Question

Why do bonds release energy?

Answer 1

Chemical bonds:

1. In order for new bonds to form between the atoms of the products during a chemical reaction, the bonds between the reactants must be broken first.
2. Bond breaking and bond formation are involved in chemical reactions. The breaking of bonds requires energy. It is a type of endothermic reaction whereas energy is released during bond formation thus it is an exothermic reaction.
3. When a bond is formed the energetic electrons lose energy as they move from high to low energy and form bonds.
4. The system loses energy when bonds are created, hence increasing the stability. It is an exothermic process because there is a loss of energy, which is then converted to heat energy and discharged into the environment.
5. The change in enthalpy for an exothermic process will always be negative, or$∆\mathrm{H}<0$.
6. Examples of exothermic reactions: Combustion, $\underset{\mathrm{Methane}}{{\mathrm{CH}}_4\left(\mathrm{g}\right)}+\underset{\mathrm{oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)}+\mathrm{Heat}$

Therefore, bonds release energy because of extra energy.