What is Oxidation?

Oxidation: A Chemical Reaction

Oxidation (or oxidisation) is a chemical reaction that often occurs when a substance is exposed to oxygen, leading to changes in its chemical composition.

A simple example is when you peel an apple and leave it out in the air. You'll soon notice it starts turning brown. This browning happens because the apple's natural chemicals react with oxygen.

Oxidation takes place in many foods after they're exposed to oxygen. The reaction causes their chemical composition to break down. Antioxidants, which can be natural or synthetic, slow down oxidation or prevent it from happening.

As food oxidises, it loses nutritional value. 

Over time, oxidation can alter the appearance and stability of rocks and minerals. One example is the rusting of iron. This process occurs when iron reacts with oxygen and water, leading to the familiar reddish-brown coating known as rust.

Oxidation in rocks and minerals occurs through a process called weathering. Weathering gradually changes the Earth's landscape by breaking down rocks and minerals through natural forces like water, ice, acids, salts, plants, animals, and temperature changes.

As oxygen interacts with these materials, it slowly breaks down old compounds. For example, when iron in rocks combines with oxygen, it forms oxide minerals. Rust, a common example, is a type of iron oxide.

When minerals oxidise, they become less resistant to further weathering.

The black markings often present in rhodonite are caused by the oxidation of manganese oxides.