<P> The net enthalpy of formation and the first four of the five energies can be determined experimentally, but the lattice energy cannot be measured directly . Instead, the lattice energy is calculated by subtracting the other four energies in the Born--Haber cycle from the net enthalpy of formation . </P> <P> The word cycle refers to the fact that one can also equate to zero the total enthalpy change for a cyclic process, starting and ending with LiF (s) in the example . This leads to 0 = − Δ H f + V + 1 2 B + IE M − EA X + U L (\ displaystyle 0 = - \ Delta (\ text (H)) _ (\ text (f)) + (\ text (V)) + (\ frac (1) (2)) (\ text (B)) + (\ text (IE)) _ (\ text (M)) - (\ text (EA)) _ (\ text (X)) + (\ text (U)) _ (\ text (L))) which is equivalent to the previous equation . </P>

How the born haber cycle for the formation of sodium chloride is compiled