Zinc +2 ion and ammonia reaction | Zn2+ and NH3
Aqueous zinc +2 ion solution is colourless. When ammonia solution is added to the Zn+2 ion, different observations can be seen according to the amount of added ammonia or concentration of ammonia.
This is an experiment in testing of zinc ion in qualitative analysis in chemistry.
Assume that, aqueous Zn2+ ion is associated with a anion such as NO3- or Cl-. ZnCl2 and Zn(NO3)2 are colourless solutions.
Zinc +2 ion and dilute ammonia solution reaction
When aqueous dilute ammonia solution is added slowly to the colourless Zn2+ solution, a white precipitate, zinc hydroxide (Zn(OH)2) is given. Zinc hydroxide is an amphoteric compound (hydroxide) and it is an insoluble hydroxide in water.
When you add more ammonia solution to the zinc hydroxide precipitate, that precipitate dissolve and give colourless solution.
Zinc hydroxide and concentrated ammonia solution reaction
If excess ammonia solution or concentrated ammonia solution is added to the Zn(OH)2 precipitate, the white precipitate is dissolved in water and water soluble a coordination compound is given.
Colourless tetraaminezinc(ii) ion is the cation of coordination compound.
tetraamminezinc(ii) ion : [Zn(NH3)4)]2+
Coordintion compounds can be following compounds.
- tetraaminezinc(ii) chloride : [Zn(NH3)4)]Cl2 - If Cl- ions are in the presence
- tetraaminezinc(ii) nitrate : [Zn(NH3)4)](NO3)2 If NO3- ions are in the presence
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