Answer:
The correct answer is -494.6 kJ/mol
Explanation:
Find enclosed the Born Haber cycle for MX. The solid compound M (M(s)) is sublimated to M(g) and then it is ionizated to M⁺. The gaseous compound X₂(g) is first dissociated to its atoms in gaseous phase X(g) and then it is ionizated to give X⁻(g). Lattice energy (LE) is the energy required to form 1 mol of MX(s) from its ions in gaseous phase.
From the cycle, we have:
ΔHºf= ΔHsub + IE + ΔHdis + EA + LE
⇒LE= ΔHºf - ΔHsub - IE - 1/2 ΔHdis - EA
LE= -169.7 kJ/mol - (74.4 kJ/mol) - (538 kJ/mol) - 1/2 (157 kJ/mol) - (-366 kJ/mol)
LE= -494.6 kJ/mol
