Question

[CoF₆]³⁻ is a coordination complex ion.

What is the oxidation number of cobalt in the complex?

Answer 1

Let the oxidation state of cobalt (Co) be x.

6 × (−1) = −6

x + (−6) = −3

x = −3 + 6

x = +3

∴ The oxidation number of cobalt in [CoF₆]³⁻ is +3.