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CH3041
CHEMICAL WEATHERING
Weathering
is classified as either:
• Physical: cracking, glaciers, landslides...
• Chemical: WATER (acidic) & gases (eg. O2)
These processes result in primary
minerals (unstable at low p and T at Earth’s surface) changing into stable secondary minerals and
dissolved materials (ions, compounds).
Mechanisms
of chemical weathering:
1) Dissolution NaCl(s) +H2O ® Na+(aq) + Cl-(aq)
2) Oxidation 4FeS2+15O2+14H2O®4Fe(OH)3 +8H2SO4
3) Acid hydrolysis CaCO3 + H2CO3® Ca2+ +2HCO3-
4) Complexation muscovite + oxalate
KAl3Si3O10(OH)2+3C2O42-+10H+® 3AlC2O4+ +3Si(OH)4+ K+
KAl3Si3O10(OH)2+3C2O42-+10H+® 3AlC2O4+ +3Si(OH)4+ K+
