The Ksp of calcium sulfate, CaSO4, is 9.1 × 10−6. What is the molar concentration of CaSO4 in a saturated solution?
...................CaSO4 ==> Ca^2+ + [SO4]^2-
I....................solid.............0..............0
C...................solid..............x.............x
E.....................solid.............x..............x
Ksp = 9.1E-6 = (Ca^2+)(SO4^2-)
Substitute the E like into the Ksp expression and solve for x = (Ca^2+) = solubility in moles/ L.
To find the molar concentration of CaSO4 in a saturated solution, we need to use the solubility product constant (Ksp) and the stoichiometry of the compound.
The solubility product constant, Ksp, is an equilibrium constant that represents the extent to which a compound can dissolve in water. For calcium sulfate (CaSO4), the Ksp value is given as 9.1 × 10−6.
CaSO4(s) ⇌ Ca2+(aq) + SO42-(aq)
Based on the stoichiometry of the reaction, the molar concentration of Ca2+ (and SO42-) in the saturated solution will be equal to the molar solubility of calcium sulfate.
Let's assume the molar solubility of CaSO4 is represented by "x mol/L".
Using the equation for the solubility product constant:
Ksp = [Ca2+][SO42-]
Substituting the molar solubility (x) into the equation:
9.1 × 10−6 = x * x
Simplifying the equation:
9.1 × 10−6 = x^2
To solve for x, take the square root of both sides of the equation:
x = sqrt(9.1 × 10−6) = 3.0 × 10^−3 mol/L
Therefore, the molar concentration of CaSO4 in a saturated solution is approximately 3.0 × 10^−3 mol/L.