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NX3 + H2O --------> HNX3^+ + OH-
     Â
IÂ Â Â Â Â Â Â Â
0.175Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
  0
           Â
0
     Â
CÂ Â Â Â Â Â
-x                               Â
+x           Â
+x
     Â
EÂ Â Â Â Â
0.175-x                       Â
+x            Â
+x
       Â
Kb   = [HNX3^+][OH-]/[NX3]
      4*10^-6 = x*x/0.175-x
4*10^-6*(0.175-x) = x^2
   x  = 0.000834
[OH-] = x = 0.000834M
POH = -log[OH-]
        =
-log0.000834Â Â = 3.08
              Â
NX3 + H2O --------> HNX3^+ + OH-
     Â
IÂ Â Â Â Â Â Â Â 0.325
                    Â
  0
           Â
0
     Â
CÂ Â Â Â Â Â
-x                               Â
+x           Â
+x
     Â
EÂ Â Â Â Â
0.325-x                       Â
+x            Â
+x
       Â
Kb   = [HNX3^+][OH-]/[NX3]
      4*10^-6 = x*x/0.325-x
4*10^-6*(0.325-x) = x^2
   x  = 0.001138
[OH-] = x = 0.001138M
Percentage of ionisation =Â Â [OH-]*100/[Base]
                                        Â
= 0.001138*100/0.325Â Â = 0.35%
part-C
HNX3+(aq)+H2O(l)⇌NX3(aq)+H3O+
  Ka = Kw/Kb
        =
1*10^-14/4*10^-6
       = 2.5*10^-9
PKa = -logKa
       = -log2.5*10^-9
     = -log0.0000000025
     = 8.6020
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