Strong acids are those that ionizes almost completely in water. to be considered a strong acid, an acid must have an acid ionization constant ka > 55. the strong acid hcl in aqueous solution undergoes the ionization reaction: hcl(aq) + h2o(l) ⇋ h3o+(aq) + cl-(aq) and its ka = 2.00 x 106. if the concentrations of h3o+ and cl- are both found to be equal to 0.153 mol/l what is the remaining concentration hcl that is not ionized