Chemical Properties of Ammonia Chemistry Notes

Chemical Properties of Ammonia Chemistry Notes

Chemical Properties of Ammonia :

Chemical properties of ammonia are as follows:

Precipitation reactions of aqueous ammonia: It precipitates metal hydroxides from aqueous solutions of metallic salts.

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Formation of complexes : Ammonia can form complexes with some cations like Ag2+, Cu2+, Ca2+, Hg2+, Zn2+ etc. The envolved reactions are as follows:

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If in above reaction NH4 OH solution is taken in excess then white precipitate dissolves in solution and a complex is formed .

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Ammonia acts as a Lewis base due to the presence of lone pair of electrons on the nitrogen atom. So ammonia can form co-ordinate bond with transition metal cations and thus forming a complex. In complex ammonia behave as ligand.

Oxidation : In presence of catalyst ammonia is oxidised into nitric oxide (NO).

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This reaction is used in Ostwald’s process.

In presence of oxidising agents like CuO, NaClO, CaOCl2 etc. ammonia is oxidised into dinitrogen. For example.

3CuO + 2NH3 → 3 Cu + N2 + 3H2O
3Ca(OCl)2 + 4NH3 → 2N2 + 3CaC2 + 6H2O
3Br2 + 8NH3 → N2 + 6NH4 Br

Reaction with halogens : Halogen reacts with ammonia in different ways.

With excess Cl2 Nitrogen trichloride is formed.

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With excess NH3 : Ammonium chloride and nitrogen are formed.

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With Br2: Ammonium bromide is formed

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With I2 : Nitrogen tri-iodide ammoniate (brown ppt) is obtained.

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NH3 NI3 acts as an explosive. In dried state when it is either rubbed or struck then it explodes with a loud noise.

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Reducing Nature : Ammonia acts as reducing agent. It reduces heavier metal oxides into metals.

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Reaction with CO2 : Ammonia reacts with carbon dioxide and forms ammonium carbonate which decomposes into urea.

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Urea acts as fertilizer.

Decomposition : On heating above 500°C or by passing electric arc through ammonia, it decomposes into dihydrogen and dinitrogen.

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Liquid ammonia as a solvent: Like water liquid ammonia is also self ionised.
NH3 + NH3 → NH4+ + NH2

Chemical Properties of Ammonia Chemistry Notes

Therefore liquid ammonia is used as non-aqueous solvent for dissolving many polar compounds.

Basic Nature : Ammonia behave as base. It reacts with acid to form salts. It turns moist red litmus blue.

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Reaction with metals : Ammonia gas when passed over molten sodium or potassium metal at 575 K then it forms corresponding amides and liberates dihydrogen.

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Reaction with Nessler’s reagent : Ammonia reacts with Nessler’s reagent (alkaline solution of KHgl.) and give a brown precipitate due to the formation of iodide of Millon’s base.

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Reaction with sodium hypochlorite : Aqueous ammonia taken excess when treated with sodium hypochlorite in presence of glue or gelatine, then hydrazine is formed.

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Chemistry Notes

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