Preparation of Sodium Carbonate Extract:
One gram of the mixture is treated with thrice its weight of anhydrous Na₂CO₃ and about 20 to 25 ml of water and boil it for about 15 minutes. The mixture is then cooled and filtered . the filterate is known as Sodium Carbonate Extract. It is used to perform wet tests.

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EXPERIMENT

OBSERVATION

INFERENCE

DryTest

1 

Action of dil HCl.

To a little of the mixture dil HCl is added and warmed.

1. Brisk efferverscence with the evolution of colourless odourless gas turning lime water milky
2. Colourless gas with the smell of rotten eggs, turning lead acetate paper black.
3. Reddish brown vapours with pungent smell

1. Presence of CO₃^2-

2. Presence of S^2-

<!--       c.    Presence of NO₂^-

2

Action of Conc. H₂SO₄.

A little of the mixture is treated with conc H₂SO₄ and warmed. If there is no reaction to the above solution Copper turnings are added and warmed 

1. Colourless gas forming thick white fumes with Conc. NH₄OH at the mouth of the test tube.
2. b)Fuming gas with reddish brown vapours, with the solution turning brown.
3. Fuming gas with violet vapours, solution turning black.
4. Reddish brown vapours on strong heating or on heating with Cu turnings.

1. Presence of Cl^-

2. Presence of Br^-

3. Presence of I^- 

<!--d.    Presence of NO₃^-

Wet test

3

To a little of the salt solution or Sodium Carbonate extract after acidification with dil HCl BaCl₂ solution is added.

White precipitate which is insoluble in dil HCl is formed

Presence of SO₄^2-

Confirmation test for Halides:

MnO₂ Test

To a little of the mixture MnO₂and Conc. H₂SO₄ is added and warmed

1. Greenish Yellow gas with pungent smell turning KI paper brown.
2. Reddish brown vapours condensing to form red droplets.
3. Violet vapours condensing to form violet solid.

1. Presence of Cl^-

2. Presence of Br^-

3. Presence of I^- 

Wet Test

AgNO₃ Test.

The Sodium Carbonate extract is acidified with dil. HNO₃ boiled and treated with AgNO₃

1. Curdy white precipitate soluble in excess of NH₄OH solution.
2. Pale Yellow ppt. sparingly soluble in NH₄OH.
3. Yellow precipitate insoluble in NH₄OH.

1. Presence of Cl^-

2. Presence of Br^-

3. Presence of I^-

Confirmation of Chloride

Chromyl Chloride Test.

The Mixture is mixed with solid K₂Cr₂O₇ and warmed with Conc. H₂SO₄. The issuing vapours are passed into H₂O in a test tube, followed by NH₄OH and Lead Acetate solution

1. Reddish brown gas dissolving in H₂O forming yellow solution.
2. Yellow ppt. is formed on adding lead acetate solution.

Presence of Cl^- confirmed.

Confirmation of NO₃^-

Brown Ring Test.

The extract is mixed with dilute H₂SO₄ and freshly prepared FeSO₄ solution. Conc. H₂SO₄ is added along the sides of the test tube without shaking.

Brown ring is formed at the junction of the two liquids.

This is due to the formation of the following comples

[Fe(H₂O)₅NO]

Penta aquo nitroso ferrus(II) Complex ion

(Nitroso ferrous sulphate)

Presence of NO₃ ^- Confirmed

Confirmation of S^2-.

The extract is treated with dilute acetic acid and Lead Acetate

Black precipitate

Presence of S^2-