Question

The pH of 0.1M solution of cyanic acid (HCNO) is 2.34. Calculate the ionization constant of the acid

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

Given pH = 2.34
Concentration (c)= 0.1 M
$pH=-log\left[H^{+}\right]$
$2.34=-log\left[H^{+}\right]$
$\therefore log\left[H^{+}\right]=-2.34$
using antilog
$\left[H^{+}\right]=4.571\times {10}^{-3}$
$K_a=\frac{a^2}{c}=\frac{{(4.571\times {10}^{-3})}^2}{0.1}$
$=2.089\times {10}^{-4}$