Difference Between Ammonia and Ammonium

Edited by Diffzy | Updated on: April 30, 2023


Difference Between Ammonia and Ammonium

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Ammonia and Ammonium are two useful compounds in our everyday life which people often confuse with each other. Ammonia is an inorganic compound of Nitrogen and Hydrogen with the formula NH3, while ammonium is an onion cation obtained by protonation ( formation of ammonium group NH4+ from ammonia NH3) of ammonia.

A question that most of us have when we hear the name of these two compounds is whether ammonia and ammonium are the same since they sound so similar.

We need to learn about the characteristics of ammonia and Ammonium to differentiate between them. Let us take a deeper look into the difference between Ammonia and Ammonium.

Ammonia VS Ammonium

While it has been mentioned earlier that ammonia is not the same as ammonium, it is also necessary to note the main difference which makes them unique. One such difference is their respective chemical formulas. Ammonia has the formula NH3 while ammonium is represented by the chemical formula NH4+. Another difference to take note of is the fact that Ammonium is ionised while Ammonia is an unionised compound. While ammonia is a polar molecule existing as a gas at room temperature, ammonium ions exist as free ions in solution or as crystallised salt compounds.

The chemical equation that depicts the relationship between ammonia and ammonium is given below:

NH3 + H2O ↔ NH4+ + OH-

To understand both compounds better, let us compare them based on various qualities and characteristics.

Difference Between Ammonia And Ammonium In Tabular Form

Parameters of Comparison Ammonia Ammonium
Definition Ammonia is a compound consisting of nitrogen and hydrogen and has the chemical formula NH3 Ammonium cation is a positively charged polyatomic ion with the chemical formula NH4+
Existence An uncharged polar molecule exists as a gas at room temperature. They are charged and exist as free ions in solution or as crystallised salt compounds.
Geometry Trigonal Pyramidal Tetrahedral
Structure One molecule has three hydrogen atoms bound to a central Nitrogen atom. One ion has four hydrogen atoms bound to a central Nitrogen atom
Odour Sharp, intensely irritating smell Do not have characteristic smells
Toxicity Toxic Free ammonium ions are not toxic by themselves
Characteristics A molecule by itself has its own set of characteristics Forms compound with other anions; therefore characteristics vary depending on the parent compo and the degree of dissociation of the compound.

What is Ammonia?

Ammonia(NH3) is a colourless, pungent gas composed of nitrogen and hydrogen. Ammonia is the simplest stable compound of these elements. It is used as a starting material for the production of various commercially important nitrogen compounds. Its structure consists of three hydrogen atoms bound to a central Nitrogen atom and has a trigonal pyramidal shape. It is also dangerous when it is in its concentrated form.   

Ammonia is lighter than air and has a density of 0.769  kg/m3 at STP. In its aqueous form, it is called ammonium hydroxide. Though Ammonia is not highly flammable, there is a chance that containers of ammonia may explode when exposed to high heat.

Preparation of Ammonia

Pure ammonia was first prepared by English physical scientist Joseph Priestly in 1774. French chemist Claude Louis Berthollet determined its exact composition in 1785. There are various methods available for the production of ammonia. Let us take a look at a few of them.

Ammonia is prepared in the laboratory by heating ammonium salt, such as ammonium chloride NH4Cl with a strong alkali, such as sodium hydroxide or calcium hydroxide.

2NH4Cl + Ca(OH)2 → CaCl2 + 2H2O + 2NH3(g)

 The chief commercial method of producing ammonia is the Haber-Bosch process. The process involves the direct reaction of elemental hydrogen and elemental nitrogen.

N2 + 3H2 → 2NH3

This reaction requires the use of a catalyst, high pressure and an elevated temperature. Though the catalyst normally used is an iron-containing iron oxide, both magnesium oxide on aluminium oxide that has been activated by alkali metal oxides and ruthenium on carbon can also be used as catalysts. In the laboratory, ammonia can also be synthesised by the hydrolysis of a metal nitride.

Mg3N2 + 6H2O → 2NH3 + 3Mg(OH)2

Properties  of Ammonia

Ammonia has a trigonal pyramidal shape with three hydrogen atoms and an unshared pair of electrons attached to the nitrogen atom. It is a polar molecule and has strong intermolecular hydrogen bonding.  The dielectric constant of ammonia (22 at −34 °C [−29 °F]) is lower than that of water(81 at 25 °C [77 °F]). Therefore,  it is a better solvent for organic materials. However, it is still high enough which makes ammonia a good ionising solvent.

Ammonia also shows the properties of a weak base since it combines with many acids to form salts. For example, when ammonia reacts with hydrochloric acid, it is converted into ammonium chloride.  All the salts that are produced from such acid-base reactions contain the ammonium cation (NH4). Its boiling point and freezing points are −33.35 °C −77.7 ° respectively. Ammonia is also regarded as an amphoteric compound. Ammonia is also able to form amides with some alkali metals and alkaline earth metals. An example is the formation of lithium amide (LiNH2) by exposing lithium to liquid ammonia.

Uses of Ammonia

Ammonia is one of the most important chemicals in the manufacture of products that people use daily. This is because ammonia provides us with more benefits than disadvantages. Let us take a look at the various uses of ammonia.

