Chemical Change: Redox Reactions

Definition

Redox reactions are one of the basic types of chemical reactions, and involve both oxidation and reduction happening simultaneously.
These reactions are characterised by the transfer of electrons between chemical species.

Oxidation and Reduction

Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion.
Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.
An easy way to remember this is through the acronym OIL RIG: Oxidation Is Loss, Reduction Is Gain (of electrons).

Oxidation States

Oxidation states are assigned to atoms to help identify the changes that occur in redox reactions.
In compounds, the sum of the oxidation states equals the overall charge of the compound.
If an atom gains an electron through reduction, its oxidation state decreases. If an atom loses an electron through oxidation, its oxidation state increases.

Redox Reactions in Practice

Redox reactions are common and important. They include many familiar reactions such as the rusting of iron, the metabolism of food in the body, and the reactions that take place in batteries to generate electricity.

Recognising Redox Reactions

Redox reactions can often be recognised as they often produce a colour change, the formation of a gas or the deposition of a solid.
In reaction equations, you can recognise a redox reaction as there will be a change in the oxidation states of two or more elements.

Redox Agents

Oxidising and reducing agents are vital components of redox reactions.
An oxidising agent oxidises something else, so it is reduced itself.
A reducing agent reduces something else, so it is oxidised itself.

Regularly practise applying these principles in varied scenarios. Remember to regularly test your understanding through self-quizzing and linking new knowledge to what you already know. This will consolidate your learning and improve knowledge retention.