AIM: – To identify the given inorganic compound for its acidic and basic radical.
APPARATUS:- Chemical Reagent, Test Tube, Test Tube holder, Spatula
PROCEDURE:-
Preliminary Test:-
| Experiment | Observation | Inference |
| Smelled the salt. | No Ammonical smell. | Ammonium absent. |
| Added dilute hydrochloric acid to the original solution. | No Effect. | Lead(II)may be present. |
| Added hydrogen disulphide, hydrochloric acid to the original solution. | No Effect. | Pb(II), Cu(II) , As(III) absent. |
| Added dilute hydrochloric acid, concentrated nitric acid, and boiled solution. Then cooled it and added solid ammonium hydroxide. | No Effect. | Al(III) ,Fe(III) absent. |
| Passed Hydrogen disulphide gas through the above formed solution. | Black coloured precipitate formed. | Co(II) or Ni(II) may be present. |
| Dissolved the precipitate in aqua regia.Evaporated residue. | Blue coloured residue remained. | Co(II) may be present. |
Confirmatory Test:-
| Experiment | Observation | Inference |
| Dissolved the blue residue in water.Added ammonium sulphocyanide to it. | Blue coloured layer floated on the surface . | Co(II) confirmed. |
Chemical Equations:-
Ionic equation:-
Co2+ + H2S(aq) –> CoS(s)(black) + 2H+
CoS(s)(black) + 2HCl(aq) + [O] –> CoCl2(aq) + H2O(l) + S
Co2+ + 4KCNS –> K2[Co(CNS)4](blue colouration) + 2K+
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