Question
Give reasons for the following:
(i) Bond enthalpy of F2 is lower than that of Cl2.
(ii) PH3 has lower boiling point than NH3Solution
(i) Bond enthalpy of F2 is lower than that of Cl2 because F atom is small in size and due to this the electron-electron repulsions between the lone pairs of F-F are very large. Thus, the bond dissociation energy of F2 is lower than that of Cl2.
(ii) PH3 has a lower boiling point than NH3 because NH3 molecule possesses intermolecular hydrogen bonding which binds them strongly whereas PH3 has weaker Vander Waal’s forces. Thus, PH3 has a lower boiling point than NH3.
