Question

What is the oxidation number of$Mn$ in the product of the alkaline oxidative fusion of $Mn{O_2}$?

Answer 1

The alkaline oxidative fusion is a redox reaction (undergoes both oxidation and reduction simultaneously) in which a compound undergoes fusion with itself only, in the presence of a base or an alkaline solution. An example of alkaline oxidative fusion is manganese dioxide.

Complete step by step answer:
During an alkaline oxidative fusion reaction, there is an increase in the oxidation state of the central atom. The process comprises of three words and they can be explained as:
Alkaline: This means that the reaction must take place in the basic conditions or in the presence of a strong base such as potassium hydroxide.
Oxidative: There is an increase in the oxidation number of the central atom.
Fusion: There must be a recombination of the compounds.
In manganese dioxide ($Mn{O_2}$), the oxidation number of $Mn$ is $+ 4$ .
The alkaline oxidative fusion reaction of $Mn{O_2}$ can be explained from the following reaction:
$4KOH + 2Mn{O_2} + {O_2} \to 2{K_2}Mn{O_4} + 2{H_2}O$
In this reaction, manganese dioxide reacts with oxygen in the presence of a strong base, potassium hydroxide, to produce potassium manganate. Now let us determine the oxidation number of potassium manganate:
Let the oxidation number of $Mn$ be $x$.
Then, $2( + 1) + x + 4( - 2) = 0$
$\Rightarrow x = + 6$
Thus, we can see that there is an increase in the oxidation number of manganese from $+ 4$ to $+ 6$.
Hence, the oxidation number of manganese in the product of alkaline oxidative fusion of $Mn{O_2}$ is $+ 6$.

Note:
The transformation in the alkaline oxidative fusion gives a green-colored melt. A test for an unknown substance for the presence of manganese can be done by heating the sample in strong $KOH$ in the presence of air. The production of a green coloration indicates the presence of $Mn$ .