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


  • 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


  • Reaction of a substance with oxygen
  • Process that causes rust
  • Explains why some rocks are red as they contain iron
Chemical Weathering


  • 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


  • 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