Question

Freshly prepared solution of sodium nitroprusside is added to the sodium extract. Appearence of a deep violet colour indicated the presence of:

• A. nitrogen
• B. sulphur
• C. both nitrogen and sulphur
• D. halogen

Answer 1

The correct option is B sulphur

Appearance of deep violet colour is due to the formation of sodium penta-cyano nitrosyl thiol ferrate(VI) which indicates the presence of sulphur.

${Na}_{2}S+{Na}_2\left[Fe{\left(CN\right)}_{5}NO\right]⟶\underset{\text{deep violet color}}{{Na}_4\left[Fe{\left(CN\right)}_{5}NOS\right]}$