Testing Ammonium Salts and ammonia gas and reactions|characteristics

Ammonium salts and ammonia identification experiments, reactions and characteristics are discussed in this tutorial. Some ammonium compounds release ammonia gas when those compounds are heated. Ammonia is a toxic gas. But it has so many industrial uses such as manufacturing nitric acid.


Identify Ammonium salts

Add aqueous strong base to any ammonium salt and heat the mixture. Then ammonia gas (NH3) is released.

ammonium chloride and sodium hydroxide reaction

Mechanism of ammonium salt and aqueous strong base

H atoms in NH4+ molecule are positively charged because electronegativity of N atom is higher than H. In OH- ion, electron density around O atom is high. So that electrons attacks H atoms (positively charged) of NH4+ molecule. As a result, one N-H bond breaks and gives NH3 and H2O as products.

Ammonium salts and hydroxides reaction mechanism


Decomposition of ammonium salts



Heating ammonium nitrate (NH4NO3)

Nitrous oxide(N2O) and water are formed when NH4NO3 is heated.

Heating ammonium nitrate

Heating ammonium nitrite (NH4NO2)

Nitrogen(N2) and water are formed when NH4NO3 is heated.

Heating ammonium nitrite


Decomposition of ammonium hydroxide (NH4OH)

NH4OH decomposes to NH3(g) and H2O(g).

Decomposition of ammonium hydroxide


Heating ammonium sulfate

When ammonium sulfate( (NH4(2SO2) is heated, it decomposes to NH3(g) and H2SO4(g).

decomposition ammonium sulfate


Decomposition of ammonium phosphate

NH3(g) and H3PO4(g) are produced by the decomposition of (NH4)3PO4.

decomposition ammonium phosphate

Heating ammonium carbonate

When ammonium carbonate( (NH4)2CO3 ) is heated, it decomposes to ammonia, carbon dioxide and water. Ammonium carbonate is a solid, but all products are in gaseous phase.

Heating ammonium carbonate (NH4)2CO3


Decomposition of ammonium dichromate

Ammonium dichromate ( (NH4)2Cr2O7 ) will decompose into nitrogen (N2) , chromium oxide ( Cr2O3 ) and water. Chromium oxide is green colour and it is an amphoteric oxide.

Decomposition of ammonium dichromate (NH<sub>4</sub>)<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub>

heating a mixture of ammonium chloride and potassium dichromate

Heating a mixture of ammonium chloride and potassium dichromate also gives nitrogen(N2) , chromium oxide ( Cr2O3 ) and water as products.

heating a mixture of ammonium chloride and potassium dichromate


Heating ammonium perchlorate

When ammonium perchlorate(NH4ClO4) is heated above 2000C, it decomposes to nitrogen(N2), chlorine(Cl2), oxygen(O2) and water.

Heating ammonium perchlorate


Decomposition of ammonium halides

Now we discuss decomposition halides ( Cl- , Br- , I- ) of NH4+ ions.


Decomposition of ammonium iodide (NH4I)

Decomposition of NH4I give NH3 and HI. But HI is not stable to heat. Therefore when furthermore heating HI decomposes to H2 and I2 gases. I2 is a purple gas.

Decomposition of ammonium iodide

Decomposition of ammonium bromide (NH4Br)

Decomposition of NH4Br give NH3 and HBr. But HBr is not stable to heat. Therefore when furthermore heating HBr decomposes to H2 and Br2 gases. Br2 is a brown gas.

Decomposition of ammonium bromide

Decomposition of ammonium chloride (NH4Cl)

Decomposition of NH4Cl give NH3 and HCl. HCl is stable to heat. Therefore it does not decompose furthermore.

Decomposition of ammonium chloride

Ammonia(NH3) gas preparing, reactions, properties

Ammonia has a lot of reactions due to its different reaction types as an acid, as a base, as a reducing agent, reactions. Ammonia is a toxic gas. When ammonia gas dissolve in water, it forms aqueous ammonium hydroxide which is basic. Ammonia has number of industrial uses such as manufacturing nitric acid.

Identify ammonia gas

  1. Add nessler reagent, then it will turn into brown colour.
  2. When get close to the concentrated HCl bottle lid, ammonium chloride (NH4Cl ) white solid fog will be made.
  3. Ammonia is a unpleasant , basic gas.
  4. Ammonia will turn red litmus to blue litmus.
  5. NH3 dissolve very well in water.
  6. A colourless gas.
ammonia and HCl


Ammonia releasing reactions

Nitride ions(N3-) ion are exceedingly strong bases and react with almost any proton donor to produce ammonia(NH3).


Magnesium nitride and water reaction

Magnesium nitride (Mg3N2) react with water and produce ammonia and magnesium hydroxide.

magnesium nitride and water reation give ammonia

Sodium nitride and water reaction

Sodium nitride(Na3N) react with water and produce ammonia and sodium hydroxide.

Sodium nitride and water reaction give ammonia

Devards's alloy, nitrate and strong alkali reaction

Devards's alloy is a mixture of metals 50% Cu , 45% Al , 5% Zn. This Devards's alloy , nitrate(NO3-) and strong alkali react and nitrate is reduced to NH3.

