The Ksp of barium sulfate (BaSO4) is 1.1 * 10-10. What is the solubility concentration of sulfate ions in a saturated solution at 25°C?

a. 1.0 x 10^-5m

b. 1.5 x10^-5m

c. 5.5 x 10^-11m

d. 7.4 x 10^-6m

Each mole of barium sulfate releases equal moles of barium ions and sulfate ions. Let the concentration of one substance be x. Thus:

Ksp = [Ba⁺²][SO₄⁻²]

1.1 x 10⁻¹⁰ = (x) (x)

x = 1.05 x 10⁻⁵

The answer is A.