The Ksp for the metal (M) complex M(OH)3 is 3.7 x 10–18. What is the pH for a saturated solution of M(OH)3?

Answer 1

M(OH)₃ (sp) <-> M⁺³(aq) + 3OH^- find concentration of OH^- to find pOH to find pH

3.7x10^-18 = x * (3x)³

3.7x10^-18 = 27x⁴

1.37x10^-18 = x⁴

x = 1.92x10^-5

3x = [OH^-] = 5.7x10^-5

-log(5.7x10^-5) = pOH = 4.24

pH+pOH = 14

pH = 14 - 4.24 = 9.76