(a) Complete the following chemical equations :
(b) How would you account for the following ?
(i) The value of electron gain enthalpy with negative sign for sulphur is higher than that for oxygen.
(ii) is an exothermic compound but is endothermic compound.
(iii) molecule has a T-shaped structure and not a trigonal planar one. 5 mark
(b) (i) Because of enthalpy of dissociation of S-S bond is higher than O-O bond and the hydration energy of is less than that of ion.
(ii) Due to smaller size of F as compared to Cl, the N-F bond is much stronger than N-Cl bond while bond dissociation energy of is much lower than that of . Therefore, energy released during the formation of molecule is more than the energy needed to break and molecules into individual atoms. In other words, formation of is an exothermic reaction.
The energy released during the formation of molecule is less than the energy needed to break and molecule into individual atoms. Thus formation of is an endothermic reaction.
(iii) The electronic configuration of Cl is It has only one half filled orbital. But to form three Cl-F bonds, we need three half filled orbitals. To achieve this, one of the electrons gets excited to 3d orbital. The resulting five orbitals of the third shell of Cl in the first excited state undergoes hybridization to give T-shaped structure to molecule. Since Cl does not undergo hybridization, therefore does not have trigonal planar structure.