pH = 1.71
[H+] = 10^-1.71 = 0.0195 M = x
Ka = 10^-pKa = 1.41 x 10^-3
HA <----------------------> H+Â Â + A-
C
-x                                Â
x        x
Ka = x^2 / C -x
1.41 x 10^-3 = x^2 / C- x
1.41 x10^-3 = 0.0195^2 / C -x
C -x = 0.269
C = 0.269 + x = 0.269 + 0.0195
C = 0.2885 M
percent unprotonated form = ( x / C ) x100
                                     Â
= (0.0195 / 0.2885) x 100
                                     Â
= 6.76 %
percent protonated form = 100 -.6.76
                                   Â
= 93.24 %
