Question

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

Answer 1

Hint: LiF in water becomes insoluble. LiCl is soluble in water as well as acetone, though. This is primarily attributed to LiF's higher ionic character than LiCl. The solubility of a water compound depends on the balance between grid and hydration capacity.

Complete step-by-step answer:
Since the ion of fluoride is far less than the ion of chloride, the LiF grid energy is greater than the LiCl energy. However, the hydration energy of fluoride ion and chloride ion is not that different. The increase in net energy in water is, however, more exothermic when LiCl is dissolved than when LiF is dissolved in gas. Therefore, weak grid energy and a higher degree of covalence render LiCl soluble not only in water but also in acetone.
In lithium fluoride, the enthalpy of lattices is very high because the fluoride ions are small. Hydration enthalpy in this case is much less. LiF is therefore water insoluble. Whereas the lattice enthalpy is very small in lithium chloride because of its large size and hydration enthalpy is high. More than LiCl has partial ionic characteristics due to chloride polarization by lithium ions. LiCl is soluble in water as well as acetone because of its low hydration energy and a partial covalent and partial ionic character.

Note: Lithium fluoride is a chemical LiF inorganic compound. The transitions to whiteness are colorless, and the size of the crystal decreases. Lithium fluoride has a bitter salt taste though it is odorless. The structure of sodium chloride is analogous, but much less soluble in water. It is used primarily as a molten salt component. LiF formation from the elements frees one of the highest reactant mass energies, second to BeO.