Chapter 19, Problem 44A

Interpretation Introduction

Interpretation:

The oxidation number of manganese in $KMn{O}_4$ is to found out.

Concept introduction:

Oxidation number is the total number of electrons that an atom either gains or losses in order to form an ionic bond with another atom.

There are some rules to assign oxidation number:

• For an atom in its elemental form, oxidation number=0
• For an ion, oxidation number=charge of ion
• The sum of oxidation number value for the atoms in a molecule equal to zero for neutral compound and equal to total charge if it is a polyatomic ion
• For group (I)A, oxidation number=+1 in all compounds
• For group (II)A, oxidation number=+2 in all compounds
• For fluorine, oxidation number=-1 in all compounds

Answer to Problem 44A

+7

Explanation of Solution

Applying the rules to calculate oxidation state of $Mn$ ,

$\begin{array}{l}+1+x+(-2\times 4)=0\\ 1+x-8=0\\ x=7\end{array}$

Conclusion

Thus the oxidation number of manganese in $KMn{O}_4$ is +7