When does chemical energy transform into thermal energy?

Chemical energy transforms into thermal energy during a chemical reaction. This process occurs when bonds between atoms in reactant molecules are broken and reformed to create new products. The breaking of these bonds requires energy, while the formation of new bonds releases energy. If the energy released during product formation is greater than the energy required to break the bonds in the reactants, the excess energy is released as heat, increasing the thermal energy of the surrounding environment.

This transformation is a key principle in many everyday phenomena, such as combustion, where the burning of fuels releases heat and light, which are forms of thermal energy. In contrast, energy stored typically refers to the potential energy held within a system, and the absence of any reaction means no energy transformation occurs. Mechanical movement involves different forms of energy transfer, generally between kinetic and potential energy, rather than a direct transformation from chemical to thermal energy.