Question

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

Answer 1

c = 0.1 M
pH = 2.34
-log[H+] = pH = -log[H+] = 2.34 = [H+] = 4.5 × 10-3
Also, [H+] = cα
= 4.5 × 10-3 = 0.1 × α = $\frac{4.5 × 10^{-3}}{0.1}$ = α
α = 45 × 10-3 = .045
Then, Kα = cα2 = 0.1 × (45 × 10-3)2 = 202.5 × 10-6 = 2.02 × 10-4