Question

The formula of sodium nitroprusside is:

• A. Na₄[Fe(CN)₅NOS]
• B. Na₂[Fe(CN)₅NO]
• C. NaFe[Fe(CN)₆]
• D. Na₂[Fe(CN)₆NO₂]

Hint:

Sodium nitroprusside contains a nitrosyl group (NO) and five cyanide ligands coordinated to Fe. The correct formula balances the complex’s charge with sodium ions.

Answer 1

The Correct Option is B

Step 1: Understand the composition of sodium nitroprusside
Sodium nitroprusside is a coordination compound composed of:

• A central Fe (iron) atom
• Five cyanide ligands (CN^-)
• One nitrosyl ligand (NO)
• Two Na⁺ ions to balance the charge

Step 2: Determine the correct structure
The nitrosyl (NO) group is a neutral ligand, and each cyanide (CN^-) carries a -1 charge. \[ \text{Total charge from ligands: } 5 \times (-1) = -5 \] \[ \text{Iron is in +2 oxidation state, so: } +2 + (-5) = -3 \Rightarrow \text{Anionic complex: } [Fe(CN)_5NO]^{2-} \] To neutralize the -2 charge of the complex ion, two sodium ions (Na⁺) are required. 
Step 3: Final answer
The correct formula is: \[ \boxed{\text{Na}_2[\text{Fe(CN)}_5\text{NO}]} \]