Question

How would you balance the following reactions using the oxidation number change method?
\[KCl{{O}_{3}}\to KCl+{{O}_{2}}\]

Answer 1

Hint: So to balance the equation using oxidation number method let us know what is oxidation number method. In this method we will assign the oxidation number to all the products as well as the reactants which are present in the reaction. Then we will see which substance is undergoing the oxidation and reduction. Then we will balance each of the atoms present thus giving the balanced equation.

Complete step-by-step answer:So the reaction given to us is \[KCl{{O}_{3}}\to KCl+{{O}_{2}}\]. This is an unbalanced equation. In this we have one atom of potassium, one atom of chlorine and three atoms of oxygen in the reactant side. And we have one atom of potassium, one atom of chlorine and two atoms of oxygen in the product side.
So firstly let us write the oxidation state of each of the atoms present in the reactant side.
So the oxidation state of potassium is +1. The oxidation state of oxygen is -2 and the oxidation state of chlorine is +5.
Whereas now in the product side the oxidation state of potassium is +1. The oxidation state of chlorine is -1 and the oxidation state of oxygen is 0 as it is a neutral molecule.
So we see that the oxygen oxidation state has been changed from -2 to 0 thus its oxidation state has been increased. So oxidation has taken place. Whereas the chlorine oxidation number has been changed from +4 to -1 thus its oxidation number has been decreased. So reduction has taken place.
So we need to equalise the oxidation number. To equalize the oxidation number we need 3 atoms of oxygen for each 1 atom of chlorine or we can say we need 6 atoms of oxygen atom for each 2 atom of chlorine. So it will give us the total charge as +12 and -12. So to do so we need to multiply the reactant by 2 and the potassium chloride in product side by 2 and oxygen in product side by 3. So now the equation will we:
\[2KCl{{O}_{3}}\to 2KCl+3{{O}_{2}}\]
Now we will check whether the equation is balanced or not. So we have 2 atoms of K, two atoms of Cl and 6 atoms of O in the reactant side. So we have 2 atoms of K, two atoms of Cl and 6 atoms of O in the product side also that means the equation is balanced. So the final balanced equation is:
\[2KCl{{O}_{3}}\to 2KCl+3{{O}_{2}}\]

Note: We can balance the equation by two methods that is oxidation number method and ion electron method. In this method the two half reactions are taken separately and balanced. These two half reactions are oxidation and reduction. These two balanced half reactions are then added at the last to get the final reaction.