Lattice enthalpy
Lattice enthalpy
Formula
MX(s) → M⁺(g) + X⁻(g) ΔH_latt > 0
Real World
MgO has a much larger lattice enthalpy (~3800 kJ mol⁻¹) than NaCl (~780 kJ mol⁻¹), which is why magnesium oxide is used as a refractory lining in steel furnaces — its ionic lattice is extremely difficult to break down even at ~1600 °C.
Exam Focus
Justify lattice enthalpy differences by referencing both ionic charge AND ionic radius — one factor alone will not gain full marks.
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