References

• The Center for High Pressure Research: Formation Processes
• PhysicalGeography.net: Weathering
• My Agricultural Information Bank: Chemical Weathering of Rocks

Resources

• NASA, Soil Science Education: Soil Forming Factors