Question

What is the oxidation state of chlorine in $KCl{O}_3$ ?

Answer 1

Hint :The total number of electrons that an atom receives or loses while forming a chemical bond with another atom is known as the oxidation number, also known as the oxidation state. When an element loses electrons, it gets a positive oxidation number, and when it absorbs electrons, it gets a negative oxidation number.

Complete Step By Step Answer:
We will first recall the oxidation states exhibited by the alkaline metals and alkaline earth metals and oxygen.
(i) All the elements of group 1, the alkaline metals exhibit oxidation state of $+1$ as they prefer to lose an electron to achieve the more stable completely filled p or d orbitals.
(ii) Similarly, the elements of group 2, the alkaline earth metals exhibit an oxidation state of $+2$ for the same reason.
(iii)Also, remember that the common oxidation state of oxygen is $-2$ , except when it reacts with a more electro-negative element, which is $F$ .
Now we will follow the steps to find the oxidation state of an element.
a) Observe the elements in the compound and write the oxidation states of some of them. Here, the given compound $KCl{O}_3$ is an ionic compound. As seen earlier, the oxidation state of potassium ( $K$ ) is $+1$ as it belongs to group 1. And the oxidation state of $O$ is $-2$ .
b) Checking on the nature of the compound we find that this ionic compound is neutral. So, the sum of oxidation states of each element is zero.
c) Let $x$ denote the oxidation state of $Cl$ in $KCl{O}_3$ . Then we get from previous discussions that, $+1+x+3\times (-2)=0$
 $\Rightarrow 1+x-6=0$
 $\Rightarrow x-5=0$
 $\Rightarrow x=+5$
Hence, the oxidation state of chlorine in $KCl{O}_3$ is $+5$ .

Note :
Note that, elements with d-orbitals like $S,Cl,P$ exhibit a range of oxidation states even while reacting with the same reactants. The compounds formed by chlorine with oxygen in its different oxidation states are $Cl{O}_4^{-}$ has $+7$ oxidation state, $Cl{O}_3^{-}$ with $+5$ state, $Cl{O}_2^{-}$ with $+3$ state and the state in chloride ion $C{l}^{-}$ is $-1$ .