sebanyak 50 mL KOH 0,5 M dicampur dengan 150 mL CH3COOH 0,5 M diperoleh pH sebesar 6 - log 2. Tetapan ionisasi asam sebesar...

50 mL KOH 0,5 M + 150 mL CH3COOH 0,5 M
pH = 6 - log 2

Ka ... ?

........... pH = 6 - log 2
- log [H^+] = 6 - log 2
........ [H^+] = 2 × 10^-6

n KOH = M × V
n KOH = 0,5 × 50 mL
n KOH = 25 mmol

n CH3COOH = M × V
n CH3COOH = 0,5 × 150 mL
n CH3COOH = 75 mmol

#Reaksi
... KOH + CH3COOH => CH3COOK + H2O
M : 25 ........... 75
R : 25 ............ 25
_______________---
S : --- ............. 50 ................. 25 ........... 25

[H^+] = Ka × Asam lemah/B. konjugasi
2 × 10^-6 = Ka × 50/25
2 × 10^-6 = Ka × 2
2 × 10^-6 / 2 = Ka
10^-6 = Ka
Ka = 10^-6