Question

Calculate the oxidation number of Co in [Co(NH₃)₃(H₂O)₂Cl]⁺.

Answer 1

Complex ion: [Co(NH₃)₃(H₂O)₂Cl]⁺ → overall charge = +1

Let oxidation number of Co = x

Cl = –1, H₂O = 0, or NH₃ = 0

Putting the value in formula,

∴ x + 0 + 0 + (–1) = +1

x – 1 = +1

x = +1 + 1

x = +2

∴ The oxidation number of Co in [Co(NH₃)₃(H₂O)₂Cl]⁺ is +2.