Question

The solubility product of $A{s}_2{O}_3$ is $10.8\times {10}^{-9}$. It is 50% dissociated in a 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

Answer: (B)

$2\times {10}^{-2}$

$2A{s}_2{O}_3$ will be dissociate as follows : $2A{s}_2{O}_3⟶4As+3O_2$

$Ksp={\left(4S\right)}^4\times {\left(3S\right)}^3$

But, as it dissociated only $50\%$, so we will take half of it and then substitute it in $Ksp$ value.

Now, $S=2\times {10}^{-2}$