Question

Would you expect the hydrides of N, O and F to have lower boiling points than hydrides of their subsequent group members ? Give reasons.

Answer 1

The hydrides of N, O and F are `NH_(3) , H_(2)O and HF` respectively. On the basis of masses of `NH_(3), H_(2)O` and HF, their boiling points are expected to be lower than the hydrides of the subsequent group members (i.e. `PH_(3), H_(2)S and HCl`) . However, due to high electronegativity of N, O and F, their hydrides undergo extensive intermolecular H-bonding . As a result , the boiling point of `NH_(3), H_(2)O` and HF are much higher than the hydrides of their subsequent group members (i.e., `PH_(3), H_(2)S and HCl`).