NCERT Class XI Chemistry Equilibrium Solutions
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Question : 62
Total: 73
A 0.02 M solution of pyridinium hydrochloride has pH = 3.44. Calculate the ionization constant of pyridine.
Solution:
Pyridinium hydrochloride is a salt of weak base and strong acid.
Therefore, pH = 7 −
(log X + p K b )
whereK b = dissociation constant of pyridine
3.44 = 7 -
(log 0.02 + p K b )
- 3.56 =−
( − 1.70 + p K b ) ⇒ - 7.12 = 1.0 - p K b
p K b = 1.70 + 7.12 = 8.82,
K b = antilog (– 8.82) = 1.513 × 10 – 9
Therefore, pH = 7 −
where
3.44 = 7 -
- 3.56 =
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