Question

The solubility product of $As _{2} O _{3}$ is $10.8 \times 10^{-9}$. It is $50 \%$ dissociated in saturated solution. The solubility of salt is

• A. $10^{-2}$
• B. $ 2\times 10^{-2}$
• C. $ 5\times 10^{-3}$
• D. $ 5.4\times 10^{-9}$

Answer 1

The Correct Option is B

$As _{2} O _{3} \rightleftharpoons 2 As ^{3+}+3 O ^{2-}$ $K_{s p} =(2 S)^{2}(3 S)^{3}$ $10.8 \times 10^{-9} =108 S^{3}$ $S =10^{-2}$ If dissociation is $50 \%$ then solubility is $2 \times 10^{-2} mol / L$.