# Bond Energy and Calculations

• Bond energy refers to the amount of energy needed to break a bond between two atoms, or the energy released when a bond is formed.
• It is measured in kilojoules per mole (kJ/mol).
• Breaking bonds requires energy (endothermic process) while forming bonds releases energy (exothermic process).

# Using Bond Energy Data in Calculations

• For a chemical reaction, the overall energy change (ΔH) can be calculated using the energies of the bonds in the reactants and products.
• The formula for this is ΔH = Energy used (bonds broken) - Energy released (bonds formed).
• If more energy is released than used, the reaction is exothermic (ΔH is negative).
• Conversely, if more energy is used than released, the reaction is endothermic (ΔH is positive).

# Example Calculations

• To calculate the energy change for a reaction, add up the bond energies for all the bonds on the reactant side (bonds broken) and the product side (bonds formed).
• Then subtract the energy of the bonds formed from the energy of the bonds broken using the formula above.

Please note that these points are general guidance, and the bond energies for specific compounds may vary based on other factors.