Q. The compound formed in the positive test for nitrogen with the Lassaigne solution of an organic compound is
A) $Fe_{4}\left\lbrack Fe(CN)_{6} \right\rbrack_{3}$
B) $Na_{3}\left\lbrack Fe(CN)_{6} \right\rbrack$
C) $Fe(CN)_{3}$
D) $Na_{4}\left\lbrack Fe(CN)_{5}NOS \right\rbrack$
Explanation
(a)
If nitrogen is present in organic compound then sodium extract contains NaCN.
$\ \ \ \ \ \ \ \ Na + C + N\overset{\ \ Fuse\ \ }{\rightarrow}NaCN$
${FeSO}_{4} + 6NaCN \rightarrow {Na}_{4}\left\lbrack Fe(CN)_{6} \right\rbrack + {Na}_{2}{SO}_{4}$
(A)
A changes to Prussian blue ${Fe}_{4}\left\lbrack Fe(CN)_{6} \right\rbrack_{3}$ on reaction with $FeCl_{3}.$
$4{FeCl}_{3} + 3{Na}_{4}\left\lbrack Fe(CN)_{6} \right\rbrack \rightarrow {Fe}_{4}\left\lbrack Fe(CN)_{6} \right\rbrack_{3} + 12NaCl$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.