Question

Determine the pH of a $0.2$M solution of pyridine $C_6{H}_{5}N.$

$K_b=1.5\times {10}^{-9}$

Answer 1

For weak base, $\left[O{H}^{-}\right]=\sqrt{K_b.C}$

$\therefore pOH=\frac{1}{2}[p{K}_b-\log C]$

$=\frac{1}{2}\left[\right[-\log (1.5\times {10}^{-9})]-\log (0.2\left)\right]$

$=4.76$

$\therefore pH=14-pOH$

$=14-4.76$

$=9.24$