Question

When $HCl$ gas is passed through a saturated solution of common salt, pure $NaCl$ is precipitated because:

• A. $HCl$ is highly ionised in solution
• B. $HCl$ is highly soluble in water
• C. The solubility product of $NaCl$ is lowered by $HCl$
• D. The ionic product of $\left[{Na}^{+}\right]\left[{Cl}^{-}\right]$ exceeds the solubility product of $NaCl$

Answer 1

The correct option is D The ionic product of $\left[{Na}^{+}\right]\left[{Cl}^{-}\right]$ exceeds the solubility product of $NaCl$

When hydrogen chloride gas (HCl) is circulated through the saturated solution. HCl and NaCl dissociate into their respective ions as:

$NaCl\to N{a}^{+}+C{l}^{-}$

$HCl\to H^{+}+C{l}^{-}$

The concentration of $C{l}^{-}$ ions increases considerably in solution due to ionization HCl.

Hence, the ionic product $\left[N{a}^{+}\right]\left[C{l}^{-}\right]$ exceeds the solubility product of sodium chloride and, therefore, pure sodium chloride precipitates out from the solution.

Therefore, option $D$ is correct.