Question

How many of the following salts will be more soluble in acid solution than in pure water?

$CdC{O}_3,Mn(OH{)}_2,PbS,PbC{l}_2$

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (C)

3

Three salts ($CdC{O}_3$, $Mn(OH{)}_2$ and $PbS$) will be more soluble in acid solution than in pure water.
$CdC{O}_3\to C{d}^{2+}+C{O}_3^{2-}$
$2H^{+}+C{O}_3^{2-}\to H_{2}C{O}_3$
As $C{O}_3^{2-}$ ions are removed from solution by formation of $H_{2}C{O}_3$, the solubility of $CdC{O}_3$ increases in acid solution.
$Mn(OH{)}_2\to M{n}^{2+}+2O{H}^{-}$
$H^{+}+O{H}^{-}\to H_{2}O$
As $O{H}^{-}$ ions are removed from solution by formation of $H_{2}O$, the solubility of $Mn(OH{)}_2$ increases in acid solution.
$PbS\to P{b}^{2+}+S^{2-}$
$2H^{+}+S^{2-}\to H_{2}S$
As $S^{2-}$ ions are removed from solution by formation of $H_{2}S$, the solubility of $PbS$ increases in acid solution.
Hence, the option (C) is the correct answer.