To analyse the given salt for acidic and basic radicals (Updated for ) • cbseBoy

To analyse the given salt for acidic and basic radicals

Experiment

Observations

Inference

1. Physical examination:

(a) Noted the colour of the given salt.

(b) Noted the smell of the salt.

White

No specific odour

Cu²⁺, Mn²⁺, Co²⁺, Ni²⁺, Fe³⁺ absent.

NH₄⁺, S^2- and CH₃COO^–may be absent.

2. Dry heating test

Heated a pinch of the salt in a dry test tube and noted the following observations :

(a) Gas evolved

(b) Sublimation

(d) Colour of the residue

A reddish brown gas evolved which turned FeSO₄ solution black.

No sublimate formed.

No crackling sound observed.

White

N0^3- may be present.

Ammonium halides, aluminium chloride, iodide may be absent.

Lead nitrate, barium

nitrate, may be absent.

Ba²⁺, Sr²⁺, Ca²⁺, Al³⁺, Mg²⁺, etc., may be present.

3. Charcoal cavity test

Mixed a pinch of the salt with double the quantity of Na₂CO₃ and heated the mixture on a charcoal cavity in the reducing flame.

White residue.

Ba²⁺, Sr²⁺, Ca²⁺, Al³⁺, Mg²⁺,

etc., may be present.

4. Cobalt nitrate test

To the above white residue added a drop of cobalt nitrate solution. Heated it in oxidising flame.

No characteristic colour.

Al³⁺, Zn²⁺„Mg²⁺, PO₄^3-, may be absent.

5. Flame test

Prepared a paste of the salt

with cone. HCl and performed flame test.

Persistent grassy green flame

on prolonged heating.

Ba²⁺ present.

6. Borax bead test

Did not perform this test since the given salt was white.

–

Cu²⁺, Mn²⁺, Co²⁺, Ni²⁺, Fe³⁺ may be absent.

7. Dil. sulphuric acid test

Treated a pinch of the salt with dil. H₂SO₄ and warmed.

No gas evolved.

CO₃^2-, S^2-, SO₃^2-, NO₂^– may be absent.

8. KMnO₄ test

To a pinch of the salt added dil. H₂SO₄ and a drop of KMnO₄ solution.

Pink colour of KMnO₄was not

discharged.

Cl^–, Br^–, I^–, C₂O₄^2-and Fe²⁺may be absent.

9. Cone, sulphuric acid test

Heated a pinch of the salt with cone, sulphuric acid and added to it a paper pellet.

A reddish brown gas evolved which turned FeSO₄ solution black.

NO₃^– may be present.

10. Confirmatory test for ni-trate

(a) Copper chips test. Heated a pinch of the salt with cone, sulphuric acid and a few copper chips.

(b) Ring test. To 2-3 ml of the salt solution, added freshly pre-pared FeSO₄ solution. Then added cone, sulphuric acid along the sides of the test tube.

Reddish brown gas evolved.

A dark brown ring formed at the junction of the two liquids.

NO₃^– confirmed.

11. Heated a pinch of salt with cone. NaOH solution

No ammonia gas evolved.

NH₄⁺ absent.

12. Preparation of Original Solution (O.S.)

Shook a pinch of the salt with water.

Solution obtained

Labelled it as Original Solution (O.S.)

13. To a part of the O.S. added 1-2 ml of dilute hydro-chloric acid.

No ppt. formed.

Group I absent. (Pb²⁺ absent)

14. Through a part of the above solution, passed H₂S gas.

No ppt. formed.

Group II absent (Pb²⁺, Cu²⁺, As³⁺, absent)

15. To the remaining solution, added a pinch of solid ammonium chloride. Boiled the solution, cooled it and added excess of ammonium hydroxide solution.

No ppt. formed.

Fe³⁺, Al³⁺ absent

16. Through a part of the above solution, passed H₂S gas.

No ppt. formed.

Group IV absent.

(Zn²⁺, Mn²⁺, Co²⁺ and Ni²⁺ absent)

17. To the remaining ammonical solution added ammonium carbonate solution.

White ppt. formed.

Group V present.

(Ca²⁺, Ba²⁺, Sr²⁺ may be present)

18. Confirmatory test for Ba²⁺ ion

Filtered the above white ppt. Dissolved the ppt. in hot dilute acetic acid.

(a) Pot. chromate test. To one part of the above solution, added a few drops of pot. chromate solution.

