explain energy changes in the formation of NACL crystal using born_haber cycle in long answer
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Answer:
BornHabercycle is a simplified method developed by Max Born and Fritz Haber in 1919 to correlate the lattice energies of ionic solids to other thermodynamic data. Lattice enthalpy or lattice energy is defined as enthalpy change which occurs when one mole of ionic solid is formed by close packing of constituent ions in gaseous state. Or it may be defined as energy released when one mole of ionic solid dissociates into its gaseous state.
For example, the formation of sodium chloride from sodium and chloride ion involves 788 kj/mol of energy and dissociation of sodium chloride into it constituent ions requires same amount of energy.
NaCl(s) + Na+(g) + CI- (g) ∆L∆LH°= 788 kj/mol
Na+(g) + CI-(g) ++ NaCI(s) ∆L∆LH°= - 788 kj/mol
When oppositely charged ions interact to form ionic solid, a large amount of energy is released and dissociation of crystal also require a lot of energy which makes melting point and boiling points of crystal very high. Born Haber cycle is used to determine this lattice energy by using other energy values like ionization energy, electron affinity, dissociation energy, sublimation energy and heat of formation.
Ionization Energy: It is the energy required to remove an electron from a neutral gaseous atom or an ion.
Electron Affinity: It is the energy released when an electron is added to an isolated neutral gaseous atom or an ion.
Dissociation energy: The energy required to dissociate a compound is called as dissociation energy. Dissociation of a compound is always an endothermic process and requires an input of energy.
Sublimation energy: The energy required to change the phase from solid to gas, by passing the liquid phase is called as sublimation energy.
Heat of formation: The energy change during the formation of a compound from its elements is known as heat of formation.
Born Haber cycle is based on Hess law which states that the standard enthalpy change of reactions is the sum of algebraic sum of the standard enthalpies of reactions into which the overall