What is the solubility of Al(OH)3 in a solution that has pH = 12?

Question

The K_sp of Al(OH)₃ is 1.0 x 10^-33. What is the solubility of Al(OH)₃ in a solution that has pH = 12?

The answer is 1*10^-27

Answer 1

Hey there!

If the pH = 12, the pOH = 2.

pOH = -log([OH-])

2 = -log([OH-])

1 x 10^-2 = [OH-]

Ksp = [Al⁺³]*[OH-]³

1 x 10^-33 = [x]*[1x10^-2]³

1 x 10^-33 = x * (1x10^-6)

x = 1 x 10^-33+6 = 1 x 10^-27

Therefore, the [Al⁺³] = 1 x 10^-27 M