Chemical energy is the energy contained in the internal structure of an atom or molecule. It is a measure of a substance's capacity to transform into another substance via a chemical reaction. This energy could be in the electronic structure of a single atom or in the bonds between atoms in a molecule. Chemical energy is converted into other forms of energy by chemical reactions.
Examples of substances that contain chemical energy include:
- Wood
- Food
- Gasoline
- Batteries
Chemical energy is released or absorbed as chemical bonds are broken and reform. It is a misconception that a substance always releases more energy than it absorbs! Chemical energy is calculated as the difference between the energy of the products and reactants. This may be measured using a calorimeter or calculated based on the bond energies of the chemical bonds.
Reference
- Schmidt-Rohr, K (2015). "Why Combustions Are Always Exothermic, Yielding About 418 kJ per Mole of O2". J. Chem. Educ. 92: 2094–2099.