In the Lassaigne's test for nitrogen in an or | vedclass

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(B) In the Lassaigne's test for nitrogen in an organic compound,the sodium fusion extract is boiled with iron $(II)$ sulphate and then acidified with

Vedclass · Accepted Answer

$Fe_{4}[Fe(CN)_{6}]_{3}$

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(B) In the Lassaigne's test for nitrogen in an organic compound,the sodium fusion extract is boiled with iron $(II)$ sulphate and then acidified with sulphuric acid.In the process,sodium cyanide first reacts with iron $(II)$ sulphate to form sodium hexacyanoferrate $(II)$.Then,on heating with sulphuric acid,some iron $(II)$ gets oxidised to iron $(III)$,which reacts with hexacyanoferrate $(II)$ to form iron $(III)$ hexacyanoferrate $(II)$,which is Prussian blue in colour.The chemical equations involved in the reaction are:$6CN^{-} + Fe^{2+} \longrightarrow [Fe(CN)_{6}]^{4-}$$3[Fe(CN)_{6}]^{4-} + 4Fe^{3+} \xrightarrow{xH_{2}O} Fe_{4}[Fe(CN)_{6}]_{3} \cdot xH_{2}O$ (Prussian blue)Hence,the Prussian blue colour is due to the formation of $Fe_{4}[Fe(CN)_{6}]_{3}$.

In the Lassaigne's test for nitrogen in an organic compound,the Prussian blue colour is obtained due to the formation of:

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