(b) Flame test. Performed flame test with the salt.

Yellow ppt.

Persistent grassy green flame on prolonged heating.

Ba²⁺ confirmed.

Result

Acid radical : NO₃^–
Basic radical : Ba²⁺.

Experiment

Observations

Inference

1. Physical examination:

(a) Noted the colour of the

given salt.

(b) Noted the smell of the salt.

White

No specific odour

Cu²⁺, Mn²⁺, Co²⁺, Ni²⁺, Fe³⁺ absent.

NH₄⁺, S^2- and CH₃COO^–may be absent.

2. Dry heating test

Heated a pinch of the salt in a dry test tube and noted the following observations :

(a) Gas evolved

(b) Sublimation

(d) Colour of the residue

A colorless gas evolved which turned lime water milky.

No sublimate formed.

No crackling sound observed.

Yellow when hot and white when cold

CO₃^2- may be present.

Ammonium halides, aluminium chloride, iodide may be absent.

Lead nitrate, barium

nitrate, may be absent.

Zn²⁺may be present.

3. Charcoal cavity test

Mixed a pinch of the salt with double the quantity of Na₂CO₃ and heated the mixture on a charcoal cavity in the reducing flame.

Yellow when hot and white when cold

Zn²⁺may be present.

4. Cobalt nitrate test

To the above white residue added a drop of cobalt nitrate solution. Heated it in oxidising flame.

Green Residue

Zn²⁺may be pesent.

5. Flame test

Prepared a paste of the salt

with cone. HCl and performed flame test.

Green flashes seen with naked eye

Zn²⁺, Mn²⁺may be present.

6. Borax bead test

Did not perform this test since the given salt was white.

–

Cu²⁺, Mn²⁺, Co²⁺, Ni²⁺, Fe³⁺ may be absent.

7. Dil. sulphuric acid test

Treated a pinch of the salt with dil. H₂SO₄ and warmed.

Shook a pinch of salt with water taken in test tube.

Colourless, odourless gas evolved with brisk effervescence, turned lime water milky.

Salt did not dissolve.

CO₃^2- present

Insoluble CO₃^2-indicated.

8. KMnO₄ test

To a pinch of the salt added dil. H₂SO₄ and a drop of KMnO₄ solution.

Pink colour of KMnO₄was not discharged.

Cl^–, Br^–, I^–, C₂O₄^2-and Fe²⁺may be absent.

9. Cone, sulphuric acid test

This test was not performed as the salt reacted with dil. H₂SO₄.

–

Cl^–, Br^–, I^–, C₂O₄^2-, CH₃COO^–and Fe²⁺may be absent.

10. Confirmatory test for carbonate

Tried to dissolve the salt in water.

To the salt added dil HCl

The salt is insoluble in water.

Brisk effervescence with evolution of colourless, odourless gas which turned lime water milky.

Insoluble carbonate.

Insoluble carbonate confirmed.

11. Heated a pinch of salt with cone. NaOH solution

No ammonia gas evolved.

NH₄⁺ absent.

12. Preparation of Original Solution (O.S.)

(a) Shook a pinch of the salt with water.

(b) Shook a pinch of the salt in dil. HCl.

Insoluble

Clear solution obtained

Labelled it as O.S.

As the O.S. was prepared in dil. HCl

13. Through a part of O.S. passed H2S gas.

No ppt. formed.

Group I absent. (Pb²⁺ absent)

14. To the remaining solution, added a pinch of solid ammonium chloride. Boiled the solution, cooled it and added excess of ammonium hydroxide solution.

No ppt. formed.

Group II absent (Pb²⁺, Cu²⁺, As³⁺, absent)

15. Through a part of the above solution, passed H₂S gas.

Group III absent

Fe³⁺, Al³⁺ absent

16. Confirmatory tests for Zn²⁺ ion

Dissolved the above dull white ppt. in dil HCl. Boiled off H₂S.

Divided the solution into two parts.

(a) To one part added NaOH

solution dropwise.

(b) To another part, added potassium ferrocyanide solution.

Dull White ppt. formed.

White ppt. soluble in excess of NaOH solution.

Bluish white ppt.

Group IV absent.

(Zn²⁺ present)

Zn²⁺ confirmed.

Result

Acid radical : CO₃^2-
Basic radical : Zn²⁺

Chemistry Lab Manual NCERT Solutions Class 11 Chemistry Sample Papers

<!–

–>