How you can identify ammonia?

Ammonia gas has characteristic properties which are used to identify it.

Some of Physical properties are:

Color: colorless

odor: characteristic strong pungent smell(ammoniacal smell )

Physiological nature: causes an irritating, burning sensation in upper part of nasal passage, fatal in large doses.

Density: Lighter than air (V.D of ammonia = 8.5)

Melting point: -77.70C

Boiling point: -33.40C

But physical properties can't be relied to identify a substance, therefore chemical tests should be used.

Chemical tests:

1. A glass rod dipped in conc. HCl acid brought near ammonia gas gives dense white fumes. This is due to formation of Ammonium Chloride

NH3 + HCl ---> NH4Cl

2. When ammonia is passed through Copper sulfate solution a pale blue precipitate of copper hydroxide is formed.

3.Colorless Nessler's Reagent turns pale brown and on passing excess ammonia gives a brown precipitate.

2K2[HgI4] + NH3 + 3KOH ---> H2N.HgO.HgI + 7KI + 2H2O

(nessler's reagent) (Brown ppt.)

4.All salts of ammonia on heating with alkali produce ammonia gas which can be identified