Question

Jika 50mL larutan CH2COOH 0,1M dilarutkan dgn 100mL larutan CH3COONa 0,2M, Ka CH3COOH 1,8 x 10^-5. tentukan pH campuran tersebut

Answer 1

N CH3COOH = M.V = 0,1 (50 ) = 5 mmol
n CH3COONa = M.V = 0,2 (100) = 20 mmol
[H+] = Ka x mmol CH3COOH/mmol CH3COO-
[H+] = 1,8x10^-5 x 5/20
[H+] = 1,8 x 10^-5 (1/4)
[H+] = 4,5 x 10^-6
pH = - log [H+] = -log (4,5 x 10^-6) = 6 - log 4,5 = 5,35
jadi pH campuran adalah 5,35