Chemistry Ksp question

Question

A generic salt, , has a molar mass of  g/mol and a solubility of  g/L at 25 °C.

What is the  of this salt at 25 °C?

Answer 1

AB3(s) ==> A³⁺(aq) + 3B^-(aq)

Ksp = [A³⁺][B]³

[A3+] = 6.40 g/L x 1 mol/307 g = 2.08x10^-2 M

[B-] = 3 x 2.08x10^-2 M = 6.24x10^-2 M

Ksp = [A³⁺][B^-]³

Ksp = (2.08x10^-2)(6.24x10^-2)³

Ksp = 5.05x10^-6