Question

What ara the differences between the homolytic and heterolytic bond dissociation ? And why homolytic dissociation energy of H-H (104 KJ/mol) is lower than its heterolytic bond dissociation energy (401 KJ/mol)?

Answer 1

Homolytic bond dissociation results in the formation of two radicals and requires less energy, while heterolytic bond dissociation forms an anion and a cation, requiring more energy due to electrostatic considerations. This is why the dissociation energy of H-H bonds is lower for homolytic (104 kJ/mol) than for heterolytic processes (401 kJ/mol).

Step-by-step explanation:

Homolytic and heterolytic bond dissociation are two different processes for the breaking of chemical bonds. In homolytic bond dissociation, each atom in the bond takes one electron from the shared pair, leading to the formation of two radicals. This requires less energy because it results in species that have no charge and thus avoids the electrostatic cost of creating charged species.

In contrast, heterolytic bond dissociation involves one atom taking both electrons from the bond, leading to the formation of a cation and an anion. This requires more energy, such as in the case of H-H bond where heterolytic dissociation energy is significantly higher (401 kJ/mol) than homolytic dissociation energy (104 kJ/mol). The higher energy is needed due to the creation of two oppositely charged ions, which requires overcoming the attraction between them.

The difference in dissociation energy between homolytic and heterolytic processes is due to the nature of the products. Radical species formed during homolytic cleavage are electrically neutral, while ionic species formed during heterolytic cleavage carry a full positive or negative charge, making the latter process more energy-intensive.

Answer 2

Following are the difference in homolytic and hetrolytic bond dissociation.

1. Homolytic dissociation is referred as the amount of energy released during homolytic fission. Homolytic fission is known as the dissociation of chemical bond in two equal fragmentswhereas, Hetrolytic dissociation is referred as the amount of energy released during Hetrolytic fission. Hetrolytic fission is known as the dissociation of chemical bond in two unequal fragments.
2. Homolytic fission gives one electron each to its fragments whereas Hetrolytic fissiongives two electron to one fragment and zero electron to other fragment.

Energy released during Homolytic fission is lower than the Hetrolytic fission as the electron distribution to its fragments is uniform in homolytic whereas electron distribution to its fragments is uniform in hetrolytic fission.

Thus bonds form in hetrolytic fission is more stronger than the the bonds formed in homolytic fission.

Hence, more energy is required to break the bonds of hetrolytic fission as compared to homolytic fission

Thus, homolytic dissociation energy of H-H (104 KJ/mol) is lower than its heterolytic bond dissociation energy (401 KJ/mol)