Question

$[Fe(CN)_6 ]^{3-}$ ion is

• A. hexacyanoferrate (II) ion
• B. hexacyanoferrate (III) ion
• C. hexacyanide iron (III) ion
• D. iron (III) hexacyanide ion

Answer 1

Answer: (B)

hexacyanoferrate (III) ion

Answer 2

The correct option is(B): hexacyanoferrate (III) ion.

Each cyanide ligand (CN −) carries a charge of -1. Since there are six cyanide ligands, they contribute a total charge of -6 (6×−1=−66×−1=−6).

The overall charge of the 3−[Fe(CN)6​]3− complex ion is -3. This means that the iron atom must have a positive oxidation state to balance the negative charge of the ligands.

Let's assume that the oxidation state of iron is x :

Charge of iron ion (Fex +) + Charge of cyanide ligands (6×−16×−1) = Overall charge of the complex ion (−3−3)

x +(−6)=−3

Solving for x , we get x =+3.

The oxidation state of iron in the complex is +3. According to the IUPAC naming convention for coordination compounds, the name should reflect both the metal's oxidation state and the ligands. In this case, the iron has an oxidation state of +3, and the ligands are cyanide ions. Therefore, the correct name is "hexacyanoferrate (III) ion."

So, the correct option is "hexacyanoferrate (III) ion."