Question

what do you mean by lattice enthalpy

Answer 1

The lattice energy or lattice enthalpy of a crystalline solid is a measure of the energy released when ions are combined to make a compound. It is a measure of the cohesive forces that bind ions. Lattice enthalpy is relevant to many practical properties including solubility, hardness, and volatility. The lattice energy is usually deduced from the Born–Haber cycle.[1]

Answer 2

The Lattice Enthalpy of an ionic solid is defined as the energy required to completely separate one mole of a solid ionic compound into gaseous constituent ions.