Equilibrium Question 149
Question: The solubility product of a salt having general formula $ MX_2, $ in water is: $ 4\times {10^{-12}} $ . The concentration of $ {M^{2+}} $ ions in the aqueous solution of the salt is [AIEEE 2005]
Options:
A) $ 2.0\times {10^{-6}}M $
B) $ 1.0\times {10^{-4}}M $
C) $ 1.6\times {10^{-4}}M $
D) $ 4.0\times {10^{-10}}M $
Show Answer
Answer:
Correct Answer: B
Solution:
$ MX_2 $ ⇌ $ \underset{S}{\mathop{{M^{2+}}}},+\underset{2S,}{\mathop{2{X^{-}}}}, $
$ K _{sp}={{(2S)}^{2}}(S)=4S^{3} $
Þ $ S=2\sqrt[3]{\frac{K _{sp}}{4}}=\sqrt[3]{\frac{4\times {10^{-12}}}{4}}=1.0\times {10^{-4}}M $ .
