A cycle of reactions used for calculating the lattice energies of ionic crystalline solids. For a compound MX, the lattice energy is the enthalpy of the reaction
M+(g) + X−(g) → M+X−(s) ΔHL
The standard enthalpy of formation of the ionic solid is the enthalpy of the reaction
M(s) + ½X2(g) → M+X−(s) ΔHf
The cycle involves equating this enthalpy (which can be measured) to the sum of the enthalpies of a number of steps proceeding from the elements to the ionic solid. The steps are:
ΔHf = ΔH1 + ΔH2 + ΔH3 + ΔH4 + ΔHL
from which ΔHL can be found. It is named after Max Born and the German chemist Fritz Haber (1868–1934).
Subjects: Chemistry — Physics.