Devards's alloy, nitrate and strong alkali reaction

Reactions of ammonia

Ammonia can behave as a acid, a base, an oxidizing reagent, a reducing agent. Therefore ammonia has wide variety of reactions.

Acidity of ammonia gas

By the reaction of alkali metals, hydrogen(H2) gas is liberated and metal amine are formed. Therefore we can say ammonia can act as an acid. In this reaction Na is oxidized into Na+ ion. Therefore ammonia behaves as an oxidizing reagent too.
2Na + 2NH3 → 2NaNH2 + H2
2K + 2NH3 → 2KNH2 + H2


Ammonia and NaH reaction

NaH is a strong base. It reacts with NH3 to give sodamide (Sodium amide, NaNH2) and H2.

Ammonia and NaH reaction

Aqueous ammonia solution

Ammonia dissolves very well in water. But ammonia partially hydrolysis and give OH-. Otherwise, we can say dissociation of ammonia in the water is weak. However aqueous ammonia solution is basic due to release of OH- ion by the reaction of ammonia and water. Ammonia is a weak base.

Aqueous ammonia solution reaction


Ammonia as a reducing agent

In some reactions, NH3 is oxidized. Oxidation number of N in ammonia is -3. Therefore NH3 can be oxidized to N2( Oxidation number of N = 0), NO( Oxidation number of N= +2).


Combustion of ammonia with O2 without catalyst

In NH3 combustion with O2 without catalyst, it gives N2(g) and H2O(g).

Ammonia combustion with oxygen, without catalyst

Combustion of ammonia with O2, with catalyst

In NH3 combustion with O2 with Cu or Pt/Rh catalyst, it gives NO(g) and H2O(g). Cu is used in the laboratory as the catalyst. But industrially Pt/Rh is used as catalyst. This reaction is used in industrial manufacturing of nitric acid. NO is easily oxidized to NO2 in the air.

Ammonia combustion with oxygen with catalyst

Heating ammonia and copper oxide

Heating ammonia and copper oxide ( CuO ) will give Cu and N2. CuO is brown and Cu is red brown. CuO is reduced Cu
NH3 is oxidized to N2.

Heating ammonia and copper oxide

Silver oxide and ammonia reaction

Silver oxide ( Ag2O ) and ammonia can react in two ways.

  1. Gaseous NH3 and Ag2O
  2. Aqueous NH3 and Ag2O

Gaseous NH3 and Ag2O

When Ag2O is heated O2(g) is emitted. That releasing O2 can react with NH3 to give N2.

Gaseous NH3 and Ag2O

Aqueous NH3 and Ag2O

NH3(aq) and Ag2O react to give [Ag(NH3)2] colourless coordination complex.

Aqueous NH3 and Ag2O

Reaction of ammonia and chlorine

There are two states of this reaction.

  1. Excess NH3 and less Cl2
  2. Less NH3 and excess NH3

Excess NH3 and less Cl2

In the first step, NH3 and Cl2 react to give N2 and HCl. Produced HCl again reacts with remaining NH3 producing NH4Cl, a solid white fog.

Excess ammonia and less chlorine

Less NH3 and excess NH3

less ammonia and excess chlorine

Forming precipitating by aqueous ammonia solution

Aqueous ammonia solution partially dissociates to give OH- in the water. Some d block cations forms precipitates with OH- ions.

Aqueous ammonia solution partially dissociates

Aqueous ammonia solution react with some d block ions to produce precipitates

Aqueous ammonia solution react with some d block ions to produce precipitates

Coordination complexes given by aqueous ammonia solution

NH3 has a one lone pair. Therefore NH3 can behave as a ligands to form coordination complexes.
First, 3d metal ions which have d7, d8, d9, d10 forms precipitates with NH3(aq). But adding more NH3(aq), those precipitates dissolve to form coordination complexes.

Coordination complexes given by aqueous ammonia solution

Uses of ammonia gas

  1. NH3 is used as a raw material to manufacture nitric acid by ostwald process.
  2. For urea manufacturing, NH3 is used as a raw material.


Nitrogen cycle and ammonia, ammonium salts

  • A bacteria, Rhizobium can convert atmospheric nitrogen(N2) to NH3 in a process known as biological nitrogen fixation.
  • Nitrosomanas bacteria convert NH3 and NH4+ salts into NO2- and NO3-.


Questions asked on ammonium salt and ammonia


How to identify ammonium carbonate and ammonium nitrate ?

Both compounds have ammonium ion.

Add both compounds to aqueous barium chloride solution.

One compound forms a white precipitate. It is barium carbonate. That is related to the ammonium carbonate.


Write chemical reaction of ammonium salt with a known alkali

Ammonium salt reacts with alkali and release ammonia gas. As alkalis, NaOH, KOH, Ba(OH)2can be used.

NH4Cl + NaOH → NH3 + NaCl + H2O


Green colour product that gives as a result when ammonium salt heats?

Ammonium dichromate gives a green colour Cr2O3 when heating.