Draw the Born-Haber cycle for the formation of LiF(s) from its elements and using this cycle calculate the lattice enthalpy of LiF(s).
Given: `DeltaH_(f)^(0)[LiF(s)]=-617kJ*mol^(-1)`,
`DeltaH_(sub)=+161kJ*mol^(-1),DeltaH^(0)(F-F)=+159kJ*moL^(-1)`,
`IE_(1)=+520kJ*mol^(-1),EA` of `F=-328kJ*mol^(-1)`.

Explanation

Following is the born-Haber cycle for the formation of LiF(s) from tis constituent elements Li(s) and `F_(2)(g)`.

[`DeltaH_(L)^(0)=`Standard lattice enthalpy]
According to Hess's law: `DeltaH_(f)^(0)LiF(s)=`Total enthalpy changes in steps (1),(2),(3),(4) and (5)
Therefore, `-617=(+161+79.5+520-328)-DeltaH_(L)^(0)`
`therefore DeltaH_(L)^(0)=+1049.5kJ*mol^(-1)`.
So, standard lattice enthalpy for `LiF=+1049.5kJ*mol^(-1)`.