Exothermic reactions release heat. This means the products have *lower* energy than the reactants.
Bond formation releases energy. When atoms bond together, they reach a more stable state, and this stability is reflected in a lower energy level.
Putting it together:
In an exothermic reaction where new bonds are forming, the energy released by forming the new bonds is greater than the energy required to break the old bonds. This excess energy is released as heat, making the reaction exothermic.
Example:
The combustion of methane (CH4) is a classic example:
* Reactants: Methane (CH4) and oxygen (O2)
* Products: Carbon dioxide (CO2) and water (H2O)
1. Breaking bonds: Energy is required to break the bonds in methane and oxygen.
2. Forming bonds: New, stronger bonds are formed in carbon dioxide and water. The energy released by forming these bonds is greater than the energy required to break the initial bonds.
3. Heat release: The excess energy is released as heat, making the reaction exothermic.
Key takeaway: Exothermic reactions where new bonds are forming are common. The energy released by forming new bonds is a driving force for the reaction, and the excess energy is released as heat.
