Question

write about bond enthalpy​

Answer 1

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Bond Enthalpy : The amount of energy required to break one mole of bond of one type, present between two atoms in the gaseous state is termed as Bond Enthalpy. For diatomic molecules the dissociation energy is the same as bond enthalpy. Bond enthalni for H, molecule is 435.8 kJ mol^-1. The bond enthalpy is a measure of strength of the bond between two atoms and can be measured experimentally. N-N bond in N, is stronger than the 0-0 bond in 02 Larger is the bond dissociation energy stronger is the bond in the molecule. For heteronuclear diatomic molecule HCl the bond enthalpy was found to be 431.0 kJ mol^-1

Answer 2

Bond Enthalpies

Bond enthalpy (also known as bond energy) is defined as the amount of energy required to break one mole of the stated bond. For example, the bond energy of a O-H single bond is 463 kJ/mol. This means that it requires 463 kJ of energy to break one mole of O-H bonds. Note: In order to break any bond, energy must be absorbed. Therefore, bond breaking is always an endothermic change (ΔH > 0). Conversely, energy is always released upon the formation of a bond. Therefore, bond making is always an exothermic change (ΔH < 0). Find a list of bond energies in the table shown at the bottom of this page.

Change in reaction enthalpy (ΔHrxn) can be approximated from bond energy data. One can assume that during a chemical change, all bonds in the reactants are broken yielding free atoms as shown in step 1 in the diagram below. Then those atoms recombine to form the new bonds found in the products (step 2).