Assign oxidation states to each element on each side of the equation.

Question:

Assign oxidation states to each element on each side of the equation.

For the following reaction KClO2 -> KCl + O2 assign oxidation states to each element on each side of the equation.
BOTH Reactants AND Products
Reactants
K

Cl

O

WHICH ELEMENT IS OXIDIZED
Products- K

Cl

O

WHICH ELEMENT IS REDUCED?
Oxidation States and Reduction/Oxidation:
The oxidation state of an atom can be determined by following certain rules as shown below:

1. Alkali metals usually have an oxidation state of +1

2. Oxygen usually has an oxidation state of -2, unless it is bonded to itself

In a reaction, we say that if an atom lost electrons, it became oxidized. Conversely, if it gained electrons, it became reduced.

Answer & Explanation:

Using the rules above, we can determine the oxidation states of the reactants and products. First, we do the reactants below:
KClO2

K = +1
O = -2
Then, we find the oxidation state of Cl by noting that the overall molecule has a net charge of 0 so the oxidation number of Cl must cancel out the oxidation numbers of the rest of the molecule:

Cl = -(+1 + 2*-2) = +3

Now we can do the same for the products.
KCl

K = +1

Cl = -1

O2

O = 0

Since K started with an oxidation number of +1 and ended with an oxidation of +1, it was neither reduced nor oxidized. However, Cl went from +3 to -1 which means it gained electrons and was reduced. O, on the other hand, went from -2 to 0 which means it lost electrons and was oxidized.