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

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 in water. It can be denoted by the symbols NH₃(aq). Although the name ammonium hydroxide suggests a base with composition

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 [NH₄⁺][OH⁻], it is actually impossible to isolate samples of NH₄OH, as these ions only comprise a significant fraction of the total amount of ammonia in extremely dilute solutions.
In aqueous solution, ammonia deprotonates

Deprotonation

Deprotonation is the removal of a proton from a molecule, forming the conjugate base.The relative ability of a molecule to give up a proton is measured by its pKa value. A low pKa value indicates that the compound is acidic and will easily give up its proton to a base...

 a small fraction of the water to give ammonium

Ammonium

The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...

 and hydroxide

Hydroxide

Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and a hydrogen atom held together by a covalent bond, and carrying a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, as a ligand, a nucleophile, and a...

 according to the following equilibrium

Chemical equilibrium

In a chemical reaction, chemical equilibrium is the state in which the concentrations of the reactants and products have not yet changed with time. It occurs only in reversible reactions, and not in irreversible reactions. Usually, this state results when the forward reaction proceeds at the same...

:

NH₃ + H₂O NH₄⁺ + OH⁻.

In a 1M ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 solution, about 0.42% of the ammonia is converted to ammonium, equivalent to a pH of 11.63.