Kb of pyridine = 10^-pKb = 1.78 x 10^-9
C5H5N + H2O <--------------------> C5H5NH+ + OH−
0.310Â 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 Â Â Â Â Â Â Â Â Â Â
0Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0
0.310 -
x                                            Â
x             Â
x
Kb = x^2 / 0.310 - x
1.78 x 10^-9 = x^2 / 0.310 - x
x = 2.35 x 10^-5
[OH-] = 2.35 x 10^-5 M
pOH = -log[OH-] = -log (2.35 x 10^-5 ) = 4.63
pH = 9.37
2)
Ka = 6.31 x 10^-5
C = 0.61
[H+] = sqrt (Ka x C)
       = sqrt (6.31 x 10^-5
x 0.61)
        = 6.2 x 10^-3
M
% ionized = ([H+] / C ) x 100
              Â
= (6.2 x 10^-3 / 0.61 ) x 100
              Â
= 1.0 %
