PROCESS OF CHEMICAL WEATHERING
Weathering is a geological destructive process which leads to formation of simple compounds from solid rocks of earth crust. When these rocks are broken by chemical reactions occurring due to their exposure to water , oxygen, acids , carbon etc., it is termed as chemical weathering. Chemical weathering is minimum in desert , arctic & alpine conditions.
Types of chemical weathering:
1.SIMPLE SOLUTION : H2O + CO2 → H2CO3 ( carbonic acid) formed during rain ,thunder & lightening . Carbonic acid has solublising properties and so it solublises certain rock minerals & helps in weathering.
2.HYDROLYSIS: water reacts with the minerals found in the rock and break them. Ex. KAlSi3O8 (orthoclase) + HOH →HAlSi3O8 ( acid silicate clay) + KOH
3.CARBONATION : carbonic acid present in rain water reacts with calcite (CaCO3) present in crevices of rocks and forms bicarbonate ( Ca (HCO3) ) which leaches down to lower layers and precipitate CaCO3 & liberate CO2 gas. Calcium carbonate so formed accumulate further and leads to karst topography.
4. OXIDATION :mainly affects Fe2+ iron . Iron mineral like FeS2 ( iron pyrite) oxidises to form hydrated ferric oxide and sulphuric acid. ex. 2FeS2 +7H2O + 15O → Fe (OH)3 + 4H2SO4.
5. HYDRATION : volume increases due to hydration . ex. 2Fe2O3 +3H2O → 2Fe2O3 . 3H2O
Weathering is a geological destructive process which leads to formation of simple compounds from solid rocks of earth crust. When these rocks are broken by chemical reactions occurring due to their exposure to water , oxygen, acids , carbon etc., it is termed as chemical weathering. Chemical weathering is minimum in desert , arctic & alpine conditions.
Types of chemical weathering:
1.SIMPLE SOLUTION : H2O + CO2 → H2CO3 ( carbonic acid) formed during rain ,thunder & lightening . Carbonic acid has solublising properties and so it solublises certain rock minerals & helps in weathering.
2.HYDROLYSIS: water reacts with the minerals found in the rock and break them. Ex. KAlSi3O8 (orthoclase) + HOH →HAlSi3O8 ( acid silicate clay) + KOH
3.CARBONATION : carbonic acid present in rain water reacts with calcite (CaCO3) present in crevices of rocks and forms bicarbonate ( Ca (HCO3) ) which leaches down to lower layers and precipitate CaCO3 & liberate CO2 gas. Calcium carbonate so formed accumulate further and leads to karst topography.
4. OXIDATION :mainly affects Fe2+ iron . Iron mineral like FeS2 ( iron pyrite) oxidises to form hydrated ferric oxide and sulphuric acid. ex. 2FeS2 +7H2O + 15O → Fe (OH)3 + 4H2SO4.
5. HYDRATION : volume increases due to hydration . ex. 2Fe2O3 +3H2O → 2Fe2O3 . 3H2O
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