Question

Ksp of Mg(oh)2 is 10-¹¹ determine the pH of 0.1M mg²+ below which Mg(oh)2 will not ppt

Answer 1

The pH of Mg²⁺ will be 9.

Explanation:

The dissociation equilibrium for magnesium hydroxide is:

We know that K_sp= [Mg²⁺]⋅[OH⁻]² , so

Also, pOH = −log( [OH]⁻)
pOH = −log(10⁻⁵) = 5
Thus, pH = 14 - 5 = 9