Hydrogen Chloride (anhydrous) — properties & hazards overview
Boiling point
−85 °C
Melting point
−114 °C
Vapour density (air=1)
~ 1.3 (heavier than air)
Water solubility
Very high (forms HCl(aq))
Toxicity
corrosive inhalation
Flammability
not flammable
Chronic risk
respiratory (chronic)
Environmental
acidic/aquatic
| Property | Value / Note |
|---|---|
| Chemical formula | HCl |
| Molar mass | 36.46 g/mol |
| Physical state (20 °C) | Colourless to slightly yellow, pungent gas (liquefies at low temp/high pressure) |
| Odour / threshold | Pungent, irritating / very low ppm range (odour is not a reliable warning) |
| Reactivity | Highly reactive acid gas; forms hydrochloric acid with water (exothermic). Attacks many metals producing H₂. |
| Flammability | Non-flammable, but hydrogen evolved from metal corrosion is flammable/explosive. |
| Typical sources/uses | Chlorination processes, chemical synthesis, semiconductor/pickling off-gas, PVC production. |
*Values are indicative; always verify with a current SDS and applicable standards for design and safety.