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# Solution for In the Lassaigne’S Test for Nitrogen in an Organic Compound, the Prussian Blue Colour is Obtained Due to the Formation Of: - CBSE (Science) Class 11 - Chemistry

ConceptQualitative Analysis of Organic Compounds - Detection of Other Elements

#### Question

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

#### Solution

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 and forms sodium hexacyanoferrate (II). Then, on heating with sulphuric acid, some iron (II) gets oxidised to form iron (III) hexacyanoferrate (II), which is Prussian blue in colour. The chemical equations involved in the reaction can be represented as

6CN^(-) + Fe^(2+) -> [Fe(CN)_6]^(4-)

Hence, the Prussian blue colour is due to the formation of Fe4[Fe(CN)6]3.

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#### APPEARS IN

NCERT Solution for Chemistry Textbook for Class 11 (2016 to Current)
Chapter 12: Organic Chemistry - Some Basic Principles and Techniques
Q: 37 | Page no. 364
Solution In the Lassaigne’S Test for Nitrogen in an Organic Compound, the Prussian Blue Colour is Obtained Due to the Formation Of: Concept: Qualitative Analysis of Organic Compounds - Detection of Other Elements.
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