By Joseph Nicholson
Updated Aug 30, 2022
Chemical energy is stored in the bonds between atoms and molecules. When a chemical reaction rearranges electrons and protons, energy is released or absorbed. The Law of Conservation of Energy guarantees that energy is never destroyed—only transformed. A reaction that lowers the system’s internal energy releases that excess as heat or light to the surroundings, while an endothermic reaction draws energy from the environment.
Living organisms rely on chemical energy. In photosynthesis, chlorophyll captures sunlight to split water into hydrogen and oxygen. The released hydrogen combines with atmospheric carbon dioxide to build carbohydrates—glucose and other sugars—that plants use for growth. Cellular respiration, the reverse process, oxidizes these carbohydrates with oxygen to produce ATP, the universal energy currency for cellular functions.
Chemical energy is not limited to biology. Combustion in gasoline engines is a chemical reaction where hydrocarbon fuel reacts with atmospheric oxygen, generating the power to turn a crankshaft. Fireworks, matchsticks, and glow sticks also rely on chemical bonds: burning phosphorus releases light and heat, while a glow stick’s activated chemical mixture emits visible light with minimal heat.
The speed of a chemical reaction depends on several controllable variables: reactant concentration, available surface area, temperature, and pressure. Engineers adjust these parameters to optimize production or minimize unwanted by‑products in industrial processes. Understanding kinetics is essential for scaling up reactions safely and efficiently.
Catalysts accelerate reactions without being consumed. In automotive catalytic converters, platinum‑group metals transform harmful exhaust gases—nitrogen oxides, carbon monoxide, and unburned hydrocarbons—into benign nitrogen, oxygen, carbon dioxide, and water. Because the catalyst remains unchanged, it can be reused countless times, making it a cornerstone of modern emission control.
For more detailed explanations, see the Wikipedia article on Chemical Energy.
