An exothermic reaction is a chemical process that releases energy, primarily in the form of heat or light.

To elaborate, an exothermic reaction is characterized by the energy of the products being lower than that of the reactants. This energy difference is emitted, typically as heat, but it can also manifest as light, sound, or electricity. The term ‘exothermic’ is derived from the Greek words ‘exo’, meaning ‘out’, and ‘thermic’, meaning ‘heat’. Essentially, an exothermic reaction is one that “releases heat.”

Exothermic reactions are prevalent in both natural and artificial processes. For example, combustion processes, such as the burning of wood or gasoline, are classic examples of exothermic reactions. Additionally, many metabolic reactions in our bodies, such as the digestion of food, also qualify as exothermic. These reactions are vital as they release the energy necessary for our bodies to function.

In an exothermic reaction, the activation energy required to initiate the reaction is greater than the energy that is released during the reaction itself. This is why these reactions often need a spark or some form of initial energy to commence. However, once initiated, they tend to propagate independently, as the energy released is sufficient to sustain the reaction.

In chemical equations, exothermic reactions are typically represented with the heat term included on the product side. For instance, in the combustion of methane, the reaction can be expressed as:

Understanding exothermic reactions is essential in various fields of science and technology, including energy production, materials science, and biological processes. It is also a fundamental concept in GCSE Chemistry, so it is important to be well-acquainted with this topic!