Chapter 19, Problem 96QRT

Use a Born-Haber cycle (← Sec. 5-13) to calculate the lattice energy of MgF₂ using these thermodynamic data.

Δ_subH Mg(s) = +146 kJ/mol;

B.E. F₂(g) = +158 kJ/mol;

I.E.₁ Mg(g) = +738 kJ/mol;

I.E.₂ Mg⁺(g) = + 1450 kJ/mol;

E.A. F(g) = −328 kJ/mol;

Δ_fH° MgF₂(s) = −1124 kJ/mol.

Compare this lattice energy with that of SrF₂, −2496 kJ/mol. Explain the difference in the values in structural terms.