(a) Given that ∆U(0 K) and ∆_fH°(298 K) for MgO are −3795 and −602 kJ mol⁻¹ respectively, derive a value for ∆_EAH°(298 K) for the reaction:

Other data: see Appendices. 

(b) Compare the calculated value with that obtained using electron affinity data from Appendix 9, and suggest reasons for any differences.

Appendix 9

Approximate enthalpy changes, ∆_EAH(298 K), associated with the gain of one electron by a gaseous atom or anion. A negative enthalpy (∆H), but a positive electron affinity (EA), corresponds to an exothermic process. ∆_EAH(298K) ≈ ∆U(0K) = −EA

Transcribed Image Text:

O(g) + 2e -0²-(g)