Chemical Weathering
Hydrolosis, Oxidation, Carbonation and Acid Rain
Chemical Weathering
- Rocks looks so different because they are subject to Chemical Weathering, which is the process by which rocks are broken down by chemical reactions.
- Exposure to things such as water, carbon dioxide, oxygen and acids
Hydrolysis
- The chemical breakdown of a substance when combined with water
- Hydro= Water Lysis= Break down
- Chemical reaction between minerals in rock and rainwater
- Most common example is feldspar with granite changing to clay
Chemical Weathering Basics
Oxidation
- Reaction of a substance with oxygen
- Process that causes rust
- Explains why some rocks are red as they contain iron
Chemical Weathering
Carbonation
- Mixing of water with carbon dioxide to make carbonic acid.
- Important in the formation of caves
- mineral calcite which is common in limestone is vulnerbale to carbonation
- mineral dissolves and gets washed away, which hollows out rock and leaves a cave behind
Lichens and Acid Rain
Lichens
- Combination of fungi and alagae that grow on rocks that produce acids to break down minerals in rocks
- When water mixes with lichens a weak acid is produced
- This is a very slow process but is a common type of chemical weathering near rivers and streams
Acid Rain
- Acid rain is produced by certain pollutants in the air
- pollutants such as sulfur dioxide, carbon dioxide and nitrogen oxide (produced by burning fossil fuels) these pollutions get put into the air where they are mixed with water
- this produces sulfuric acid, carbonic acid, nitric acid which chemically weathers rocks