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: Sodium Nitroprusside Composition
Sodium nitroprusside is a coordination compound containing:

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

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