Question

Manganese dioxide does not undergo any change during the decomposition of potassium chlorate. Give reason.​

Answer 1

When potassium chlorate (KClO3) is heated in the presence of manganese dioxide catalyst, it decomposes to form potassium chloride and oxygen gas.

The balanced chemical equation is

2KClO

3

→

Δ

2KCl+3O

2

Answer 2

Manganese dioxide does not undergo any change during the decomposition of potassium chlorate because Manganese dioxide acts as a catalyst in this decomposition reaction.

By definition, "Catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change".

Characteristics of a catalyst;

1. Catalysts are used to accelerate the rate of the reaction.
2. They remain unchanged at the end of the reaction.
3. Catalysts do not need to be used in big quantities.
4. They do not change the position of the equilibrium state of a reversible reaction.
5. Catalyst can not start a reaction.
6. Catalysts are mostly specific in their reaction, which means they do not work for all reactions.

Here is the decomposition reaction of potassium chlorate($KClO_3$),

$KClO_3\xrightarrow{\text{MnO2}}} KCl+O_2$

Where $MnO_2$ works as a catalyst.

Let's see the reduction reaction,

$ClO_3^{-}+6H^{+}+6e^{-}\xrightarrow{\text{MnO2}}}Cl^{-}+3H_2O(l) --(1)\\H_2O(l)\longrightarrow\frac{1}{2}O_2(g)+2H^{+}+2O^{-}--(2)\\\\3*(2)+(1) Gives,\\\\ClO_3^{-}+6H^{+}+6e^{-}+3H_2O(l)\longrightarrow\frac{3}{2} O_2(g)+6H^{+}+6e^{-}+Cl^{-}+3H_2O(l)$

After canceling out, we get;

$ClO_3^{-}\longrightarrow\frac{3}{2}O_2(g)+Cl^{-}$

So $MnO_2$ remains unchanged at the end of the process.