Question

What is the difference between oxides , peroxides and superoxides ?

Answer 1

Oxides, oxidation state `-II`; peroxides, oxidation state `-I`; superoxides, oxidation state `-1/2`.

Explanation:

These oxygen derivatives differ by oxidation number. Typical oxides are `Na_2O`, `Fe_2O_3`, `BaO`; these feature the oxide anion, `O^(2-)`.

Peroxides are derivatives of hydrogen peroxide, `H-O-O-H`, and feature an `O-O` bond. The formal oxidation state of oxygen here is `O^(-I)`, i.e. the peroxide dianion is considered to be `""^(-)O-O^(-)`

Superoxides have a formal oxidation state of `-1/2`, and are known as alkali metal salts, i.e. `MO_2` `(M=K, Na, Rb)`. They are a portable form of oxygen, and are used as oxygen supplies for firefighters.