Hydrochloric Acid (solution) — properties & hazards overview
HCl content (w/w)
~ 10–37%
pH (20 °C)
< 1 (strong acid)
Density (20 °C)
~ 1.05–1.19 g/cm³ (↑ with %)
Fuming
Yes, at higher % (HCl vapours)
Toxicity
corrosive inhalation
Flammability
not flammable
Chronic risk
respiratory (chronic)
Environmental
acidic/aquatic
| Property | Value / Note |
|---|---|
| Chemical formula | Aqueous solution of hydrogen chloride, HCl in water |
| Common strengths | Technical: 30–33%; “concentrated”: up to ~37% w/w |
| Physical state (20 °C) | Clear, colourless to slightly yellow liquid with pungent acid odour |
| Boiling behaviour | HCl–H₂O forms an azeotrope ~20–21% at ~110 °C (approx.) |
| Vapour / off-gas | Emits HCl vapour; off-gassing increases with concentration & temperature (“fuming”) |
| Reactivity | Strong acid; reacts with metals to evolve H₂; highly corrosive to many materials |
| Typical uses | Pickling, pH control/neutralisation, metal cleaning, chemical synthesis |
*Values are indicative and concentration-dependent. Always consult the latest SDS and local regulations for design and safety.