Question

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

• A. Fe4[Fe(CN)6]3
• B. Na3[Fe(CN)6
• C. Fe(CN)3
• D. Na4[Fe(CN)5NOS]

Answer 1

Answer: (A)

Fe4$Fe(CN)6$3

Answer 2

If nitrogen is present in organic compound, then sodium extract contains Na4 [Fe(CN)6]

Na + C + N $\xrightarrow { \text { fuse } }$ NaCN

FeSO4 + 6NaCN $\longrightarrow$ Na4[Fe(CN)6] + Na2SO4

(1)

A changes to prussian blue Fe4[Fe(CN)6]3

on reaction with FeCl3

4FeCl3 + 3Na4[Fe(CN)6 $\longrightarrow$ Fe4[Fe(CN)6]3 + 12 NaCl