Chemical Energy Definition and Examples

What Is Chemical Energy?

Wood is a source of chemical energy, which may be released during a combustion reaction.
Wood is a source of chemical energy, which may be released during a combustion reaction. Vitelle / Getty Images

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. Educ92: 2094–2099.