Sebanyak 100 mL larutan CH3COOH 0,10 M (Ka = 1,8×10^−5) dicampur dengan 100 mL larutan CH3COOK 0,20 M. Nilai pH yang dihasilkan adalah.... 

A. 5 - log 3,6 

B. 5 - log 1,8 

C. 6 - log 9 

D. 6 + log 9 

E. 8 + log 9

CH3COOH = 10 M

V = 100 mL

CH3COOK = 0,20 M

V = 100 mL

(Ka = 1,8×10^−5) 

•mol CH3COOH = M. V 

mol CH3COOH = 0,10 . 100 

mol CH3COOH = 10 mmol

•mol CH3COOK = M . V 

mol CH3COOK = 0,20 . 100 

mol CH3COOK = 20 mmol

H+ = ka x mol CH3COOH/mol CH3COOK

H+ = 1,8x10^-5 . 10/20

H+ = 9x10^-6 M

pH = -log [H+]

pH = -log 9x10^-6

pH = 6-log 9

Jadi, nilai pH yang dihasilkan adalah (C) 6-log 9