Chemical energy is stored in substances that can undergo reactions to form products with more stable bonds, resulting in energy release. Examples include gasoline and TNT, which release energy when their bonds are broken and reformed. The process of bond breaking requires energy, while bond formation releases energy, leading to exothermic reactions when more energy is released than consumed. A common example is the combustion of methane with oxygen, producing carbon dioxide and water, which is exothermic due to the high bond enthalpy of carbon dioxide. Overall, substances with high chemical potential energy can release significant energy during reactions.