H₂CO₃
Compound · Acid
Carbonic acid
碳酸
Carbonic acid (碳酸), formula H₂CO₃, is a acid with a molar mass of 62.02 g/mol (CAS 463-79-6). Colourless; exists only in solution, cannot be isolated pure; formed when co₂ dissolves in water; readily decomposes.
Key facts
| Molar mass | 62.02 g/mol |
|---|---|
| Category | Acid |
| State at 25°C | Liquid |
| CAS | 463-79-6 |
Structure
HO–C(=O)–OH
Diprotic weak acid, exists only in aqueous solution
Physical properties
| Appearance | Colourless; exists only in solution, cannot be isolated pure |
|---|---|
| Melting point | — |
| Boiling point | — |
| Density | — |
| Solubility | Formed when CO₂ dissolves in water; readily decomposes |
Key reactions
H₂CO₃ ⇌ H₂O + CO₂↑
Unstable; decomposes on warming or reduced pressure
H₂CO₃ ⇌ H⁺ + HCO₃⁻
Diprotic weak acid, ionises stepwise
Main uses
- Source of tang in carbonated drinks
- Part of ocean and blood carbonate buffering
Hazard
LowWeak acid; ordinary contact is essentially harmless
Constituent elements
Data sources
Molar mass is computed from IUPAC (CIAAW) standard atomic weights; formula, properties and reactions can be verified on PubChem, NIST and Wikipedia. The CAS number is the substance's unique registry identifier. Educational reference only.