How do oxidation and reduction relate to each other?

Oxidation and reduction are two complementary chemical reactions that always occur together, known as a redox reaction.

In more detail, oxidation and reduction are two types of chemical reactions that often occur simultaneously. They are part of a larger process known as a redox (reduction-oxidation) reaction. Oxidation refers to the loss of electrons during a reaction by a molecule, atom or ion. On the other hand, reduction refers to the gain of electrons by a molecule, atom or ion.

The terms 'oxidation' and 'reduction' can be remembered by the acronym 'OIL RIG', which stands for 'Oxidation Is Loss, Reduction Is Gain' - referring to the loss or gain of electrons respectively. In a redox reaction, the substance that loses electrons (undergoes oxidation) is known as the reducing agent, because it 'donates' electrons, thereby reducing another substance. Conversely, the substance that gains electrons (undergoes reduction) is known as the oxidising agent, because it 'accepts' electrons, thereby oxidising another substance.

For example, in the reaction between hydrogen and fluorine to form hydrofluoric acid (HF), hydrogen is oxidised (loses an electron) and fluorine is reduced (gains an electron). Here, hydrogen acts as the reducing agent and fluorine as the oxidising agent.

Understanding the relationship between oxidation and reduction is crucial in many areas of chemistry, including electrochemistry, industrial processes, and biological systems. For instance, the process of respiration, which is vital for life, is a redox reaction where glucose is oxidised and oxygen is reduced.