Question

how can you estimate qualitatively the presence of Cl, Br, I by Lassaige's test ?​

Answer 1

AnSwer :-

It is a very reliable method to detect halogens (Cl, Br, I ) in and organic compounds. The sodium fusion extract combines with the halogen to form sodium halide.

$\sf { Na + X \longrightarrow NaX}$

From thee extract, the halogen can be detected by the following tests.

Silver nitrate test :- The extract is boiled with dilute new nitric acid upon cooling a few drops of silver nitrate solution are added.

➠ a white precipitate partially soluble in Ammonium hydroxide solution indicate the presence of chloride in the organic compound.

$\sf NaCl + AgNO_3 \longrightarrow AgCl + NaNO_3$

➠ a pale yellow precipitate partially soluble in Ammonium hydroxide solution indicates the presence of bromine in the Organic Compound.

$\sf NaBr + AgNO_3 \longrightarrow AgBr + NaNO_3$

➠ a yellow precipitate, completely insoluble in Ammonium hydroxide solution indicate the presence of iodine in the organic compound .

$\sf NaI + AgNO_3 \longrightarrow AgI + NaNO_3$