Question

The Ksp of calcium sulfate, CaSO4, is 9.0 × 10-6. What is the concentration of CaSO4 in a saturated solution? A. 3.0 × 10-3 Molar B. 9.0 × 10-3 Molar C. 3.0 × 10-6 Molar D. 9.0 × 10-6 Molar

Answer 1

Answer: The concentration of $CaSO_4$  in a saturated solution is $3.0\times 10^{-3}M$

Explanation:

Solubility product is defined as the equilibrium constant in which a solid ionic compound is dissolved to produce its ions in solution. It is represented as $K_{sp}$

The equation for the ionization of $CaSO_4$  is given as:

$K_{sp}$ of $CaSO_4$  = $9.0\times 10^{-6}$

By stoichiometry of the reaction:

1 mole of  $CaSO_4$ gives 1 mole of $Ca^{2+}$ and 1 mole of $SO_4^{2-}$

When the solubility of $CaSO_4$ is S moles/liter, then the solubility of $Ca^{2+}$ will be S moles\liter and solubility of $SO_4^{2-}$ will be S moles/liter.

$K_{sp}=[Ca^{2+}][SO_4^{2-}]$

$9.0\times 10^{-6}=[s][s]$

$9.0\times 10^{-6}=s^2$

$s=3.0\times 10^{-3}M$

Thus concentration of $CaSO_4$  in a saturated solution is $3.0\times 10^{-3}M$