Question

Why only $A{s}^{3+}$ gets precipitated as $A{s}_2{S}_3$ and not $Z{n}^{2+}$ as $ZnS$ when $H_{2}S$ is passed through an acidic solution containing $A{s}^{3+}$ and $Z{n}^{2+}?$

• A. Solubility product of $A{s}_2{S}_3$ is less than that of $ZnS$
• B. Enough $A{s}^{3+}$ are present in acidic medium
• C. Zinc salt does not ionise in acidic medium
• D. Solubility product changes in presence of an acid

Answer 1

Answer: (A)

$K_{sp}$ of $A{s}_2{S}_3$ is less than $ZnS$. In acid medium ionisation of $H_{2}S$ is suppresed (common ion effect) and $K_{sp}$ of $ZnS$ does not exceed.