Question
Knowing the electron gain enthalpy values for O O– and O O2– as -141 and 702 kJ mol–1 respectively, how can you account for the formation of a large number of oxides having O2-species and not O–?
Solution
Stability of an ionic compound depend on its lattice energy. More the lattice energy of a compound more stable it will be.The electron gain enthalpy value for O → O– is –141 kj mol–1 and O → O2– is 702 kj mol–1. Combination of oxygen with other elements is often strongly exothermic which helps in sustaining the reaction. However, to initiate the reaction some external heating is required as bond dissociation enthalpy of oxygen-oxgen double bond is high (493.4 kj mol–1). Hence, we find the formation of a large number of oxides having O2– species and not O–
