Question

Calculate the oxidation number of the central metal atom (underlined) in the following complex species:

[Fe(H₂O)₆]Cl₃

Answer 1

The complex ion is: [Fe(H₂O)₆]³⁺

This association with 3 chloride ions (Cl⁻) balances the overall charge, making it neutral.

Now, let’s find the oxidation number of Fe:

• Let the oxidation number of Fe be x.

• Water (H₂O) is a neutral ligand, so its oxidation number is 0.

• Therefore, the sum of oxidation numbers in the complex ion must equal the overall charge of the complex, which is +3.

The oxidation number equation:

x + 6(0) = +3

x = +3

Thus, the oxidation number of Fe in [Fe(H₂O)₆]³⁺ is +3.