Question

Define lattice energy?

Answer 1

Lattice energy:

• Lattice energy can be defined as the energy required to convert one mole of an ionic solid or crystalline solids into gaseous ionic constituents.
• It is expressed in terms of $\mathrm{kJ}{\mathrm{mol}}^{-1}$.
• Lattice energy is always exothermic; the more exothermic the lattice energy, the stronger the ionic bonding in the lattice.
• Example: $\mathrm{NaCl}\left(\mathrm{s}\right)\to {\mathrm{Na}}^{+}\left(\mathrm{g}\right)+{\mathrm{Cl}}^{-}\left(\mathrm{g}\right)$
• Lattice energy can be calculated by the Born - Haber cycle.