Ammonium hydroxide

Ammonium hydroxide

Identifiers
CAS Number	1336-21-6 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:18219 Y
ChemSpider	14218 Y
ECHA InfoCard	100.014.225
E number	E527 (acidity regulators, ...)
KEGG	C01358 N
UNII	5138Q19F1X Y
InChI InChI=1S/H3N.H2O/h1H3;1H2 Y Key: VHUUQVKOLVNVRT-UHFFFAOYSA-N Y InChI=1/H3N.H2O/h1H3;1H2 Key: VHUUQVKOLVNVRT-UHFFFAOYAI
SMILES [OH-].[NH4+]
Properties
Chemical formula	NH4OH
Molar mass	35.04 g/mol
Appearance	Colourless liquid
Odor	"Fishy", highly pungent
Density	0.91 g/cm3 (25 % w/w) 0.88 g/cm3 (35 % w/w)
Melting point	−57.5 °C (−71.5 °F; 215.7 K) (25% w/w) −91.5 °C (35% w/w)
Boiling point	37.7 °C (99.9 °F; 310.8 K) (25% w/w)
Solubility in water	Miscible
Magnetic susceptibility (χ)	-31.5·10−6 cm3/mol
Thermochemistry
Std molar entropy (So298)	111 J·mol−1·K−1
Std enthalpy of formation (ΔfHo298)	−80 kJ·mol−1
Hazards
EU classification (DSD)	N C
R-phrases	R34, R50
S-phrases	(S1/2), S26, S36/37/39, S45, S61
Related compounds
Other anions	Ammonium chloride Ammonium cyanide
Other cations	Tetramethylammonium hydroxide
Related compounds	Ammonia Hydroxylamine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Ammonia solution, also known as ammonium hydroxide, ammonia water, ammonical liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or simply ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH₃(aq). Although the name ammonium hydroxide suggests an alkali with composition [NH₄⁺][OH⁻], it is actually impossible to isolate samples of NH₄OH, as these ions do not comprise a significant fraction of the total amount of ammonia except in extremely dilute solutions.

In aqueous solution, ammonia deprotonates a small fraction of the water to give ammonium and hydroxide according to the following equilibrium:

In a 1M ammonia solution, about 1.42% of the ammonia is converted to ammonium, equivalent to a pH of 11.63. The base ionization constant is

Like other gases, ammonia exhibits decreasing solubility in solvent liquids as the temperature of the solvent increases. Ammonia solutions decrease in density as the concentration of dissolved ammonia increases. At 15.6 °C (60.1 °F), the density of a saturated solution is 0.88 g/ml and contains 35% ammonia by mass, 308 g/l w/v, (308 grams of ammonia per litre of solution) and has a molarity of approximately 18 mol L⁻¹. At higher temperatures, the molarity of the saturated solution decreases and the density increases.

When solutions that are saturated at cold temperatures are sealed in containers and subsequently warmed, the concentration of the solution decreases and the vapor pressure of ammonia gas increases. Unsealing such containers can lead to a burst of ammonia gas. In extreme cases, the containers could rupture.

From a chemist's perspective, one should be aware that the concentration of a saturated solution is continually dropping as the container is handled in a warmer environment. Thus, old samples of ammonium hydroxide will deviate from 18 M, as can be verified by titration.

Household ammonia is dilute ammonium hydroxide, which is also an ingredient of numerous other cleaning agents, including many window cleaning formulas. In addition to use as an ingredient in cleansers with other cleansing ingredients, ammonium hydroxide in water is also sold as a cleaning agent by itself, usually labeled as simply "ammonia". It may be sold plain, lemon-scented (and typically colored yellow), or pine-scented (green). Commonly available ammonia with soap added is known as "Cloudy ammonia".