Question

In sulphur detection of an organic compound, sodium nitroprusside solution is added to sodium extract. Formation of violet colour is due to:

• A. $N{a}_{3}Fe(CN{)}_6$
• B. $N{a}_4\left[Fe\right(CN{)}_{5}NOS]$
• C. $Fe(CNS{)}_3$
• D. None of these

Answer 1

The correct option is B $N{a}_4\left[Fe\right(CN{)}_{5}NOS]$

If sulphur is present in the organic compound, sodium fusion will convert it into sodium sulphide. Sulphide ions are readily identified using sodium nitroprusside.

$Na+S\to N{a}_{2}S$

$N{a}_{2}S+N{a}_2\left[Fe\right(CN{)}_{5}NO]\to N{a}_4[Fe\left(CN{)}_{5}NOS\right]$