Account for the following :
Although Fluorine has less negative electron gain enthalpy yet F2 is a strong oxidizing agent.
The oxidizing capability of a substance depends upon three factors: bond dissociation enthalpy, electron gain enthalpy, and hydration energy.
Although electron gain enthalpy of fluorine is less negative as compared to chlorine, fluorine is a stronger oxidizing agent than chlorine, because of low enthalpy of dissociation of F-F bond (158.8/ kJ mol-1) and high hydration enthalpy of F- (515/ kJ mol-1).
Due to its small size, Fluorine's hydration energy is very high hence better the oxidizing power. Fluorine has a greater electron-electron repulsion among the lone pairs in the small-sized F2 molecule where they are much closer to each other than in the case of Cl2, hence the enthalpy of dissociation of F2 is lower than Cl2 which makes it better oxidizing agent.