Formation of Na4[Fe(CN)5NOS], a purple coloured complex formed by addition of sodium nitroprusside in sodium carbonate extract of salt indicates the presence of:
- Sulphide ion
- Sulphite ion
- Sulphate ion
- Sodium ion
Answer
(1) Sulphide ion
Solution
Sodium nitroprusside, Na2[Fe(CN)5NO], reacts with sulphide ion in alkaline (sodium carbonate) extract:
Na2S + Na2[Fe(CN)5NO] Na4[Fe(CN)5NOS]
The product, sodium thionitroprusside, is purple (violet). Sulphite and sulphate ions do not give this colour, and Na+ is present in the reagent and the extract anyway.
The purple colour confirms the sulphide ion, S2-.
Answer: (1)