Ammonia

Melting point−77.73 °C (−107.91 °F; 195.42 K) (Triple point at 6.060 kPa, 195.4 K) Boiling point−33.34 °C (−28.01 °F; 239.81 K) Critical point (T, P) 132.4 °C (405.5 K), 111.3 atm (11,280 kPa)

Solubility in water

530 g/L (20 °C)
320 g/L (25 °C)

Solubilitysoluble in chloroform, ether, ethanol, methanol Vapor pressure857.3 kPa Acidity (pK_a) 32.5 (−33 °C), 9.24 (of ammonium) Basicity (pK_b) 4.75 Conjugate acid Ammonium Conjugate base Amide

Magnetic susceptibility (χ)

−18.0×10 cm/mol

Refractive index (n_D)

1.3327 Viscosity

10.07 µPa·s (25 °C)
0.276 mPa·s (−40 °C)

Structure

C_3v

1.42 DThermochemistry

Std molar
entropy(S₂₉₈)

193 J/(mol·K)

Std enthalpy of
formation(Δ_fH₂₉₈)

−46 kJ/mol Hazards GHS labelling:

Pictograms

Signal word

Danger

Hazard statements

H314, H331, H410

Precautionary statements

P260, P273, P280, P303+P361+P353, P304+P340+P311, P305+P351+P338+P310NFPA 704 (fire diamond)

Autoignition
temperature

651 °C (1,204 °F; 924 K) Explosive limits15.0–33.6% Lethal dose or concentration (LD, LC):

LD₅₀ (median dose)

350 mg/kg (rat, oral)

LC₅₀ (median concentration)

40,300 ppm (rat, 10 min)
28,595 ppm (rat, 20 min)
20,300 ppm (rat, 40 min)
11,590 ppm (rat, 1 hr)
7338 ppm (rat, 1 hr)
4837 ppm (mouse, 1 hr)
9859 ppm (rabbit, 1 hr)
9859 ppm (cat, 1 hr)
2000 ppm (rat, 4 hr)
4230 ppm (mouse, 1 hr)

LC_Lo (lowest published)

5000 ppm (mammal, 5 min)
5000 ppm (human, 5 min)

NIOSH (US health exposure limits):

PEL (Permissible)

50 ppm (25 ppm ACGIH-TLV; 35 ppm STEL)

REL (Recommended)

TWA 25 ppm (18 mg/m) ST 35 ppm (27 mg/m)

IDLH (Immediate danger)

300 ppm Safety data sheet (SDS) ICSC 0414 (anhydrous) Related compounds

Related nitrogen hydrides

Related compounds

Supplementary data page Ammonia (data page)

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

verify ( ?)

Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the formulaN H₃. A stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pungent smell. It is widely used in fertilizers, refrigerants, explosives, cleaning agents, and is a precursor for numerous chemicals. Renewable ammonia is considered as an important energy carrier in future energy systems. Biologically, it is a common nitrogenous waste, and it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to fertilisers. Around 70% of ammonia produced industrially is used to make fertilisers in various forms and composition, such as urea and diammonium phosphate. Ammonia in pure form is also applied directly into the soil.

Ammonia, either directly or indirectly, is also a building block for the synthesis of many chemicals. In many countries, it is classified as an extremely hazardous substance. Ammonia is toxic, causing damage to cells and tissues. For this reason it is excreted by most animals in the urine, in the form of dissolved urea.

Ammonia is produced biologically in a process called nitrogen fixation, but even more is generated industrially by the Haber process. The process helped revolutionise agriculture by providing cheap fertilizers. Conventional ammonia production accounts for about 500 million ton/year CO₂ emissions. The global industrial production of ammonia in 2021 was 235 million tonnes. Industrial ammonia is transported by road in tankers, by rail in tank wagons, by sea in gas carriers, or in cylinders. Ammonia occurs in nature and has been detected in the interstellar medium.

Ammonia boils at −33.34 °C (−28.012 °F) at a pressure of one atmosphere, but the liquid can often be handled in the laboratory without external cooling. Household ammonia or ammonium hydroxide is a solution of ammonia in water.