Question

Calculate second electron affinity of oxygen for the process: O\(^-\)(g) + e\(^-\)(g) \(\rightarrow\) O\(^{2-}\)(g) using the following data:
(i) Heat of sublimation of Mg(s) = +147.7 kJ mol\(^{-1}\)
(ii) Ionisation energy of Mg(g) to form Mg\(^{2+}\)(g) = +2189.0 kJ mol\(^{-1}\)
(iii) Bond dissociation energy for O\(_2\) = +498.4 kJ mol\(^{-1}\)
(iv) First electron affinity of O(g) = -141.0 kJ mol\(^{-1}\)
(v) Heat of formation of MgO = -601.7 kJ mol\(^{-1}\)
(vi) Lattice energy of MgO = -3791.0 kJ mol\(^{-1}\)

• A. 235.6 kJ mol\(^{-1}\)
• B. 468.7 kJ mol\(^{-1}\)
• C. 544.4 kJ mol\(^{-1}\)
• D. 744.4 kJ mol\(^{-1}\)

Hint:

Second EA is endothermic (positive) because adding electron to O\(^-\) is energetically unfavourable.

Answer 1

The Correct Option is D