The Lassaigne’s extract is boiled with dil. H | vedclass

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Question

(B) During the preparation of Lassaigne's extract,if nitrogen and sulfur are present in the organic compound,they form $NaCN$ and $Na_2S$ respectively

Vedclass · Accepted Answer

$Na_2S$ and $NaCN$ are decomposed by $HNO_3$

Vedclass · Answer

(B) During the preparation of Lassaigne's extract,if nitrogen and sulfur are present in the organic compound,they form $NaCN$ and $Na_2S$ respectively.These species interfere with the test for halogens using $AgNO_3$ because they form precipitates ($AgCN$ and $Ag_2S$) that can mask the presence of silver halides $(AgX)$.Boiling the extract with dil. $HNO_3$ decomposes these interfering ions into volatile gases ($HCN$ and $H_2S$),which are removed from the solution.$Na_2S + 2HNO_3 	o 2NaNO_3 + H_2S \uparrow$$NaCN + HNO_3 	o NaNO_3 + HCN \uparrow$

The Lassaigne’s extract is boiled with dil. $HNO_3$ before testing for halogens because

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