Difficulty: Easy
Correct Answer: carbonation
Explanation:
Introduction / Context:
Chemical weathering alters minerals via reactions with water, acids, oxygen, and dissolved species. Identifying the correct reaction mechanism helps explain karst landscapes, soil pH, and mineral stability.
Given Data / Assumptions:
Concept / Approach:
Carbonation refers to reactions of carbonic acid (H2CO3) and its dissociation products (HCO3^−, CO3^2−) with minerals—especially carbonates like calcite—often increasing solubility and forming bicarbonate in solution. It is central to limestone dissolution and cave development.
Step-by-Step Solution:
CO2 dissolves in water → forms carbonic acid.Carbonic acid reacts with minerals (e.g., CaCO3) → forms calcium bicarbonate in solution.This process is termed carbonation.
Verification / Alternative check:
Karst terrains with sinkholes and caves are classic field evidence of carbonation dominating weathering.
Why Other Options Are Wrong:
Hydrolysis — reaction with water splitting ions; common in silicate breakdown but not specifically carbonate/bicarbonate-driven.Oxidation — electron loss (e.g., Fe2+ to Fe3+), unrelated to carbonate ions.Solution — general dissolution without specifying the carbonate chemistry.Chelation — organic ligand complexing metals; different mechanism.
Common Pitfalls:
Using “solution” generically; here the named carbonate-driven mechanism is carbonation.
Final Answer:
carbonation
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