HCl
Compound · Acid
Hydrochloric acid (HCl)
盐酸 (氯化氢)
Hydrochloric acid (HCl) (盐酸 (氯化氢)), formula HCl, is a acid with a molar mass of 36.46 g/mol (CAS 7647-01-0). Colourless pungent gas; aqueous solution is hydrochloric acid; extremely soluble in water.
Key facts
| Molar mass | 36.46 g/mol |
|---|---|
| Category | Acid |
| State at 25°C | Gas |
| CAS | 7647-01-0 |
Structure
H–Cl
Diatomic polar molecule (aqueous solution is hydrochloric acid)
Physical properties
| Appearance | Colourless pungent gas; aqueous solution is hydrochloric acid |
|---|---|
| Melting point | −114 °C |
| Boiling point | −85 °C |
| Density | 1.49 g/L (气体) |
| Solubility | Extremely soluble in water |
Key reactions
HCl + NaOH → NaCl + H₂O
Neutralises to salt and water
2HCl + CaCO₃ → CaCl₂ + H₂O + CO₂↑
Reacts with carbonates, releasing CO₂
Zn + 2HCl → ZnCl₂ + H₂↑
Displaces hydrogen from active metals
Main uses
- Metal pickling / rust removal
- Main component of stomach acid
- Pharmaceutical and chemical synthesis
Hazard
ModerateCorrosive; fumes irritate eyes and respiratory tract
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.