The compound formed in the positive test for nitrogen with the Lassaigne solution of an organic compound is;

F e_{4} [F e (C N)_{6}]_{3}

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N a_{3} [F e (C N)_{6}]

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F e (C N)_{3}

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N a_{4} [F e (C N)_{5} N O S]

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Solution

The correct option is A $F e_{4} [F e (C N)_{6}]_{3}$
The carbon and nitrogen present in the organic compound on fusion with sodium metal gives sodium cyanide $(N a C N)$ soluble in water. This is converted in to sodium ferrocyanide by the addition of sufficient quantity of ferrous sulphate.

Ferric ions generated during the process react with ferrocyanide to form prussian blue precipitate of ferric ferrocyanide.
$N a + C + N \to N a C N$

$6 N a C N + F e S O_{4} \to N a_{4} [F e (C N)_{6}] S o d i u m f e r r o c y a n i d e + N a_{2} S O_{4}$
$N a_{4} [F e (C N)_{6}] + F e^{3 +} \to F e_{4} [F e (C N)_{6}]_{3} F e r r i c f e r r o c y a n i d e$

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Similar questions

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

(a) Na₄[Fe(CN)₆] (b) Fe₄[Fe(CN)₆]₃ (c) Fe₂[Fe(CN)₆] (d) Fe₃[Fe(CN)₆]₄

{N H}_{2} - {N H}_{2}

{F e}_{4} {[F e ({C N}_{6})]}_{3}

F e {S o}_{4}, F e {C I}_{3}

Discuss and give chemical reaction of Lassaigne Test for

1. Nitrogen in the organic compound.

2. Nitrogen and Sulphur, both in the organic compound.

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