NH4+ + H2O <==> NH3.H2O + H+[NH3.H2O][H+]/[NH4+] == [NH3.H2O][H+][OH-]/[NH4+][OH-] ==Kw/Kb ==10^0-14/1.8*10^-5[H+] ==(10^0-14/1.8*10^-5 *0.1)^1/2 ==
