IV. Percent Ionization. Instead of characterizing a weak acid by its K a , we can calculate how much it ionizes. The concentration of ionized acid is simply equal to the [H + ] at equilibrium. IV. Sample Problem. Find the % ionization of a 0.200 M acetic acid solution if its pK a = 4.74.
HCl(aq) + H2O(l) H3O+(aq) + Cl-(aq)
HCOOH(aq) + H2O(l) H3O+(aq) + HCOO-(aq)
B(aq) + H2O(l) BH+(aq) + OH-(aq)