Cl₂
Compound · Gas
Chlorine
氯气
Chlorine (氯气), formula Cl₂, is a gas with a molar mass of 70.9 g/mol (CAS 7782-50-5). Yellow-green gas with a sharp irritating smell; dissolves in water to form chlorine water.
Key facts
| Molar mass | 70.9 g/mol |
|---|---|
| Category | Gas |
| State at 25°C | Gas |
| CAS | 7782-50-5 |
Structure
Cl–Cl
Yellow-green diatomic molecule; a strong oxidiser
Physical properties
| Appearance | Yellow-green gas with a sharp irritating smell |
|---|---|
| Melting point | −101 °C |
| Boiling point | −34 °C |
| Density | 3.21 g/L (气体) |
| Solubility | Dissolves in water to form chlorine water |
Key reactions
Cl₂ + H₂O ⇌ HCl + HClO
Disproportionates in water to HCl and HClO
Cl₂ + 2NaOH → NaCl + NaClO + H₂O
Reacts with alkali — bleach production
2Na + Cl₂ →(点燃) 2NaCl
Combines directly with metals
Main uses
- Disinfecting tap water and pools
- Bleaching paper and textiles
- Making PVC and other chlorinated chemicals
Hazard
HighHighly toxic irritant gas; inhalation damages the lungs
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.