How do you balance this redox reaction using the oxidation number method? KClO3(s) → KCl(s)+O2(g)

1 Answer
Sep 24, 2014

Answer:

2KClO₃ → 2KCl + 3O₂

Explanation:

For one method, see How do you balance redox equations by oxidation number method?

Your unbalanced equation is

KClO₃ → KCl + O₂

Step 1. The oxidation numbers are:

Left hand side: K = +1; O = -2; Cl = +5
Right hand side: K = +1; Cl = -1; O = 0

Step 2. The changes in oxidation number are:

O: -2 → 0; Change = +2
Cl: +5 → -1; Change = -6

Step 3. Equalize the changes in oxidation number.

You need 3 atoms of O for every 1 atom of Cl or 6 atoms of O for every 2 atoms of Cl. This gives us total changes of +12 and -12.

Step 4. Insert coefficients to get these numbers.

2 KClO₃ → 2 KCl + 3 O₂

Every substance now has a coefficient.

Step 5. Check that all atoms balance.

Left hand side: 2 K; 2 Cl; 6 O
Right hand side: 2 K; 2 Cl; 6 O

The balanced equation is

2KClO₃ → 2KCl + 3O₂