solubility equation

Question

What is the solubility of  Ca(OH)2 if Ksp= 5.2 x 10^-6. Use the solubility to determine the [OH-] (Show your work)

Answer 1

Ksp = [Ca²⁺][OH^-]²

Let x = [Ca²⁺] and then [OH^-] = 2x since Ca(OH)₂ ==> Ca²⁺ + 2OH^-

Ksp = 5.2x10^-6 = [x][2x]² = 4x³

x= 1.1x10^-2 M = [Ca²⁺] = solubility of Ca(OH)₂. If you want it in g/100 ml, correct accordingly.

So, [OH^-] = 2x1.1x10^-2 = 2.2x10^-2 M