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Chemistry Question on Mole concept and Molar Masses

The percentage of pyridine (C5H5N) that forms pyridinium ion (C5​H5​N+H) in a 0.10 M aqueous pyridine solution (Kb​ for C5H5N = 1.7×10−9) is

A

0.00006

B

0.00013

C

0.0077

D

0.016

Answer

0.00013

Explanation

Solution

C5​H5​N + H2​O → C5​H5​NH++OH−1
Pyridine or C5​H5​N is a weak base , hence Kb = Cα2
α=KbC\alpha=\sqrt{\frac{ K _{ b }}{ C }}
=1.7×10−90.1=\sqrt{\frac{1.7 \times 10^{-9}}{0.1}}
=1.7×10−8=\sqrt{1.7 \times 10^{-8}}
= 1.3 x 10-4
Percentage of pyridine that forms pyridinium ion, α = 1.3 x 10-4 x 100
= 0.013%
The correct option is: B - 0.013%