Question

At equilibrium , if to a saturated solution of $NaCl,HCl$ is passed , $NaCl$ gets precipitated because
A. HCl is a strong acid
B. HCl is a weak acid.
C. Ionic product of sodium chloride is greater than solubility product.
D. Solubility of sodium chloride decreases

Answer 1

Hint: A salt forms precipitate only when the product of the concentration of its cation and anion is greater than its solubility product. Solubility product of a salt depends on the number of ions formed in a reaction or the concentration of the ions at equilibrium.

Complete Step by Step Answer:
Sodium chloride is a salt of hydrochloric acid and sodium hydroxide. Thus it dissociate in sodium ion and chloride ion. The dissociation is given as follows-
$NaCl\rightleftharpoons N{{a}^{+}}+C{{l}^{-}}$
Thus solubility product is given as follows-
$Ksp=[N{{a}^{+}}][C{{l}^{-}}]$
Hydrochloric acid is a strong acid. Thus it dissociate in hydrogen ion and chloride ion. The dissociation is given as follows-
$HCl\rightleftharpoons {{H}^{+}}+C{{l}^{-}}$
Thus sodium chloride and hydrochloric acid both form chloride ions. Thus due to the common ion effect the solubility product of the sodium chloride decreases and ultimately the concentration of the corresponding ions increases. So, the sodium chloride is precipitated.
Thus the correct option is C.

Note: Precipitate is an insoluble solid substance that is formed from a solution. The process of forming precipitate is called precipitation. It is only formed when the concentration of the species in solution is higher in amount or the solubility of the species decreases due to common ion effect.