Bond Dissociation Energy is defined as the energy required to break a covalent bond and can be used to calculate what quantity?

Bond Dissociation Energy is defined as the energy required to break a covalent bond and can be used to calculate what quantity?

• A. The energy released when a bond forms
• B. The energy required to break the bond between two covalently bonded atoms
• C. The energy required to break the bond between two covalently bonded atoms that can be used to calculate the overall enthalpy
• D. The energy barrier for bond rotation

Answer: (C)

Bond dissociation energy is the energy needed to break a covalent bond, separating the bonded atoms into individual atoms (homolytic cleavage). This quantity is the key parameter in the bond-enthalpy method for estimating the enthalpy change of a reaction: you add up the energies required to break all bonds that's happening in the reaction and subtract the energies released when new bonds form. In other words, the energy to break the bond can be used to calculate the overall enthalpy of the process because ΔHrxn is essentially the difference between bonds broken and bonds formed. So the best description is that bond dissociation energy is the energy required to break the bond, and this value can be used to determine the overall enthalpy of a reaction by accounting for both broken and formed bonds. The other ideas—energy released on bond formation or a rotational energy barrier—don’t describe BDE or its main usage.

Bond dissociation energy is the energy needed to break a covalent bond, separating the bonded atoms into individual atoms (homolytic cleavage). This quantity is the key parameter in the bond-enthalpy method for estimating the enthalpy change of a reaction: you add up the energies required to break all bonds that's happening in the reaction and subtract the energies released when new bonds form. In other words, the energy to break the bond can be used to calculate the overall enthalpy of the process because ΔHrxn is essentially the difference between bonds broken and bonds formed.

So the best description is that bond dissociation energy is the energy required to break the bond, and this value can be used to determine the overall enthalpy of a reaction by accounting for both broken and formed bonds. The other ideas—energy released on bond formation or a rotational energy barrier—don’t describe BDE or its main usage.