Chapter 12.2, Problem 12.3CC

Interpretation Introduction

Interpretation:

The two hypothetical ionic compounds $A{B}_2$ and ${\text{ CB}}_2$ having almost same lattice energies are very soluble and slightly soluble in water respectively.  The difference in solubility between these two compounds has to be explained.

Concept Introduction:

• The energy released when gaseous state ions of unlike charges that are infinitely farther apart combine to form a stable ionic solid is called Lattice energy.  Conversely, the energy required to break the electrostatic force of attraction between the ions of unlike charges in the ionic solid and revert them to gaseous state is also termed as Lattice energy of an ionic solid.
• Hydration energy refers to the quantity of energy released when one mole of ion gets hydrated at constant pressure.  Hydration energy of an ion depends upon its ionic size.
• Solubility of an ionic compound is primarily influenced by two factors – lattice energy and hydration energy.