Exothermic Reaction - GCSE Biology Definition

An exothermic reaction is a type of chemical reaction that releases energy into the surroundings, usually in the form of heat or light. In these reactions, the total energy of the products is less than the total energy of the reactants, causing the extra energy to be given off. This is why you might feel heat coming from an exothermic reaction. A common example is when you burn wood or fuel, as the reaction releases energy that you can feel as heat or see as flames. Exothermic reactions are important in everyday processes and even in biological systems, like when our bodies break down food to release energy.