What does oxidation refer to in a chemical context?

In a chemical context, oxidation refers specifically to the gain of oxygen by a substance. This process involves the interaction of a substance with oxygen, which often results in the formation of oxides. A classic example is when iron reacts with oxygen to form iron oxide, commonly known as rust.

Understanding oxidation in this way is essential as it is a crucial part of various chemical reactions, particularly combustion and respiration, where substances typically gain oxygen. This concept is foundational in redox (reduction-oxidation) reactions, which are central to many areas of chemistry, including organic and inorganic reactions.

The other options do not accurately represent oxidation in the traditional chemical sense. For instance, loss of oxygen would be referred to as reduction, and gaining hydrogen also correlates with a reduction process. In contrast, the loss of hydrogen, known as dehydrogenation, can also indicate an oxidative process but is more specific to organic chemistry and does not encompass the broader definition of oxidation as it relates to the gain of oxygen.