Carbonic Acid Formation

Definition

The reaction of dissolved carbon dioxide with water to form carbonic acid, the first chemical (rather than physical) step in the carbonate equilibrium.

CO2 is a nonpolar molecule but its individual bonds are highly polar, which makes the carbon atom a target for the lone pair of electrons on the oxygen of water. The result is CO2(aq) plus H2O reacting to form H2CO3. Only a very small fraction of dissolved CO2 participates, but it initiates the acid dissociation steps that produce bicarbonate and carbonate.

Related concepts

Carbonate Equilibrium · Carbonation (Dissolution of CO2) · Bond Polarity of CO2

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Part of The Blueprint of Water · 🧪 chemistry