The process of forming an ionic salt from its constituent metallic and nonmetallic elements is called the born-haber cycle, which is a series of thermochemical processes, each with a δh, that add up (think of hess’s law) to complete a 5 step process for the formation of the salt. given the following data, calculate the lattice energy per mole of lif(s) formed. li(s) → li(g) δh°

Answer :  The lattice energy per mole of Li(s) formed is -1016.6 kJ

Explanation :  

The formation of lithium fluoride is,

= enthalpy of formation of lithium fluoride = -594.1 kJ

The steps involved in the born-Haber cycle for the formation of :

(1) Conversion of solid lithium into gaseous lithium atoms.

= sublimation energy of lithium  = +155.2 kJ

(2) Conversion of gaseous lithium atoms into gaseous lithium ions.

= ionization energy of lithium  = +520 kJ

(3) Conversion of molecular gaseous fluorine into gaseous fluorine atoms.

= dissociation energy of fluorine = +75.3 kJ

(4) Conversion of gaseous fluorine atoms into gaseous fluorine ions.

= electron affinity energy of fluorine = -328 kJ

(5) Conversion of gaseous cations and gaseous anion into solid lithium iodide.

= lattice energy of lithium fluoride = ?

To calculate the overall energy from the born-Haber cycle, the equation used will be:

Now put all the given values in this equation, we get:

Therefore, the lattice energy per mole of Li(s) formed is -1016.6 kJ