Ammonium

Ammonium
2-D skeletal version of the ammonium ion
Ball-and-stick model of the ammonium cation
Space-filling model of the ammonium cation
Names
IUPAC name
Ammonium
Systematic IUPAC name
Azanium[1]
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
MeSHD000644
Properties
NH+
4
Molar mass18.04 g·mol−1
Acidity (pKa)9.25
Conjugate baseAmmonia
Structure
Tetrahedral
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

The ammonium cation is a positively charged polyatomic ion with the chemical formula NH+
4
. It is formed by the protonation of ammonia (NH3). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary ammonium cations (NR+
4
), where one or more hydrogen atoms are replaced by organic groups (indicated by R).

Acid base properties

Fumes from hydrochloric acid and ammonia forming a white cloud of ammonium chloride.

The ammonium ion is generated when ammonia, a weak base, reacts with Brønsted acids (proton donors):

H+ + NH3 → NH+
4

The ammonium ion is mildly acidic, reacting with Brønsted bases to return to the uncharged ammonia molecule:

NH+
4
+ B → HB + NH3

Thus, treatment of concentrated solutions of ammonium salts with strong base gives ammonia. When ammonia is dissolved in water, a tiny amount of it converts to ammonium ions:

H2O + NH3 ⇌ OH + NH+
4

The degree to which ammonia forms the ammonium ion depends on the pH of the solution. If the pH is low, the equilibrium shifts to the right: more ammonia molecules are converted into ammonium ions. If the pH is high (the concentration of hydrogen ions is low), the equilibrium shifts to the left: the hydroxide ion abstracts a proton from the ammonium ion, generating ammonia.

Formation of ammonium compounds can also occur in the vapor phase; for example, when ammonia vapor comes in contact with hydrogen chloride vapor, a white cloud of ammonium chloride forms, which eventually settles out as a solid in a thin white layer on surfaces.

The conversion of ammonium back to ammonia is easily accomplished by the addition of a strong base.

Other Languages
Afrikaans: Ammonium
العربية: أمونيوم
تۆرکجه: آمونیوم
беларуская: Амоній
български: Амоний
bosanski: Amonij
català: Amoni
čeština: Amonný kation
Deutsch: Ammonium
eesti: Ammoonium
Ελληνικά: Αμμώνιο
español: Amonio
Esperanto: Amonio
euskara: Amonio
فارسی: آمونیوم
français: Ammonium
Gaeilge: Amóiniam
한국어: 암모늄 이온
Հայերեն: Ամոնիում
हिन्दी: अमोनियम
hrvatski: Amonij
Ido: Amonio
Bahasa Indonesia: Amonium
italiano: Ammonio
ქართული: ამონიუმი
қазақша: Аммоний
latviešu: Amonija jons
Nederlands: Ammonium
norsk: Ammonium
norsk nynorsk: Ammonium
oʻzbekcha/ўзбекча: Ammoniy
ਪੰਜਾਬੀ: ਅਮੋਨੀਅਮ
polski: Jon amonowy
português: Amónio
română: Amoniu
русский: Аммоний
Simple English: Ammonium
slovenščina: Amonijev ion
Soomaaliga: Ammonium
српски / srpski: Amonijum
svenska: Ammonium
тоҷикӣ: Аммоний
Türkçe: Amonyum
українська: Амоній
Tiếng Việt: Amoni
中文: