Question

What is the oxidation state of $Co$ in ${[Co{(CN)_6}]^{3 - }}$ ?

Answer 1

Hint: To solve this question, first we will assume the oxidation state for $Co$ , then we will create the equation in which L.H.S, i.e. sum of oxidation states of all the elements, will be equal to the given overall charge $ - 3$ , that’s how we will find the assumed oxidation state.

Complete step-by-step answer:
We can find the oxidation state of $Co$ by assuming it first.
Let the oxidation state of $Co$ in ${[Co{(CN)_6}]^{3 - }}$ be $x$ .
Since, the overall charge on the given complex compound is $ - 3$ :
The sum of oxidation states of all the elements in the given complex compound should be equal to $ - 3$ .
Therefore,
$x + 6( - 1) = - 3$
$\Rightarrow x = - 3 + 6$
$\Rightarrow x = 3 $

Hence, the Oxidation state of $Co$ in ${[Co{(CN)_6}]^{3 - }}$ is $ + 3$ .

Note:The steps to find the oxidation state:
(1) Any free element has an oxidation number equal to zero.
(2) The oxidation number always has the same value as the net charge corresponding to the ion.
(3) And then find the assumed variable’s value.