Question

When potassium chlorate $\left( {KCl{O_3}} \right)$ is heated in the presence of a manganese dioxide catalyst, it decomposes to form potassium chloride and oxygen gas. Represent this in the form of a balanced chemical equation.

Answer 1

Hint – Here we will proceed by using the concept of decomposition reaction in order to balance the given equation.

Complete step-by-step answer:
Decomposition reaction – It is defined as the chemical reaction in which a chemical compound breaks on heating to give two or more than two chemical compounds. It is considered as the opposite of a combination reaction.
When potassium chlorate $\left( {KCl{O_3}} \right)$is heated in the presence of a manganese dioxide catalyst, it decomposes to form potassium chloride and oxygen gas.
Potassium chlorate - $KCl{O_3}$
Pure form of potassium chlorate exists in crystalline state.
The reaction goes the way in which oxygen is evolved on heating the compound leaving the potassium chloride residue.
$2KCl{O_3}\xrightarrow{\vartriangle }2KCl + 3{O_2}$
The decomposition is faster in the presence of $Mn{O_2}$(Manganese dioxide ) It is a very effective catalyst for the decomposition of potassium chlorate. It allows the decomposition to occur at a lower temperature.
From above equation, we get
(a). Molecular weight of potassium chlorate is 122.5 As you can see in the above reaction 2 moles of the reactant gives 3 moles of oxygen.
(b). Therefore, for 245 grams of potassium chlorate, 96 grams of oxygen gas is evolved.
(c ). $2 \times 122.5 = 245$g of $KCl{O_3}$and $3 \times 32 = 96$g of oxygen.
(d). $96 \div 245 = 0.3917 \times 100 = 39.17\% $
(e ). We can observe 39.17% loss in weight after heating a pure sample of $KCl{O_3}$.

Note – Whenever we come up with this type of question, where we are asked to balance a decompose reaction then it is important to write and balance decomposition reactions. These reactions often involve an energy source such as heat, light or electricity that breaks apart the bonds of compounds. (Here we balanced potassium chlorate).