pada suhu tertentu Ksp senyawa hidroksida M(OH)2 yaitu 4x10^12. pH larutan jenuh tersebut?

Ksp = 4 × 10^-12

M(OH)2 => M^{2+} + 2 OH^{-}
......s...................s...............2s.....

Ksp = [ M2+] [ OH- ]²
Ksp = s ( 2s )²
Ksp = 4s³
s = ³√ Ksp / 4 = ³√ 4 × 10^-12 / 4 = ³√10^-12 = 10^-4 mol/L

[OH-] = 2s = 2 × 10^-4 M

pOH = - log [OH-] = - log ( 2 × 10^-4) = 4 - log 2

pH = 14 - pOH = 10 + log 2

M(OH)2 ⇒ M+ + 2OH-
     s             s      2s
 
             Ksp = [M+] [OH-]²
   4 x 10^12  = (s) (2s)²
   4 x 10^12 = (s ) (4s²)
   4 x 10^12 = 4.s³
                s³ = (4 x 10^12) / 4
                s³ = 10^12
                s  = ∛(10^12)
                s  = 10^4  M

[OH-] = 2 x s
          = 2 x 10^4

POH = - log [OH-]
         = - log (2 x 10^4)
         = 4 - log 2

PH = 14 - (4 - log 2)
       = 14 - 4 + log 2
       = 10 + log 2