Question

# : On heating $KCl{{O}_{3}}$ we get,[A]$KCl{{O}_{2}}+{{O}_{2}}$[B]$KCl+{{O}_{2}}$[C]$KCl+{{O}_{3}}$[D]$KCl+{{O}_{2}}+{{O}_{3}}$

Hint: $KCl{{O}_{3}}$ is an oxidant and may explode on prolonged exposure to heat. Potassium chlorate undergoes a decomposition reaction on heating which gives an inorganic residue. The residue thus obtained is heat resistant and is a common inorganic salt.

$KCl{{O}_{3}}$ or potassium chlorate is a white crystalline compound which produces oxygen when heated in presence of a catalyst.
When heated in presence of a catalyst, like manganese dioxide it gives oxygen and an ionic inorganic salt, potassium chloride. The reaction is-
$2KCl{{O}_{3}}(s)\to 2KCl(s)+3{{O}_{2}}(g)$
As we can see from the above reaction, 2 moles of potassium chlorate gives 3 moles of oxygen gas and 2 moles of potassium chloride.
However, in absence of a catalyst, the reaction moves forward differently.
On heating without a catalyst, potassium chlorate turns into potassium perchlorate which on further heating decomposes into oxygen and potassium chloride. The reaction is-
\begin{align} & 4KCl{{O}_{3}}\to 3KCl{{O}_{4}}+KCl \\ & KCl{{O}_{4}}\to KCl+2{{O}_{2}} \\ \end{align}
From the above reactions, we can say that 4 moles of potassium chlorate forms 3 moles of potassium perchlorate when heated. Each mole of potassium perchlorate gives 2 moles of oxygen and 1 mole of potassium chloride on further heating.
The final product obtained is the same in both the cases but the later reaction is more time consuming. Presence of a catalyst gives the product directly.
Therefore, it is clear from the above reactions that the correct answer is [B] $KCl+{{O}_{2}}$.

It is important to remember here that Potassium chlorate undergoes an oxidation-reduction reaction also known as red-ox reaction. Here, chlorine gets reduced and oxygen gets oxidised. Also , oxygen gas is evolved during the reaction. It is also important to remember that it does not form $KCl{{O}_{2}}$ on heating.