The solubility of calcium sulfate at 30°c is 0.209 g/100 ml solution. calculate its ksp.

Answer is: Ksp for calcium sulfate is 2.36·10⁻⁴.

Balanced chemical reaction (dissociation):

CaSO₄ (s) → Ba²⁺ (aq) + SO₄²⁻ (aq).

m (CaSO₄) = 0.209 g.

n (CaSO₄) = m (CaSO₄) : M (CaSO₄).

n (CaSO₄) = 0.209 g : 136.14 g/mol.

n (CaSO₄) = 0.00153 mol.

s (CaSO₄) = n (CaSO₄) : V (CaSO₄).

s (CaSO₄) = 0.00153 mol : 0.1 L = 0.0153 M.

Ksp = [Ca²⁺] · [SO₄²⁻].

[Ca²⁺] = [SO₄²⁻] = s (CaSO₄).

Ksp = (0.0153 M) ² = 2.36·10⁻⁴.