Detection of Nitrogen in Organic Compound by Lassaigne’s Solution

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composition of organic compound

Detection of Nitrogen:


Step 1:

Take 2ml of lassaigne’s filtrate in a test tube and add a few drops of sodium hydroxide (NaOH) solution to it.

Nitrogen detection step 1

Step 2:

Now add a few ml of freshly prepared ferrous sulphate (FeSO4) solution to the test tube.

Nitrogen detection step 2

Step 3:

Boil the solution.

Nitrogen detection step 3

The sodium cyanide formed during the preparation of lassaigne’s solution is converted to sodium Ferrocyanide.

Step 4:

Add a few drops of FeCl3 solution to a test tube.

Finally, acidify it with concentrated HCl.

Nitrogen detection step 4
Reactions for detection of nitrogen

The appearance of blue or greenish-blue ( Prussian blue ) colour or ppt of ferric ferrocyanide proves the presence of nitrogen in the organic compound.

If a blood-red colour appeared instead of Prussian blue colour then it proves that both nitrogen and sulphur are present in an organic compound.

Preparation of Lassaigne’s solution ( in Urdu/Hindi)

Detection of Nitrogen in Organic compounds( in Urdu /Hindi)

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