Question

For an organic compound containing N and S, which of the following statement(s) is/are correct?

• A. Sodium fusion extract gives prussian blue colour with $FeC{l}_3$
• B. Sodium thiocyanate is formed in lassaigne extract.
• C. Sodium fusion extract gives blood red colour with $FeC{l}_3$
• D. Using excess $Na$ in fusion extract, both cyanide and sulphide ions are formed.

Answer 1

Answer: (B), (C), (D)

Using excess $Na$ in fusion extract, both cyanide and sulphide ions are formed.

If both nitrogen and sulphur are present in an organic compound, Sodium thiocyanate is formed in the sodium extract.
$Na+C+N+S⟶NaSCN$

When the sodium extract containing $SC{N}^{-}$ ion is treated with $FeC{l}_3$ solution, it gives blood red colouration by formation of $\left[Fe\right(SCN){]}^{2+}$

$F{e}^{3+}+SC{N}^{-}⟶\underset{\text{Blood red colour}}{\left[Fe\right(SCN){]}^{2+}}$

If sodium fusion is carried out with an excess of sodium, then the sodium thiocyanate formed is further decomposed to yield cyanide and sulphide. Cyanide and sulphide ions give their usual tests.
$NaSCN+2Na\stackrel{\Delta }{⟶}NaCN+N{a}_{2}S$
Thus, statement (b), (c) and (d) are correct.