Why is LiF almost insoluble in water whereas LiCl soluble not only in water but also in acetone ?

Explanation

Difference in lattice enthalpy and hydrogen enthalpy of `LiCl` is higher, i.e.`-31 kJ mol^(-1)[-876-(-845)]`than that of `LiF`, i.e. `-14 kJ "mol"^(-1)[-1019-(-1005)]` and hence `LiF` is sparingly soluble in water while `LiCl` insoluble. It means that `LiF` is almost insoluble in water because of much higher lattice energy `(-1005 kJ "mol"^(-1))`than that of `LiCl(-845 kJ "mol"^(-1))`. Futhermore, `Li^(o+)` ion can polarise bigger `Cl^(ө)` ion more easily than the smaller `F^(ө)` ion.As a result, according to Fajans rules, `LiCl` has more covalent character than `LiF` and hence is soluble in organic solvents like acetone.