Ammonia
Summary: Ammonia (NH₃) is a pungent, colourless alkaline gas manufactured by the Haber process (N₂ + 3H₂ ⇌ 2NH₃). It is mainly used to make NPK fertilisers (~80% of production) and nitric acid. Tags: igcse chemistry ammonia haber keyword Created: 2026-07-14 Last Updated: 2026-07-14
Definition
Ammonia is a compound of nitrogen and hydrogen with the formula NH₃. It is a colourless gas with a characteristic pungent smell, lighter than air, and highly soluble in water (forming an alkaline solution: NH₃ + H₂O ⇌ NH₄⁺ + OH⁻).
Key Properties
| Property | Value/Description |
|---|---|
| Formula | NH₃ |
| State at RTP | Gas |
| Smell | Pungent, characteristic |
| Solubility in water | Very soluble (forms NH₄OH — alkaline) |
| pH of aqueous solution | ~11 (weak alkali) |
| Boiling point | −33°C |
| Test | Damp red litmus paper turns blue |
Manufacture (Haber Process)
N₂(g) + 3H₂(g) ⇌ 2NH₃(g) — 450°C, 200 atm, iron catalyst. See Haber Process and Ammonia for full details.
Uses
- NPK fertilisers (ammonium nitrate, ammonium sulfate, urea)
- Nitric acid manufacture (Ostwald process)
- Household cleaning products
- Refrigerant gas (anhydrous ammonia)
See Also
- Haber Process and Ammonia — Full topic page
- Reversible Reactions — Equilibrium concepts
- NPK Fertiliser
- Acids and Bases — Ammonia as a weak base
- IGCSE-Chem-Index