Ammonia Solution (aqueous) — properties & hazards overview

Name: Ammonia solution (ammonium hydroxide) Formula: NH₃(aq) / NH₄OH CAS: 1336-21-6 UN: 2672 (solution)
WARNING — strongly caustic solution that releases ammonia vapours (irritant/toxic). Provide vigorous ventilation and capture vents with acid scrubbing (pH-controlled). Avoid mixing with oxidizers/bleach (chloramine risk). Use high-efficiency demisting.
NH₃ content (w/w)
~ 5–30%
pH (20 °C)
~ 11–13 (strongly basic)
Boiling point
≈ 100 °C (varies with % NH₃)
NH₃ off-gas
Significant; ventilation required
Toxicity
NH₃ vapour irritant/toxic
Flammability
liquid N/A; NH₃ gas flammable
Chronic risk
respiratory/dermal
Environmental
aquatic toxicity
PropertyValue / Note
Chemical formulaNH₃ dissolved in water (often written as NH₄OH)
Molar mass (NH₃)17.03 g/mol
Physical state (20 °C)Clear, colourless liquid with pungent odour
Density (20 °C)~ 0.91–0.99 g/cm³ (depends on % NH₃)
Vapour pressureDominated by NH₃ above the solution; increases strongly with concentration & temperature
Odour / thresholdSharp, irritating / ~ 5 ppm typical detection
Water miscibilityFully miscible (forms ammonium hydroxide; absorption is exothermic)
Typical usespH control, cleaning agents, fertiliser production, chemical synthesis

*Values are indicative and concentration-dependent. Always consult the current SDS and local regulations for design and safety.

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