Question

What is the oxidation state of:

i. Na in Na₂O₂?

ii. K in KO₂?

Answer 1

i. Oxidation state of Na in sodium peroxide (Na₂O₂):

Let x be the oxidation state of Na in Na₂O₂. 

The net charge on peroxide ion (O\(^{2-}_{2}\)) is -2.

Since any compound is electrically neutral, it has an overall charge as zero.

∴ 2x + (-2) = 0 

∴ x = + 1 

∴ Oxidation state of Na in Na₂O₂ is + 1

ii. Oxidation state of K in potassium dioxide/potassium superoxide (KO₂):
Let x be the oxidation state of K in KO₂

The net charge on superoxide ion (O^-₂) is -1

Since any compound is electrically neutral, it has an overall charge as zero.

∴ x + (-1) = 0 

x = + 1 

∴ Oxidation state of K in KO₂ is + 1. 

[Note: Oxidation state of alkali metal is always +1.]