Ammonium Salts

Ammonium cation is found in a variety of salts such as ammonium carbonate, ammonium chloride, and ammonium nitrate. Most simple ammonium salts are very soluble in water. An exception is ammonium hexachloroplatinate, the formation of which was once used as a test for ammonium. The ammonium salts of nitrate and especially perchlorate are highly explosive, in these cases, ammonium is the reducing agent.

In an unusual process, ammonium ions form an amalgam. Such species are prepared by the addition of sodium amalgam to a solution of ammonium chloride.^[2] This amalgam eventually decomposes to release ammonia and hydrogen.^[3]

To find whether the ammonium ion is present in the salt, first, the salt is heated in presence of alkali hydroxide releasing a gas with a characteristic smell which of course is ammonia.

• {\displaystyle {\ce {[NH4]+ + OH- ->[heat] NH3 + H2O}}}

To further confirm ammonia it passed through a glass rod dipped in an HCl solution (hydrochloric acid) creating white dense fumes of ammonium chloride.

• {\displaystyle {\ce {NH3_{(g)}{}+ HCl_{(aq)}-> [NH4]Cl_{(s)}}}}

Ammonia when passed through CuSO4 (copper(II) sulfate) solution turns from blue to deep blue color forming Schweizer's reagent.

• {\displaystyle {\ce {CuSO4_{(aq)}{}+ 4 NH3_{(aq)}{}+ 4 H2O -> [Cu(NH3)4(H2O)2](OH)2_{(aq)}{}+ H2SO4_{(aq)}}}}

Ammonia or ammonium ion when added to Nessler's reagent gives a brown color precipitate known as the iodide of Million's base in basic medium.

Ammonium ion when added to chloroplatinic acid gives a yellow precipitate.

• {\displaystyle {\ce {H2[PtCl6]_{(aq)}{}+ [NH4]+_{(aq)}-> [NH4]2[PtCl6]_{(s)}{}+ 2 H+}}}

Ammonium ion when added to sodium cobaltinitrite gives a yellow precipitate.

• {\displaystyle {\ce {Na3[Co(NO2)6]_{(aq)}{}+ 3 [NH4]+_{(aq)}-> [NH4]3[Co(NO2)6]_{(s)}{}+ 3 Na+_{(aq)}}}}

Ammonium ion gives a white precipitate when added to potassium bitartrate.

• {\displaystyle {\ce {KC4H5O6_{(aq)}{}+ [NH4]+_{(aq)}-> [NH4]C4H5O6_{(s)}{}+ K+_{(aq)}}}}

This article is from  Wikipedia https://en.wikipedia.org/wiki/Ammonium