Buffers and Ksp

Question

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

I tried doing 7.5x10^-12= (3x)^3 so then I got 7.5x10^-12/ 27 = x^3 and from there I took the cube root and got 6.5x10^-12. How would I solve this?

Answer 1

La(IO₃)₃(s) <==> La³⁺(aq) + 3IO₃^-(aq)

Let x = solubility of La³⁺ and the 3x = solubility of IO₃^-

Ksp = 7.5x10-12 = (x)(3x)³ = 27x⁴

x4 = 2.78x10^-13

x = 7.26x10^-4 M = solubility of La(IO₃)₃ in water