In Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives bl

Question

In Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives blood red colour with $\mathrm{Fe}^{3+}$ due to the formation of\

Professor PC Thomas Classes · Answer

(b) : In case, nitrogen and sulphur both are present in an organic compound, sodium thiocyanate is formed. It gives blood red colour and no Prussian blue since there are no free cyanide.\ $\mathrm{Na}+\mathrm{C}+\mathrm{N}+\mathrm{S} \longrightarrow \mathrm{NaSCN}$\ $\mathrm{Fe}^{3+}+\mathrm{SCN}^{-} \longrightarrow \underset{	ext { Blood red }}{[\mathrm{Fe}(\mathrm{SCN})]^{2+}}$