Page 63 - Copy of E-Modul Kimia Larutan Asam Basa SR BENAR 2_Neat

K e g i a t a n P e m b e l a j a r a n 3

p H L A R U T A N A S A M B A S A

Contoh Soal

-5
Hitung pH larutan NH 0,4 M dengan Kb NH = 10
3
3

Penyelesaian:

Diketahui : NH adalah basa lemah bervalensi 1
3
Mb = 0,01 M

Kb = 10 -5

Ditanya : pH

Jawab :
-
[OH ] =
-
[OH ] =
-
[OH ] =
-
[OH ] =

-
pOH = - log [OH ] 14 = pH + pOH

= - log 2 x 10 -3 pH = 14 - pOH

= 3 - log 2 = 14 - (3 - log 2)

= 11 + log 2

4 9