Question

What is the oxidation state of cobalt in the complex, [Co(NH₃)₄(H₂O)Br](NO₃)₂?

Answer 1

The oxidation state of cobalt in the complex, [Co(NH₃)₄(H₂O)Br](NO₃)₂

Let the oxidation number of Co be x.

Co = x, NH₃ = 4, H₂O = 1 Br⁻ = −1

x + (4 × 0) + (0) + (−1) =  +2

x − 1 = +2

x = +3