Finding solubility in Water

Question

What is the solubility of La(IO₃)₃ in water? (Ksp of La(IO₃)₃ is 7.5 × 10⁻¹²)

Answer 1

The Ksp expression for La(IO₃)₃ in water is Ksp = [La][IO₃]³

For the purpose of this, it's simplest to replace La and IO₃ with S (for solubility)... for each La(IO₃)₃ molecule dissolved there is one La and three IO₃, meaning that the Ksp = [S][3S]³, which becomes 27S⁴ when multiplied out. To solve for S we now do 7.5 × 10^⁻¹² = 27S⁴, yielding 7.25979529×10^-4 as S (solubility)