  • Ammonia in Household Cleaning Products:- Ammonium hydroxide, which is also known as household ammonia, is an ingredient in many household cleaning products. It is used to clean a variety of surfaces since it is effective in breaking down household grime or stains from animal fats or vegetable oils. Ammonia is used as an antimicrobial agent or an antiseptic. It is also used as fuel. It is commonly used in glass cleaning solutions to help avoid streaking since it evaporates quickly.
  • Agriculture:- Ammonia is a basic ingredient of ammonium nitrate fertiliser, which releases nitrogen. Nitrogen is an essential nutrient for growing plants. Therefore, about 90 per cent of ammonia produced worldwide is used in fertiliser, to help sustain food production. Since the production of food crops naturally depletes the soil of its nutrient supplies, farmers rely on fertiliser to keep their soils productive. Ammonia is also used as an antifungal agent on certain fruits and also as a preservative.
  • Ammonia in Industrial/Manufacturing:- Ammonia can absorb substantial amounts of heat from its surroundings when used as a refrigerant gas. Ammonia can be used to purify water and is used in the treatment of waste and wastewater. It also is used in the manufacture of pharmaceuticals. It is used to manufacture several compounds like nitric acid, Hydrogen cyanide, Ammonium carbonate, Amino acids, etc.
  • Petroleum and Mining:- Ammonia is also beneficial in the petroleum industry.  It is used to counterbalance the acid constituents of oil which are in crude form. It also helps to keep equipment away from corrosion and is used in mining for the extraction of several metals.

Side Effects of Ammonia

Though ammonia has many benefits to proclaim, it also has many disadvantages, some of it even life-threatening for mankind. Let us take a look at these ill effects of ammonia. Some of the side effects of ammonia include immediate burning of the eyes, nose, throat and respiratory tract for people. It can result in blindness, lung damage or death. Long-term exposure to Ammonia fumes can also lead to social anxiety disorder, obesity and even depression in certain cases. It can also cause coughing, throat irritation, and narrowing of the bronchi.

Now that we have learned about the characteristics, benefits and ill effects of ammonia, let us delve into the properties, uses and side effects of Ammonium.

What is Ammonium?

Ammonium (NH4+) is an onium cation obtained by the protonation of ammonia (NH3). Ammonium is a positively charged polyatomic ion i.e., it consists of more than one atom. It is also used to refer to positively charged or protonated substituted amines and quaternary ammonium cations. It consists of a nitrogen atom attached to four hydrogen atoms. Ammonium has a positive charge on its nitrogen atom because the unpaired electrons on nitrogen are used to bond with the proton. The loss of electrons gives way to a positive charge on the atom.

Now let us take a look at how ammonium is prepared.

Preparation of Ammonium

Ammonium (NH4+) is formed when a neutral ammonia compound (NH3) is protonated or takes on an additional positively charged hydrogen atom. The pH of the solution plays a very important role in the production of NH4+ from NH3.

NH3+ H+ → NH4+

Properties of Ammonium

The Ammonium ion is mildly acidic. The nitrogen atom of ammonia also does not have a lone pair. It is formed when ammonia, which is a weak base, reacts with Bronsted acids(proton donors). It can be converted back to the uncharged ammonia through a reaction with Bronsted bases.

NH4+ +B- →HB +NH3

It is implied that treating a concentrated solution of ammonium salts with a strong base produces ammonia. When ammonia is dissolved in water, a small portion is converted to ammonium ions. The degree of conversion from ammonia to ammonium depends on the pH of the solution.

If the pH is low, more ammonia molecules are converted to ammonium ions. If the pH is high, then a high number of ammonium molecules are converted to ammonia.

H2O+NH3<≈> OH- + NH4+

Ammonium ions are also a waste product of animals. Ammonium is also an important source of nitrogen for many plant species.

Ill effects of Ammonium

  • Ammonium hydroxide is a corrosive chemical which can severely irritate and burn the skin and eyes leading to eye damage.
  • Ammonium hydroxide is not combustible, however, in a fire ammonia vapours are formed which may result in an explosion.
  • Inhaling ammonium can damage the lungs and can even lead to pulmonary edema, which is a build-up of fluid in the lungs.
  • Repeated contact with the skin can cause irritation, itching and dry skin.

Now that we have discussed in detail both ammonia and Ammonium, let us try to point out the key differences between them.

Main Differences between Ammonia and Ammonium in Points

  • Ammonia is a neutral compound whereas ammonium is a cation.
  • Ammonia is an inorganic compound of Nitrogen and Hydrogen while ammonium is an onion cation obtained by the protonation of ammonium.
  • Ammonia emits a strong smell while ammonium has no smell at all.
  • Ammonia is unionised while ammonium is ionised.
  • Ammonia is toxic to aquatic life while ammonium is not harmful to them.
  • Ammonia has a lone electron pair but ammonium ion does not have any lone electron pairs.
  • Ammonia has a chemical formula of NH3 with one nitrogen atom and three hydrogen atoms while Ammonium has a chemical formula of NH4+ with a central nitrogen atom and four hydrogen atoms.
  • The IUPAC name of ammonia is azane while the IUPAC name of ammonium is azanium.
  • Ammonia exists as a gas at room temperature while ammonium exists as free ions or as crystallised salt compounds.


From the in-depth discussion about the definition, qualities, properties and formation of both ammonia and Ammonium, we have finally been able to produce a clear-cut answer to the question - Are ammonia and ammonium the same? It can be said with utmost clarity that there are a lot of differences between ammonia and ammonium and that they are two different chemical compounds although they sound and spell nearly the same.

We were able to understand the difference in the chemical formula of both compounds, the properties of both compounds and their uses and disadvantages. We were also able to understand the various processes by which ammonia and ammonium were formed. From all of our findings, we can conclude that there are a lot of differences between ammonia and ammonium and that they are not the same.


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"Difference Between Ammonia and Ammonium." Diffzy.com, 2023. Mon. 05 Jun. 2023. <https://www.diffzy.com/article/difference-between-ammonia-and-ammonium-1247>.

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