Presentation of chemical weathering
-
Upload
sabeh-khan -
Category
Education
-
view
136 -
download
2
Transcript of Presentation of chemical weathering
Presentation of Presentation of Chemical WeatheringChemical Weathering
Muhammad Tauheed
Department of Geology
Roll No 5211Semester 4th
Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic.
These reactions include oxidation, hydrolysis, and solution (carbonation). These processes either form or destroy minerals.
Chemical Weathering
• These chemical processes need water, and occur more rapidly at higher temperature.
• Warm, damp climates are best. Chemical weathering (especially hydrolysis and oxidation) is the first stage in the production of soils.
Where does it occur?
Oxidation is the reaction of rock minerals with oxygen, thus changing the mineral composition of the rock. When minerals in rock oxidize, they become less resistant to weathering. Iron, a commonly known mineral, becomes red or rust colored when oxidized.
e.g: rusting of rock
Oxidation
• The breakdown of rock by acidic water to produce clay and soluble salts
• Hydrolysis takes place when acid rain reacts with rock forming minerals such as feldspar to produce clay and salts that are removed in solution.
• e.g: clay formation
Hydrolysis
Solution
• Removal of rock in solution by acidic rainwater. In particular, limestone is weathered by rainwater containing dissolved CO2, (this process is sometimes called carbonation).
• e.g: sinkholes
• The process by which rock minerals reacting with carbonic acid. Carbonic acid is formed when water combines with carbon dioxide. Carbonic acid dissolves or breaks down minerals in the rock. CO2 + H2O → H2CO3
• (carbon dioxide + water → carbonic acid) • e.g : dissolve limestone produce cavern
Carbonation