Besarnya pH larutan dari 100 ml CH3COOK 0,4 M (ka=10-5 sepuluh pangkat minus lima) adalah...

[OH-] = √Kw / Ka . [kation]
[OH-] = √10^-14 / 10^-5 . 4 x 10^-1
[OH-] = √10^-9 . 4 x 10^-1
[OH-] = √4 x 10^-10
[OH-] = 2 x 10^-5

pOH = -log [OH-]
pOH = -log 2 x 10^-5
pOH = 5 - log2

pH = 14 - (5 - log2)
pH = 14 - 5 + log2
pH = 9 + log2
pH = 9,3

→ Atau :

pH = 1/2 (14 + pKa + log[G])
pH = 1/2 (14 + (-log10^-5) + log4 x 10^-1)
pH = 1/2 (14 + 5 + (-1 + log4)
pH = 1/2 (14 + 5 - 1 + log4)
pH = 1/2 (18 + log4)
pH = 9 + log4/2
pH = 9 + 0,3
pH = 9,3