What is the oxidation number of oxygen in oxide, peroxide and superoxide.

To determine the oxidation number of oxygen in different compounds, we need to consider the specific type of compound we are dealing with: oxides, peroxides, and superoxides. Each of these has distinct characteristics that influence the oxidation state of oxygen.

Oxides

In most oxides, the oxidation number of oxygen is typically -2. This is the most common oxidation state for oxygen in compounds. For example, in water (H₂O) and carbon dioxide (CO₂), oxygen has an oxidation state of -2. This is because oxygen generally gains two electrons to achieve a stable electron configuration, similar to that of noble gases.

Examples of Oxides

• In magnesium oxide (MgO), magnesium has an oxidation state of +2, while oxygen is -2.
• In iron(III) oxide (Fe₂O₃), iron has an oxidation state of +3, and oxygen remains at -2.

Peroxides

In peroxides, the oxidation number of oxygen is -1. Peroxides contain the O₂^2- ion, where two oxygen atoms are bonded together. This unique bonding leads to a different oxidation state compared to regular oxides. A common example of a peroxide is hydrogen peroxide (H₂O₂), where each oxygen has an oxidation state of -1.

Examples of Peroxides

• In sodium peroxide (Na₂O₂), sodium has an oxidation state of +1, while each oxygen is -1.
• In barium peroxide (BaO₂), barium has an oxidation state of +2, and again, each oxygen is -1.

Superoxides

In superoxides, the oxidation number of oxygen is -1/2. Superoxides contain the O₂^- ion, which means that each oxygen atom in the superoxide ion has a fractional oxidation state. A well-known example of a superoxide is potassium superoxide (KO₂), where the overall charge of the superoxide ion is -1.

Examples of Superoxides

• In potassium superoxide (KO₂), potassium has an oxidation state of +1, and each oxygen is -1/2.
• In rubidium superoxide (RbO₂), rubidium also has an oxidation state of +1, with the same -1/2 for each oxygen.

In summary, the oxidation number of oxygen varies depending on the type of compound:

• In oxides, it is -2.
• In peroxides, it is -1.
• In superoxides, it is -1/2.

This variation is crucial for understanding the reactivity and properties of these compounds in chemical reactions.