Question

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

Answer 1

(1) For a substance to dissolve in water, its hydration energy must be greater than its lattice energy, (2) Due to the small size of $L{i}^{+}$ ion and $F^{-}$ ions, lattice energy of $LiF$ is very high. $LiF$ is covalent in nature Therefore, $LiF$ is insoluble in water. (3) Due to the larger size of $C{l}^{-}$ ion, the lattice energy of $LiCl$ is less than its hydration energy. Hence, $LiCl$ is soluble in water and in acetone.