Question

Calculate the solubility (in g/L) of CaSO 4 ( s ) CaSO4(s) in 0.400 M Na 2 SO 4 ( aq ) at 25 ° C 0.400 M Na2SO4(aq) at 25°C. The K sp Ksp of CaSO 4 CaSO4 is 4.93 × 10 − 5 4.93×10−5.

Answer 1

Explanation:

Ionization equation for $CaSO_{4}$ is as follows.

     $CaSO_{4} \rightarrow Ca^{2+} + SO^{2-}_{4}$

        s              s           s

Now, the expression for the solubility product is as follows.

          $K_{sp} = [Ca^{2+}][SO^{2-}_{4}]$

                = $s \times s$

                = $s^{2}$

As the concentration of $Na_{2}SO_{4}$ is given as 0.4 M.

So,  $[Na_{2}SO_{4}] = [SO^{2-}_{4}]$ = 0.4 M

Putting the given values as follows.

           $K_{sp} = [Ca^{2+}][SO^{2-}_{4}]$

     $4.93 \times 10^{-5} = [Ca^{2+}] \times 0.4$

              $[Ca^{2+}]$ = 12.325 \times 10^{-5}[/tex]

Hence, the solubility of $CaSO_{4}$ in $Na_{2}SO_{4}$ is $12.325 \times 10^{-5}$.

Therefore, solubility of $CaSO_{4}$ in g/ml as follows.

        $12.325 \times 10^{-5} \times 136 g/mol$

           = 0.0167 g/L

Thus, we can conclude that solubility of $CaSO_{4}$ is 0.0167 g/L.