Question

Is $AgCl$ soluble in water ?

Answer 1

Hint: The solubility of an ionic compound depends on its lattice energy and hydration energy. For solubility, compare both energies for a given compound. The compound is soluble in water if and only if its lattice energy is lesser than its hydration energy.

Complete answer:
The solubility of Silver Chloride can be in two different ways. Firstly it is according to the Fajan Rule which tells us about the polarizing power of any ion . According to this polarizing power of ions depends on charge by radius ratio . For $AgCl$ , $A{g^ + }$ has more polarizing power and thus as a result covalent character is developed in the compound. We can also say $AgCl$ has become non polar in nature. Since water is polar so it will dissolve only polar compounds .Hence $AgCl$ is insoluble in water.
Secondly , the solubility of a compound can be explained on the basis of its lattice energy and hydration energy. In the case of $AgCl$ the attraction between the $AgCl$ molecule itself is greater than attraction between $AgCl$ and water . Thus the hydration enthalpy of the ${\text{ aq}}{\text{. }}AgCl$ is not sufficient to overcome the lattice enthalpy of its ions.
Thus we can say that $AgCl$ is insoluble in water.

Note:
$NaCl$ is soluble in water whereas $AgCl$ don’t .This is explained by Fajan Rule . Also $KCl$ is soluble in water too. The solubility product also helps in knowing the solubility of the given compound. The solubility product of $AgCl$ in water is $1.7{\text{ }} \times {\text{ 1}}{{\text{0}}^{ - 10}}{\text{ mo}}{{\text{l}}^2}{\text{ d}}{{\text{m}}^{ - 6}}$ .