Sebanyak 50 mL NaOH 0,1 M dicampurkan dengan 50mL larutan CH3COOH 0,1 M. Tentukan pH campuran (Ka CH3COOH = 1x10-5)

50 mL NaOH 0,1 M + 50 mL CH3COOH 0,1 M
Ka = 1 × 10^-5

pH ... ?

n NaOH = M × V
n NaOH = 0,1 × 50 mL
n NaOH = 5 mmol

n CH3COOH = M × V
n CH3COOH = 0,1 × 50 mL
n CH3COOH = 5 mmol

#Reaksi
... NaOH + CH3COOH => CH3COONa + H2O
M : . 5 ................ 5
R : .. 5 ................ 5
________________---
S : .. --- .............. --- .................... 5 .............. 5

M = n / V total
M = 5 / (50 + 50)
M = 5 / 100
M = 0,05

[OH^-] = √( Kw/Ka × M )
[OH^-] = √( 10^-14/10^-5 × 0,05 )
[OH^-] = √( 10^-9 × 0,05 )
[OH^-] = √( 10^-11 × 5 )
[OH^-] = 10^-5,5 × √5

pOH = - log [OH^-]
pOH = - log 10^-5,5 × √5
pOH = 5,5 - log √5

pH = 14 - pOH
pH = 14 - (5,5 - log √5)
pH = 14 - 5,5 + log √5
pH = 8,5 + log √5
pH = 8,5 + 0,35
pH = 8,85