# What is the oxidation of Cl in "perchlorate anion", ClO_4^(-)?

Sep 12, 2016

The oxidation number of $C l$ in $\text{perchlorate}$ is $+ V I I$.

#### Explanation:

With an $A {l}^{3 +}$ gegenion, th charge on perchlorate is clearly $- 1$.

Thus $C {l}_{\text{Oxidation number"+4xxO_"Oxidation number}}$ $\equiv$ $- 1$.

${O}_{\text{Oxidation number}}$ is almost always $- I I$, and it is here. This $C {l}_{\text{Oxidation number}} = V I I +$.

In perchlorate salts, chlorine assumes its maximum oxidation number, its group number. For chlorate, $C l {O}_{3}^{-}$, $C {l}_{\text{Oxidation number}} = V +$.