
Oxidation state of ${\text{Mn}}$ in ${\text{MnO}}_4^ - $ is:
Answer
439.9k+ views
Hint:Oxidation number is the charge acquired by the species may be positive, negative or zero by gain or loss of electrons. To solve this we must know the oxidation number of oxygen.
Complete answer
We are given a polyatomic anion ${\text{MnO}}_4^ - $. In the given polyatomic anion, we have to find the oxidation number of manganese.
We know that the charge on an oxygen atom is $ - 2$.
Sum of all the oxidation numbers in a polyatomic ion is equal to the charge on the ion. Thus, the total charge on the polyatomic anion is $ - 1$.
Thus,
Charge on ${\text{MnO}}_4^ - $ $ = {\text{ON of Mn}} + 4 \times \left( {{\text{ON of O}}} \right)$
Substitute $ - 1$ for the charge on ${\text{MnO}}_4^ - $, x for the oxidation number of ${\text{Mn}}$ and $ - 2$ for the charge on ${\text{O}}$. Thus,
$ \Rightarrow - 1 = \left( x \right) + \left( {{\text{4}} \times \left( { - 2} \right)} \right)$
$\Rightarrow x = - 1 + 8$
$\Rightarrow x = + 7$
Thus, the oxidation number of ${\text{Mn}}$ in ${\text{MnO}}_4^ - $ is $ + 7$.
Note: Rules for assigning the oxidation number to elements are as follows:
i) The oxidation number of an element in its free or uncombined state is always zero.
ii) The oxidation number of monatomic ions is the same as that of the positive or negative charge on the ion.
iii) The sum of all the oxidation numbers in a neutral compound is zero.
iv) The sum of oxidation numbers in a polyatomic ion is equal to the total charge on the polyatomic ion.
v) The oxidation number of alkali metals is always $ + 1$.
vi) The oxidation number of alkaline earth metals is always $ + 2$.
vii) The oxidation number of hydrogen is always $ + 1$.
viii) The oxidation number of oxygen is always $ - 2$.
Complete answer
We are given a polyatomic anion ${\text{MnO}}_4^ - $. In the given polyatomic anion, we have to find the oxidation number of manganese.
We know that the charge on an oxygen atom is $ - 2$.
Sum of all the oxidation numbers in a polyatomic ion is equal to the charge on the ion. Thus, the total charge on the polyatomic anion is $ - 1$.
Thus,
Charge on ${\text{MnO}}_4^ - $ $ = {\text{ON of Mn}} + 4 \times \left( {{\text{ON of O}}} \right)$
Substitute $ - 1$ for the charge on ${\text{MnO}}_4^ - $, x for the oxidation number of ${\text{Mn}}$ and $ - 2$ for the charge on ${\text{O}}$. Thus,
$ \Rightarrow - 1 = \left( x \right) + \left( {{\text{4}} \times \left( { - 2} \right)} \right)$
$\Rightarrow x = - 1 + 8$
$\Rightarrow x = + 7$
Thus, the oxidation number of ${\text{Mn}}$ in ${\text{MnO}}_4^ - $ is $ + 7$.
Note: Rules for assigning the oxidation number to elements are as follows:
i) The oxidation number of an element in its free or uncombined state is always zero.
ii) The oxidation number of monatomic ions is the same as that of the positive or negative charge on the ion.
iii) The sum of all the oxidation numbers in a neutral compound is zero.
iv) The sum of oxidation numbers in a polyatomic ion is equal to the total charge on the polyatomic ion.
v) The oxidation number of alkali metals is always $ + 1$.
vi) The oxidation number of alkaline earth metals is always $ + 2$.
vii) The oxidation number of hydrogen is always $ + 1$.
viii) The oxidation number of oxygen is always $ - 2$.
Recently Updated Pages
Master Class 12 Business Studies: Engaging Questions & Answers for Success

Master Class 12 English: Engaging Questions & Answers for Success

Master Class 12 Social Science: Engaging Questions & Answers for Success

Master Class 12 Chemistry: Engaging Questions & Answers for Success

Class 12 Question and Answer - Your Ultimate Solutions Guide

Master Class 11 Economics: Engaging Questions & Answers for Success

Trending doubts
Which one of the following is a true fish A Jellyfish class 12 biology CBSE

Draw a labelled sketch of the human eye class 12 physics CBSE

a Tabulate the differences in the characteristics of class 12 chemistry CBSE

Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE

Why is the cell called the structural and functional class 12 biology CBSE

What are the major means of transport Explain each class 12 social science CBSE
