NCERT Class XI Chemistry Equilibrium Solutions

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Question : 51
Total: 73
The pH of 0.005 M codeine (C18H21NO3) solution is 9.95. Calculate its ionization constant and pKb.
Solution:  
[H+] = antilog (- 9.95) = 1.12 × 1010
[OH] =
1.0×1014
1.12×1010
= 8.92 × 105 M
But Kb =
[M+][OH]
[MOH]
=
(8.92×105)2
0.005
= 1.59 × 106
pKb = - log Kb = - log (1.59 × 106) = 5.80
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