Calculate the percent dissociation for a 0.21 M solution of chlorous acid (HClO2, Ka = 1.2 10-2).?

Answer 1

Ka = [H+][ClO2-]/[HClO2] = 1.2 x 10^-2

Let [H+] = [ClO2-] = x. Then [HClO2] = 0.21 - x. But x is so small that [HClO2] is essentially 0.21.

(x)(x)/(0.21) = 1.2 x 10^-2

x^2 = 2.5 x 10^-3 = 25.2 x 10^-4

x = 5.0 x 10^-2

5.0x10^-2/0.21 x 100% = 24% dissociated