Question

Solubility of an ionic compound in water is mainly dependent on:
a. Lattice enthalpy
b. Hydration enthalpy
Both these factors oppose each other, and the resultant of these factors determines the solubility of an ionic compound in water. If the lattice enthalpy has a larger value, the compound is less soluble. If the hydration enthalpy has larger value, the compound is highly soluble in water.

Compounds of alkaline earth metals are less soluble than alkali metals, due to:

• A. Their high hydration enthalpy
• B. Their high lattice enthalpy
• C. Their increased covalent character
• D. Their high ionisation enthalpy

Answer 1

The correct option is B Their high lattice enthalpy

Alkaline earth metals are smaller in size than their respctive alkali metals. They also have more charge hence high charge density i.e. high lattice energy. As lattice energy becomes larger, solubility decreases.