Question

In the second group of qualitative analysis, $H_{2}S$ is passed through a solution acidified with $HCl$ in order to :

• A. Limit the concentration of $S^{2-}$ ions
• B. Increase the solubility of $H_{2}S$
• C. Increase the concentration of $S^{2-}$ ions
• D. Add the $C{l}^{-}$ ions

Answer 1

The correct option is A Limit the concentration of $S^{2-}$ ions

Option (A) is correct.
In the second group of qualitative analysis, $H_{2}S$ is passed through a solution acidified with $HCl$ in order to limit the concentration of $S^{2-}$ ions.
The dissociation of $H_{2}S$ is suppressed in the presence of $HCl$ due to common ion effect, and thus, only II group radicals are precipitated.