Question

Calculate the percent dissociation of HNO2 (Ka=4.5×10−4) in 0.050 M HNO2.

Answer 1

Ka = 4.5 x 10^-4

concentration of HNO2 = 0.050 M

HNO2   -----------> NO2- + H+

0.05                         0            0

0.05 - x                    x            x

Ka = x^2 / 0.05 - x

4.5 x 10^-4 = x^2 / 0.05 - x

x = 4.52 x 10^-3

% dissociation = x / [H+] ) x 100

                        = (4.52 x 10^-3 /0.05) x 100

% dissociation = 9.04 %