larutan jenuh Mg(OH)2 mempunyai pH= 9 tentukan harga Ksp Mg(OH)2 tersebut

Mg(OH)2 pH = 9

Ksp ... ?

pH = 9
pOH = 14 - pH
pOH = 14 - 9
pOH = 5
- log [OH^-] = 5
[OH^-] = 10^-5

[OH^-] = b × Mb
10^-5 = 2 × Mb
Mb = 10^-5/2
Mb = 0,5 × 10^-5
Mb = 5 × 10^-6

Kelarutan Mg(OH)2 = 5 × 10^-6

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

Ksp = [ Mg^{2+} ] . [ OH^- ]^2
Ksp = s . (2s)^2
Ksp = s . 4s^2
Ksp = 4 s^3
Ksp = 4 (5 × 10^-6)^3
Ksp = 4 (125 × 10^-18)
Ksp = 500 × 10^-18
Ksp = 5 × 10^-16