How do you balance KClO_3(s) -> KCl(s) + O_2(g)?

1 Answer
Apr 22, 2018

Using oxidation states.

Explanation:

We have to realize that this is a redox reaction.
Chlorine is being reduced while oxygen is being oxidized.
Chlorine oxidation state is +5 in KClO_3 and is reduced to Cl- which has an oxidation state of -1.
Oxygen oxidation state is -2 in KClO_3 and is oxidised to O_2 which has an oxidation state of 0.
Write Half Reactions.
Cl^(5+) + 6e = Cl^-
2O^(2-) = O_2 + 4e
Balance electrons in accordance to conservation of charges.
4Cl^(5+) + 24e = 4Cl^-
12O^(2-) = 6O_2 + 24e

Thus interpreting this means that there is 4KClO_3, 4KCl, 6O_2. This balances both atoms and charges making it fully balanced.
Thus simplify the equation by a factor of 2,
2KClO_3 = 2KCl + 3O2