NOₓ (NO / NO₂) — properties & hazards overview
NO boiling point
−152 °C
NO₂ boiling point
~ 21 °C (N₂O₄/NO₂ equilibrium)
Behaviour
NO oxidizes → NO₂; NO₂ hydrolyses → HNO₂/HNO₃
Flammability
Non-flammable (oxidizing)
Toxicity
high (NO₂ severe irritant)
Flammability
not flammable
Chronic risk
respiratory effects
Environmental
acid rain / ozone
| Property | Value / Note |
|---|---|
| NO (nitric oxide) | Colourless gas; weak odour; readily oxidizes to NO₂ in air |
| NO₂ (nitrogen dioxide) | Reddish-brown gas with sharp odour; dimerizes to N₂O₄; strong lung irritant |
| Solubility | NO₂ hydrolyses to nitrous/nitric acids → increases effective absorption in alkaline liquor |
| Sources | Combustion/exhaust, nitration, nitric acid plants, pickling, thermal oxidizers startup |
*Values indicative; composition varies by process.