The determination of lattice energy of an ionic compound using Born-Haber cycle and the law that is used has to be given.
The enthalpy change for given set of reactants to the given set of products is the same, whether the process takes place in single or sequence of steps. This is called as Hess’s law.
Enthalpy is generally calculated from the standard enthalpy of formation.
The amount of energy that is necessary for the conversion of one mole of ionic solid to its constituent ions in gaseous phase is called Lattice energy.
Born-Haber cycle is a method to study reaction energies. The cycle involves in the formation of an ionic compound from metal reaction that is often Group 1 or group 2 with a Halogen or non metallic element such as Oxygen.
To explain: The determination of lattice energy of an ionic compound using Born-Haber cycle