apakah terjadi larutan ienyangga jika 100 ml CH3COOH 0,5M direaksikan dengan 200 ml NaOH 0,2 M hitung pH campuran Ka= 10^-5

Diketahui :
V larutan CH3COOH = 100 ml = 0,1 L
Molaritas CH3COOH = 0,5 M = 0,5 mol/L
V larutan NaOH = 200 ml = 0,2 L
Molaritas NaOH = 0,2 M = 0,2 mol/L
Ka = 10^-5

Ditanya : pH campuran ?

Jawab :

n CH3COOH :
= M.V
= 0,5 mol/L . 0,1 L
= 0,05 mol

n NaOH :
= M V
= 0,2 mol/L . 0,2 L
= 0,04 mol

mol garam :
_______CH3COOH + NaOH —> CH3COONa + H2O
awal : 0,05_______0,04__________________
reaksi:0,04_______0,04______0,04___0,04
akhir :0,01__________________0,04___0,04

n garam = 0,04 mol
n Asam = 0,01 mol

[H+] :
= Ka × n asam / n garam
= 10^-5 × 0,01 mol / 0,04 mol
= 2,5 × 10^-6

pH campuran :
= – log [H+]
= – log 2,5 × 10^-6
= – ( log 2,5 + log 10^-6)
= – log 2,5 – log 10^-6
= 6 – log 2,5