NH4Cl is the salt of strong acid and weak base
so cation involve in salt hydrolysis
NH4+ + H2O ---------------------> NH4OH + H+
0.038Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0 ------------------initial
0.038-x                                    Â
x               Â
x -----------------at equilibrium
Ka = [NH4OH][H+]/[NH+]
Ka = x^2 / (0.038-x)
Kw / Kb = x^2 / (0.038-x)
1 x 10^-14 / 1.8 x 10^-5 = x^2 / (0.038-x)
5.56 x 10^-10 =x^2 / (0.038-x)
x^2 + 5.56 x 10^-10 x - 2.11 x10^-11 =0
x = 4.59 x 10^-6
x = [H+] = 4.59 x 10^-6 M
pH = -log[H+]
pH= -log (4.59 x 10^-6)
pH = 5.34
