Cations

Test Observation InferencePhysical Appearance    Colour White NH4+,  Pb2+, Al3+ , Zn2+, Ba2+,

Ca2+ , Sr2+ and Mg2+  Blue Cu2+  Green Ni2+  Brown Fe3+  Red Co2+  Light pink Mn2+Odour Smell of NH3 NH4+  Smell of vinegar CH3COO-  Smell of rotten eggs H2-Dry Heating Colourless gas evolved CO32- , SO32-,  S2- and Cl-  Blown gas evolved Br-, NO3-  Violet gas evolved I-  Crackling sound Pb(NO3)2 and Ba(NO3)2  Brown residue Cu2+Flame Test Greenish blue Cu2+  Light green Ba2+  Brick red Ca2+  Crimson red Sr2+

Aim: -   To identify the given inorganic compound for its acidic and basic radical.

Group Group Reagent RadicalsZero Group O.S. + NaOH + Heat NH4

+

I Group O.S. + HCl Pb2+

 II Group O.S. + HCI + H2S Cu2+

 III Group O.S. +NH4Cl + NH4OH AI3+ ,Fe3+

IV Group O.S. + NH4CI + NH4OH +H2S 

Ni2+ ,Mn2+ , Zn2+ ,Co2+

V Group O.S. + NH4CI + NH4OH +(NH4)2CO3 Ba2+, Ca2+, Sr2+

 VI Group O.S  + NH4CI + NH4OH + NaH2PO4 Mg2+

Apparatus: - Chemical Reagent, Test Tube, Test Tube holder, Spatula, Burner

Physical Observation

1. Smell or odour 2. State 3. Colour 4. Solubility in H 2O

Basic Radical

Preliminary Test:-

Confirmatory Test:-

Acidic Radical

Preliminary Test:-

Confirmatory Test:-

Result:- The given salt contains ____as acidic radical and ____as basic radical.Group 0:- NH4

+

Preliminary Test:-

S.N.Experiment Observation Inference

1. Smelled the salt. Ammonical smell. NH4+ may be present.

Confirmatory Test:-

S.N.Experiment Observation Inference

1. Added sodium hydroxide solution to the salt.

Ammonical smelling gas evolved.

NH4+ confirmed.

 Chemical Equations:- Ionic equation:- NH4++OH- --- NH3+H2O

Group 1:- Pb 2+ , Ag +

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

White coloured precipitate is formed.

Pb2+ may be present.

Confirmatory Test:-

ExperimentObservation Inference

Added potassium iodide. Yellow coloured precipitate formed.

Pb2+  confirmed.

 Chemical Equations:-

Ionic equation:-Pb2+(aq)+ HCl (aq) -- PbCl2 (white)

Pb2+(aq) +2I- --(aq) PbI2(s) (Yellow)

Ag1+

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

White coloured precipitate is formed.

Pb2+, Ag1+ may be present.

Added precipitate in hot water.

No effect. Ag1+ may be present.

Confirmatory Test:-

ExperimentObservation Inference

Added potassium chromate to original solution.

Brick red coloured precipitate formed.

Ag1+ confirmed.

 Chemical Equations:-

Ionic equation:- Ag++HCl(aq) -AgCl (s) white +H+

2AgCl(s)+K2Cr2O7 -- Ag2CrO4 Yellow +2KCl

Group 2:- Pb2+, Cu2+, As3+

Preliminary Test:- Pb2+

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+ may be present.

Added H2S, hydrochloric acid to original solution.

Black coloured precipitate formed.

Pb2+ may be present.

Confirmatory Test:-

ExperimentObservation Inference

Added potassium iodide to original solution. Yellow coloured precipitate formed.

Pb2+  confirmed.

 Chemical Equations:- Ionic equation:- Pb2++HCl -- PbCl2(l) + 2H+

Pb2++ KI (aq) ----- PbI2(s) Yellow +2K+

Cu2+

Group 3:- Fe3+, Al3+, As3+

IRON

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+ may be present.

Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+, Cu2+, As3+ absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

Reddish Brown precipitate formed.

Fe3+may be present.

 

Confirmatory Test:-

ExperimentObservation Inference

Dissolved the precipitate formed with hydrochloric . Added potassium sulphocyanide.

Blood red colouration. Fe3+  confirmed.

 Chemical Equations:-

Ionic equation:-

Al3+

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+ may be present.

Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+ , Cu2+, As3+ absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

Gelatinous white precipitate formed.

AI3+ may be present.

 

Confirmatory Test:-

ExperimentObservation Inference

Dissolved the precipitate formed with hydrochloric acid and added drops of blue litmus. Then added ammonium hydroxide till alkaline.

Blue coloured precipitate floated on surface .

AI3+   confirmed.

 

Chemical Equations:-Ionic equation:-

Group 4:- Mn 2+ , Zn 2+ , Ni 2+ , Co 2+

MANGANESE

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+may be present.

Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+, Cu2+, As3+ absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

No Effect. AI3+ ,Fe3+ absent.

Passed H2S gas through above formed solution.

Flesh(buff) coloured precipitate formed.

Mn2+ may be present.

 

Confirmatory Test:-

ExperimentObservation Inference

Added lead dioxide to above solution, then added concentrated nitric acid. Boiled it.

Pink Colouration formed. Mn2+ Confirmed.

Chemical Equations:-Ionic equation:-

ZINC

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+may be present.

Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+, Cu2+, As3+ absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

No Effect. AI3+ ,Fe3+ absent.

Passed H2S gas through above formed solution.

White coloured precipitate formed.

Zn2+ may be present.

 

Confirmatory Test:-

ExperimentObservation Inference

Dissolved the precipitate in concentrated hydrochloric acid and boiled it.Added potassium ferrocyanide to it

Bluish white coloured precipitate formed.

Zn2+ Confirmed.

 

Chemical Equations:-Ionic equation:-

NICKEL

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+ may be present.

Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+, Cu2+, As3+ absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

No Effect. AI3+ ,Fe3+ absent.

Passed H2S gas through above formed solution.

Black coloured precipitate formed.

Co2+ or Ni2+ may be present.

Dissolved the precipitate in aqua regia.Evaporated residue.

Yellow coloured residue remained.

Ni2+ may be present.

Confirmatory Test:-

ExperimentObservation Inference

Dissolved the yellow residue in water. Added ammonium hydroxide till alkaline then added dimethylglyxoglime solution.

Bright red precipitate formed.

Ni2+ confirmed.

 Chemical Equations:-Ionic equation:-

COBALT

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell.

NH4+ absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+ may be present.

Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+, Cu2+, As3+ absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

No Effect. AI3+ ,Fe3+ absent.

Passed H2S gas through above formed solution.

Black coloured precipitate formed.

Co2+ or Ni2+ may be present.

Dissolved the precipitate in aqua regia.Evaporated residue.

Blue coloured residue remained.

Co2+ may be present.

 

Confirmatory Test:-

ExperimentObservation Inference

Dissolved the blue residue in water.Added ammonium sulphocyanide to it.

Blue coloured layer floated on surface .

Co2+confirmed.

 Chemical Equations:-Ionic equation:-

Group 5:- Ca 2+ , Ba 2 + , Sr 2+

CALCIUM

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to No Effect. Pb2+may be present.

original solution.Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+, Cu2+, As3+ absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

No Effect. AI3+ ,Fe3+ absent.

Passed H2S gas through above formed solution.

No Effect. Ni2+ ,Mn2+ , Zn2+ ,Co2+ absent.

Added ammonium carbonate to above solution.

White precipitate is formed.

Ba(II), Sr(II), Ca(II) may be present.

 Confirmatory Test:-

ExperimentObservation Inference

Dissolved precipitate in acetic acid and boiled it. Added few drops of ammonium oxalate to above solution and then added ammonium hydroxide.

White precipitate is formed.

 Ca2+ Confirmed.

 Chemical Equations:-Ionic equation:-

BARIUM

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+may be present.

Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+, Cu2+, As3+ absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

No Effect. AI3+ ,Fe3+ absent.

Passed H2S gas through above formed solution.

No Effect. Ni2+ ,Mn2+ , Zn2+ ,Co2+ absent.

Added ammonium carbonate to above solution.

White precipitate is formed.

Ba2+, Ca2+, Sr2+ may be present.

 Confirmatory Test:-

ExperimentObservation Inference

Dissolved precipitate in acetic acid and boiled it.Added few drops of potassium chromate to above solution.

Yellow precipitate is formed. Ba2+ Confirmed.

 Chemical Equations:- Ionic equation:-

STRONTIUM

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+may be present.

Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+, Cu2+, As3+absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

No Effect. AI3+ ,Fe3+ absent.

Passed H2S gas through above formed solution.

No Effect. Ni2+ ,Mn2+ , Zn2+ ,Co2+ absent.

Added ammonium carbonate to above solution.

White precipitate is formed.

Ba2+, Ca2+, Sr2+ may be present.

 Confirmatory Test:-

ExperimentObservation Inference

Dissolved precipitate in acetic acid and boiled it. Added few drops of ammonium sulphate to above solution and then added ammonium hydroxide.

White precipitate is formed.

 Sr2+ Confirmed.

 Chemical Equations:-Ionic equation:- Sr2++(NH4)2CO3(aq) --SrCO3(s)white +2NH4+(aq)

SrCO3(s) 2CH3COOH(aq) -- (CH3COO)2Sr +CO2(g) +H2O(l)

Sr2+(aq)+(NH4)2SO4(aq) --Sr SO4(s)white +2NH4+(aq)

Group 6:- Mg 2+

Preliminary Test:-

ExperimentObservation Inference

Smelled the salt. No Ammonical smell. NH4+ absent.

Added dilute hydrochloric acid to original solution.

No Effect. Pb2+may be present.

Added H2S, hydrochloric acid to original solution.

No Effect. Pb2+, Cu2+, As(III) absent.

Added dilute hydrochloric acid, concentrated nitric acid and boiled solution. Then cooled it and added solid ammonium hydroxide.

No Effect. AI3+ ,Fe3+ absent.

Passed H2S gas through above formed solution.

No Effect. Ni2+ ,Mn2+ , Zn2+ ,Co2+ absent.

Added ammonium carbonate to above solution.

No Effect. Mg 2+ may be present.

 Confirmatory Test:-

ExperimentObservation Inference

Added ammonium chloride, ammonium hydroxide and disodium hydrogen phosphate to original solution.

White precipitate is formed.  Mg2+ Confirmed.

 Chemical Equations:-

Ionic equation:-Mg2++HPO42-(aq) +NH4

+(aq) --- Mg(NH4)PO4 white +H+