Step1 HCl is comletely ionized in aqueous solution; amount of unionized HCl is very small. Step2 Equalibrium constant = [H3O+][Cl-]/[HCl] Step3 As the quantity i denominator is very small; hence equalibrium constant is very large. Solution Step1 HCl is comletely ionized in aqueous solution; amount of unionized HCl is very small. Step2 Equalibrium constant = [H3O+][Cl-]/[HCl] Step3 As the quantity i denominator is very small; hence equalibrium constant is very large..