Question

$K_{sp}$ of $CaS{O}_4\cdot 5H_{2}O$ is $9\times {10}^{-6}$, find the volume of $1g$ of $CaS{O}_4(M.Wt.=136)$

• A. $2.45litre$
• B. $5.1litre$
• C. $4.52litre$
• D. $3.2litre$

Answer 1

The correct option is A $2.45litre$

$CaS{O}_{4\left(s\right)}\rightleftharpoons \underset{S}{C{a}_{\left(aq\right)}^{2+}}+\underset{S}{S{O}_{4\left(aq\right)}^{2-}}$

$K_{sp}=S^2=9\times {10}^{-6}$

$S=3\times {10}^{-3}mol{L}^{-1}$

Solubility in g $litr{e}^{-1}=$ molecular mass $\times S$

$=136\times 3\times {10}^{-3}=408\times {10}^{-3}g{L}^{-1}$

$408\times {10}^{-3}g$ of $CaS{O}_4$ present in $1Litre$

$1g$ of $CaS{O}_4$ present is $\frac{1}{408\times {10}^{-3}}=2.45litre$.