Final answer:
Exothermic reactions release energy into the environment, often as heat, due to the rearrangement of chemical bonds, like the burning of methane. In biology, these are also referred to as catabolic reactions, which involve the breakdown of complex molecules to release energy for life processes.
Step-by-step explanation:
Chemical reactions that release energy into the environment are known as exothermic reactions. These reactions are characterized by the release of energy as the chemical bonds in the reactants break and new bonds form to create the products. The energy released may come in the form of heat, light, or other forms of energy. A common example of an exothermic reaction is the combustion of methane gas, typical in kitchen burners.
Conversely, there are also reactions that absorb energy from their surroundings; these are called endothermic reactions. An example of endothermic reaction is the process of photosynthesis.
The law of conservation of energy states that in any chemical reaction, energy cannot be created or destroyed, but it can be transformed from one form to another. During exothermic reactions, the energy stored in chemical bonds is released, often as heat, making the surroundings warmer. In the context of biology, exothermic reactions can be called catabolic reactions, where complex molecules like glucose are broken down to release energy that organisms use to carry out their life processes.