Calculate lattice energy of ionic compounds using Born-Haber thermodynamic cycle with enthalpies of formation, sublimation, ionization, and electron affinity.
Lattice Energy (U)
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Lattice Energy Magnitude
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Ionic Bond Strength
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The Born-Haber cycle is used to calculate the lattice energy of ionic compounds by applying Hess's law to various thermodynamic processes including sublimation, ionization, electron affinity, and formation.
Lattice energy is the energy required to completely separate one mole of an ionic solid into gaseous ions, or conversely, the energy released when gaseous ions combine to form one mole of an ionic solid.
Lattice energy is calculated using the equation: U = ΔH°f - ΔHsub - ΣIE - ½D - ΣEA, where each term represents different thermodynamic processes in the cycle.
Lattice energy depends on the charges of the ions and the distance between them. Higher charges and smaller ionic radii result in stronger electrostatic attractions and higher lattice energies.
Lattice energy is positive because energy must be supplied to overcome the strong electrostatic attractions between oppositely charged ions in the crystal lattice.
NaCl has a lattice energy of about 786 kJ/mol, while MgO has a much higher lattice energy of about 3791 kJ/mol due to the higher charges on Mg²⁺ and O²⁻ ions.