Question

Campuran 50 ml larutan NH4OH 0,02 M dengan 50 ml larutan HCl 0,02 M mempunyai pH ....(Kb NH4OH = 10^-5)
A.5
B.6
C.8
D.10
E.11

Answer 1

Penyelesaian :

Dik : 
volume NH4OH = 50 mL = 0,05 liter
Molaritas NH4OH = 0,02 M
volume HCl = 50 mL = 0,05 liter
Molaritas HCl = 0,02 M
Kb NH4OH =10^-5
Dit : pH campuran ?

Jawab :
mol NH4OH = V x M
mol NH4OH = 5.10^-2 x 2.10^-2
mol NH4OH = 10.10^-4

Persamaan reaksi :
NH4OH → NH4+ + OH-

Karena koefisien NH4OH = OH- maka,
mol NH4OH = mol [OH-]
mol [OH-] = 10.10^-4

mol HCl = V x M
mol HCl = 5.10^-2 x 2.10^-2
mol HCl = 10.10^-4

Persamaan reaksi :
HCl → H+ + Cl-

Karena koefisien HCl = H+ maka,
mol HCl = mol [H+]
mol [H+] = 10.10^-4

ternyata mol [OH-] = mol [H+] maka, pH = netral
pH = 7

semoga membantu :)