Question

What is the charge of $Mn$ in $KMn{O_4}$.

Answer 1

Hint: Potassium Permanganate contains ionic bonds and covalent bonds. Potassium is bonded with permanganate ions through ionic bonds. Here the central metal atom is $Mn$. Therefore we will calculate the oxidation state of central metal which is the charge of $Mn$in the given compound.

Complete answer:
 Since we know that $KMn{O_4}$ is the symbolic representation of potassium permanganate. Here potassium is bonded to the permanganate ion through the ionic bond. It can be shown as,
$KMn{O_4}{\text{ }} \to {\text{ }}{{\text{K}}^ + }{\text{ + Mn}}{{\text{O}}_4}^ - $
Thus the overall charge of the permanganate ion is $ - 1$. But for finding the oxidation state of $Mn$ in $KMn{O_4}$, we can assume it to be $x$. Also for a neutral compound, the sum of oxidation states of all atoms present in the compound is always equal to zero. We know that the oxidation state of oxygen atoms is $ - 2$. Also, the charge present on potassium atoms is $ + 1$. Hence we can calculate the oxidation state of $Mn$ as,
$ + 1{\text{ + x + ( - 2)}} \times {\text{4 = 0}}$
$ + 1{\text{ + x - 8 = 0}}$
${\text{x = + 7}}$
Thus the oxidation state of $Mn$ in $KMn{O_4}$ is equal to $ + 7$. Therefore we can say that the charge of $Mn$ in $KMn{O_4}$ is $ + 7$. Potassium permanganate is also used as an oxidising agent. The manganese is present in its maximum oxidation state in $KMn{O_4}$. Thus the oxidation state of $Mn$ can be reduced and thus it behaves as an oxidising agent which oxidises others and reduces itself.

Note:
Manganese can have a maximum value of oxidation state of $ + 7$. The oxidation state cannot be greater than $ + 7$ for manganese. It can vary between $ - 7$ to $ + 7$. It acts as an oxidising agent in acidic medium which is useful for oxidation of organic products.