Carbonic acid 碳酸
- Not to be confused with Carbolic acid, an antiquated name for phenol.
- Carbonic acid is also an archaic name for carbon dioxide.
Carbonic acid is a chemical compound with the chemical formula H2CO3 (equivalently OC(OH)2). It is also a name sometimes given to solutions of carbon dioxide in water (carbonated water), because such solutions contain small amounts of H2CO3. In physiology, carbonic acid is described as volatile acid or respiratory acid, because it is the only acid excreted as a gas by the lungs.