Question

Jika 50 ml KOH 0,5 M dicampur dengan 50 ml CH3COOH 0,5 M (ka= 10*-6), maka pH campuran yang terjadi adalah..?
a. 4-log 2
b. 5-log 2
c. 5-log 5
d. 9-log 5
e.9+ log 5
plisssss caranya gmana????

Answer 1

Diket dan dit:
*n KOH = 50 mL x 0,5 M = 25 mmol
*n CH3COOH = 50 mL x 0,5 M = 25 mmol
*Ka = 10^-6
*pH ?
 
    CH3COOH + KOH --> CH3COOK + H2O
m      25             25
b      -25            -25            +25
s        -                -              25

Bersisa garam, sehingga:
[CH3COOK] = [CH3COO-] = 25 mmol / 100 mL = 0,25 Molar

Maka:
[OH-] = √Kw x [CH3COO-] / Ka
= √10^-14 x 0,25 / 10^-6
= 5 x 10^-5

pOH = 5 - log 5
pH = 9  + log 5 (E)