Question

When sodium nitroprusside is added to sodium fusion extract the presence of sulphur is indicated by the formation of a violet colored complex. Its formula is

• A. \([Fe(CN)_5(NO)(SO_4)]^{4+}\)
• B. \([Fe(CN)_5NOS]^{4-}\)
• C. \([Fe(CN)_5(NO_2)(SO_4)]^{3-}\)
• D. \([Fe(CN)_5(NO_3)(SO_4)]^{3-}\)
• E. \([Fe(CN)_5(NO)(SO_4)]^{4-}\)

Hint:

Use the formation of specific colored complexes as a diagnostic tool in qualitative analysis to detect certain elements or groups.

Answer 1

The Correct Option is B

Step 1: Sodium nitroprusside reacts with sulfur-containing compounds to form a violet complex due to the modification of the iron-cyanide complex. 
Step 2: The correct formula of the violet complex formed in the presence of sulfur is \([Fe(CN)_5NOS]^{4-}\), where \(NOS\) stands for the nitrosylsulphur ligand. 
Step 3: This complex is particularly known for its diagnostic color change when interacting with sulfur. 
Step 4: Hence, option (B) correctly represents the composition of the violet complex.