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

Explanation

Difference in lattice enthalpy and hydration enthalpy of LiCl is higher , i.e., `-42` kJ `mol^(-1) [-887 -(-845)]` than that of LiF , i.e., `-16 k J mol^(-1) [-1021 - (-1005)]` and hence LiF is sparingly soluble in water while LiCl is soluble . In a nutshell , we can say that LiF is almost insoluble in water because of much higher lattice energy `(-1005 k J mol^(-1))` than that of LiCl `(-845 kJ mol^(-1))` . Furthermore , `Li^(+)` ion can polarize bigger `Cl^(-)` ion more easily than the smaller `F^(-)` ion . As a result , according to Fajan rules , LiCl has more covalent character than LiF and hence is soluble in organic solvents like acetone