Bond dissociation energy of F, is less than that of Cl, but the bond dissociation energy of HF is greater

Question

Explain giving reasons:

Bond dissociation energy of F, is less than that of Cl, but the bond dissociation energy of HF is greater than that of HCI.

Answer 1

In F₂, the interelectronic repulsion between the bonded atoms make the bond weaker. In Cl₂ the interelectronic repulsion is less and stable. Thus F₂ has lower bond dissociation energy than Cl₂. On the other HF molecule has greater electrone gativity difference than that of HCI so HF has shorter bond length than HCI and its dissociation energy is higher-than HCI.