Question

What is the role of $Mn{{O}_{2}}$ in the preparation of ${{O}_{2}}$ from $KCl{{O}_{3}}$?

Answer 1

Hint: The formation of ${{O}_{2}}$ from $KCl{{O}_{3}}$ is a thermal decomposition reaction
The rate of the reaction can be altered using a catalyst.

Complete step by step answer:
So in the question it is asked what the role is of $Mn{{O}_{2}}$ in the thermal decomposition reaction of $KCl{{O}_{3}}$.
When Potassium chlorate i.e. $KCl{{O}_{3}}$ is heated or when we supply heat energy, it gets decomposed to $KCl$ and ${{O}_{2}}$.
So the thermal decomposition of $KCl{{O}_{3}}$ is one of the processes through which we can produce oxygen,in the lab.
And the reaction involved is,
$2KCl{{O}_{3}}\xrightarrow[Mn{{O}_{2}}]{\Delta }2KCl+3{{O}_{2}}$
 So here we can see that, $Mn{{O}_{2}}$ is also used in the reaction ,but not as the reactant.
$Mn{{O}_{2}}$ is used as a catalyst in this reaction.
 A catalyst is a substance, by the addition of it in the chemical reaction could accelerate the forward reaction and it alters the rate of the reaction.
Catalyst is that substance which decreases the activation energy of the reaction, so that more atoms possess the minimum energy for the effective collision, which leads to the reaction to proceed at an increased rate.
The process in which the reaction is carried out with the help of a catalyst is called catalysis. Catalyst does not involve in the reaction, it just takes an alternate path for proceeding the reaction in optimum conditions.
So in the decomposition reaction of $KCl{{O}_{3}}$, $Mn{{O}_{2}}$ acts as a positive catalyst i.e. when $Mn{{O}_{2}}$ is added to the reaction mixture, then we can do this thermal decomposition reaction at a lower temperature ie at about 200 to 240K whereas if this reaction is to be carried out in the absence of the catalyst, then we have to apply a heat of $630-670K$ to proceed the reaction.

Note: Pyrolusite is the other name for manganese dioxide and it is one of the common catalysts used in many reactions, due to its high catalytic activity. As it is stable even at the temperature range of ${{500}^{\circ }}C$, it finds application in many reactions and if the temperature is too high it gets converted to $M{{n}_{2}}{{O}_{3}}$.