Question

$MY$ and $N{Y}_3$, two nearly insoluble salts, have the same $K_{sp}$ values of $6.2\times {10}^{-13}$ at room temperature. Which statement would be true in regard to $MY$ and $N{Y}_3$?

• A. The molar solubility of $MY$ in water is less than that of $N{Y}_3$
• B. The salts $MY$ and $N{Y}_3$ are more soluble in 0.5 M $KY$ than in pure water
• C. The addition of the salt of $KY$ to solution of $MY$ and $N{Y}_3$ will have no effect on their solubilities
• D. The molar sulubilities of $MY$ and $N{Y}_3$ in water are identical

Answer 1

The correct option is A

The molar solubility of $MY$ in water is less than that of $N{Y}_3$

For $MY$,

$K_{sp}=S^2$

$\therefore S=(6.2\times {10}^{-13}{)}^{\frac{1}{2}}$

For $N{Y}_3,$

$K_{sp}=27S^{\prime 4}$

$\therefore S^{\prime }={\left(\frac{6.2\times {10}^{-13}}{27}\right)}^{\frac{1}{4}}$

$S$ is greater than 1 and $S^{\prime }$ is definitely lower than 1.