Which is the relationship between Ksp and molar solubility, x, for Fe(OH)3?

Question

answer choices

Ksp= x^2

Ksp= 4x^3

Ksp= 27x^4

Ksp= 108x^5

None of these

Answer 1

Fe(OH)₃(s) ==> Fe³⁺(aq) + 3OH^-(aq)

Let x = [Fe³⁺] and then [OH^-] = 3x

Ksp = [Fe³⁺][OH-]³ = (x)(3x)³ = 27x⁴

Ksp= 27x^4