Combustion reactions are typically irreversible because they release a significant amount of energy in the form of heat and light, converting reactants (usually a fuel and oxygen) into highly stable products, such as carbon dioxide and water. The products of combustion are stable and do not readily revert back to the reactants. For example, burning methane (CH₄) in oxygen produces carbon dioxide (CO₂) and water (H₂O). The products are thermodynamically stable, and there is a large energy release, making it extremely difficult for the reaction to reverse. The energy released in combustion reactions further ensures that they proceed to completion and do not easily go backward.